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kolibrios/programs/develop/libraries/libs-dev/libimg/png/libpng/png.asm
IgorA 722650c58d libimg can save 24-bit *.png images 
git-svn-id: svn://kolibrios.org@6733 a494cfbc-eb01-0410-851d-a64ba20cac60
2016-11-21 16:00:11 +00:00

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; png.asm - location for general purpose libpng functions
; Last changed in libpng 1.6.25 [September 1, 2016]
; Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
; (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
; (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
; This code is released under the libpng license.
; For conditions of distribution and use, see the disclaimer
; and license in png.inc
crc_table rd 256
include '../../../../../../KOSfuncs.inc'
include '../../../../../../fs/kfar/trunk/kfar_arc/crc.inc'
include '../../../../../../fs/kfar/trunk/zlib/deflate.inc'
include 'pngtokos.inc' ;integrate png to kos
;files from libpng
include 'pnglibconf.inc'
include 'pngpriv.inc'
include 'png.inc'
include 'pngstruct.inc'
include 'pnginfo.inc'
include 'pngerror.asm'
include 'pngtrans.asm'
include 'pngget.asm'
include 'pngwrite.asm'
include 'pngmem.asm'
include 'pngset.asm'
include 'pngwutil.asm'
include 'pngwio.asm'
include 'pngwtran.asm'
; Generate a compiler error if there is an old png.inc in the search path.
;typedef png_libpng_version_1_6_25 Your_png_h_is_not_version_1_6_25;
; Tells libpng that we have already handled the first "num_bytes" bytes
; of the PNG file signature. If the PNG data is embedded into another
; stream we can set num_bytes = 8 so that libpng will not attempt to read
; or write any of the magic bytes before it starts on the IHDR.
;if PNG_READ_SUPPORTED
;void (png_structrp png_ptr, int num_bytes)
align 4
proc png_set_sig_bytes uses eax edi, png_ptr:dword, num_bytes:dword
png_debug 1, 'in png_set_sig_bytes'
mov edi,[png_ptr]
cmp edi,0
je .end_f ;if (..==0) return
mov eax,[num_bytes]
cmp eax,0
jge @f
xor eax,eax
@@:
cmp eax,8
jle @f ;if (..>8)
png_error edi, 'Too many bytes for PNG signature'
@@:
mov byte[edi+png_struct.sig_bytes],al
.end_f:
ret
endp
; Checks whether the supplied bytes match the PNG signature. We allow
; checking less than the full 8-byte signature so that those apps that
; already read the first few bytes of a file to determine the file type
; can simply check the remaining bytes for extra assurance. Returns
; an integer less than, equal to, or greater than zero if sig is found,
; respectively, to be less than, to match, or be greater than the correct
; PNG signature (this is the same behavior as strcmp, memcmp, etc).
;int (bytep sig, png_size_t start, png_size_t num_to_check)
align 4
proc png_sig_cmp, sig:dword, start:dword, num_to_check:dword
; byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
; if (num_to_check > 8)
; num_to_check = 8;
; else if (num_to_check < 1)
; return (-1);
; if (start > 7)
; return (-1);
; if (start + num_to_check > 8)
; num_to_check = 8 - start;
; return ((int)(memcmp(&sig[start], &png_signature[start], num_to_check)));
ret
endp
;end if /* READ */
; Function to allocate memory for zlib
;voidpf (voidpf png_ptr, uInt items, uInt size)
align 4
proc png_zalloc uses edx ecx, png_ptr:dword, items:dword, size:dword
cmp dword[png_ptr],0
jne @f
xor eax,eax
jmp .end_f ;if (..==0) return 0
@@:
xor eax,eax
not eax
xor edx,edx
mov ecx,[size]
div ecx
cmp [items],eax
jl @f ;if (..>=..)
png_warning [png_ptr], 'Potential overflow in png_zalloc()'
xor eax,eax
jmp .end_f
@@:
mov ecx,[size]
imul ecx,[items]
stdcall png_malloc_warn, [png_ptr], ecx
.end_f:
ret
endp
; Function to free memory for zlib
;void (voidpf png_ptr, voidpf ptr)
align 4
proc png_zfree, png_ptr:dword, p2ptr:dword
stdcall png_free, [png_ptr], [p2ptr]
ret
endp
; Reset the CRC variable to 32 bits of 1's. Care must be taken
; in case CRC is > 32 bits to leave the top bits 0.
;void (png_structrp png_ptr)
align 4
proc png_reset_crc uses eax edi, png_ptr:dword
; The cast is safe because the crc is a 32-bit value.
mov edi,[png_ptr]
stdcall [calc_crc32], 0, Z_NULL, 0
mov dword[edi+png_struct.crc],eax
ret
endp
; Calculate the CRC over a section of data. We can only pass as
; much data to this routine as the largest single buffer size. We
; also check that this data will actually be used before going to the
; trouble of calculating it.
;void (png_structrp png_ptr, bytep ptr, png_size_t length)
align 4
proc png_calculate_crc uses eax ebx edi, png_ptr:dword, ptr:dword, length:dword
locals
need_crc dd 1
safe_length dd ?
endl
mov edi,[png_ptr]
PNG_CHUNK_ANCILLARY [edi+png_struct.chunk_name]
cmp eax,0 ;if (..!=0)
je @f
mov eax,[edi+png_struct.flags]
and eax,PNG_FLAG_CRC_ANCILLARY_MASK
cmp eax,PNG_FLAG_CRC_ANCILLARY_USE or PNG_FLAG_CRC_ANCILLARY_NOWARN
jne .end0 ;if (..==..)
mov dword[need_crc],0
jmp .end0
@@: ;else ;critical
mov eax,[edi+png_struct.flags]
and eax,PNG_FLAG_CRC_CRITICAL_IGNORE
cmp eax,0
je .end0 ;if (..!=0)
mov dword[need_crc],0
.end0:
; 'uLong' is defined in zlib.inc as unsigned long; this means that on some
; systems it is a 64-bit value. crc32, however, returns 32 bits so the
; following cast is safe. 'uInt' may be no more than 16 bits, so it is
; necessary to perform a loop here.
cmp dword[need_crc],0
je .end_f
cmp dword[length],0
jle .end_f ;if (..!=0 && ..>0)
mov eax,[edi+png_struct.crc] ;Should never issue a warning
.cycle0: ;do
mov ebx,[length]
mov [safe_length],ebx
;#ifndef __COVERITY__
; if (safe_length == 0)
; safe_length = (uInt)-1 ;evil, but safe
;end if
stdcall [calc_crc32], eax, [ptr], [safe_length]
; The following should never issue compiler warnings; if they do the
; target system has characteristics that will probably violate other
; assumptions within the libpng code.
mov ebx,[safe_length]
add [ptr],ebx
sub [length],ebx
cmp dword[length],0
jg .cycle0 ;while (..>0)
; And the following is always safe because the crc is only 32 bits.
mov [edi+png_struct.crc],eax
.end_f:
ret
endp
; Check a user supplied version number, called from both read and write
; functions that create a png_struct.
;int (png_structrp png_ptr, charp user_png_ver)
align 4
proc png_user_version_check, png_ptr:dword, user_png_ver:dword
; Libpng versions 1.0.0 and later are binary compatible if the version
; string matches through the second '.'; we must recompile any
; applications that use any older library version.
; if (user_png_ver != NULL)
; {
; int i = -1;
; int found_dots = 0;
; do
; {
; i++;
; if (user_png_ver[i] != PNG_LIBPNG_VER_STRING[i])
; png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
; if (user_png_ver[i] == '.')
; found_dots++;
; } while (found_dots < 2 && user_png_ver[i] != 0 &&
; PNG_LIBPNG_VER_STRING[i] != 0);
; }
; else
; png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
; if ((png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH) != 0)
; {
if PNG_WARNINGS_SUPPORTED eq 1
; size_t pos = 0;
; char m[128];
; pos = png_safecat(m, (sizeof m), pos,
; "Application built with libpng-");
; pos = png_safecat(m, (sizeof m), pos, user_png_ver);
; pos = png_safecat(m, (sizeof m), pos, " but running with ");
; pos = png_safecat(m, (sizeof m), pos, PNG_LIBPNG_VER_STRING);
; png_warning(png_ptr, m);
end if
if PNG_ERROR_NUMBERS_SUPPORTED eq 1
; png_ptr->flags = 0;
end if
; return 0;
; }
; Success return.
xor eax,eax
inc eax
.end_f:
ret
endp
; Generic function to create a png_struct for either read or write - this
; contains the common initialization.
;png_structp (charp user_png_ver, voidp error_ptr,
; png_error_ptr error_fn, png_error_ptr warn_fn, voidp mem_ptr,
; png_malloc_ptr malloc_fn, png_free_ptr free_fn)
align 4
proc png_create_png_struct uses ebx ecx edi esi, user_png_ver:dword, error_ptr:dword, error_fn:dword, warn_fn:dword, mem_ptr:dword, malloc_fn:dword, free_fn:dword
locals
if PNG_SETJMP_SUPPORTED eq 1
create_jmp_buf dd ? ;jmp_buf
end if
create_struct png_struct
endl
; This temporary stack-allocated structure is used to provide a place to
; build enough context to allow the user provided memory allocator (if any)
; to be called.
xor eax,eax
mov ecx,sizeof.png_struct
mov edi,ebp
sub edi,ecx
mov ebx,edi
rep stosb
; Added at libpng-1.2.6
if PNG_USER_LIMITS_SUPPORTED eq 1
mov dword[ebx+png_struct.user_width_max], PNG_USER_WIDTH_MAX
mov dword[ebx+png_struct.user_height_max], PNG_USER_HEIGHT_MAX
; Added at libpng-1.2.43 and 1.4.0
mov dword[ebx+png_struct.user_chunk_cache_max], PNG_USER_CHUNK_CACHE_MAX
; Added at libpng-1.2.43 and 1.4.1, required only for read but exists
; in png_struct regardless.
mov dword[ebx+png_struct.user_chunk_malloc_max], PNG_USER_CHUNK_MALLOC_MAX
end if
; The following two API calls simply set fields in png_struct, so it is safe
; to do them now even though error handling is not yet set up.
if PNG_USER_MEM_SUPPORTED eq 1
stdcall png_set_mem_fn, ebx, [mem_ptr], [malloc_fn], [free_fn]
end if
; (*error_fn) can return control to the caller after the error_ptr is set,
; this will result in a memory leak unless the error_fn does something
; extremely sophisticated. The design lacks merit but is implicit in the
; API.
stdcall png_set_error_fn, ebx, [error_ptr], [error_fn], [warn_fn]
if PNG_SETJMP_SUPPORTED eq 1
stdcall setjmp,... ;create_jmp_buf
cmp eax,0
j... .end0 ;if (!setjmp(create_jmp_buf))
; Temporarily fake out the longjmp information until we have
; successfully completed this function. This only works if we have
; setjmp() support compiled in, but it is safe - this stuff should
; never happen.
; create_struct.jmp_buf_ptr = &create_jmp_buf;
mov dword[ebx+png_struct.jmp_buf_size],0 ;stack allocation
; create_struct.longjmp_fn = longjmp;
end if
; Call the general version checker (shared with read and write code):
stdcall png_user_version_check, ebx, [user_png_ver]
cmp eax,0
je .end0 ;if (..!=0)
stdcall png_malloc_warn, ebx, sizeof.png_struct
;eax = png_ptr
cmp eax,0
je .end0 ;if (..!=0)
; png_ptr->zstream holds a back-pointer to the png_struct, so
; this can only be done now:
mov [ebx+png_struct.zstream.zalloc], png_zalloc
mov [ebx+png_struct.zstream.zfree], png_zfree
mov [ebx+png_struct.zstream.opaque], eax
if PNG_SETJMP_SUPPORTED eq 1
; Eliminate the local error handling:
mov [ebx+png_struct.jmp_buf_ptr], 0
mov [ebx+png_struct.jmp_buf_size], 0
mov [ebx+png_struct.longjmp_fn], 0
end if
mov ecx,sizeof.png_struct
mov edi,eax
mov esi,ebx
rep movsb ;*png_ptr = create_struct
; This is the successful return point
jmp .end_f
.end0:
; A longjmp because of a bug in the application storage allocator or a
; simple failure to allocate the png_struct.
xor eax,eax
.end_f:
ret
endp
; Allocate the memory for an info_struct for the application.
;png_infop (png_structrp png_ptr)
align 4
proc png_create_info_struct uses ebx ecx edi, png_ptr:dword
png_debug 1, 'in png_create_info_struct'
;ebx - info_ptr dd ? ;png_inforp
mov edi,[png_ptr]
cmp edi,0
jne @f ;if (..==0) return 0
xor eax,eax
jmp .end_f
@@:
; Use the internal API that does not (or at least should not) error out, so
; that this call always returns ok. The application typically sets up the
; error handling *after* creating the info_struct because this is the way it
; has always been done in 'example.asm'.
stdcall png_malloc_base, edi, sizeof.png_info_def
mov ebx,eax
cmp eax,0
je @f
mov edi,eax
xor eax,eax
mov ecx,sizeof.png_info_def
rep stosb ;memset(...
@@:
mov eax,ebx
.end_f:
ret
endp
; This function frees the memory associated with a single info struct.
; Normally, one would use either png_destroy_read_struct() or
; png_destroy_write_struct() to free an info struct, but this may be
; useful for some applications. From libpng 1.6.0 this function is also used
; internally to implement the png_info release part of the 'struct' destroy
; APIs. This ensures that all possible approaches free the same data (all of
; it).
;void (png_structrp png_ptr, png_infopp info_ptr_ptr)
align 4
proc png_destroy_info_struct uses eax ebx ecx edi, png_ptr:dword, info_ptr_ptr:dword
png_debug 1, 'in png_destroy_info_struct'
cmp dword[png_ptr],0
je .end_f ;if (..==0) return
mov edi,[info_ptr_ptr]
cmp edi,0 ;if (..!=0)
je .end_f
; Do this first in case of an error below; if the app implements its own
; memory management this can lead to png_free calling png_error, which
; will abort this routine and return control to the app error handler.
; An infinite loop may result if it then tries to free the same info
; ptr.
mov dword[edi],0
stdcall png_free_data, [png_ptr], edi, PNG_FREE_ALL, -1
mov ebx,edi
xor eax,eax
mov ecx,sizeof.png_info_def
rep stosb
stdcall png_free, [png_ptr], ebx
.end_f:
ret
endp
; Initialize the info structure. This is now an internal function (0.89)
; and applications using it are urged to use png_create_info_struct()
; instead. Use deprecated in 1.6.0, internal use removed (used internally it
; is just a memset).
; NOTE: it is almost inconceivable that this API is used because it bypasses
; the user-memory mechanism and the user error handling/warning mechanisms in
; those cases where it does anything other than a memset.
;void (png_infopp ptr_ptr, png_size_t png_info_struct_size)
align 4
proc png_info_init_3, ptr_ptr:dword, png_info_struct_size:dword
; png_inforp info_ptr = *ptr_ptr;
png_debug 1, 'in png_info_init_3'
; if (info_ptr == NULL)
; return;
; if ((sizeof (png_info)) > png_info_struct_size)
; {
; *ptr_ptr = NULL;
; The following line is why this API should not be used:
; free(info_ptr);
; info_ptr = png_malloc_base(NULL, (sizeof *info_ptr));
; if (info_ptr == NULL)
; return;
; *ptr_ptr = info_ptr;
; }
; Set everything to 0
; memset(info_ptr, 0, (sizeof *info_ptr));
ret
endp
; The following API is not called internally
;void (png_structrp png_ptr, png_inforp info_ptr, int freer, uint_32 mask)
align 4
proc png_data_freer uses edi esi, png_ptr:dword, info_ptr:dword, freer:dword, mask:dword
png_debug 1, 'in png_data_freer'
mov edi,[png_ptr]
cmp edi,0
je .end_f
mov esi,[info_ptr]
cmp esi,0
je .end_f ;if (..==0 || ..==0) return
; if (freer == PNG_DESTROY_WILL_FREE_DATA)
; info_ptr->free_me |= mask;
; else if (freer == PNG_USER_WILL_FREE_DATA)
; info_ptr->free_me &= ~mask;
; else
; png_error(png_ptr, "Unknown freer parameter in png_data_freer");
.end_f
ret
endp
;void (png_structrp png_ptr, png_inforp info_ptr, uint_32 mask, int num)
align 4
proc png_free_data uses eax edi esi, png_ptr:dword, info_ptr:dword, mask:dword, num:dword
png_debug 1, 'in png_free_data'
mov edi,[png_ptr]
cmp edi,0
je .end_f
mov esi,[info_ptr]
cmp esi,0
je .end_f ;if (..==0 || ..==0) return
if PNG_TEXT_SUPPORTED eq 1
; Free text item num or (if num == -1) all text items
; if (info_ptr->text != 0 &&
; ((mask & PNG_FREE_TEXT) & info_ptr->free_me) != 0)
; {
; if (num != -1)
; {
; png_free(png_ptr, info_ptr->text[num].key);
; info_ptr->text[num].key = NULL;
; }
; else
; {
; int i;
; for (i = 0; i < info_ptr->num_text; i++)
; png_free(png_ptr, info_ptr->text[i].key);
; png_free(png_ptr, info_ptr->text);
; info_ptr->text = NULL;
; info_ptr->num_text = 0;
; }
; }
end if
if PNG_tRNS_SUPPORTED eq 1
; Free any tRNS entry
mov eax,[mask]
and eax,PNG_FREE_TRNS
and eax,[esi+png_info_def.free_me]
cmp eax,0
je @f ;if (..!=0)
and dword[esi+png_info_def.valid], not PNG_INFO_tRNS
stdcall png_free, edi, [esi+png_info_def.trans_alpha]
mov dword[esi+png_info_def.trans_alpha],0
mov word[esi+png_info_def.num_trans],0
@@:
end if
if PNG_sCAL_SUPPORTED eq 1
; Free any sCAL entry
mov eax,[mask]
and eax,PNG_FREE_SCAL
and eax,[esi+png_info_def.free_me]
cmp eax,0
je @f ;if (..!=0)
stdcall png_free, edi, [esi+png_info_def.scal_s_width]
stdcall png_free, edi, [esi+png_info_def.scal_s_height]
mov dword[esi+png_info_def.scal_s_width],0
mov dword[esi+png_info_def.scal_s_height],0
and dword[esi+png_info_def.valid], not PNG_INFO_sCAL
@@:
end if
if PNG_pCAL_SUPPORTED eq 1
; Free any pCAL entry
; if (((mask & PNG_FREE_PCAL) & info_ptr->free_me) != 0)
; {
; png_free(png_ptr, info_ptr->pcal_purpose);
; png_free(png_ptr, info_ptr->pcal_units);
; info_ptr->pcal_purpose = NULL;
; info_ptr->pcal_units = NULL;
; if (info_ptr->pcal_params != NULL)
; {
; int i;
; for (i = 0; i < info_ptr->pcal_nparams; i++)
; png_free(png_ptr, info_ptr->pcal_params[i]);
;
; png_free(png_ptr, info_ptr->pcal_params);
; info_ptr->pcal_params = NULL;
; }
; info_ptr->valid &= ~PNG_INFO_pCAL;
; }
end if
if PNG_iCCP_SUPPORTED eq 1
; Free any profile entry
mov eax,[mask]
and eax,PNG_FREE_ICCP
and eax,[esi+png_info_def.free_me]
cmp eax,0
je @f ;if (..!=0)
stdcall png_free, edi, [esi+png_info_def.iccp_name]
stdcall png_free, edi, [esi+png_info_def.iccp_profile]
mov dword[esi+png_info_def.iccp_name],0
mov dword[esi+png_info_def.iccp_profile],0
and dword[esi+png_info_def.valid], not PNG_INFO_iCCP
@@:
end if
if PNG_sPLT_SUPPORTED eq 1
; Free a given sPLT entry, or (if num == -1) all sPLT entries
; if (info_ptr->splt_palettes != 0 &&
; ((mask & PNG_FREE_SPLT) & info_ptr->free_me) != 0)
; {
; if (num != -1)
; {
; png_free(png_ptr, info_ptr->splt_palettes[num].name);
; png_free(png_ptr, info_ptr->splt_palettes[num].entries);
; info_ptr->splt_palettes[num].name = NULL;
; info_ptr->splt_palettes[num].entries = NULL;
; }
; else
; {
; int i;
; for (i = 0; i < info_ptr->splt_palettes_num; i++)
; {
; png_free(png_ptr, info_ptr->splt_palettes[i].name);
; png_free(png_ptr, info_ptr->splt_palettes[i].entries);
; }
; png_free(png_ptr, info_ptr->splt_palettes);
; info_ptr->splt_palettes = NULL;
; info_ptr->splt_palettes_num = 0;
; info_ptr->valid &= ~PNG_INFO_sPLT;
; }
; }
end if
if PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED eq 1
; if (info_ptr->unknown_chunks != 0 &&
; ((mask & PNG_FREE_UNKN) & info_ptr->free_me) != 0)
; {
; if (num != -1)
; {
; png_free(png_ptr, info_ptr->unknown_chunks[num].data);
; info_ptr->unknown_chunks[num].data = NULL;
; }
; else
; {
; int i;
; for (i = 0; i < info_ptr->unknown_chunks_num; i++)
; png_free(png_ptr, info_ptr->unknown_chunks[i].data);
; png_free(png_ptr, info_ptr->unknown_chunks);
; info_ptr->unknown_chunks = NULL;
; info_ptr->unknown_chunks_num = 0;
; }
; }
end if
if PNG_hIST_SUPPORTED eq 1
; Free any hIST entry
mov eax,[mask]
and eax,PNG_FREE_HIST
and eax,[esi+png_info_def.free_me]
cmp eax,0
je @f ;if (..!=0)
stdcall png_free, edi, [esi+png_info_def.hist]
mov dword[esi+png_info_def.hist],0
and dword[esi+png_info_def.valid], not PNG_INFO_hIST
@@:
end if
; Free any PLTE entry that was internally allocated
mov eax,[mask]
and eax,PNG_FREE_PLTE
and eax,[esi+png_info_def.free_me]
cmp eax,0
je @f ;if (..!=0)
stdcall png_free, edi, [esi+png_info_def.palette]
mov dword[esi+png_info_def.palette],0
and dword[esi+png_info_def.valid],not PNG_INFO_PLTE
mov dword[esi+png_info_def.num_palette],0
@@:
if PNG_INFO_IMAGE_SUPPORTED eq 1
; Free any image bits attached to the info structure
; if (((mask & PNG_FREE_ROWS) & info_ptr->free_me) != 0)
; {
; if (info_ptr->row_pointers != 0)
; {
; uint_32 row;
; for (row = 0; row < info_ptr->height; row++)
; png_free(png_ptr, info_ptr->row_pointers[row]);
; png_free(png_ptr, info_ptr->row_pointers);
; info_ptr->row_pointers = NULL;
; }
; info_ptr->valid &= ~PNG_INFO_IDAT;
; }
end if
; if (num != -1)
; mask &= ~PNG_FREE_MUL;
mov eax,[mask]
not eax
and [esi+png_info_def.free_me],eax
.end_f:
ret
endp
; This function returns a pointer to the io_ptr associated with the user
; functions. The application should free any memory associated with this
; pointer before png_write_destroy() or png_read_destroy() are called.
