; pngerror.asm - stub functions for i/o and memory allocation

; Last changed in libpng 1.6.24 [August 4, 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.h

; This file provides a location for all error handling.  Users who
; need special error handling are expected to write replacement functions
; and use png_set_error_fn() to use those functions.  See the instructions
; at each function.

; This function is called whenever there is a fatal error.  This function
; should not be changed.  If there is a need to handle errors differently,
; you should supply a replacement error function and use png_set_error_fn()
; to replace the error function at run-time.

;if PNG_ERROR_TEXT_SUPPORTED
;void png_error(png_const_structrp png_ptr, charp error_message)
;{
if PNG_ERROR_NUMBERS_SUPPORTED eq 1
;   char msg[16];
;   if (png_ptr != NULL)
;   {
;      if ((png_ptr->flags &
;         (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT)) != 0)
;      {
;         if (*error_message == PNG_LITERAL_SHARP)
;         {
		;Strip "#nnnn " from beginning of error message.
;            int offset;
;            for (offset = 1; offset<15; offset++)
;               if (error_message[offset] == ' ')
;                  break;

;            if ((png_ptr->flags & PNG_FLAG_STRIP_ERROR_TEXT) != 0)
;            {
;               int i;
;               for (i = 0; i < offset - 1; i++)
;                  msg[i] = error_message[i + 1];
;               msg[i - 1] = '\0';
;               error_message = msg;
;            }

;            else
;               error_message += offset;
;         }

;         else
;         {
;            if ((png_ptr->flags & PNG_FLAG_STRIP_ERROR_TEXT) != 0)
;            {
;               msg[0] = '0';
;               msg[1] = '\0';
;               error_message = msg;
;            }
;         }
;      }
;   }
end if
;   if (png_ptr != NULL && png_ptr->error_fn != NULL)
;      (*(png_ptr->error_fn))(png_ptr, error_message);

	; If the custom handler doesn't exist, or if it returns,
	; use the default handler, which will not return.
;   png_default_error(png_ptr, error_message);
;}
;#else
;void png_err(png_const_structrp png_ptr)
;{
	; Prior to 1.5.2 the error_fn received a NULL pointer, expressed
	; erroneously as '\0', instead of the empty string "".  This was
	; apparently an error, introduced in libpng-1.2.20, and png_default_error
	; will crash in this case.

;   if (png_ptr != NULL && png_ptr->error_fn != NULL)
;      (*(png_ptr->error_fn))(png_ptr, "");

	; If the custom handler doesn't exist, or if it returns,
	; use the default handler, which will not return.
;   png_default_error(png_ptr, "");
;}
;end if /* ERROR_TEXT */

; Utility to safely appends strings to a buffer.  This never errors out so
; error checking is not required in the caller.

;size_t (charp buffer, size_t bufsize, size_t pos, charp string)
align 4
proc png_safecat uses ebx ecx edi esi, buffer:dword, bufsize:dword, pos:dword, string:dword
	mov edi,[buffer]
	cmp edi,0
	je .end0
	mov ebx,[pos]
	mov ecx,[bufsize]
	cmp ebx,ecx
	jge .end0 ;if (..!=0 && ..<..)
		mov esi,[string]
		cmp esi,0
		je .end1 ;if (..!=0)
		dec ecx
		@@:
			cmp byte[esi],0
			je .end1
			cmp ebx,ecx
			jge .end1
			movsb
			inc ebx
			jmp @b
align 4
		.end1:
		xor al,al
		stosb
	.end0:
	mov eax,ebx
	ret
endp

;#if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_TIME_RFC1123_SUPPORTED)
; Utility to dump an unsigned value into a buffer, given a start pointer and
; and end pointer (which should point just *beyond* the end of the buffer!)
; Returns the pointer to the start of the formatted string.

;charp png_format_number(charp start, charp end, int format,
;    png_alloc_size_t number)
;{
;   int count = 0;    /* number of digits output */
;   int mincount = 1; /* minimum number required */
;   int output = 0;   /* digit output (for the fixed point format) */

;   *--end = '\0';

;   /* This is written so that the loop always runs at least once, even with
;    * number zero.

;   while (end > start && (number != 0 || count < mincount))
;   {

;      char digits[] = "0123456789ABCDEF";

;      switch (format)
;      {
;         case PNG_NUMBER_FORMAT_fixed:
;            /* Needs five digits (the fraction) */
;            mincount = 5;
;            if (output != 0 || number % 10 != 0)
;            {
;               *--end = digits[number % 10];
;               output = 1;
;            }
;            number /= 10;
;            break;

;         case PNG_NUMBER_FORMAT_02u:
;            /* Expects at least 2 digits. */
;            mincount = 2;
;            /* FALL THROUGH */

;         case PNG_NUMBER_FORMAT_u:
;            *--end = digits[number % 10];
;            number /= 10;
;            break;

;         case PNG_NUMBER_FORMAT_02x:
;            /* This format expects at least two digits */
;            mincount = 2;
;            /* FALL THROUGH */

;         case PNG_NUMBER_FORMAT_x:
;            *--end = digits[number & 0xf];
;            number >>= 4;
;            break;

;         default: /* an error */
;            number = 0;
;            break;
;      }

	; Keep track of the number of digits added
;      ++count;

	; Float a fixed number here:
;      if ((format == PNG_NUMBER_FORMAT_fixed) && (count == 5) && (end > start))
;      {
	; End of the fraction, but maybe nothing was output?  In that case
	; drop the decimal point.  If the number is a true zero handle that
	; here.