;voidp (png_structrp png_ptr)
align 4
proc png_get_io_ptr, png_ptr:dword
mov eax,[png_ptr]
cmp eax,0
je @f ;if (..==0) return 0
mov eax,[eax+png_struct.io_ptr]
@@:
ret
endp
;#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
; Initialize the default input/output functions for the PNG file. If you
; use your own read or write routines, you can call either png_set_read_fn()
; or png_set_write_fn() instead of png_init_io(). If you have defined
; PNG_NO_STDIO or otherwise disabled PNG_STDIO_SUPPORTED, you must use a
; function of your own because "FILE *" isn't necessarily available.
;void (png_structrp png_ptr, png_FILE_p fp)
align 4
proc png_init_io uses eax edi, png_ptr:dword, fp:dword
png_debug 1, 'in png_init_io'
mov edi,[png_ptr]
cmp edi,0
je @f ;if (..==0) return
mov eax,[fp]
mov [edi+png_struct.io_ptr],eax
@@:
ret
endp
; PNG signed integers are saved in 32-bit 2's complement format. ANSI C-90
; defines a cast of a signed integer to an unsigned integer either to preserve
; the value, if it is positive, or to calculate:
; (UNSIGNED_MAX+1) + integer
; Where UNSIGNED_MAX is the appropriate maximum unsigned value, so when the
; negative integral value is added the result will be an unsigned value
; correspnding to the 2's complement representation.
;void (bytep buf, int_32 i)
align 4
proc png_save_int_32, buf:dword, i:dword
stdcall png_save_uint_32, [buf], [i]
ret
endp
;# ifdef PNG_TIME_RFC1123_SUPPORTED
; Convert the supplied time into an RFC 1123 string suitable for use in
; a "Creation Time" or other text-based time string.
;int (char out[29], const_timep ptime)
align 4
short_months db 'Jan',0, 'Feb',0, 'Mar',0, 'Apr',0, 'May',0, 'Jun',0,\
'Jul',0, 'Aug',0, 'Sep',0, 'Oct',0, 'Nov',0, 'Dec',0
align 4
proc png_convert_to_rfc1123_buffer, out_29:dword, ptime:dword
cmp dword[out_29],0
jne @f
xor eax,eax
jmp .end_f ;if (..==0) return 0
@@:
; if (ptime->year > 9999 /* RFC1123 limitation */ ||
; ptime->month == 0 || ptime->month > 12 ||
; ptime->day == 0 || ptime->day > 31 ||
; ptime->hour > 23 || ptime->minute > 59 ||
; ptime->second > 60)
; return 0;
; {
; size_t pos = 0;
; char number_buf[5]; /* enough for a four-digit year */
;# define APPEND_STRING(string) pos = png_safecat(out_29, 29, pos, (string))
;# define APPEND_NUMBER(format, value)\
; APPEND_STRING(PNG_FORMAT_NUMBER(number_buf, format, (value)))
;# define APPEND(ch) if (pos < 28) out_29[pos++] = (ch)
; APPEND_NUMBER(PNG_NUMBER_FORMAT_u, (unsigned)ptime->day);
; APPEND(' ');
; APPEND_STRING(short_months[(ptime->month - 1)]);
; APPEND(' ');
; APPEND_NUMBER(PNG_NUMBER_FORMAT_u, ptime->year);
; APPEND(' ');
; APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->hour);
; APPEND(':');
; APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->minute);
; APPEND(':');
; APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->second);
; APPEND_STRING(" +0000"); /* This reliably terminates the buffer */
;# undef APPEND
;# undef APPEND_NUMBER
;# undef APPEND_STRING
; }
xor eax,eax
inc eax
.end_f:
ret
endp
;# if PNG_LIBPNG_VER < 10700
; To do: remove the following from libpng-1.7
; Original API that uses a private buffer in png_struct.
; Deprecated because it causes png_struct to carry a spurious temporary
; buffer (png_struct::time_buffer), better to have the caller pass this in.
;charp (png_structrp png_ptr, const_timep ptime)
align 4
proc png_convert_to_rfc1123, png_ptr:dword, ptime:dword
; if (png_ptr != NULL)
; {
; The only failure above if png_ptr != NULL is from an invalid ptime
; if (png_convert_to_rfc1123_buffer(png_ptr->time_buffer, ptime) == 0)
; png_warning(png_ptr, "Ignoring invalid time value");
; else
; return png_ptr->time_buffer;
; }
; return NULL;
ret
endp
;# endif /* LIBPNG_VER < 10700 */
;# endif /* TIME_RFC1123 */
;end if /* READ || WRITE */
;charp (png_structrp png_ptr)
align 4
proc png_get_copyright, png_ptr:dword
jmp .end_0
@@: db 'libpng version 1.6.25 - September 1, 2016',13,10,\
' Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson',13,10,\
' Copyright (c) 1996-1997 Andreas Dilger',13,10,\
' Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.',0
.end_0:
mov eax,@b
ret
endp
; The following return the library version as a short string in the
; format 1.0.0 through 99.99.99zz. To get the version of *.inc files
; used with your application, print out PNG_LIBPNG_VER_STRING, which
; is defined in png.inc.
; Note: now there is no difference between png_get_libpng_ver() and
; png_get_header_ver(). Due to the version_nn_nn_nn typedef guard,
; it is guaranteed that png.asm uses the correct version of png.inc.
;charp (png_structrp png_ptr)
align 4
proc png_get_libpng_ver, png_ptr:dword
; Version of *.asm files used when building libpng
; return png_get_header_ver(png_ptr);
ret
endp
;charp (png_structrp png_ptr)
align 4
proc png_get_header_ver, png_ptr:dword
; Version of *.inc files used when building libpng
; return PNG_LIBPNG_VER_STRING;
ret
endp
;charp (png_structrp png_ptr)
align 4
proc png_get_header_version, png_ptr:dword
; Returns longer string containing both version and date
;if __STDC__
; return PNG_HEADER_VERSION_STRING
;# ifndef PNG_READ_SUPPORTED
; " (NO READ SUPPORT)"
;# endif
; PNG_STRING_NEWLINE;
;#else
; return PNG_HEADER_VERSION_STRING;
;end if
ret
endp
; NOTE: this routine is not used internally!
; Build a grayscale palette. Palette is assumed to be 1 << bit_depth
; large of png_color. This lets grayscale images be treated as
; paletted. Most useful for gamma correction and simplification
; of code. This API is not used internally.
;void (int bit_depth, png_colorp palette)
align 4
proc png_build_grayscale_palette, bit_depth:dword, palette:dword
; int num_palette;
; int color_inc;
; int i;
; int v;
png_debug 1, 'in png_do_build_grayscale_palette'
; if (palette == NULL)
; return;
; switch (bit_depth)
; {
; case 1:
; num_palette = 2;
; color_inc = 0xff;
; break;
;
; case 2:
; num_palette = 4;
; color_inc = 0x55;
; break;
;
; case 4:
; num_palette = 16;
; color_inc = 0x11;
; break;
;
; case 8:
; num_palette = 256;
; color_inc = 1;
; break;
;
; default:
; num_palette = 0;
; color_inc = 0;
; break;
; }
;
; for (i = 0, v = 0; i < num_palette; i++, v += color_inc)
; {
; palette[i].red = (byte)(v & 0xff);
; palette[i].green = (byte)(v & 0xff);
; palette[i].blue = (byte)(v & 0xff);
; }
ret
endp
;int (png_structrp png_ptr, bytep chunk_name)
align 4
proc png_handle_as_unknown uses ecx edi esi, png_ptr:dword, chunk_name:dword
; Check chunk_name and return "keep" value if it's on the list, else 0
; bytep p, p_end;
mov edi,[png_ptr]
cmp edi,0
je .end0
cmp dword[chunk_name],0
je .end0
cmp dword[edi+png_struct.num_chunk_list],0
je .end0
jmp @f
.end0: ;if (..==0 || ..==0 || ..==0)
mov eax,PNG_HANDLE_CHUNK_AS_DEFAULT
jmp .end_f
@@:
; p_end = png_ptr->chunk_list;
; p = p_end + png_ptr->num_chunk_list*5; /* beyond end */
; The code is the fifth byte after each four byte string. Historically this
; code was always searched from the end of the list, this is no longer
; necessary because the 'set' routine handles duplicate entries correcty.
; do /* num_chunk_list > 0, so at least one */
; {
; p -= 5;
; if (memcmp(chunk_name, p, 4) == 0)
; return p[4];
; }
; while (p > p_end);
; This means that known chunks should be processed and unknown chunks should
; be handled according to the value of png_ptr->unknown_default; this can be
; confusing because, as a result, there are two levels of defaulting for
; unknown chunks.
mov eax,PNG_HANDLE_CHUNK_AS_DEFAULT
.end_f:
ret
endp
;int (png_structrp png_ptr, uint_32 chunk_name)
align 4
proc png_chunk_unknown_handling, png_ptr:dword, chunk_name:dword
; byte chunk_string[5];
; PNG_CSTRING_FROM_CHUNK(chunk_string, chunk_name);
; return png_handle_as_unknown(png_ptr, chunk_string);
ret
endp
; This function, added to libpng-1.0.6g, is untested.
;int (png_structrp png_ptr)
align 4
proc png_reset_zstream, png_ptr:dword
mov eax,[png_ptr]
cmp eax,0
jne @f ;if (..==0)
mov eax,Z_STREAM_ERROR
jmp .end_f
@@:
; WARNING: this resets the window bits to the maximum!
add eax,png_struct.zstream
stdcall inflateReset,eax
.end_f:
ret
endp
; This function was added to libpng-1.0.7
;uint_32 png_access_version_number(void)
align 4
png_access_version_number:
; Version of *.asm files used when building libpng
mov eax,PNG_LIBPNG_VER
ret
;#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
; Ensure that png_ptr->zstream.msg holds some appropriate error message string.
; If it doesn't 'ret' is used to set it to something appropriate, even in cases
; like Z_OK or Z_STREAM_END where the error code is apparently a success code.
;void (png_structrp png_ptr, int ret)
align 4
proc png_zstream_error uses eax edi, png_ptr:dword, p2ret:dword
; Translate 'p2ret' into an appropriate error string, priority is given to the
; one in zstream if set. This always returns a string, even in cases like
; Z_OK or Z_STREAM_END where the error code is a success code.
mov edi,[png_ptr]
cmp dword[edi+png_struct.zstream.msg],0
jne .end_f ;if (..==0) switch (p2ret)
mov eax,[p2ret]
; default:
cmp eax,Z_OK
jne @f
cStr dword[edi+png_struct.zstream.msg],'unexpected zlib return code'
jmp .end_f
@@:
cmp eax,Z_STREAM_END
jne @f
; Normal exit
cStr dword[edi+png_struct.zstream.msg],'unexpected end of LZ stream'
jmp .end_f
@@:
cmp eax,Z_NEED_DICT
jne @f
; This means the deflate stream did not have a dictionary; this
; indicates a bogus PNG.
cStr dword[edi+png_struct.zstream.msg],'missing LZ dictionary'
jmp .end_f
@@:
cmp eax,Z_ERRNO
jne @f
; gz APIs only: should not happen
cStr dword[edi+png_struct.zstream.msg],'zlib IO error'
jmp .end_f
@@:
cmp eax,Z_STREAM_ERROR
jne @f
; internal libpng error
cStr dword[edi+png_struct.zstream.msg],'bad parameters to zlib'
jmp .end_f
@@:
cmp eax,Z_DATA_ERROR
jne @f
cStr dword[edi+png_struct.zstream.msg],'damaged LZ stream'
jmp .end_f
@@:
cmp eax,Z_MEM_ERROR
jne @f
cStr dword[edi+png_struct.zstream.msg],'insufficient memory'
jmp .end_f
@@:
cmp eax,Z_BUF_ERROR
jne @f
; End of input or output; not a problem if the caller is doing
; incremental read or write.
cStr dword[edi+png_struct.zstream.msg],'truncated'
jmp .end_f
@@:
cmp eax,Z_VERSION_ERROR
jne @f
cStr dword[edi+png_struct.zstream.msg],'unsupported zlib version'
jmp .end_f
@@:
cmp eax,PNG_UNEXPECTED_ZLIB_RETURN
jne .end_f
; Compile errors here mean that zlib now uses the value co-opted in
; pngpriv.inc for PNG_UNEXPECTED_ZLIB_RETURN; update the switch above
; and change pngpriv.inc. Note that this message is "... return",
; whereas the default/Z_OK one is "... return code".
cStr dword[edi+png_struct.zstream.msg],'unexpected zlib return'
; break;
.end_f:
ret
endp
; png_convert_size: a PNGAPI but no longer in png.inc, so deleted
; at libpng 1.5.5!
; Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.asm)
;if PNG_GAMMA_SUPPORTED /* always set if COLORSPACE */
;int (png_structrp png_ptr,
; png_colorspacerp colorspace, png_fixed_point gAMA, int from)
; This is called to check a new gamma value against an existing one. The
; routine returns false if the new gamma value should not be written.
;
; 'from' says where the new gamma value comes from:
;
; 0: the new gamma value is the libpng estimate for an ICC profile
; 1: the new gamma value comes from a gAMA chunk
; 2: the new gamma value comes from an sRGB chunk
align 4
proc png_colorspace_check_gamma, png_ptr:dword, colorspace:dword, gAMA:dword, from:dword
; png_fixed_point gtest;
;
; if ((colorspace->flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
; (png_muldiv(&gtest, colorspace->gamma, PNG_FP_1, gAMA) == 0 ||
; png_gamma_significant(gtest) != 0))
; {
; Either this is an sRGB image, in which case the calculated gamma
; approximation should match, or this is an image with a profile and the
; value libpng calculates for the gamma of the profile does not match the
; value recorded in the file. The former, sRGB, case is an error, the
; latter is just a warning.
; if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0 || from == 2)
; {
; png_chunk_report(png_ptr, "gamma value does not match sRGB",
; PNG_CHUNK_ERROR);
; /* Do not overwrite an sRGB value */
; return from == 2;
; }
; else /* sRGB tag not involved */
; {
; png_chunk_report(png_ptr, "gamma value does not match libpng estimate",
; PNG_CHUNK_WARNING);
; return from == 1;
; }
; }
; return 1;
ret
endp
;void (png_structrp png_ptr, png_colorspacerp colorspace, png_fixed_point gAMA)
align 4
proc png_colorspace_set_gamma, png_ptr:dword, colorspace:dword, gAMA:dword
; Changed in libpng-1.5.4 to limit the values to ensure overflow can't
; occur. Since the fixed point representation is asymetrical it is
; possible for 1/gamma to overflow the limit of 21474 and this means the
; gamma value must be at least 5/100000 and hence at most 20000.0. For
; safety the limits here are a little narrower. The values are 0.00016 to
; 6250.0, which are truly ridiculous gamma values (and will produce
; displays that are all black or all white.)
; In 1.6.0 this test replaces the ones in pngrutil.c, in the gAMA chunk
; handling code, which only required the value to be >0.
; charp errmsg;
; if (gAMA < 16 || gAMA > 625000000)
; errmsg = "gamma value out of range";
;# ifdef PNG_READ_gAMA_SUPPORTED
; Allow the application to set the gamma value more than once
; else if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
; (colorspace->flags & PNG_COLORSPACE_FROM_gAMA) != 0)
; errmsg = "duplicate";
;# endif
; Do nothing if the colorspace is already invalid
; else if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
; return;
; else
; {
; if (png_colorspace_check_gamma(png_ptr, colorspace, gAMA,
; 1/*from gAMA*/) != 0)
; {
; /* Store this gamma value. */
; colorspace->gamma = gAMA;
; colorspace->flags |=
; (PNG_COLORSPACE_HAVE_GAMMA | PNG_COLORSPACE_FROM_gAMA);
; }
; At present if the check_gamma test fails the gamma of the colorspace is
; not updated however the colorspace is not invalidated. This
; corresponds to the case where the existing gamma comes from an sRGB
; chunk or profile. An error message has already been output.
; return;
; }
; Error exit - errmsg has been set.
; colorspace->flags |= PNG_COLORSPACE_INVALID;
; png_chunk_report(png_ptr, errmsg, PNG_CHUNK_WRITE_ERROR);
.end_f:
ret
endp
;void (png_structrp png_ptr, png_inforp info_ptr)
align 4
proc png_colorspace_sync_info uses eax esi, png_ptr:dword, info_ptr:dword
mov esi,[info_ptr]
mov ax,[esi+png_info_def.colorspace.flags]
and ax,PNG_COLORSPACE_INVALID
cmp ax,0
je @f ;if (..!=0)
; Everything is invalid
and dword[esi+png_info_def.valid], not (PNG_INFO_gAMA or PNG_INFO_cHRM or PNG_INFO_sRGB or PNG_INFO_iCCP)
if PNG_COLORSPACE_SUPPORTED eq 1
; Clean up the iCCP profile now if it won't be used.
stdcall png_free_data, [png_ptr], esi, PNG_FREE_ICCP, -1 ;not used
end if
jmp .end0
@@: ;else
if PNG_COLORSPACE_SUPPORTED eq 1
; Leave the INFO_iCCP flag set if the pngset.c code has already set
; it; this allows a PNG to contain a profile which matches sRGB and
; yet still have that profile retrievable by the application.
mov ax,[esi+png_info_def.colorspace.flags]
and ax,PNG_COLORSPACE_MATCHES_sRGB
cmp ax,0
je @f ;if (..!=0)
or dword[esi+png_info_def.valid], PNG_INFO_sRGB
jmp .end1
@@: ;else
and dword[esi+png_info_def.valid], not PNG_INFO_sRGB
.end1:
mov ax,[esi+png_info_def.colorspace.flags]
and ax,PNG_COLORSPACE_HAVE_ENDPOINTS
cmp ax,0
je @f ;if (..!=0)
or dword[esi+png_info_def.valid], PNG_INFO_cHRM
jmp .end2
@@: ;else
and dword[esi+png_info_def.valid], not PNG_INFO_cHRM
.end2:
end if
mov ax,[esi+png_info_def.colorspace.flags]
and ax,PNG_COLORSPACE_HAVE_GAMMA
cmp ax,0
je @f ;if (..!=0)
or dword[esi+png_info_def.valid], PNG_INFO_gAMA
jmp .end0
@@: ;else
and dword[esi+png_info_def.valid], not PNG_INFO_gAMA
.end0:
ret
endp
;void (png_structrp png_ptr, png_inforp info_ptr)
align 4
proc png_colorspace_sync uses ecx edi esi, png_ptr:dword, info_ptr:dword
mov edi,[info_ptr]
cmp edi,0
je @f ;if (..==0) ;reduce code size; check here not in the caller
mov ecx,sizeof.png_colorspace
mov esi,[png_ptr]
mov esi,[esi+png_struct.colorspace]
mov edi,[edi+png_info_def.colorspace]
rep movsb
stdcall png_colorspace_sync_info, [png_ptr], [info_ptr]
@@:
ret
endp
;end if /* GAMMA */
;if PNG_COLORSPACE_SUPPORTED
; Added at libpng-1.5.5 to support read and write of true CIEXYZ values for
; cHRM, as opposed to using chromaticities. These internal APIs return
; non-zero on a parameter error. The X, Y and Z values are required to be
; positive and less than 1.0.
;int (png_xy *xy, const png_XYZ *XYZ)
align 4
proc png_xy_from_XYZ, xy:dword, XYZ:dword
; int_32 d, dwhite, whiteX, whiteY;
; d = XYZ->red_X + XYZ->red_Y + XYZ->red_Z;
; if (png_muldiv(&xy->redx, XYZ->red_X, PNG_FP_1, d) == 0)
; return 1;
; if (png_muldiv(&xy->redy, XYZ->red_Y, PNG_FP_1, d) == 0)
; return 1;
; dwhite = d;
; whiteX = XYZ->red_X;
; whiteY = XYZ->red_Y;
; d = XYZ->green_X + XYZ->green_Y + XYZ->green_Z;
; if (png_muldiv(&xy->greenx, XYZ->green_X, PNG_FP_1, d) == 0)
; return 1;
; if (png_muldiv(&xy->greeny, XYZ->green_Y, PNG_FP_1, d) == 0)
; return 1;
; dwhite += d;
; whiteX += XYZ->green_X;
; whiteY += XYZ->green_Y;
; d = XYZ->blue_X + XYZ->blue_Y + XYZ->blue_Z;
; if (png_muldiv(&xy->bluex, XYZ->blue_X, PNG_FP_1, d) == 0)
; return 1;
; if (png_muldiv(&xy->bluey, XYZ->blue_Y, PNG_FP_1, d) == 0)
; return 1;
; dwhite += d;
; whiteX += XYZ->blue_X;
; whiteY += XYZ->blue_Y;
; The reference white is simply the sum of the end-point (X,Y,Z) vectors,
; thus:
; if (png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite) == 0)
; return 1;
; if (png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite) == 0)
; return 1;
; return 0;
ret
endp
;int (png_XYZ *XYZ, const png_xy *xy)
align 4
proc png_XYZ_from_xy, XYZ:dword, xy:dword
; png_fixed_point red_inverse, green_inverse, blue_scale;
; png_fixed_point left, right, denominator;
; Check xy and, implicitly, z. Note that wide gamut color spaces typically
; have end points with 0 tristimulus values (these are impossible end
; points, but they are used to cover the possible colors). We check
; xy->whitey against 5, not 0, to avoid a possible integer overflow.
; if (xy->redx < 0 || xy->redx > PNG_FP_1) return 1;
; if (xy->redy < 0 || xy->redy > PNG_FP_1-xy->redx) return 1;
; if (xy->greenx < 0 || xy->greenx > PNG_FP_1) return 1;
; if (xy->greeny < 0 || xy->greeny > PNG_FP_1-xy->greenx) return 1;
; if (xy->bluex < 0 || xy->bluex > PNG_FP_1) return 1;
; if (xy->bluey < 0 || xy->bluey > PNG_FP_1-xy->bluex) return 1;
; if (xy->whitex < 0 || xy->whitex > PNG_FP_1) return 1;
; if (xy->whitey < 5 || xy->whitey > PNG_FP_1-xy->whitex) return 1;
; The reverse calculation is more difficult because the original tristimulus
; value had 9 independent values (red,green,blue)x(X,Y,Z) however only 8
; derived values were recorded in the cHRM chunk;
; (red,green,blue,white)x(x,y). This loses one degree of freedom and
; therefore an arbitrary ninth value has to be introduced to undo the
; original transformations.
; Think of the original end-points as points in (X,Y,Z) space. The
; chromaticity values (c) have the property:
; C
; c = ---------
; X + Y + Z
; For each c (x,y,z) from the corresponding original C (X,Y,Z). Thus the
; three chromaticity values (x,y,z) for each end-point obey the
; relationship:
; x + y + z = 1
; This describes the plane in (X,Y,Z) space that intersects each axis at the
; value 1.0; call this the chromaticity plane. Thus the chromaticity
; calculation has scaled each end-point so that it is on the x+y+z=1 plane
; and chromaticity is the intersection of the vector from the origin to the
; (X,Y,Z) value with the chromaticity plane.
; To fully invert the chromaticity calculation we would need the three
; end-point scale factors, (red-scale, green-scale, blue-scale), but these
; were not recorded. Instead we calculated the reference white (X,Y,Z) and
; recorded the chromaticity of this. The reference white (X,Y,Z) would have
; given all three of the scale factors since:
; color-C = color-c * color-scale
; white-C = red-C + green-C + blue-C
; = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
; But cHRM records only white-x and white-y, so we have lost the white scale
; factor:
; white-C = white-c*white-scale
; To handle this the inverse transformation makes an arbitrary assumption
; about white-scale:
; Assume: white-Y = 1.0
; Hence: white-scale = 1/white-y
; Or: red-Y + green-Y + blue-Y = 1.0
; Notice the last statement of the assumption gives an equation in three of
; the nine values we want to calculate. 8 more equations come from the
; above routine as summarised at the top above (the chromaticity
; calculation):
; Given: color-x = color-X / (color-X + color-Y + color-Z)
; Hence: (color-x - 1)*color-X + color.x*color-Y + color.x*color-Z = 0
; This is 9 simultaneous equations in the 9 variables "color-C" and can be
; solved by Cramer's rule. Cramer's rule requires calculating 10 9x9 matrix
; determinants, however this is not as bad as it seems because only 28 of
; the total of 90 terms in the various matrices are non-zero. Nevertheless
; Cramer's rule is notoriously numerically unstable because the determinant
; calculation involves the difference of large, but similar, numbers. It is
; difficult to be sure that the calculation is stable for real world values
; and it is certain that it becomes unstable where the end points are close
; together.
; So this code uses the perhaps slightly less optimal but more
; understandable and totally obvious approach of calculating color-scale.
; This algorithm depends on the precision in white-scale and that is
; (1/white-y), so we can immediately see that as white-y approaches 0 the
; accuracy inherent in the cHRM chunk drops off substantially.
; libpng arithmetic: a simple inversion of the above equations
; ------------------------------------------------------------
; white_scale = 1/white-y
; white-X = white-x * white-scale
; white-Y = 1.0
; white-Z = (1 - white-x - white-y) * white_scale
; white-C = red-C + green-C + blue-C
; = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
; This gives us three equations in (red-scale,green-scale,blue-scale) where
; all the coefficients are now known:
; red-x*red-scale + green-x*green-scale + blue-x*blue-scale
; = white-x/white-y
; red-y*red-scale + green-y*green-scale + blue-y*blue-scale = 1
; red-z*red-scale + green-z*green-scale + blue-z*blue-scale
; = (1 - white-x - white-y)/white-y
; In the last equation color-z is (1 - color-x - color-y) so we can add all
; three equations together to get an alternative third:
; red-scale + green-scale + blue-scale = 1/white-y = white-scale
; So now we have a Cramer's rule solution where the determinants are just
; 3x3 - far more tractible. Unfortunately 3x3 determinants still involve
; multiplication of three coefficients so we can't guarantee to avoid
; overflow in the libpng fixed point representation. Using Cramer's rule in
; floating point is probably a good choice here, but it's not an option for
; fixed point. Instead proceed to simplify the first two equations by
; eliminating what is likely to be the largest value, blue-scale:
; blue-scale = white-scale - red-scale - green-scale
; Hence:
; (red-x - blue-x)*red-scale + (green-x - blue-x)*green-scale =
; (white-x - blue-x)*white-scale
; (red-y - blue-y)*red-scale + (green-y - blue-y)*green-scale =
; 1 - blue-y*white-scale
; And now we can trivially solve for (red-scale,green-scale):
; green-scale =
; (white-x - blue-x)*white-scale - (red-x - blue-x)*red-scale
; -----------------------------------------------------------
; green-x - blue-x
; red-scale =
; 1 - blue-y*white-scale - (green-y - blue-y) * green-scale
; ---------------------------------------------------------
; red-y - blue-y
; Hence:
; red-scale =
; ( (green-x - blue-x) * (white-y - blue-y) -
; (green-y - blue-y) * (white-x - blue-x) ) / white-y
; -------------------------------------------------------------------------
; (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
; green-scale =
; ( (red-y - blue-y) * (white-x - blue-x) -
; (red-x - blue-x) * (white-y - blue-y) ) / white-y
; -------------------------------------------------------------------------
; (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
; Accuracy:
; The input values have 5 decimal digits of accuracy. The values are all in
; the range 0 < value < 1, so simple products are in the same range but may
; need up to 10 decimal digits to preserve the original precision and avoid
; underflow. Because we are using a 32-bit signed representation we cannot
; match this; the best is a little over 9 decimal digits, less than 10.
; The approach used here is to preserve the maximum precision within the
; signed representation. Because the red-scale calculation above uses the
; difference between two products of values that must be in the range -1..+1
; it is sufficient to divide the product by 7; ceil(100,000/32767*2). The
; factor is irrelevant in the calculation because it is applied to both
; numerator and denominator.
; Note that the values of the differences of the products of the
; chromaticities in the above equations tend to be small, for example for
; the sRGB chromaticities they are:
; red numerator: -0.04751
; green numerator: -0.08788
; denominator: -0.2241 (without white-y multiplication)
; The resultant Y coefficients from the chromaticities of some widely used
; color space definitions are (to 15 decimal places):
; sRGB
; 0.212639005871510 0.715168678767756 0.072192315360734
; Kodak ProPhoto
; 0.288071128229293 0.711843217810102 0.000085653960605
; Adobe RGB
; 0.297344975250536 0.627363566255466 0.075291458493998
; Adobe Wide Gamut RGB
; 0.258728243040113 0.724682314948566 0.016589442011321
; By the argument, above overflow should be impossible here. The return
; value of 2 indicates an internal error to the caller.
; if (png_muldiv(&left, xy->greenx-xy->bluex, xy->redy - xy->bluey, 7) == 0)
; return 2;
; if (png_muldiv(&right, xy->greeny-xy->bluey, xy->redx - xy->bluex, 7) == 0)
; return 2;
; denominator = left - right;
; Now find the red numerator.
; if (png_muldiv(&left, xy->greenx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
; return 2;
; if (png_muldiv(&right, xy->greeny-xy->bluey, xy->whitex-xy->bluex, 7) == 0)
; return 2;
; Overflow is possible here and it indicates an extreme set of PNG cHRM
; chunk values. This calculation actually returns the reciprocal of the
; scale value because this allows us to delay the multiplication of white-y
; into the denominator, which tends to produce a small number.
; if (png_muldiv(&red_inverse, xy->whitey, denominator, left-right) == 0 ||
; red_inverse <= xy->whitey /* r+g+b scales = white scale */)
; return 1;
; Similarly for green_inverse:
; if (png_muldiv(&left, xy->redy-xy->bluey, xy->whitex-xy->bluex, 7) == 0)
; return 2;
; if (png_muldiv(&right, xy->redx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
; return 2;
; if (png_muldiv(&green_inverse, xy->whitey, denominator, left-right) == 0 ||
; green_inverse <= xy->whitey)
; return 1;
; And the blue scale, the checks above guarantee this can't overflow but it
; can still produce 0 for extreme cHRM values.
; blue_scale = png_reciprocal(xy->whitey) - png_reciprocal(red_inverse) -
; png_reciprocal(green_inverse);
; if (blue_scale <= 0)
; return 1;
; And fill in the png_XYZ:
; if (png_muldiv(&XYZ->red_X, xy->redx, PNG_FP_1, red_inverse) == 0)
; return 1;
; if (png_muldiv(&XYZ->red_Y, xy->redy, PNG_FP_1, red_inverse) == 0)
; return 1;
; if (png_muldiv(&XYZ->red_Z, PNG_FP_1 - xy->redx - xy->redy, PNG_FP_1,
; red_inverse) == 0)
; return 1;
; if (png_muldiv(&XYZ->green_X, xy->greenx, PNG_FP_1, green_inverse) == 0)
; return 1;
; if (png_muldiv(&XYZ->green_Y, xy->greeny, PNG_FP_1, green_inverse) == 0)
; return 1;
; if (png_muldiv(&XYZ->green_Z, PNG_FP_1 - xy->greenx - xy->greeny, PNG_FP_1,
; green_inverse) == 0)
; return 1;
; if (png_muldiv(&XYZ->blue_X, xy->bluex, blue_scale, PNG_FP_1) == 0)
; return 1;
; if (png_muldiv(&XYZ->blue_Y, xy->bluey, blue_scale, PNG_FP_1) == 0)
; return 1;
; if (png_muldiv(&XYZ->blue_Z, PNG_FP_1 - xy->bluex - xy->bluey, blue_scale,
; PNG_FP_1) == 0)
; return 1;
; return 0; /*success*/
ret
endp
;int (png_XYZ *XYZ)
align 4
proc png_XYZ_normalize, XYZ:dword
; int_32 Y;
; if (XYZ->red_Y < 0 || XYZ->green_Y < 0 || XYZ->blue_Y < 0 ||
; XYZ->red_X < 0 || XYZ->green_X < 0 || XYZ->blue_X < 0 ||
; XYZ->red_Z < 0 || XYZ->green_Z < 0 || XYZ->blue_Z < 0)
; return 1;
; Normalize by scaling so the sum of the end-point Y values is PNG_FP_1.
; IMPLEMENTATION NOTE: ANSI requires signed overflow not to occur, therefore
; relying on addition of two positive values producing a negative one is not
; safe.
; Y = XYZ->red_Y;
; if (0x7fffffff - Y < XYZ->green_X)
; return 1;
; Y += XYZ->green_Y;
; if (0x7fffffff - Y < XYZ->blue_X)
; return 1;
; Y += XYZ->blue_Y;
; if (Y != PNG_FP_1)
; {
; if (png_muldiv(&XYZ->red_X, XYZ->red_X, PNG_FP_1, Y) == 0)
; return 1;
; if (png_muldiv(&XYZ->red_Y, XYZ->red_Y, PNG_FP_1, Y) == 0)
; return 1;
; if (png_muldiv(&XYZ->red_Z, XYZ->red_Z, PNG_FP_1, Y) == 0)
; return 1;
; if (png_muldiv(&XYZ->green_X, XYZ->green_X, PNG_FP_1, Y) == 0)
; return 1;
; if (png_muldiv(&XYZ->green_Y, XYZ->green_Y, PNG_FP_1, Y) == 0)
; return 1;
; if (png_muldiv(&XYZ->green_Z, XYZ->green_Z, PNG_FP_1, Y) == 0)
; return 1;
; if (png_muldiv(&XYZ->blue_X, XYZ->blue_X, PNG_FP_1, Y) == 0)
; return 1;
; if (png_muldiv(&XYZ->blue_Y, XYZ->blue_Y, PNG_FP_1, Y) == 0)
; return 1;
; if (png_muldiv(&XYZ->blue_Z, XYZ->blue_Z, PNG_FP_1, Y) == 0)
; return 1;
; }
; return 0;
ret
endp
;int (const png_xy *xy1, const png_xy *xy2, int delta)
align 4
proc png_colorspace_endpoints_match, xy1:dword, xy2:dword, delta:dword
; Allow an error of +/-0.01 (absolute value) on each chromaticity
; if (PNG_OUT_OF_RANGE(xy1->whitex, xy2->whitex,delta) ||
; PNG_OUT_OF_RANGE(xy1->whitey, xy2->whitey,delta) ||
; PNG_OUT_OF_RANGE(xy1->redx, xy2->redx, delta) ||
; PNG_OUT_OF_RANGE(xy1->redy, xy2->redy, delta) ||
; PNG_OUT_OF_RANGE(xy1->greenx, xy2->greenx,delta) ||
; PNG_OUT_OF_RANGE(xy1->greeny, xy2->greeny,delta) ||
; PNG_OUT_OF_RANGE(xy1->bluex, xy2->bluex, delta) ||
; PNG_OUT_OF_RANGE(xy1->bluey, xy2->bluey, delta))
; return 0;
; return 1;
ret
endp
; Added in libpng-1.6.0, a different check for the validity of a set of cHRM
; chunk chromaticities. Earlier checks used to simply look for the overflow
; condition (where the determinant of the matrix to solve for XYZ ends up zero
; because the chromaticity values are not all distinct.) Despite this it is
; theoretically possible to produce chromaticities that are apparently valid
; but that rapidly degrade to invalid, potentially crashing, sets because of
; arithmetic inaccuracies when calculations are performed on them. The new
; check is to round-trip xy -> XYZ -> xy and then check that the result is
; within a small percentage of the original.
;int (png_XYZ *XYZ, const png_xy *xy)
align 4
proc png_colorspace_check_xy, XYZ:dword, xy:dword
; int result;
; png_xy xy_test;
; As a side-effect this routine also returns the XYZ endpoints.
; result = png_XYZ_from_xy(XYZ, xy);
; if (result != 0)
; return result;
; result = png_xy_from_XYZ(&xy_test, XYZ);
; if (result != 0)
; return result;
; if (png_colorspace_endpoints_match(xy, &xy_test,
; 5/*actually, the math is pretty accurate*/) != 0)
; return 0;
; Too much slip
; return 1;
ret
endp
; This is the check going the other way. The XYZ is modified to normalize it
; (another side-effect) and the xy chromaticities are returned.
;int (png_xy *xy, png_XYZ *XYZ)
align 4
proc png_colorspace_check_XYZ, xy:dword, XYZ:dword
; int result;
; png_XYZ XYZtemp;
; result = png_XYZ_normalize(XYZ);
; if (result != 0)
; return result;
; result = png_xy_from_XYZ(xy, XYZ);
; if (result != 0)
; return result;
; XYZtemp = *XYZ;
; return png_colorspace_check_xy(&XYZtemp, xy);
ret
endp
; Used to check for an endpoint match against sRGB
;const png_xy sRGB_xy = /* From ITU-R BT.709-3 */
; /* color x y */
; /* red */ 64000, 33000,
; /* green */ 30000, 60000,
; /* blue */ 15000, 6000,
; /* white */ 31270, 32900
;int (png_structrp png_ptr,
; png_colorspacerp colorspace, const png_xy *xy, const png_XYZ *XYZ,
; int preferred)
align 4
proc png_colorspace_set_xy_and_XYZ, png_ptr:dword, colorspace:dword, xy:dword, XYZ:dword, preferred:dword
; if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
; return 0;
; The consistency check is performed on the chromaticities; this factors out
; variations because of the normalization (or not) of the end point Y
; values.
; if (preferred < 2 &&
; (colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
; {
; The end points must be reasonably close to any we already have. The
; following allows an error of up to +/-.001
; if (png_colorspace_endpoints_match(xy, &colorspace->end_points_xy,
; 100) == 0)
; {
; colorspace->flags |= PNG_COLORSPACE_INVALID;
; png_benign_error(png_ptr, "inconsistent chromaticities");
; return 0; /* failed */
; }
; Only overwrite with preferred values
; if (preferred == 0)
; return 1; /* ok, but no change */
; }
; colorspace->end_points_xy = *xy;
; colorspace->end_points_XYZ = *XYZ;
; colorspace->flags |= PNG_COLORSPACE_HAVE_ENDPOINTS;
; /* The end points are normally quoted to two decimal digits, so allow +/-0.01
; on this test.
; if (png_colorspace_endpoints_match(xy, &sRGB_xy, 1000) != 0)
; colorspace->flags |= PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB;
;
; else
; colorspace->flags &= PNG_COLORSPACE_CANCEL(
; PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
; return 2; /* ok and changed */
ret
endp
;int (png_structrp png_ptr,
; png_colorspacerp colorspace, const png_xy *xy, int preferred)
align 4
proc png_colorspace_set_chromaticities, png_ptr:dword, colorspace:dword, xy:dword, preferred:dword
; We must check the end points to ensure they are reasonable - in the past
; color management systems have crashed as a result of getting bogus
; colorant values, while this isn't the fault of libpng it is the
; responsibility of libpng because PNG carries the bomb and libpng is in a
; position to protect against it.
; png_XYZ XYZ;
; switch (png_colorspace_check_xy(&XYZ, xy))
; {
; case 0: /* success */
; return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, xy, &XYZ,
; preferred);
; case 1:
; We can't invert the chromaticities so we can't produce value XYZ
; values. Likely as not a color management system will fail too.
; colorspace->flags |= PNG_COLORSPACE_INVALID;
; png_benign_error(png_ptr, "invalid chromaticities");
; break;
;
; default:
; libpng is broken; this should be a warning but if it happens we
; want error reports so for the moment it is an error.
; colorspace->flags |= PNG_COLORSPACE_INVALID;
; png_error(png_ptr, "internal error checking chromaticities");
; }
xor eax,eax
.end_f:
ret
endp
;int (png_structrp png_ptr,
; png_colorspacerp colorspace, const png_XYZ *XYZ_in, int preferred)
align 4
proc png_colorspace_set_endpoints, png_ptr:dword, colorspace:dword, XYZ_in:dword, preferred:dword
; png_XYZ XYZ = *XYZ_in;
; png_xy xy;
; switch (png_colorspace_check_XYZ(&xy, &XYZ))
; {
; case 0:
; return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, &xy, &XYZ,
; preferred);
; case 1:
; End points are invalid.
; colorspace->flags |= PNG_COLORSPACE_INVALID;
; png_benign_error(png_ptr, "invalid end points");
; break;
; default:
; colorspace->flags |= PNG_COLORSPACE_INVALID;
; png_error(png_ptr, "internal error checking chromaticities");
; }
xor eax,eax
.end_f:
ret
endp
; Error message generation
;char (uint_32 byte)
align 4
proc png_icc_tag_char, p1byte:dword
mov eax,[p1byte]
cmp al,32
jl @f
cmp al,126
jg @f ;if (..>=.. && ..<=..) return
mov al,'?'
@@:
and eax,0xff
ret
endp
;void (char *name, uint_32 tag)
align 4
proc png_icc_tag_name uses eax edi, name:dword, tag:dword
mov edi,[name]
mov byte[edi],39
mov byte[edi+5],39
inc edi
mov eax,[tag]
shr eax,24
stdcall png_icc_tag_char,eax
stosb
mov eax,[tag]
shr eax,16
stdcall png_icc_tag_char,eax
stosb
mov eax,[tag]
shr eax,8
stdcall png_icc_tag_char,eax
stosb
stdcall png_icc_tag_char,[tag]
stosb
ret
endp
;int (png_alloc_size_t it)
align 4
proc is_ICC_signature_char, it:dword
; return it == 32 || (it >= 48 && it <= 57) || (it >= 65 && it <= 90) ||
; (it >= 97 && it <= 122);
ret
endp
;int (png_alloc_size_t it)
align 4
proc is_ICC_signature, it:dword
; return is_ICC_signature_char(it >> 24) /* checks all the top bits */ &&
; is_ICC_signature_char((it >> 16) & 0xff) &&
; is_ICC_signature_char((it >> 8) & 0xff) &&
; is_ICC_signature_char(it & 0xff);
ret
endp
;int (png_structrp png_ptr, png_colorspacerp colorspace,
; charp name, png_alloc_size_t value, charp reason)
align 4
proc png_icc_profile_error, png_ptr:dword, colorspace:dword, name:dword, value:dword, reason:dword
locals
pos dd ? ;size_t
message rb 196 ;char[] ;see below for calculation
endl
mov eax,[colorspace]
cmp eax,0
je @f ;if (..!=0)
or word[eax+png_colorspace.flags], PNG_COLORSPACE_INVALID
@@:
; pos = png_safecat(message, (sizeof message), 0, "profile '"); /* 9 chars */
; pos = png_safecat(message, pos+79, pos, name); /* Truncate to 79 chars */
; pos = png_safecat(message, (sizeof message), pos, "': "); /* +2 = 90 */
; if (is_ICC_signature(value) != 0)
; {
; So 'value' is at most 4 bytes and the following cast is safe
; png_icc_tag_name(message+pos, (uint_32)value);
; pos += 6; /* total +8; less than the else clause */
; message[pos++] = ':';
; message[pos++] = ' ';
; }
if PNG_WARNINGS_SUPPORTED eq 1
; else
; {
; char number[PNG_NUMBER_BUFFER_SIZE]; /* +24 = 114*/
; pos = png_safecat(message, (sizeof message), pos,
; png_format_number(number, number+(sizeof number),
; PNG_NUMBER_FORMAT_x, value));
; pos = png_safecat(message, (sizeof message), pos, "h: "); /*+2 = 116*/
; }
end if
; The 'reason' is an arbitrary message, allow +79 maximum 195
; pos = png_safecat(message, (sizeof message), pos, reason);
; This is recoverable, but make it unconditionally an app_error on write to
; avoid writing invalid ICC profiles into PNG files (i.e., we handle them
; on read, with a warning, but on write unless the app turns off
; application errors the PNG won't be written.)
; png_chunk_report(png_ptr, message,
; (colorspace != NULL) ? PNG_CHUNK_ERROR : PNG_CHUNK_WRITE_ERROR);
xor eax,eax
ret
endp
if PNG_sRGB_SUPPORTED eq 1
;color X Y Z
sRGB_XYZ dd 41239, 21264, 1933,\ ;red
35758, 71517, 11919,\ ;green
18048, 7219, 95053 ;blue
end if
;int (png_structrp png_ptr, png_colorspacerp colorspace, int intent)
align 4
proc png_colorspace_set_sRGB uses ebx ecx edi esi, png_ptr:dword, colorspace:dword, intent:dword
; sRGB sets known gamma, end points and (from the chunk) intent.
; IMPORTANT: these are not necessarily the values found in an ICC profile
; because ICC profiles store values adapted to a D50 environment; it is
; expected that the ICC profile mediaWhitePointTag will be D50; see the
; checks and code elsewhere to understand this better.
; These XYZ values, which are accurate to 5dp, produce rgb to gray
; coefficients of (6968,23435,2366), which are reduced (because they add up
; to 32769 not 32768) to (6968,23434,2366). These are the values that
; libpng has traditionally used (and are the best values given the 15bit
; algorithm used by the rgb to gray code.)
; Do nothing if the colorspace is already invalidated.
mov ebx,[colorspace]
mov ax,[ebx+png_colorspace.flags]
and ax,PNG_COLORSPACE_INVALID
cmp ax,0
je @f ;if (..!=0)
xor eax,eax
jmp .end_f
@@:
; Check the intent, then check for existing settings. It is valid for the
; PNG file to have cHRM or gAMA chunks along with sRGB, but the values must
; be consistent with the correct values. If, however, this function is
; called below because an iCCP chunk matches sRGB then it is quite
; conceivable that an older app recorded incorrect gAMA and cHRM because of
; an incorrect calculation based on the values in the profile - this does
; *not* invalidate the profile (though it still produces an error, which can
; be ignored.)
mov edi,[png_ptr]
cmp dword[intent],0
jl @f
cmp dword[intent],PNG_sRGB_INTENT_LAST
jge @f
jmp .end0
@@: ;if (..<0 || ..>=..)
cStr ,'sRGB'
cStr ecx,'invalid sRGB rendering intent'
stdcall png_icc_profile_error, edi, ebx, eax, [intent], ecx
jmp .end_f
.end0:
mov ax,[ebx+png_colorspace.flags]
and ax,PNG_COLORSPACE_HAVE_INTENT
cmp ax,0
je @f
movzx eax,word[ebx+png_colorspace.rendering_intent]
cmp eax,[intent]
je @f ;if (..!=0 && ..!=..)
cStr ,'sRGB'
cStr ecx,'inconsistent rendering intents'
stdcall png_icc_profile_error, edi, ebx, eax, [intent], ecx
jmp .end_f
@@:
mov ax,[ebx+png_colorspace.flags]
and ax,PNG_COLORSPACE_FROM_sRGB
cmp ax,0
je @f ;if (..!=0)
png_benign_error edi, 'duplicate sRGB information ignored'
xor eax,eax
jmp .end_f
@@:
; If the standard sRGB cHRM chunk does not match the one from the PNG file
; warn but overwrite the value with the correct one.
mov ax,[ebx+png_colorspace.flags]
and ax,PNG_COLORSPACE_HAVE_ENDPOINTS
cmp ax,0
je @f ;if (..!=0 &&
; !png_colorspace_endpoints_match(&sRGB_xy, &colorspace->end_points_xy,
; 100))
cStr ,'cHRM chunk does not match sRGB'
stdcall png_chunk_report, edi, eax, PNG_CHUNK_ERROR
@@:
; This check is just done for the error reporting - the routine always
; returns true when the 'from' argument corresponds to sRGB (2).
stdcall png_colorspace_check_gamma, edi, ebx, PNG_GAMMA_sRGB_INVERSE, 2 ;from sRGB
; intent: bugs in GCC force 'int' to be used as the parameter type.
mov eax,[intent]
mov [ebx+png_colorspace.rendering_intent],ax
or word[ebx+png_colorspace.flags], PNG_COLORSPACE_HAVE_INTENT
; endpoints
; colorspace->end_points_xy = sRGB_xy;
; colorspace->end_points_XYZ = sRGB_XYZ;
or word[ebx+png_colorspace.flags], (PNG_COLORSPACE_HAVE_ENDPOINTS or PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB)
; gamma
mov dword[ebx+png_colorspace.gamma], PNG_GAMMA_sRGB_INVERSE
or word[ebx+png_colorspace.flags], PNG_COLORSPACE_HAVE_GAMMA
; Finally record that we have an sRGB profile
or word[ebx+png_colorspace.flags], (PNG_COLORSPACE_MATCHES_sRGB or PNG_COLORSPACE_FROM_sRGB)
xor eax,eax
inc eax ;set
.end_f:
ret
endp
;if PNG_iCCP_SUPPORTED
; Encoded value of D50 as an ICC XYZNumber. From the ICC 2010 spec the value
; is XYZ(0.9642,1.0,0.8249), which scales to:
; (63189.8112, 65536, 54060.6464)
D50_nCIEXYZ db \ ;byte[12]
0x00, 0x00, 0xf6, 0xd6, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0xd3, 0x2d
;int /* bool */
;(png_structrp png_ptr, png_colorspacerp colorspace, charp name, uint_32 profile_length)
align 4
proc icc_check_length, png_ptr:dword, colorspace:dword, name:dword, profile_length:dword
cmp dword[profile_length],132
jge @f ;if (..<..)
; return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
; "too short");
jmp .end_f
@@:
xor eax,eax
inc eax
.end_f:
ret
endp
;int (png_structrp png_ptr, png_colorspacerp colorspace,
; charp name, uint_32 profile_length)
align 4
proc png_icc_check_length, png_ptr:dword, colorspace:dword, name:dword, profile_length:dword
; if (!icc_check_length(png_ptr, colorspace, name, profile_length))
; return 0;
; This needs to be here because the 'normal' check is in
; png_decompress_chunk, yet this happens after the attempt to
; png_malloc_base the required data. We only need this on read; on write
; the caller supplies the profile buffer so libpng doesn't allocate it. See
; the call to icc_check_length below (the write case).
if PNG_SET_USER_LIMITS_SUPPORTED eq 1
; else if (png_ptr->user_chunk_malloc_max > 0 &&
; png_ptr->user_chunk_malloc_max < profile_length)
; return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
; "exceeds application limits");
elseif PNG_USER_CHUNK_MALLOC_MAX > 0
; else if (PNG_USER_CHUNK_MALLOC_MAX < profile_length)
; return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
; "exceeds libpng limits");
else ;!SET_USER_LIMITS
; This will get compiled out on all 32-bit and better systems.
; else if (PNG_SIZE_MAX < profile_length)
; return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
; "exceeds system limits");
end if ;!SET_USER_LIMITS
xor eax,eax
inc eax
.end_f:
ret
endp
;int (png_structrp png_ptr, png_colorspacerp colorspace,
; charp name, uint_32 profile_length,
; bytep profile/* first 132 bytes only */, int color_type)
align 4
proc png_icc_check_header, png_ptr:dword, colorspace:dword, name:dword, profile_length:dword, profile:dword, color_type:dword
; uint_32 temp;
; Length check; this cannot be ignored in this code because profile_length
; is used later to check the tag table, so even if the profile seems over
; long profile_length from the caller must be correct. The caller can fix
; this up on read or write by just passing in the profile header length.
; temp = png_get_uint_32(profile);
; if (temp != profile_length)
; return png_icc_profile_error(png_ptr, colorspace, name, temp,
; "length does not match profile");
; temp = (uint_32) (*(profile+8));
; if (temp > 3 && (profile_length & 3))
; return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
; "invalid length");
; temp = png_get_uint_32(profile+128); /* tag count: 12 bytes/tag */
; if (temp > 357913930 || /* (2^32-4-132)/12: maximum possible tag count */
; profile_length < 132+12*temp) /* truncated tag table */
; return png_icc_profile_error(png_ptr, colorspace, name, temp,
; "tag count too large");
; The 'intent' must be valid or we can't store it, ICC limits the intent to
; 16 bits.
; temp = png_get_uint_32(profile+64);
; if (temp >= 0xffff) /* The ICC limit */
; return png_icc_profile_error(png_ptr, colorspace, name, temp,
; "invalid rendering intent");
; This is just a warning because the profile may be valid in future
; versions.
; if (temp >= PNG_sRGB_INTENT_LAST)
; (void)png_icc_profile_error(png_ptr, NULL, name, temp,
; "intent outside defined range");
; At this point the tag table can't be checked because it hasn't necessarily
; been loaded; however, various header fields can be checked. These checks
; are for values permitted by the PNG spec in an ICC profile; the PNG spec
; restricts the profiles that can be passed in an iCCP chunk (they must be
; appropriate to processing PNG data!)
; Data checks (could be skipped). These checks must be independent of the
; version number; however, the version number doesn't accomodate changes in
; the header fields (just the known tags and the interpretation of the
; data.)
; temp = png_get_uint_32(profile+36); /* signature 'ascp' */
; if (temp != 0x61637370)
; return png_icc_profile_error(png_ptr, colorspace, name, temp,
; "invalid signature");
; Currently the PCS illuminant/adopted white point (the computational
; white point) are required to be D50,
; however the profile contains a record of the illuminant so perhaps ICC
; expects to be able to change this in the future (despite the rationale in
; the introduction for using a fixed PCS adopted white.) Consequently the
; following is just a warning.
; if (memcmp(profile+68, D50_nCIEXYZ, 12) != 0)
; (void)png_icc_profile_error(png_ptr, NULL, name, 0/*no tag value*/,
; "PCS illuminant is not D50");
; The PNG spec requires this:
; "If the iCCP chunk is present, the image samples conform to the colour
; space represented by the embedded ICC profile as defined by the
; International Color Consortium [ICC]. The colour space of the ICC profile
; shall be an RGB colour space for colour images (PNG colour types 2, 3, and
; 6), or a greyscale colour space for greyscale images (PNG colour types 0
; and 4)."
; This checking code ensures the embedded profile (on either read or write)
; conforms to the specification requirements. Notice that an ICC 'gray'
; color-space profile contains the information to transform the monochrome
; data to XYZ or L*a*b (according to which PCS the profile uses) and this
; should be used in preference to the standard libpng K channel replication
; into R, G and B channels.
; Previously it was suggested that an RGB profile on grayscale data could be
; handled. However it it is clear that using an RGB profile in this context
; must be an error - there is no specification of what it means. Thus it is
; almost certainly more correct to ignore the profile.
; temp = png_get_uint_32(profile+16); /* data colour space field */
; switch (temp)
; {
; case 0x52474220: /* 'RGB ' */
; if ((color_type & PNG_COLOR_MASK_COLOR) == 0)
; return png_icc_profile_error(png_ptr, colorspace, name, temp,
; "RGB color space not permitted on grayscale PNG");
; break;
; case 0x47524159: /* 'GRAY' */
; if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
; return png_icc_profile_error(png_ptr, colorspace, name, temp,
; "Gray color space not permitted on RGB PNG");
; break;
; default:
; return png_icc_profile_error(png_ptr, colorspace, name, temp,
; "invalid ICC profile color space");
; }
; It is up to the application to check that the profile class matches the
; application requirements; the spec provides no guidance, but it's pretty
; weird if the profile is not scanner ('scnr'), monitor ('mntr'), printer
; ('prtr') or 'spac' (for generic color spaces). Issue a warning in these
; cases. Issue an error for device link or abstract profiles - these don't
; contain the records necessary to transform the color-space to anything
; other than the target device (and not even that for an abstract profile).
; Profiles of these classes may not be embedded in images.
; temp = png_get_uint_32(profile+12); /* profile/device class */
; switch (temp)
; {
; case 0x73636e72: /* 'scnr' */
; case 0x6d6e7472: /* 'mntr' */
; case 0x70727472: /* 'prtr' */
; case 0x73706163: /* 'spac' */
; /* All supported */
; break;
; case 0x61627374: /* 'abst' */
; /* May not be embedded in an image */
; return png_icc_profile_error(png_ptr, colorspace, name, temp,
; "invalid embedded Abstract ICC profile");
; case 0x6c696e6b: /* 'link' */
; /* DeviceLink profiles cannot be interpreted in a non-device specific
; fashion, if an app uses the AToB0Tag in the profile the results are
; undefined unless the result is sent to the intended device,
; therefore a DeviceLink profile should not be found embedded in a
; PNG.
; return png_icc_profile_error(png_ptr, colorspace, name, temp,
; "unexpected DeviceLink ICC profile class");
; case 0x6e6d636c: /* 'nmcl' */
; /* A NamedColor profile is also device specific, however it doesn't
; contain an AToB0 tag that is open to misinterpretation. Almost
; certainly it will fail the tests below.
; (void)png_icc_profile_error(png_ptr, NULL, name, temp,
; "unexpected NamedColor ICC profile class");
; break;
; default:
; /* To allow for future enhancements to the profile accept unrecognized
; profile classes with a warning, these then hit the test below on the
; tag content to ensure they are backward compatible with one of the
; understood profiles.
; (void)png_icc_profile_error(png_ptr, NULL, name, temp,
; "unrecognized ICC profile class");
; break;
; }
; For any profile other than a device link one the PCS must be encoded
; either in XYZ or Lab.
; temp = png_get_uint_32(profile+20);
; switch (temp)
; {
; case 0x58595a20: /* 'XYZ ' */
; case 0x4c616220: /* 'Lab ' */
; break;
; default:
; return png_icc_profile_error(png_ptr, colorspace, name, temp,
; "unexpected ICC PCS encoding");
; }
; return 1;
ret
endp
;int (png_structrp png_ptr, png_colorspacerp colorspace,
; charp name, uint_32 profile_length,
; bytep profile /* header plus whole tag table */)
align 4
proc png_icc_check_tag_table, png_ptr:dword, colorspace:dword, name:dword, profile_length:dword, profile:dword
; uint_32 tag_count = png_get_uint_32(profile+128);
; uint_32 itag;
; bytep tag = profile+132; /* The first tag */
; First scan all the tags in the table and add bits to the icc_info value
; (temporarily in 'tags').
; for (itag=0; itag < tag_count; ++itag, tag += 12)
; {
; uint_32 tag_id = png_get_uint_32(tag+0);
; uint_32 tag_start = png_get_uint_32(tag+4); /* must be aligned */
; uint_32 tag_length = png_get_uint_32(tag+8);/* not padded */
; The ICC specification does not exclude zero length tags, therefore the
; start might actually be anywhere if there is no data, but this would be
; a clear abuse of the intent of the standard so the start is checked for
; being in range. All defined tag types have an 8 byte header - a 4 byte
; type signature then 0.
; if ((tag_start & 3) != 0)
; {
; CNHP730S.icc shipped with Microsoft Windows 64 violates this, it is
; only a warning here because libpng does not care about the
; alignment.
; (void)png_icc_profile_error(png_ptr, NULL, name, tag_id,
; "ICC profile tag start not a multiple of 4");
; }
; This is a hard error; potentially it can cause read outside the
; profile.
; if (tag_start > profile_length || tag_length > profile_length - tag_start)
; return png_icc_profile_error(png_ptr, colorspace, name, tag_id,
; "ICC profile tag outside profile");
; }
xor eax,eax
inc eax ;success, maybe with warnings
.end_f:
ret
endp
;if PNG_sRGB_SUPPORTED
;#if PNG_sRGB_PROFILE_CHECKS >= 0
; Information about the known ICC sRGB profiles
struct png_sRGB_checks
adler dd ? ;uint_32
crc dd ?
length dd ?
md5 rd 4 ;uint_32[4]
have_md5 db ? ;byte
is_broken db ? ;byte
intent dw ? ;uint_16
ends
;# define PNG_MD5(a,b,c,d) { a, b, c, d }, (a!=0)||(b!=0)||(c!=0)||(d!=0)
;# define PNG_ICC_CHECKSUM(adler, crc, md5, intent, broke, date, length, fname)\
; { adler, crc, length, md5, broke, intent },
;[] =
; This data comes from contrib/tools/checksum-icc run on downloads of
; all four ICC sRGB profiles from www.color.org.
; adler32, crc32, MD5[4], intent, date, length, file-name
; PNG_ICC_CHECKSUM(0x0a3fd9f6, 0x3b8772b9,
; PNG_MD5(0x29f83dde, 0xaff255ae, 0x7842fae4, 0xca83390d), 0, 0,
; "2009/03/27 21:36:31", 3048, "sRGB_IEC61966-2-1_black_scaled.icc")
; ICC sRGB v2 perceptual no black-compensation:
; PNG_ICC_CHECKSUM(0x4909e5e1, 0x427ebb21,
; PNG_MD5(0xc95bd637, 0xe95d8a3b, 0x0df38f99, 0xc1320389), 1, 0,
; "2009/03/27 21:37:45", 3052, "sRGB_IEC61966-2-1_no_black_scaling.icc")
; PNG_ICC_CHECKSUM(0xfd2144a1, 0x306fd8ae,
; PNG_MD5(0xfc663378, 0x37e2886b, 0xfd72e983, 0x8228f1b8), 0, 0,
; "2009/08/10 17:28:01", 60988, "sRGB_v4_ICC_preference_displayclass.icc")
; ICC sRGB v4 perceptual
; PNG_ICC_CHECKSUM(0x209c35d2, 0xbbef7812,
; PNG_MD5(0x34562abf, 0x994ccd06, 0x6d2c5721, 0xd0d68c5d), 0, 0,
; "2007/07/25 00:05:37", 60960, "sRGB_v4_ICC_preference.icc")
; The following profiles have no known MD5 checksum. If there is a match
; on the (empty) MD5 the other fields are used to attempt a match and
; a warning is produced. The first two of these profiles have a 'cprt' tag
; which suggests that they were also made by Hewlett Packard.
; PNG_ICC_CHECKSUM(0xa054d762, 0x5d5129ce,
; PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 0,
; "2004/07/21 18:57:42", 3024, "sRGB_IEC61966-2-1_noBPC.icc")
; This is a 'mntr' (display) profile with a mediaWhitePointTag that does not
; match the D50 PCS illuminant in the header (it is in fact the D65 values,
; so the white point is recorded as the un-adapted value.) The profiles
; below only differ in one byte - the intent - and are basically the same as
; the previous profile except for the mediaWhitePointTag error and a missing
; chromaticAdaptationTag.
; PNG_ICC_CHECKSUM(0xf784f3fb, 0x182ea552,
; PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 0, 1/*broken*/,
; "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 perceptual")
; PNG_ICC_CHECKSUM(0x0398f3fc, 0xf29e526d,
; PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 1/*broken*/,
; "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 media-relative")
;
;int (png_structrp png_ptr, bytep profile, uLong adler)
align 4
proc png_compare_ICC_profile_with_sRGB, png_ptr:dword, profile:dword, adler:dword
; The quick check is to verify just the MD5 signature and trust the
; rest of the data. Because the profile has already been verified for
; correctness this is safe. png_colorspace_set_sRGB will check the 'intent'
; field too, so if the profile has been edited with an intent not defined
; by sRGB (but maybe defined by a later ICC specification) the read of
; the profile will fail at that point.
; uint_32 length = 0;
; uint_32 intent = 0x10000; /* invalid */
if PNG_sRGB_PROFILE_CHECKS > 1
; uLong crc = 0; /* the value for 0 length data */
end if
; uint i;
if PNG_SET_OPTION_SUPPORTED eq 1
; First see if PNG_SKIP_sRGB_CHECK_PROFILE has been set to "on"
; if (((png_ptr->options >> PNG_SKIP_sRGB_CHECK_PROFILE) & 3) ==
; PNG_OPTION_ON)
; return 0;
end if
; for (i=0; i < (sizeof png_sRGB_checks) / (sizeof png_sRGB_checks[0]); ++i)
; {
; if (png_get_uint_32(profile+84) == png_sRGB_checks[i].md5[0] &&
; png_get_uint_32(profile+88) == png_sRGB_checks[i].md5[1] &&
; png_get_uint_32(profile+92) == png_sRGB_checks[i].md5[2] &&
; png_get_uint_32(profile+96) == png_sRGB_checks[i].md5[3])
; {
; This may be one of the old HP profiles without an MD5, in that
; case we can only use the length and Adler32 (note that these
; are not used by default if there is an MD5!)
;# if PNG_sRGB_PROFILE_CHECKS == 0
; if (png_sRGB_checks[i].have_md5 != 0)
; return 1+png_sRGB_checks[i].is_broken;
;# endif
; Profile is unsigned or more checks have been configured in.
; if (length == 0)
; {
; length = png_get_uint_32(profile);
; intent = png_get_uint_32(profile+64);
; }
; Length *and* intent must match
; if (length == (uint_32) png_sRGB_checks[i].length &&
; intent == (uint_32) png_sRGB_checks[i].intent)
; {
; Now calculate the adler32 if not done already.
; if (adler == 0)
; {
; adler = adler32(0, NULL, 0);
; adler = adler32(adler, profile, length);
; }
; if (adler == png_sRGB_checks[i].adler)
; {
; These basic checks suggest that the data has not been
; modified, but if the check level is more than 1 perform
; our own crc32 checksum on the data.
;# if PNG_sRGB_PROFILE_CHECKS > 1
; if (crc == 0)
; {
; crc = calc_crc32(0, NULL, 0);
; crc = calc_crc32(crc, profile, length);
; }
; /* So this check must pass for the 'return' below to happen.
; if (crc == png_sRGB_checks[i].crc)
;# endif
; {
; if (png_sRGB_checks[i].is_broken != 0)
; {
; These profiles are known to have bad data that may cause
; problems if they are used, therefore attempt to
; discourage their use, skip the 'have_md5' warning below,
; which is made irrelevant by this error.
; png_chunk_report(png_ptr, "known incorrect sRGB profile",
; PNG_CHUNK_ERROR);
; }
; Warn that this being done; this isn't even an error since
; the profile is perfectly valid, but it would be nice if
; people used the up-to-date ones.
; else if (png_sRGB_checks[i].have_md5 == 0)
; {
; png_chunk_report(png_ptr,
; "out-of-date sRGB profile with no signature",
; PNG_CHUNK_WARNING);
; }
; return 1+png_sRGB_checks[i].is_broken;
; }
; }
;# if PNG_sRGB_PROFILE_CHECKS > 0
; The signature matched, but the profile had been changed in some
; way. This probably indicates a data error or uninformed hacking.
; Fall through to "no match".
; png_chunk_report(png_ptr,
; "Not recognizing known sRGB profile that has been edited",
; PNG_CHUNK_WARNING);
; break;
;# endif
; }
; }
; }
; return 0; /* no match */
ret
endp
;void (png_structrp png_ptr,
; png_colorspacerp colorspace, bytep profile, uLong adler)
align 4
proc png_icc_set_sRGB uses eax, png_ptr:dword, colorspace:dword, profile:dword, adler:dword
; Is this profile one of the known ICC sRGB profiles? If it is, just set
; the sRGB information.
; if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler) != 0)
; (void)png_colorspace_set_sRGB(png_ptr, colorspace,
; (int)/*already checked*/png_get_uint_32(profile+64));
ret
endp
;end if /* PNG_sRGB_PROFILE_CHECKS >= 0 */
;end if /* sRGB */
;int (png_structrp png_ptr, png_colorspacerp colorspace,
; charp name, uint_32 profile_length, bytep profile,
; int color_type)
align 4
proc png_colorspace_set_ICC, png_ptr:dword, colorspace:dword, name:dword, profile_length:dword, profile:dword, color_type:dword
; if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
; return 0;
; if (icc_check_length(png_ptr, colorspace, name, profile_length) != 0 &&
; png_icc_check_header(png_ptr, colorspace, name, profile_length, profile,
; color_type) != 0 &&
; png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
; profile) != 0)
; {
;# if defined(PNG_sRGB_SUPPORTED) && PNG_sRGB_PROFILE_CHECKS >= 0
; If no sRGB support, don't try storing sRGB information
; png_icc_set_sRGB(png_ptr, colorspace, profile, 0);
;# endif
; return 1;
; }
; Failure case
xor eax,eax
.end_f:
ret
endp
;end if /* iCCP */
;void (png_structrp png_ptr)
align 4
proc png_colorspace_set_rgb_coefficients, png_ptr:dword
; Set the rgb_to_gray coefficients from the colorspace.
; if (png_ptr->rgb_to_gray_coefficients_set == 0 &&
; (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
; {
; png_set_background has not been called, get the coefficients from the Y
; values of the colorspace colorants.
; png_fixed_point r = png_ptr->colorspace.end_points_XYZ.red_Y;
; png_fixed_point g = png_ptr->colorspace.end_points_XYZ.green_Y;
; png_fixed_point b = png_ptr->colorspace.end_points_XYZ.blue_Y;
; png_fixed_point total = r+g+b;
; if (total > 0 &&
; r >= 0 && png_muldiv(&r, r, 32768, total) && r >= 0 && r <= 32768 &&
; g >= 0 && png_muldiv(&g, g, 32768, total) && g >= 0 && g <= 32768 &&
; b >= 0 && png_muldiv(&b, b, 32768, total) && b >= 0 && b <= 32768 &&
; r+g+b <= 32769)
; {
; We allow 0 coefficients here. r+g+b may be 32769 if two or
; all of the coefficients were rounded up. Handle this by
; reducing the *largest* coefficient by 1; this matches the
; approach used for the default coefficients in pngrtran.c
; int add = 0;
;
; if (r+g+b > 32768)
; add = -1;
; else if (r+g+b < 32768)
; add = 1;
; if (add != 0)
; {
; if (g >= r && g >= b)
; g += add;
; else if (r >= g && r >= b)
; r += add;
; else
; b += add;
; }
; /* Check for an internal error. */
; if (r+g+b != 32768)
; png_error(png_ptr,
; "internal error handling cHRM coefficients");
; else
; {
; png_ptr->rgb_to_gray_red_coeff = (uint_16)r;
; png_ptr->rgb_to_gray_green_coeff = (uint_16)g;
; }
; }
; This is a png_error at present even though it could be ignored -
; it should never happen, but it is important that if it does, the
; bug is fixed.
; else
; png_error(png_ptr, "internal error handling cHRM->XYZ");
; }
ret
endp
;end if /* COLORSPACE */
;void (png_structrp png_ptr,
; uint_32 width, uint_32 height, int bit_depth,
; int color_type, int interlace_type, int compression_type, int filter_type)
align 4
proc png_check_IHDR uses eax ebx edi, png_ptr:dword, width:dword, height:dword, bit_depth:dword, color_type:dword, interlace_type:dword, compression_type:dword, filter_type:dword
mov edi,[png_ptr]
xor ebx,ebx
; Check for width and height valid values
cmp dword[width],0
jne @f ;if (..==0)
png_warning edi, 'Image width is zero in IHDR'
inc ebx
@@:
cmp dword[width],PNG_UINT_31_MAX
jle @f ;if (..>..)
png_warning edi, 'Invalid image width in IHDR'
inc ebx
@@:
; 48 - big_row_buf hack
; 1 - filter byte
; 8 - 8-byte RGBA pixels
; 1 - extra max_pixel_depth pad
mov eax,[width]
add eax,7
and eax,not 7
cmp eax,((PNG_SIZE_MAX -48 -1) / 8) -1
jle @f ;if (..>..)
; The size of the row must be within the limits of this architecture.
; Because the read code can perform arbitrary transformations the
; maximum size is checked here. Because the code in png_read_start_row
; adds extra space "for safety's sake" in several places a conservative
; limit is used here.
; NOTE: it would be far better to check the size that is actually used,
; but the effect in the real world is minor and the changes are more
; extensive, therefore much more dangerous and much more difficult to
; write in a way that avoids compiler warnings.
png_warning edi, 'Image width is too large for this architecture'
inc ebx
@@:
if PNG_SET_USER_LIMITS_SUPPORTED eq 1
mov eax,[edi+png_struct.user_width_max]
cmp dword[width],eax
else
cmp dword[width],PNG_USER_WIDTH_MAX
end if
jle @f ;if (..>..)
png_warning edi, 'Image width exceeds user limit in IHDR'
inc ebx
@@:
cmp dword[height],0
jne @f ;if (..==0)
png_warning edi, 'Image height is zero in IHDR'
inc ebx
@@:
cmp dword[height],PNG_UINT_31_MAX
jle @f ;if (..>..)
png_warning edi, 'Invalid image height in IHDR'
inc ebx
@@:
if PNG_SET_USER_LIMITS_SUPPORTED eq 1
mov eax,[edi+png_struct.user_height_max]
cmp dword[height],eax
else
cmp dword[height],PNG_USER_HEIGHT_MAX
end if
jle @f ;if (..>..)
png_warning edi, 'Image height exceeds user limit in IHDR'
inc ebx
@@:
; Check other values
cmp dword[bit_depth],1
je @f
cmp dword[bit_depth],2
je @f
cmp dword[bit_depth],4
je @f
cmp dword[bit_depth],8
je @f
cmp dword[bit_depth],16
je @f ;if (..!=.. && ...)
png_warning edi, 'Invalid bit depth in IHDR'
inc ebx
@@:
cmp dword[color_type],0
jl @f
cmp dword[color_type],1
je @f
cmp dword[color_type],5
je @f
cmp dword[color_type],6
jg @f
jmp .end0
@@: ;if (..<0 || ..==1 || ..==5 || ..>6)
png_warning edi, 'Invalid color type in IHDR'
inc ebx
.end0:
cmp dword[color_type],PNG_COLOR_TYPE_PALETTE
jne @f
cmp dword[bit_depth],8
jg .beg1
@@:
cmp dword[color_type],PNG_COLOR_TYPE_RGB
je @f
cmp dword[color_type],PNG_COLOR_TYPE_GRAY_ALPHA
je @f
cmp dword[color_type],PNG_COLOR_TYPE_RGB_ALPHA
jne .end1
@@:
cmp dword[bit_depth],8
jge .end1
.beg1: ;if (((..==..) && ..>..) || ((..==.. || ..==.. || ..==..) && ..<..))
png_warning edi, 'Invalid color type/bit depth combination in IHDR'
inc ebx
.end1:
cmp dword[interlace_type],PNG_INTERLACE_LAST
jl @f ;if (..>=..)
png_warning edi, 'Unknown interlace method in IHDR'
inc ebx
@@:
cmp dword[compression_type],PNG_COMPRESSION_TYPE_BASE
je @f ;if (..!=..)
png_warning edi, 'Unknown compression method in IHDR'
inc ebx
@@:
if PNG_MNG_FEATURES_SUPPORTED eq 1
; Accept filter_method 64 (intrapixel differencing) only if
; 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
; 2. Libpng did not read a PNG signature (this filter_method is only
; used in PNG datastreams that are embedded in MNG datastreams) and
; 3. The application called png_permit_mng_features with a mask that
; included PNG_FLAG_MNG_FILTER_64 and
; 4. The filter_method is 64 and
; 5. The color_type is RGB or RGBA
; if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0 &&
; png_ptr->mng_features_permitted != 0)
png_warning edi, 'MNG features are not allowed in a PNG datastream'
; if (filter_type != PNG_FILTER_TYPE_BASE)
; {
; if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
; (filter_type == PNG_INTRAPIXEL_DIFFERENCING) &&
; ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
; (color_type == PNG_COLOR_TYPE_RGB ||
; color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
; {
png_warning edi, 'Unknown filter method in IHDR'
inc ebx
; }
; if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0)
; {
png_warning edi, 'Invalid filter method in IHDR'
inc ebx
; }
; }
else
cmp dword[filter_type],PNG_FILTER_TYPE_BASE
je @f ;if (..!=..)
png_warning edi, 'Unknown filter method in IHDR'
inc ebx
@@:
end if
cmp ebx,0
je @f
png_error edi, 'Invalid IHDR data'
@@:
ret
endp
;#if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
; ASCII to fp functions
; Check an ASCII formated floating point value, see the more detailed
; comments in pngpriv.inc
; The following is used internally to preserve the sticky flags */
;#define png_fp_add(state, flags) ((state) |= (flags))
;#define png_fp_set(state, value) ((state) = (value) | ((state) & PNG_FP_STICKY))
;int (charp string, png_size_t size, int *statep, png_size_tp whereami)
align 4
proc png_check_fp_number, string:dword, size:dword, statep:dword, whereami:dword
; int state = *statep;
; png_size_t i = *whereami;
; while (i < size)
; {
; int type;
; First find the type of the next character
; switch (string[i])
; {
; case 43: type = PNG_FP_SAW_SIGN; break;
; case 45: type = PNG_FP_SAW_SIGN + PNG_FP_NEGATIVE; break;
; case 46: type = PNG_FP_SAW_DOT; break;
; case 48: type = PNG_FP_SAW_DIGIT; break;
; case 49: case 50: case 51: case 52:
; case 53: case 54: case 55: case 56:
; case 57: type = PNG_FP_SAW_DIGIT + PNG_FP_NONZERO; break;
; case 69:
; case 101: type = PNG_FP_SAW_E; break;
; default: goto PNG_FP_End;
; }
; Now deal with this type according to the current
; state, the type is arranged to not overlap the
; bits of the PNG_FP_STATE.
; switch ((state & PNG_FP_STATE) + (type & PNG_FP_SAW_ANY))
; {
; case PNG_FP_INTEGER + PNG_FP_SAW_SIGN:
; if ((state & PNG_FP_SAW_ANY) != 0)
; goto PNG_FP_End; /* not a part of the number */
; png_fp_add(state, type);
; break;
; case PNG_FP_INTEGER + PNG_FP_SAW_DOT:
; Ok as trailer, ok as lead of fraction.
; if ((state & PNG_FP_SAW_DOT) != 0) /* two dots */
; goto PNG_FP_End;
; else if ((state & PNG_FP_SAW_DIGIT) != 0) /* trailing dot? */
; png_fp_add(state, type);
; else
; png_fp_set(state, PNG_FP_FRACTION | type);
; break;
; case PNG_FP_INTEGER + PNG_FP_SAW_DIGIT:
; if ((state & PNG_FP_SAW_DOT) != 0) /* delayed fraction */
; png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT);
; png_fp_add(state, type | PNG_FP_WAS_VALID);
; break;
; case PNG_FP_INTEGER + PNG_FP_SAW_E:
; if ((state & PNG_FP_SAW_DIGIT) == 0)
; goto PNG_FP_End;
; png_fp_set(state, PNG_FP_EXPONENT);
; break;
; /* case PNG_FP_FRACTION + PNG_FP_SAW_SIGN: goto PNG_FP_End; ** no sign in fraction */
; /* case PNG_FP_FRACTION + PNG_FP_SAW_DOT: goto PNG_FP_End; ** Because SAW_DOT is always set */
; case PNG_FP_FRACTION + PNG_FP_SAW_DIGIT:
; png_fp_add(state, type | PNG_FP_WAS_VALID);
; break;
; case PNG_FP_FRACTION + PNG_FP_SAW_E:
; This is correct because the trailing '.' on an
; integer is handled above - so we can only get here
; with the sequence ".E" (with no preceding digits).
; if ((state & PNG_FP_SAW_DIGIT) == 0)
; goto PNG_FP_End;
; png_fp_set(state, PNG_FP_EXPONENT);
; break;
; case PNG_FP_EXPONENT + PNG_FP_SAW_SIGN:
; if ((state & PNG_FP_SAW_ANY) != 0)
; goto PNG_FP_End; /* not a part of the number */
; png_fp_add(state, PNG_FP_SAW_SIGN);
; break;
; /* case PNG_FP_EXPONENT + PNG_FP_SAW_DOT: goto PNG_FP_End; */
; case PNG_FP_EXPONENT + PNG_FP_SAW_DIGIT:
; png_fp_add(state, PNG_FP_SAW_DIGIT | PNG_FP_WAS_VALID);
; break;
; /* case PNG_FP_EXPONEXT + PNG_FP_SAW_E: goto PNG_FP_End; */
; default: goto PNG_FP_End; /* I.e. break 2 */
; }
; The character seems ok, continue.
; ++i;
; }
;
;PNG_FP_End:
; Here at the end, update the state and return the correct
; return code.
; *statep = state;
; *whereami = i;
; return (state & PNG_FP_SAW_DIGIT) != 0;
ret
endp
; The same but for a complete string.
;int (charp string, png_size_t size)
align 4
proc png_check_fp_string, string:dword, size:dword
; int state=0;
; png_size_t char_index=0;
;
; if (png_check_fp_number(string, size, &state, &char_index) != 0 &&
; (char_index == size || string[char_index] == 0))
; return state /* must be non-zero - see above */;
; return 0; /* i.e. fail */
ret
endp
;end if /* pCAL || sCAL */
;if PNG_sCAL_SUPPORTED
;# ifdef PNG_FLOATING_POINT_SUPPORTED
; Utility used below - a simple accurate power of ten from an integral
; exponent.
;double (int power)
align 4
proc png_pow10, power:dword
; int recip = 0;
; double d = 1;
; Handle negative exponent with a reciprocal at the end because
; 10 is exact whereas .1 is inexact in base 2
; if (power < 0)
; {
; if (power < DBL_MIN_10_EXP) return 0;
; recip = 1, power = -power;
; }
; if (power > 0)
; {
; Decompose power bitwise.
; double mult = 10;
; do
; {
; if (power & 1) d *= mult;
; mult *= mult;
; power >>= 1;
; }
; while (power > 0);
; if (recip != 0) d = 1/d;
; }
; else power is 0 and d is 1
; return d;
ret
endp
; Function to format a floating point value in ASCII with a given
; precision.
;void (png_structrp png_ptr, charp ascii, png_size_t size,
; double fp, uint precision)
align 4
proc png_ascii_from_fp, png_ptr:dword, ascii:dword, size:dword, fp:dword, precision:dword
; We use standard functions from math.h, but not printf because
; that would require stdio. The caller must supply a buffer of
; sufficient size or we will png_error. The tests on size and
; the space in ascii[] consumed are indicated below.
; if (precision < 1)
; precision = DBL_DIG;
; Enforce the limit of the implementation precision too.
; if (precision > DBL_DIG+1)
; precision = DBL_DIG+1;
; Basic sanity checks
; if (size >= precision+5) /* See the requirements below. */
; {
; if (fp < 0)
; {
; fp = -fp;
; *ascii++ = 45; /* '-' PLUS 1 TOTAL 1 */
; --size;
; }
; if (fp >= DBL_MIN && fp <= DBL_MAX)
; {
; int exp_b10; /* A base 10 exponent */
; double base; /* 10^exp_b10 */
; First extract a base 10 exponent of the number,
; the calculation below rounds down when converting
; from base 2 to base 10 (multiply by log10(2) -
; 0.3010, but 77/256 is 0.3008, so exp_b10 needs to
; be increased. Note that the arithmetic shift
; performs a floor() unlike C arithmetic - using a
; C multiply would break the following for negative
; exponents.
; (void)frexp(fp, &exp_b10); /* exponent to base 2 */
; exp_b10 = (exp_b10 * 77) >> 8; /* <= exponent to base 10 */
; /* Avoid underflow here. */
; base = png_pow10(exp_b10); /* May underflow */
; while (base < DBL_MIN || base < fp)
; {
; /* And this may overflow. */
; double test = png_pow10(exp_b10+1);
; if (test <= DBL_MAX)
; ++exp_b10, base = test;
; else
; break;
; }
; Normalize fp and correct exp_b10, after this fp is in the
; range [.1,1) and exp_b10 is both the exponent and the digit
; *before* which the decimal point should be inserted
; (starting with 0 for the first digit). Note that this
; works even if 10^exp_b10 is out of range because of the
; test on DBL_MAX above.
; fp /= base;
; while (fp >= 1) fp /= 10, ++exp_b10;
; Because of the code above fp may, at this point, be
; less than .1, this is ok because the code below can
; handle the leading zeros this generates, so no attempt
; is made to correct that here.
; {
; uint czero, clead, cdigits;
; char exponent[10];
; Allow up to two leading zeros - this will not lengthen
; the number compared to using E-n.
; if (exp_b10 < 0 && exp_b10 > -3) /* PLUS 3 TOTAL 4 */
; {
; czero = -exp_b10; /* PLUS 2 digits: TOTAL 3 */
; exp_b10 = 0; /* Dot added below before first output. */
; }
; else
; czero = 0; /* No zeros to add */
; Generate the digit list, stripping trailing zeros and
; inserting a '.' before a digit if the exponent is 0.
; clead = czero; /* Count of leading zeros */
; cdigits = 0; /* Count of digits in list. */
; do
; {
; double d;
; fp *= 10;
; Use modf here, not floor and subtract, so that
; the separation is done in one step. At the end
; of the loop don't break the number into parts so
; that the final digit is rounded.
; if (cdigits+czero+1 < precision+clead)
; fp = modf(fp, &d);
; else
; {
; d = floor(fp + .5);
; if (d > 9)
; {
; /* Rounding up to 10, handle that here. */
; if (czero > 0)
; {
; --czero, d = 1;
; if (cdigits == 0) --clead;
; }
; else
; {
; while (cdigits > 0 && d > 9)
; {
; int ch = *--ascii;
; if (exp_b10 != (-1))
; ++exp_b10;
; else if (ch == 46)
; {
; ch = *--ascii, ++size;
; /* Advance exp_b10 to '1', so that the
; * decimal point happens after the
; * previous digit.
; exp_b10 = 1;
; }
; --cdigits;
; d = ch - 47; /* I.e. 1+(ch-48) */
; }
; /* Did we reach the beginning? If so adjust the
; * exponent but take into account the leading
; * decimal point.
; if (d > 9) /* cdigits == 0 */
; {
; if (exp_b10 == (-1))
; {
; Leading decimal point (plus zeros?), if
; we lose the decimal point here it must
; be reentered below.
; int ch = *--ascii;
; if (ch == 46)
; ++size, exp_b10 = 1;
; /* Else lost a leading zero, so 'exp_b10' is
; * still ok at (-1)
; }
; else
; ++exp_b10;
; /* In all cases we output a '1' */
; d = 1;
; }
; }
; }
; fp = 0; /* Guarantees termination below. */
; }
; if (d == 0)
; {
; ++czero;
; if (cdigits == 0) ++clead;
; }
; else
; {
; /* Included embedded zeros in the digit count. */
; cdigits += czero - clead;
; clead = 0;
; while (czero > 0)
; {
; exp_b10 == (-1) means we just output the decimal
; place - after the DP don't adjust 'exp_b10' any
; more!
; if (exp_b10 != (-1))
; {
; if (exp_b10 == 0) *ascii++ = 46, --size;
; /* PLUS 1: TOTAL 4 */
; --exp_b10;
; }
; *ascii++ = 48, --czero;
; }
; if (exp_b10 != (-1))
; {
; if (exp_b10 == 0)
; *ascii++ = 46, --size; /* counted above */
; --exp_b10;
; }
; *ascii++ = (char)(48 + (int)d), ++cdigits;
; }
; }
; while (cdigits+czero < precision+clead && fp > DBL_MIN);
; /* The total output count (max) is now 4+precision */
; Check for an exponent, if we don't need one we are
; done and just need to terminate the string. At
; this point exp_b10==(-1) is effectively if flag - it got
; to '-1' because of the decrement after outputting
; the decimal point above (the exponent required is
; *not* -1!)
; if (exp_b10 >= (-1) && exp_b10 <= 2)
; {
; The following only happens if we didn't output the
; leading zeros above for negative exponent, so this
; doesn't add to the digit requirement. Note that the
; two zeros here can only be output if the two leading
; zeros were *not* output, so this doesn't increase
; the output count.
; while (--exp_b10 >= 0) *ascii++ = 48;
; *ascii = 0;
; /* Total buffer requirement (including the '\0') is
; 5+precision - see check at the start.
; return;
; }
; Here if an exponent is required, adjust size for
; the digits we output but did not count. The total
; digit output here so far is at most 1+precision - no
; decimal point and no leading or trailing zeros have
; been output.
; size -= cdigits;
;
; *ascii++ = 69, --size; /* 'E': PLUS 1 TOTAL 2+precision */
; The following use of an unsigned temporary avoids ambiguities in
; the signed arithmetic on exp_b10 and permits GCC at least to do
; better optimization.
; {
; uint uexp_b10;
; if (exp_b10 < 0)
; {
; *ascii++ = 45, --size; /* '-': PLUS 1 TOTAL 3+precision */
; uexp_b10 = -exp_b10;
; }
; else
; uexp_b10 = exp_b10;
; cdigits = 0;
; while (uexp_b10 > 0)
; {
; exponent[cdigits++] = (char)(48 + uexp_b10 % 10);
; uexp_b10 /= 10;
; }
; }
; Need another size check here for the exponent digits, so
; this need not be considered above.
; if (size > cdigits)
; {
; while (cdigits > 0) *ascii++ = exponent[--cdigits];
; *ascii = 0;
; return;
; }
; }
; }
; else if (!(fp >= DBL_MIN))
; {
; *ascii++ = 48; /* '0' */
; *ascii = 0;
; return;
; }
; else
; {
; *ascii++ = 105; /* 'i' */
; *ascii++ = 110; /* 'n' */
; *ascii++ = 102; /* 'f' */
; *ascii = 0;
; return;
; }
; }
; Here on buffer too small.
; png_error(png_ptr, "ASCII conversion buffer too small");
ret
endp
;# endif /* FLOATING_POINT */
; Function to format a fixed point value in ASCII.
;void (png_structrp png_ptr, charp ascii, png_size_t size, png_fixed_point fp)
align 4
proc png_ascii_from_fixed, png_ptr:dword, ascii:dword, size:dword, fp:dword
; Require space for 10 decimal digits, a decimal point, a minus sign and a
; trailing \0, 13 characters:
cmp dword[size],12
jle .end0 ;if (..>..)
; uint_32 num;
; Avoid overflow here on the minimum integer.
; if (fp < 0)
; *ascii++ = 45, num = -fp;
; else
; num = fp;
; if (num <= 0x80000000) /* else overflowed */
; {
; uint ndigits = 0, first = 16 /* flag value */;
; char digits[10];
; while (num)
; {
; Split the low digit off num:
; uint tmp = num/10;
; num -= tmp*10;
; digits[ndigits++] = (char)(48 + num);
; Record the first non-zero digit, note that this is a number
; starting at 1, it's not actually the array index.
; if (first == 16 && num > 0)
; first = ndigits;
; num = tmp;
; }
; if (ndigits > 0)
; {
; while (ndigits > 5) *ascii++ = digits[--ndigits];
; The remaining digits are fractional digits, ndigits is '5' or
; smaller at this point. It is certainly not zero. Check for a
; non-zero fractional digit:
; if (first <= 5)
; {
; uint i;
; *ascii++ = 46; /* decimal point */
; ndigits may be <5 for small numbers, output leading zeros
; then ndigits digits to first:
; i = 5;
; while (ndigits < i) *ascii++ = 48, --i;
; while (ndigits >= first) *ascii++ = digits[--ndigits];
; Don't output the trailing zeros!
; }
; }
; else
; *ascii++ = 48;
; And null terminate the string:
; *ascii = 0;
; return;
; }
.end0:
; Here on buffer too small.
png_error [png_ptr], 'ASCII conversion buffer too small'
ret
endp
;end if /* SCAL */
;png_fixed_point (png_structrp png_ptr, double fp, charp text)
align 4
proc png_fixed, png_ptr:dword, fp:dword, text:dword
; double r = floor(100000 * fp + .5);
; if (r > 2147483647. || r < -2147483648.)
; png_fixed_error(png_ptr, text);
; return (png_fixed_point)r;
ret
endp
; muldiv functions
; This API takes signed arguments and rounds the result to the nearest
; integer (or, for a fixed point number - the standard argument - to
; the nearest .00001). Overflow and divide by zero are signalled in
; the result, a boolean - true on success, false on overflow.
;int (png_fixed_point_p res, png_fixed_point a, int_32 times, int_32 divisor)
align 4
proc png_muldiv, res:dword, a:dword, p3times:dword, divisor:dword
; Return a * times / divisor, rounded.
; if (divisor != 0)
; {
; if (a == 0 || p3times == 0)
; {
; *res = 0;
; return 1;
; }
; else
; {
if PNG_FLOATING_ARITHMETIC_SUPPORTED eq 1
; double r = a;
; r *= p3times;
; r /= divisor;
; r = floor(r+.5);
; /* A png_fixed_point is a 32-bit integer. */
; if (r <= 2147483647. && r >= -2147483648.)
; {
; *res = (png_fixed_point)r;
; return 1;
; }
else
; int negative = 0;
; uint_32 A, T, D;
; uint_32 s16, s32, s00;
; if (a < 0)
; negative = 1, A = -a;
; else
; A = a;
; if (p3times < 0)
; negative = !negative, T = -p3times;
; else
; T = p3times;
; if (divisor < 0)
; negative = !negative, D = -divisor;
; else
; D = divisor;
; Following can't overflow because the arguments only
; have 31 bits each, however the result may be 32 bits.
; s16 = (A >> 16) * (T & 0xffff) +
; (A & 0xffff) * (T >> 16);
; Can't overflow because the a*times bit is only 30
; bits at most.
; s32 = (A >> 16) * (T >> 16) + (s16 >> 16);
; s00 = (A & 0xffff) * (T & 0xffff);
; s16 = (s16 & 0xffff) << 16;
; s00 += s16;
; if (s00 < s16)
; ++s32; /* carry */
; if (s32 < D) /* else overflow */
; {
; s32.s00 is now the 64-bit product, do a standard
; division, we know that s32 < D, so the maximum
; required shift is 31.
; int bitshift = 32;
; png_fixed_point result = 0; /* NOTE: signed */
; while (--bitshift >= 0)
; {
; uint_32 d32, d00;
; if (bitshift > 0)
; d32 = D >> (32-bitshift), d00 = D << bitshift;
; else
; d32 = 0, d00 = D;
; if (s32 > d32)
; {
; if (s00 < d00) --s32; /* carry */
; s32 -= d32, s00 -= d00, result += 1<<bitshift;
; }
; else
; if (s32 == d32 && s00 >= d00)
; s32 = 0, s00 -= d00, result += 1<<bitshift;
; }
; /* Handle the rounding. */
; if (s00 >= (D >> 1))
; ++result;
; if (negative != 0)
; result = -result;
; /* Check for overflow. */
; if ((negative != 0 && result <= 0) ||
; (negative == 0 && result >= 0))
; {
; *res = result;
; return 1;
; }
; }
end if
; }
; }
xor eax,eax
ret
endp
; The following is for when the caller doesn't much care about the
; result.
;png_fixed_point (png_structrp png_ptr, png_fixed_point a, int_32 times,
; int_32 divisor)
align 4
proc png_muldiv_warn, png_ptr:dword, a:dword, p3times:dword, divisor:dword
; png_fixed_point result;
; if (png_muldiv(&result, a, p3times, divisor) != 0)
; return result;
png_warning [png_ptr], 'fixed point overflow ignored'
xor eax,eax
ret
endp
; Calculate a reciprocal, return 0 on div-by-zero or overflow.
;png_fixed_point (png_fixed_point a)
align 4
proc png_reciprocal, a:dword
if PNG_FLOATING_ARITHMETIC_SUPPORTED eq 1
; double r = floor(1E10/a+.5);
; if (r <= 2147483647. && r >= -2147483648.)
; return (png_fixed_point)r;
else
; png_fixed_point res;
; if (png_muldiv(&res, 100000, 100000, a) != 0)
; return res;
end if
; return 0; /* error/overflow */
ret
endp
; This is the shared test on whether a gamma value is 'significant' - whether
; it is worth doing gamma correction.
;int (png_fixed_point gamma_val)
align 4
proc png_gamma_significant, gamma_val:dword
; return gamma_val < PNG_FP_1 - PNG_GAMMA_THRESHOLD_FIXED ||
; gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED;
ret
endp
;if PNG_READ_GAMMA_SUPPORTED
; A local convenience routine.
;png_fixed_point (png_fixed_point a, png_fixed_point b)
align 4
proc png_product2, a:dword, b:dword
; The required result is 1/a * 1/b; the following preserves accuracy.
if PNG_FLOATING_ARITHMETIC_SUPPORTED eq 1
; double r = a * 1E-5;
; r *= b;
; r = floor(r+.5);
; if (r <= 2147483647. && r >= -2147483648.)
; return (png_fixed_point)r;
else
; png_fixed_point res;
; if (png_muldiv(&res, a, b, 100000) != 0)
; return res;
end if
; return 0; /* overflow */
ret
endp
; The inverse of the above.
;png_fixed_point (png_fixed_point a, png_fixed_point b)
align 4
proc png_reciprocal2, a:dword, b:dword
; The required result is 1/a * 1/b; the following preserves accuracy.
if PNG_FLOATING_ARITHMETIC_SUPPORTED eq 1
; if (a != 0 && b != 0)
; {
; double r = 1E15/a;
; r /= b;
; r = floor(r+.5);
;
; if (r <= 2147483647. && r >= -2147483648.)
; return (png_fixed_point)r;
; }
else
; This may overflow because the range of png_fixed_point isn't symmetric,
; but this API is only used for the product of file and screen gamma so it
; doesn't matter that the smallest number it can produce is 1/21474, not
; 1/100000
; png_fixed_point res = png_product2(a, b);
; if (res != 0)
; return png_reciprocal(res);
end if
; return 0; /* overflow */
ret
endp
;end if /* READ_GAMMA */
;if PNG_READ_GAMMA_SUPPORTED /* gamma table code */
;#ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED
; Fixed point gamma.
; The code to calculate the tables used below can be found in the shell script
; contrib/tools/intgamma.sh
; To calculate gamma this code implements fast log() and exp() calls using only
; fixed point arithmetic. This code has sufficient precision for either 8-bit
; or 16-bit sample values.
; The tables used here were calculated using simple 'bc' programs, but C double
; precision floating point arithmetic would work fine.
; 8-bit log table
; This is a table of -log(value/255)/log(2) for 'value' in the range 128 to
; 255, so it's the base 2 logarithm of a normalized 8-bit floating point
; mantissa. The numbers are 32-bit fractions.
;const uint_32
;png_8bit_l2[128] =
; 4270715492U, 4222494797U, 4174646467U, 4127164793U, 4080044201U, 4033279239U,
; 3986864580U, 3940795015U, 3895065449U, 3849670902U, 3804606499U, 3759867474U,
; 3715449162U, 3671346997U, 3627556511U, 3584073329U, 3540893168U, 3498011834U,
; 3455425220U, 3413129301U, 3371120137U, 3329393864U, 3287946700U, 3246774933U,
; 3205874930U, 3165243125U, 3124876025U, 3084770202U, 3044922296U, 3005329011U,
; 2965987113U, 2926893432U, 2888044853U, 2849438323U, 2811070844U, 2772939474U,
; 2735041326U, 2697373562U, 2659933400U, 2622718104U, 2585724991U, 2548951424U,
; 2512394810U, 2476052606U, 2439922311U, 2404001468U, 2368287663U, 2332778523U,
; 2297471715U, 2262364947U, 2227455964U, 2192742551U, 2158222529U, 2123893754U,
; 2089754119U, 2055801552U, 2022034013U, 1988449497U, 1955046031U, 1921821672U,
; 1888774511U, 1855902668U, 1823204291U, 1790677560U, 1758320682U, 1726131893U,
; 1694109454U, 1662251657U, 1630556815U, 1599023271U, 1567649391U, 1536433567U,
; 1505374214U, 1474469770U, 1443718700U, 1413119487U, 1382670639U, 1352370686U,
; 1322218179U, 1292211689U, 1262349810U, 1232631153U, 1203054352U, 1173618059U,
; 1144320946U, 1115161701U, 1086139034U, 1057251672U, 1028498358U, 999877854U,
; 971388940U, 943030410U, 914801076U, 886699767U, 858725327U, 830876614U,
; 803152505U, 775551890U, 748073672U, 720716771U, 693480120U, 666362667U,
; 639363374U, 612481215U, 585715177U, 559064263U, 532527486U, 506103872U,
; 479792461U, 453592303U, 427502463U, 401522014U, 375650043U, 349885648U,
; 324227938U, 298676034U, 273229066U, 247886176U, 222646516U, 197509248U,
; 172473545U, 147538590U, 122703574U, 97967701U, 73330182U, 48790236U,
; 24347096U, 0U
if 0
; The following are the values for 16-bit tables - these work fine for the
; 8-bit conversions but produce very slightly larger errors in the 16-bit
; log (about 1.2 as opposed to 0.7 absolute error in the final value). To
; use these all the shifts below must be adjusted appropriately.
; 65166, 64430, 63700, 62976, 62257, 61543, 60835, 60132, 59434, 58741, 58054,
; 57371, 56693, 56020, 55352, 54689, 54030, 53375, 52726, 52080, 51439, 50803,
; 50170, 49542, 48918, 48298, 47682, 47070, 46462, 45858, 45257, 44661, 44068,
; 43479, 42894, 42312, 41733, 41159, 40587, 40020, 39455, 38894, 38336, 37782,
; 37230, 36682, 36137, 35595, 35057, 34521, 33988, 33459, 32932, 32408, 31887,
; 31369, 30854, 30341, 29832, 29325, 28820, 28319, 27820, 27324, 26830, 26339,
; 25850, 25364, 24880, 24399, 23920, 23444, 22970, 22499, 22029, 21562, 21098,
; 20636, 20175, 19718, 19262, 18808, 18357, 17908, 17461, 17016, 16573, 16132,
; 15694, 15257, 14822, 14390, 13959, 13530, 13103, 12678, 12255, 11834, 11415,
; 10997, 10582, 10168, 9756, 9346, 8937, 8531, 8126, 7723, 7321, 6921, 6523,
; 6127, 5732, 5339, 4947, 4557, 4169, 3782, 3397, 3014, 2632, 2251, 1872, 1495,
; 1119, 744, 372
end if
;int_32 (uint x)
align 4
proc png_log8bit, x:dword
; uint lg2 = 0;
; Each time 'x' is multiplied by 2, 1 must be subtracted off the final log,
; because the log is actually negate that means adding 1. The final
; returned value thus has the range 0 (for 255 input) to 7.994 (for 1
; input), return -1 for the overflow (log 0) case, - so the result is
; always at most 19 bits.
; if ((x &= 0xff) == 0)
; return -1;
; if ((x & 0xf0) == 0)
; lg2 = 4, x <<= 4;
; if ((x & 0xc0) == 0)
; lg2 += 2, x <<= 2;
; if ((x & 0x80) == 0)
; lg2 += 1, x <<= 1;
; result is at most 19 bits, so this cast is safe:
; return (int_32)((lg2 << 16) + ((png_8bit_l2[x-128]+32768)>>16));
ret
endp
; The above gives exact (to 16 binary places) log2 values for 8-bit images,
; for 16-bit images we use the most significant 8 bits of the 16-bit value to
; get an approximation then multiply the approximation by a correction factor
; determined by the remaining up to 8 bits. This requires an additional step
; in the 16-bit case.
; We want log2(value/65535), we have log2(v'/255), where:
; value = v' * 256 + v''
; = v' * f
; So f is value/v', which is equal to (256+v''/v') since v' is in the range 128
; to 255 and v'' is in the range 0 to 255 f will be in the range 256 to less
; than 258. The final factor also needs to correct for the fact that our 8-bit
; value is scaled by 255, whereas the 16-bit values must be scaled by 65535.
; This gives a final formula using a calculated value 'x' which is value/v' and
; scaling by 65536 to match the above table:
; log2(x/257) * 65536
; Since these numbers are so close to '1' we can use simple linear
; interpolation between the two end values 256/257 (result -368.61) and 258/257
; (result 367.179). The values used below are scaled by a further 64 to give
; 16-bit precision in the interpolation:
; Start (256): -23591
; Zero (257): 0
; End (258): 23499
;int_32 (uint_32 x)
align 4
proc png_log16bit, x:dword
; uint lg2 = 0;
; As above, but now the input has 16 bits.
; if ((x &= 0xffff) == 0)
; return -1;
; if ((x & 0xff00) == 0)
; lg2 = 8, x <<= 8;
; if ((x & 0xf000) == 0)
; lg2 += 4, x <<= 4;
; if ((x & 0xc000) == 0)
; lg2 += 2, x <<= 2;
; if ((x & 0x8000) == 0)
; lg2 += 1, x <<= 1;
; Calculate the base logarithm from the top 8 bits as a 28-bit fractional
; value.
; lg2 <<= 28;
; lg2 += (png_8bit_l2[(x>>8)-128]+8) >> 4;
; Now we need to interpolate the factor, this requires a division by the top
; 8 bits. Do this with maximum precision.
; x = ((x << 16) + (x >> 9)) / (x >> 8);
; Since we divided by the top 8 bits of 'x' there will be a '1' at 1<<24,
; the value at 1<<16 (ignoring this) will be 0 or 1; this gives us exactly
; 16 bits to interpolate to get the low bits of the result. Round the
; answer. Note that the end point values are scaled by 64 to retain overall
; precision and that 'lg2' is current scaled by an extra 12 bits, so adjust
; the overall scaling by 6-12. Round at every step.
; x -= 1U << 24;
; if (x <= 65536U) /* <= '257' */
; lg2 += ((23591U * (65536U-x)) + (1U << (16+6-12-1))) >> (16+6-12);
; else
; lg2 -= ((23499U * (x-65536U)) + (1U << (16+6-12-1))) >> (16+6-12);
; Safe, because the result can't have more than 20 bits:
; return (int_32)((lg2 + 2048) >> 12);
ret
endp
; The 'exp()' case must invert the above, taking a 20-bit fixed point
; logarithmic value and returning a 16 or 8-bit number as appropriate. In
; each case only the low 16 bits are relevant - the fraction - since the
; integer bits (the top 4) simply determine a shift.
; The worst case is the 16-bit distinction between 65535 and 65534. This
; requires perhaps spurious accuracy in the decoding of the logarithm to
; distinguish log2(65535/65534.5) - 10^-5 or 17 bits. There is little chance
; of getting this accuracy in practice.
; To deal with this the following exp() function works out the exponent of the
; frational part of the logarithm by using an accurate 32-bit value from the
; top four fractional bits then multiplying in the remaining bits.
; NOTE: the first entry is deliberately set to the maximum 32-bit value.
align 4
png_32bit_exp dd 4294967295, 4112874773, 3938502376, 3771522796, 3611622603, 3458501653,\
3311872529, 3171459999, 3037000500, 2908241642, 2784941738, 2666869345,\
2553802834, 2445529972, 2341847524, 2242560872
; Adjustment table; provided to explain the numbers in the code below.
;#if 0
;for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"}
; 11 44937.64284865548751208448
; 10 45180.98734845585101160448
; 9 45303.31936980687359311872
; 8 45364.65110595323018870784
; 7 45395.35850361789624614912
; 6 45410.72259715102037508096
; 5 45418.40724413220722311168
; 4 45422.25021786898173001728
; 3 45424.17186732298419044352
; 2 45425.13273269940811464704
; 1 45425.61317555035558641664
; 0 45425.85339951654943850496
;end if
;uint_32 (png_fixed_point x)
align 4
proc png_exp, x:dword
; if (x > 0 && x <= 0xfffff) /* Else overflow or zero (underflow) */
; {
; Obtain a 4-bit approximation
; uint_32 e = png_32bit_exp[(x >> 12) & 0x0f];
; Incorporate the low 12 bits - these decrease the returned value by
; multiplying by a number less than 1 if the bit is set. The multiplier
; is determined by the above table and the shift. Notice that the values
; converge on 45426 and this is used to allow linear interpolation of the
; low bits.
; if (x & 0x800)
; e -= (((e >> 16) * 44938U) + 16U) >> 5;
; if (x & 0x400)
; e -= (((e >> 16) * 45181U) + 32U) >> 6;
; if (x & 0x200)
; e -= (((e >> 16) * 45303U) + 64U) >> 7;
; if (x & 0x100)
; e -= (((e >> 16) * 45365U) + 128U) >> 8;
; if (x & 0x080)
; e -= (((e >> 16) * 45395U) + 256U) >> 9;
; if (x & 0x040)
; e -= (((e >> 16) * 45410U) + 512U) >> 10;
; And handle the low 6 bits in a single block.
; e -= (((e >> 16) * 355U * (x & 0x3fU)) + 256U) >> 9;
; Handle the upper bits of x.
; e >>= x >> 16;
; return e;
; }
; Check for overflow
; if (x <= 0)
; return png_32bit_exp[0];
; Else underflow
; return 0;
ret
endp
;byte (png_fixed_point lg2)
align 4
proc png_exp8bit, lg2:dword
; Get a 32-bit value:
; uint_32 x = png_exp(lg2);
; Convert the 32-bit value to 0..255 by multiplying by 256-1. Note that the
; second, rounding, step can't overflow because of the first, subtraction,
; step.
; x -= x >> 8;
; return (byte)(((x + 0x7fffffU) >> 24) & 0xff);
ret
endp
;uint_16 (png_fixed_point lg2)
align 4
proc png_exp16bit, lg2:dword
; Get a 32-bit value:
; uint_32 x = png_exp(lg2);
; Convert the 32-bit value to 0..65535 by multiplying by 65536-1:
; x -= x >> 16;
; return (uint_16)((x + 32767U) >> 16);
ret
endp
;end if /* FLOATING_ARITHMETIC */
;byte (uint value, png_fixed_point gamma_val)
align 4
proc png_gamma_8bit_correct, value:dword, gamma_val:dword
; if (value > 0 && value < 255)
; {
if PNG_FLOATING_ARITHMETIC_SUPPORTED eq 1
; 'value' is unsigned, ANSI-C90 requires the compiler to correctly
; convert this to a floating point value. This includes values that
; would overflow if 'value' were to be converted to 'int'.
; Apparently GCC, however, does an intermediate conversion to (int)
; on some (ARM) but not all (x86) platforms, possibly because of
; hardware FP limitations. (E.g. if the hardware conversion always
; assumes the integer register contains a signed value.) This results
; in ANSI-C undefined behavior for large values.
; Other implementations on the same machine might actually be ANSI-C90
; conformant and therefore compile spurious extra code for the large
; values.
; We can be reasonably sure that an unsigned to float conversion
; won't be faster than an int to float one. Therefore this code
; assumes responsibility for the undefined behavior, which it knows
; can't happen because of the check above.
; Note the argument to this routine is an (uint) because, on
; 16-bit platforms, it is assigned a value which might be out of
; range for an (int); that would result in undefined behavior in the
; caller if the *argument* ('value') were to be declared (int).
; double r = floor(255*pow((int)/*SAFE*/value/255.,gamma_val*.00001)+.5);
; return (byte)r;
else
; int_32 lg2 = png_log8bit(value);
; png_fixed_point res;
; if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
; return png_exp8bit(res);
; Overflow.
; value = 0;
end if
; }
; return (byte)(value & 0xff);
ret
endp
;uint_16 (uint value, png_fixed_point gamma_val)
align 4
proc png_gamma_16bit_correct, value:dword, gamma_val:dword
; if (value > 0 && value < 65535)
; {
if PNG_FLOATING_ARITHMETIC_SUPPORTED eq 1
; The same (uint)->(double) constraints apply here as above,
; however in this case the (uint) to (int) conversion can
; overflow on an ANSI-C90 compliant system so the cast needs to ensure
; that this is not possible.
; double r = floor(65535*pow((int_32)value/65535.,
; gamma_val*.00001)+.5);
; return (uint_16)r;
else
; int_32 lg2 = png_log16bit(value);
; png_fixed_point res;
; if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
; return png_exp16bit(res);
; Overflow.
; value = 0;
end if
; }
; return (uint_16)value;
ret
endp
; This does the right thing based on the bit_depth field of the
; png_struct, interpreting values as 8-bit or 16-bit. While the result
; is nominally a 16-bit value if bit depth is 8 then the result is
; 8-bit (as are the arguments.)
;uint_16 (png_structrp png_ptr, uint value, png_fixed_point gamma_val)
align 4
proc png_gamma_correct, png_ptr:dword, value:dword, gamma_val:dword
; if (png_ptr->bit_depth == 8)
; return png_gamma_8bit_correct(value, gamma_val);
;
if PNG_16BIT_SUPPORTED eq 1
; else
; return png_gamma_16bit_correct(value, gamma_val);
else
; should not reach this
xor eax,eax
end if ;16BIT
.end_f:
ret
endp
;if PNG_16BIT_SUPPORTED
; Internal function to build a single 16-bit table - the table consists of
; 'num' 256 entry subtables, where 'num' is determined by 'shift' - the amount
; to shift the input values right (or 16-number_of_signifiant_bits).
; The caller is responsible for ensuring that the table gets cleaned up on
; png_error (i.e. if one of the mallocs below fails) - i.e. the *table argument
; should be somewhere that will be cleaned.
;void (png_structrp png_ptr, uint_16pp *ptable, uint shift, png_fixed_point gamma_val)
align 4
proc png_build_16bit_table, png_ptr:dword, ptable:dword, shift:dword, gamma_val:dword
; Various values derived from 'shift':
; uint num = 1U << (8U - shift);
if PNG_FLOATING_ARITHMETIC_SUPPORTED eq 1
; CSE the division and work round wacky GCC warnings (see the comments
; in png_gamma_8bit_correct for where these come from.)
; double fmax = 1./(((int_32)1 << (16U - shift))-1);
end if
; uint max = (1U << (16U - shift))-1U;
; uint max_by_2 = 1U << (15U-shift);
; uint i;
; uint_16pp table = *ptable =
; (uint_16pp)png_calloc(png_ptr, num * (sizeof (uint_16p)));
; for (i = 0; i < num; i++)
; {
; uint_16p sub_table = table[i] =
; (uint_16p)png_malloc(png_ptr, 256 * (sizeof (uint_16)));
; The 'threshold' test is repeated here because it can arise for one of
; the 16-bit tables even if the others don't hit it.
; if (png_gamma_significant(gamma_val) != 0)
; {
; The old code would overflow at the end and this would cause the
; 'pow' function to return a result >1, resulting in an
; arithmetic error. This code follows the spec exactly; ig is
; the recovered input sample, it always has 8-16 bits.
; We want input * 65535/max, rounded, the arithmetic fits in 32
; bits (unsigned) so long as max <= 32767.
; uint j;
; for (j = 0; j < 256; j++)
; {
; uint_32 ig = (j << (8-shift)) + i;
if PNG_FLOATING_ARITHMETIC_SUPPORTED eq 1
; Inline the 'max' scaling operation:
; See png_gamma_8bit_correct for why the cast to (int) is
; required here.
; double d = floor(65535.*pow(ig*fmax, gamma_val*.00001)+.5);
; sub_table[j] = (uint_16)d;
else
; if (shift != 0)
; ig = (ig * 65535U + max_by_2)/max;
;
; sub_table[j] = png_gamma_16bit_correct(ig, gamma_val);
end if
; }
; }
; else
; {
; We must still build a table, but do it the fast way.
; uint j;
;
; for (j = 0; j < 256; j++)
; {
; uint_32 ig = (j << (8-shift)) + i;
;
; if (shift != 0)
; ig = (ig * 65535U + max_by_2)/max;
;
; sub_table[j] = (uint_16)ig;
; }
; }
; }
ret
endp
; NOTE: this function expects the *inverse* of the overall gamma transformation
; required.
;void (png_structrp png_ptr, uint_16pp *ptable, uint shift, png_fixed_point gamma_val)
align 4
proc png_build_16to8_table, png_ptr:dword, ptable:dword, shift:dword, gamma_val:dword
; uint num = 1U << (8U - shift);
; uint max = (1U << (16U - shift))-1U;
; uint i;
; uint_32 last;
; uint_16pp table = *ptable =
; (uint_16pp)png_calloc(png_ptr, num * (sizeof (uint_16p)));
; 'num' is the number of tables and also the number of low bits of low
; bits of the input 16-bit value used to select a table. Each table is
; itself indexed by the high 8 bits of the value.
; for (i = 0; i < num; i++)
; table[i] = (uint_16p)png_malloc(png_ptr,
; 256 * (sizeof (uint_16)));
; 'gamma_val' is set to the reciprocal of the value calculated above, so
; pow(out,g) is an *input* value. 'last' is the last input value set.
;
; In the loop 'i' is used to find output values. Since the output is
; 8-bit there are only 256 possible values. The tables are set up to
; select the closest possible output value for each input by finding
; the input value at the boundary between each pair of output values
; and filling the table up to that boundary with the lower output
; value.
; The boundary values are 0.5,1.5..253.5,254.5. Since these are 9-bit
; values the code below uses a 16-bit value in i; the values start at
; 128.5 (for 0.5) and step by 257, for a total of 254 values (the last
; entries are filled with 255). Start i at 128 and fill all 'last'
; table entries <= 'max'
; last = 0;
; for (i = 0; i < 255; ++i) /* 8-bit output value */
; {
; Find the corresponding maximum input value
; uint_16 out = (uint_16)(i * 257U); /* 16-bit output value */
; Find the boundary value in 16 bits:
; uint_32 bound = png_gamma_16bit_correct(out+128U, gamma_val);
; Adjust (round) to (16-shift) bits:
; bound = (bound * max + 32768U)/65535U + 1U;
;
; while (last < bound)
; {
; table[last & (0xffU >> shift)][last >> (8U - shift)] = out;
; last++;
; }
; }
; And fill in the final entries.
; while (last < (num << 8))
; {
; table[last & (0xff >> shift)][last >> (8U - shift)] = 65535U;
; last++;
; }
ret
endp
;end if /* 16BIT */
; Build a single 8-bit table: same as the 16-bit case but much simpler (and
; typically much faster). Note that libpng currently does no sBIT processing
; (apparently contrary to the spec) so a 256-entry table is always generated.
;void (png_structrp png_ptr, bytepp ptable, png_fixed_point gamma_val)
align 4
proc png_build_8bit_table, png_ptr:dword, ptable:dword, gamma_val:dword
; uint i;
; bytep table = *ptable = (bytep)png_malloc(png_ptr, 256);
; if (png_gamma_significant(gamma_val) != 0)
; for (i=0; i<256; i++)
; table[i] = png_gamma_8bit_correct(i, gamma_val);
; else
; for (i=0; i<256; ++i)
; table[i] = (byte)(i & 0xff);
ret
endp
; Used from png_read_destroy and below to release the memory used by the gamma
; tables.
;void (png_structrp png_ptr)
align 4
proc png_destroy_gamma_table, png_ptr:dword
; png_free(png_ptr, png_ptr->gamma_table);
; png_ptr->gamma_table = NULL;
if PNG_16BIT_SUPPORTED eq 1
; if (png_ptr->gamma_16_table != NULL)
; {
; int i;
; int istop = (1 << (8 - png_ptr->gamma_shift));
; for (i = 0; i < istop; i++)
; {
; png_free(png_ptr, png_ptr->gamma_16_table[i]);
; }
; png_free(png_ptr, png_ptr->gamma_16_table);
; png_ptr->gamma_16_table = NULL;
; }
end if ;16BIT
;#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
; defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
; defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
; png_free(png_ptr, png_ptr->gamma_from_1);
; png_ptr->gamma_from_1 = NULL;
; png_free(png_ptr, png_ptr->gamma_to_1);
; png_ptr->gamma_to_1 = NULL;
if PNG_16BIT_SUPPORTED eq 1
; if (png_ptr->gamma_16_from_1 != NULL)
; {
; int i;
; int istop = (1 << (8 - png_ptr->gamma_shift));
; for (i = 0; i < istop; i++)
; {
; png_free(png_ptr, png_ptr->gamma_16_from_1[i]);
; }
; png_free(png_ptr, png_ptr->gamma_16_from_1);
; png_ptr->gamma_16_from_1 = NULL;
; }
; if (png_ptr->gamma_16_to_1 != NULL)
; {
; int i;
; int istop = (1 << (8 - png_ptr->gamma_shift));
; for (i = 0; i < istop; i++)
; {
; png_free(png_ptr, png_ptr->gamma_16_to_1[i]);
; }
; png_free(png_ptr, png_ptr->gamma_16_to_1);
; png_ptr->gamma_16_to_1 = NULL;
; }
end if ;16BIT
;end if /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
ret
endp
; We build the 8- or 16-bit gamma tables here. Note that for 16-bit
; tables, we don't make a full table if we are reducing to 8-bit in
; the future. Note also how the gamma_16 tables are segmented so that
; we don't need to allocate > 64K chunks for a full 16-bit table.
;void (png_structrp png_ptr, int bit_depth)
align 4
proc png_build_gamma_table, png_ptr:dword, bit_depth:dword
png_debug 1, 'in png_build_gamma_table'
; Remove any existing table; this copes with multiple calls to
; png_read_update_info. The warning is because building the gamma tables
; multiple times is a performance hit - it's harmless but the ability to
; call png_read_update_info() multiple times is new in 1.5.6 so it seems
; sensible to warn if the app introduces such a hit.
; if (png_ptr->gamma_table != NULL || png_ptr->gamma_16_table != NULL)
; {
; png_warning(png_ptr, "gamma table being rebuilt");
; png_destroy_gamma_table(png_ptr);
; }
; if (bit_depth <= 8)
; {
; png_build_8bit_table(png_ptr, &png_ptr->gamma_table,
; png_ptr->screen_gamma > 0 ?
; png_reciprocal2(png_ptr->colorspace.gamma,
; png_ptr->screen_gamma) : PNG_FP_1);
;
if (PNG_READ_BACKGROUND_SUPPORTED eq 1) | (PNG_READ_ALPHA_MODE_SUPPORTED eq 1) | (PNG_READ_RGB_TO_GRAY_SUPPORTED eq 1)
; if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
; {
; png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1,
; png_reciprocal(png_ptr->colorspace.gamma));
;
; png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1,
; png_ptr->screen_gamma > 0 ?
; png_reciprocal(png_ptr->screen_gamma) :
; png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
; }
end if ;READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY
; }
if PNG_16BIT_SUPPORTED eq 1
; else
; {
; byte shift, sig_bit;
;
; if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
; {
; sig_bit = png_ptr->sig_bit.red;
;
; if (png_ptr->sig_bit.green > sig_bit)
; sig_bit = png_ptr->sig_bit.green;
;
; if (png_ptr->sig_bit.blue > sig_bit)
; sig_bit = png_ptr->sig_bit.blue;
; }
; else
; sig_bit = png_ptr->sig_bit.gray;
; 16-bit gamma code uses this equation:
; ov = table[(iv & 0xff) >> gamma_shift][iv >> 8]
; Where 'iv' is the input color value and 'ov' is the output value -
; pow(iv, gamma).
; Thus the gamma table consists of up to 256 256-entry tables. The table
; is selected by the (8-gamma_shift) most significant of the low 8 bits
; of the color value then indexed by the upper 8 bits:
;
; table[low bits][high 8 bits]
; So the table 'n' corresponds to all those 'iv' of:
; <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1>
; if (sig_bit > 0 && sig_bit < 16U)
; /* shift == insignificant bits */
; shift = (byte)((16U - sig_bit) & 0xff);
; else
; shift = 0; /* keep all 16 bits */
; if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
; {
; PNG_MAX_GAMMA_8 is the number of bits to keep - effectively
; the significant bits in the *input* when the output will
; eventually be 8 bits. By default it is 11.
; if (shift < (16U - PNG_MAX_GAMMA_8))
; shift = (16U - PNG_MAX_GAMMA_8);
; }
; if (shift > 8U)
; shift = 8U; /* Guarantees at least one table! */
; png_ptr->gamma_shift = shift;
; NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now
; PNG_COMPOSE). This effectively smashed the background calculation for
; 16-bit output because the 8-bit table assumes the result will be
; reduced to 8 bits.
; if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
; png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
; png_ptr->screen_gamma > 0 ? png_product2(png_ptr->colorspace.gamma,
; png_ptr->screen_gamma) : PNG_FP_1);
;
; else
; png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift,
; png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma,
; png_ptr->screen_gamma) : PNG_FP_1);
;
if (PNG_READ_BACKGROUND_SUPPORTED eq 1) | (PNG_READ_ALPHA_MODE_SUPPORTED eq 1) | (PNG_READ_RGB_TO_GRAY_SUPPORTED eq 1)
; if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
; {
; png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift,
; png_reciprocal(png_ptr->colorspace.gamma));
; Notice that the '16 from 1' table should be full precision, however
; the lookup on this table still uses gamma_shift, so it can't be.
; TODO: fix this.
; png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift,
; png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
; png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
; }
end if ;READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY
; }
end if ;16BIT
ret
endp
;end if /* READ_GAMMA */
; HARDWARE OR SOFTWARE OPTION SUPPORT
;int (png_structrp png_ptr, int option, int onoff)
align 4
proc png_set_option uses ecx, png_ptr:dword, option:dword, onoff:dword
mov eax,[png_ptr]
cmp eax,0
je @f
mov ecx,[option]
cmp ecx,0
jl @f
cmp ecx,PNG_OPTION_NEXT
jge @f
bt ecx,0 ;cmp (ecx & 1), 0
jc @f ;if (..!=0 && ..>=0 && ..<.. && ..==0)
; int mask = 3 << option;
; int setting = (2 + (onoff != 0)) << option;
; int current = png_ptr->options;
; png_ptr->options = (byte)(((current & ~mask) | setting) & 0xff);
; return (current & mask) >> option;
jmp .end_f
@@:
mov eax,PNG_OPTION_INVALID
.end_f:
ret
endp
; sRGB support
if (PNG_SIMPLIFIED_READ_SUPPORTED eq 1) | (PNG_SIMPLIFIED_WRITE_SUPPORTED eq 1)
; sRGB conversion tables; these are machine generated with the code in
; contrib/tools/makesRGB.c. The actual sRGB transfer curve defined in the
; specification (see the article at http://en.wikipedia.org/wiki/SRGB)
; is used, not the gamma=1/2.2 approximation use elsewhere in libpng.
; The sRGB to linear table is exact (to the nearest 16-bit linear fraction).
; The inverse (linear to sRGB) table has accuracies as follows:
; For all possible (255*65535+1) input values:
; error: -0.515566 - 0.625971, 79441 (0.475369%) of readings inexact
; For the input values corresponding to the 65536 16-bit values:
; error: -0.513727 - 0.607759, 308 (0.469978%) of readings inexact
; In all cases the inexact readings are only off by one.
if PNG_SIMPLIFIED_READ_SUPPORTED eq 1
; The convert-to-sRGB table is only currently required for read.
align 4
png_sRGB_table dw 0,20,40,60,80,99,119,139,\
159,179,199,219,241,264,288,313,\
340,367,396,427,458,491,526,562,\
599,637,677,718,761,805,851,898,\
947,997,1048,1101,1156,1212,1270,1330,\
1391,1453,1517,1583,1651,1720,1790,1863,\
1937,2013,2090,2170,2250,2333,2418,2504,\
2592,2681,2773,2866,2961,3058,3157,3258,\
3360,3464,3570,3678,3788,3900,4014,4129,\
4247,4366,4488,4611,4736,4864,4993,5124,\
5257,5392,5530,5669,5810,5953,6099,6246,\
6395,6547,6700,6856,7014,7174,7335,7500,\
7666,7834,8004,8177,8352,8528,8708,8889,\
9072,9258,9445,9635,9828,10022,10219,10417,\
10619,10822,11028,11235,11446,11658,11873,12090,\
12309,12530,12754,12980,13209,13440,13673,13909,\
14146,14387,14629,14874,15122,15371,15623,15878,\
16135,16394,16656,16920,17187,17456,17727,18001,\
18277,18556,18837,19121,19407,19696,19987,20281,\
20577,20876,21177,21481,21787,22096,22407,22721,\
23038,23357,23678,24002,24329,24658,24990,25325,\
25662,26001,26344,26688,27036,27386,27739,28094,\
28452,28813,29176,29542,29911,30282,30656,31033,\
31412,31794,32179,32567,32957,33350,33745,34143,\
34544,34948,35355,35764,36176,36591,37008,37429,\
37852,38278,38706,39138,39572,40009,40449,40891,\
41337,41785,42236,42690,43147,43606,44069,44534,\
45002,45473,45947,46423,46903,47385,47871,48359,\
48850,49344,49841,50341,50844,51349,51858,52369,\
52884,53401,53921,54445,54971,55500,56032,56567,\
57105,57646,58190,58737,59287,59840,60396,60955,\
61517,62082,62650,63221,63795,64372,64952,65535
end if ;SIMPLIFIED_READ
; The base/delta tables are required for both read and write (but currently
; only the simplified versions.)
align 4
png_sRGB_base dw 128,1782,3383,4644,5675,6564,7357,8074,\
8732,9346,9921,10463,10977,11466,11935,12384,\
12816,13233,13634,14024,14402,14769,15125,15473,\
15812,16142,16466,16781,17090,17393,17690,17981,\
18266,18546,18822,19093,19359,19621,19879,20133,\
20383,20630,20873,21113,21349,21583,21813,22041,\
22265,22487,22707,22923,23138,23350,23559,23767,\
23972,24175,24376,24575,24772,24967,25160,25352,\
25542,25730,25916,26101,26284,26465,26645,26823,\
27000,27176,27350,27523,27695,27865,28034,28201,\
28368,28533,28697,28860,29021,29182,29341,29500,\
29657,29813,29969,30123,30276,30429,30580,30730,\
30880,31028,31176,31323,31469,31614,31758,31902,\
32045,32186,32327,32468,32607,32746,32884,33021,\
33158,33294,33429,33564,33697,33831,33963,34095,\
34226,34357,34486,34616,34744,34873,35000,35127,\
35253,35379,35504,35629,35753,35876,35999,36122,\
36244,36365,36486,36606,36726,36845,36964,37083,\
37201,37318,37435,37551,37668,37783,37898,38013,\
38127,38241,38354,38467,38580,38692,38803,38915,\
39026,39136,39246,39356,39465,39574,39682,39790,\
39898,40005,40112,40219,40325,40431,40537,40642,\
40747,40851,40955,41059,41163,41266,41369,41471,\
41573,41675,41777,41878,41979,42079,42179,42279,\
42379,42478,42577,42676,42775,42873,42971,43068,\
43165,43262,43359,43456,43552,43648,43743,43839,\
43934,44028,44123,44217,44311,44405,44499,44592,\
44685,44778,44870,44962,45054,45146,45238,45329,\
45420,45511,45601,45692,45782,45872,45961,46051,\
46140,46229,46318,46406,46494,46583,46670,46758,\
46846,46933,47020,47107,47193,47280,47366,47452,\
47538,47623,47709,47794,47879,47964,48048,48133,\
48217,48301,48385,48468,48552,48635,48718,48801,\
48884,48966,49048,49131,49213,49294,49376,49458,\
49539,49620,49701,49782,49862,49943,50023,50103,\
50183,50263,50342,50422,50501,50580,50659,50738,\
50816,50895,50973,51051,51129,51207,51285,51362,\
51439,51517,51594,51671,51747,51824,51900,51977,\
52053,52129,52205,52280,52356,52432,52507,52582,\
52657,52732,52807,52881,52956,53030,53104,53178,\
53252,53326,53400,53473,53546,53620,53693,53766,\
53839,53911,53984,54056,54129,54201,54273,54345,\
54417,54489,54560,54632,54703,54774,54845,54916,\
54987,55058,55129,55199,55269,55340,55410,55480,\
55550,55620,55689,55759,55828,55898,55967,56036,\
56105,56174,56243,56311,56380,56448,56517,56585,\
56653,56721,56789,56857,56924,56992,57059,57127,\
57194,57261,57328,57395,57462,57529,57595,57662,\
57728,57795,57861,57927,57993,58059,58125,58191,\
58256,58322,58387,58453,58518,58583,58648,58713,\
58778,58843,58908,58972,59037,59101,59165,59230,\
59294,59358,59422,59486,59549,59613,59677,59740,\
59804,59867,59930,59993,60056,60119,60182,60245,\
60308,60370,60433,60495,60558,60620,60682,60744,\
60806,60868,60930,60992,61054,61115,61177,61238,\
61300,61361,61422,61483,61544,61605,61666,61727,\
61788,61848,61909,61969,62030,62090,62150,62211,\
62271,62331,62391,62450,62510,62570,62630,62689,\
62749,62808,62867,62927,62986,63045,63104,63163,\
63222,63281,63340,63398,63457,63515,63574,63632,\
63691,63749,63807,63865,63923,63981,64039,64097,\
64155,64212,64270,64328,64385,64443,64500,64557,\
64614,64672,64729,64786,64843,64900,64956,65013,\
65070,65126,65183,65239,65296,65352,65409,65465
align 4
png_sRGB_delta db 207,201,158,129,113,100,90,82,77,72,68,64,61,59,56,54,\
52,50,49,47,46,45,43,42,41,40,39,39,38,37,36,36,\
35,34,34,33,33,32,32,31,31,30,30,30,29,29,28,28,\
28,27,27,27,27,26,26,26,25,25,25,25,24,24,24,24,\
23,23,23,23,23,22,22,22,22,22,22,21,21,21,21,21,\
21,20,20,20,20,20,20,20,20,19,19,19,19,19,19,19,\
19,18,18,18,18,18,18,18,18,18,18,17,17,17,17,17,\
17,17,17,17,17,17,16,16,16,16,16,16,16,16,16,16,\
16,16,16,16,15,15,15,15,15,15,15,15,15,15,15,15,\
15,15,15,15,14,14,14,14,14,14,14,14,14,14,14,14,\
14,14,14,14,14,14,14,13,13,13,13,13,13,13,13,13,\
13,13,13,13,13,13,13,13,13,13,13,13,13,13,12,12,\
12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,\
12,12,12,12,12,12,12,12,12,12,12,12,11,11,11,11,\
11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,\
11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,\
11,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,\
10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,\
10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,\
10,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,\
9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,\
9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,\
9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,\
9,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,\
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,\
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,\
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,\
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,\
8,8,8,8,8,8,8,8,8,7,7,7,7,7,7,7,\
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,\
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,\
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
end if ;SIMPLIFIED READ/WRITE sRGB support
; SIMPLIFIED READ/WRITE SUPPORT
;int (voidp argument)
align 4
proc png_image_free_function uses ebx ecx edi esi, argument:dword
locals
; png_imagep image = argument;
; png_controlp cp = image->opaque;
c png_control
endl
; Double check that we have a png_ptr - it should be impossible to get here
; without one.
mov ebx,[argument]
mov esi,[ebx+png_image.opaque] ;esi = cp
cmp dword[esi+png_control.png_ptr],0
jne @f ;if (..==0)
xor eax,eax
jmp .end_f
@@:
; First free any data held in the control structure.
if PNG_STDIO_SUPPORTED eq 1
; if (cp->owned_file != 0)
; {
; FILE *fp = cp->png_ptr->io_ptr;
; cp->owned_file = 0;
; Ignore errors here.
; if (fp != NULL)
; {
; cp->png_ptr->io_ptr = NULL;
; (void)fclose(fp);
; }
; }
end if
; Copy the control structure so that the original, allocated, version can be
; safely freed. Notice that a png_error here stops the remainder of the
; cleanup, but this is probably fine because that would indicate bad memory
; problems anyway.
mov ecx,sizeof.png_control
mov edi,ebp
sub edi,ecx ;edi = &c
rep movsb
sub edi,sizeof.png_control
sub esi,sizeof.png_control
mov dword[ebx+png_image.opaque],edi
stdcall png_free, [edi+png_control.png_ptr], esi
; Then the structures, calling the correct API.
; if (c.for_write != 0)
; {
if PNG_SIMPLIFIED_WRITE_SUPPORTED eq 1
; png_destroy_write_struct(&c.png_ptr, &c.info_ptr);
else
; png_error(c.png_ptr, "simplified write not supported");
end if
jmp .end2
.end1: ;else
if PNG_SIMPLIFIED_READ_SUPPORTED eq 1
; png_destroy_read_struct(&c.png_ptr, &c.info_ptr, NULL);
else
; png_error(c.png_ptr, "simplified read not supported");
end if
.end2:
; Success.
xor eax,eax
inc eax
.end_f:
ret
endp
;void (png_imagep image)
align 4
proc png_image_free uses eax ebx, image:dword
; Safely call the real function, but only if doing so is safe at this point
; (if not inside an error handling context). Otherwise assume
; png_safe_execute will call this API after the return.
mov ebx,[image]
cmp ebx,0
je @f
cmp dword[ebx+png_image.opaque],0
je @f
mov eax,[ebx+png_image.opaque]
cmp dword[eax+png_control.error_buf],0
jne @f ;if (..!=0 && ..!=0 && ..==0)
; Ignore errors here:
stdcall png_safe_execute, ebx, png_image_free_function, ebx
mov dword[ebx+png_image.opaque],0
@@:
ret
endp
;int (png_imagep image, charp error_message)
align 4
proc png_image_error uses ebx, image:dword, error_message:dword
; Utility to log an error.
mov ebx,[image]
mov eax,ebx
add eax,png_image.message
stdcall png_safecat, eax, sizeof.png_image.message, 0, [error_message]
or dword[ebx+png_image.warning_or_error], PNG_IMAGE_ERROR
stdcall png_image_free, ebx
xor eax,eax
ret
endp
;end if /* READ || WRITE */
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