;         if (output != 0)
;            *--end = '.';
;         else if (number == 0) /* and !output */
;            *--end = '0';
;      }
;   }

;   return end;
;}
;end if

;if PNG_WARNINGS_SUPPORTED
; This function is called whenever there is a non-fatal error.  This function
; should not be changed.  If there is a need to handle warnings differently,
; you should supply a replacement warning function and use
; png_set_error_fn() to replace the warning function at run-time.

;void png_warning(png_const_structrp png_ptr, charp warning_message)
;{
;   int offset = 0;
;   if (png_ptr != NULL)
;   {
if PNG_ERROR_NUMBERS_SUPPORTED eq 1
;   if ((png_ptr->flags &
;       (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT)) != 0)
end if
;      {
;         if (*warning_message == PNG_LITERAL_SHARP)
;         {
;            for (offset = 1; offset < 15; offset++)
;               if (warning_message[offset] == ' ')
;                  break;
;         }
;      }
;   }
;   if (png_ptr != NULL && png_ptr->warning_fn != NULL)
;      (*(png_ptr->warning_fn))(png_ptr, warning_message + offset);
;   else
;      png_default_warning(png_ptr, warning_message + offset);
;}

; These functions support 'formatted' warning messages with up to
; PNG_WARNING_PARAMETER_COUNT parameters.  In the format string the parameter
; is introduced by @<number>, where 'number' starts at 1.  This follows the
; standard established by X/Open for internationalizable error messages.

;void
;png_warning_parameter(png_warning_parameters p, int number,
;    charp string)
;{
;   if (number > 0 && number <= PNG_WARNING_PARAMETER_COUNT)
;      (void)png_safecat(p[number-1], (sizeof p[number-1]), 0, string);
;}

;void
;png_warning_parameter_unsigned(png_warning_parameters p, int number, int format,
;    png_alloc_size_t value)
;{
;   char buffer[PNG_NUMBER_BUFFER_SIZE];
;   png_warning_parameter(p, number, PNG_FORMAT_NUMBER(buffer, format, value));
;}

;void (png_warning_parameters p, int number, int format, int_32 value)
align 4
proc png_warning_parameter_signed, p:dword, number:dword, format:dword, value:dword
;   png_alloc_size_t u;
;   charp str;
;   char buffer[PNG_NUMBER_BUFFER_SIZE];

	; Avoid overflow by doing the negate in a png_alloc_size_t:
;   u = (png_alloc_size_t)value;
;   if (value < 0)
;      u = ~u + 1;

;   str = PNG_FORMAT_NUMBER(buffer, format, u);

;   if (value < 0 && str > buffer)
;      *--str = '-';

;   png_warning_parameter(p, number, str);
	ret
endp

;void (png_const_structrp png_ptr, png_warning_parameters p, charp message)
align 4
proc png_formatted_warning, png_ptr:dword, p:dword, message:dword
	; The internal buffer is just 192 bytes - enough for all our messages,
	; overflow doesn't happen because this code checks!  If someone figures
	; out how to send us a message longer than 192 bytes, all that will
	; happen is that the message will be truncated appropriately.

;   size_t i = 0; /* Index in the msg[] buffer: */
;   char msg[192];

	; Each iteration through the following loop writes at most one character
	; to msg[i++] then returns here to validate that there is still space for
	; the trailing '\0'.  It may (in the case of a parameter) read more than
	; one character from message[]; it must check for '\0' and continue to the
	; test if it finds the end of string.

;   while (i<(sizeof msg)-1 && *message != '\0')
;   {
	; '@' at end of string is now just printed (previously it was skipped);
	; it is an error in the calling code to terminate the string with @.

;      if (p != NULL && *message == '@' && message[1] != '\0')
;      {
;         int parameter_char = *++message; /* Consume the '@' */
;         char valid_parameters[] = "123456789";
;         int parameter = 0;

		; Search for the parameter digit, the index in the string is the
		; parameter to use.

;         while (valid_parameters[parameter] != parameter_char &&
;            valid_parameters[parameter] != '\0')
;            ++parameter;

		; If the parameter digit is out of range it will just get printed.
;         if (parameter < PNG_WARNING_PARAMETER_COUNT)
;         {
		; Append this parameter
;            charp parm = p[parameter];
;            charp pend = p[parameter] + (sizeof p[parameter]);

		; No need to copy the trailing '\0' here, but there is no guarantee
		; that parm[] has been initialized, so there is no guarantee of a
		; trailing '\0':

;            while (i<(sizeof msg)-1 && *parm != '\0' && parm < pend)
;               msg[i++] = *parm++;

	; Consume the parameter digit too:
;            ++message;
;            continue;
;         }

	; else not a parameter and there is a character after the @ sign; just
	; copy that.  This is known not to be '\0' because of the test above.

;      }

	; At this point *message can't be '\0', even in the bad parameter case
	; above where there is a lone '@' at the end of the message string.

;      msg[i++] = *message++;
;   }

	; i is always less than (sizeof msg), so:
;   msg[i] = '\0';

	; And this is the formatted message. It may be larger than
	; PNG_MAX_ERROR_TEXT, but that is only used for 'chunk' errors and these
	; are not (currently) formatted.

;   png_warning(png_ptr, msg);
	ret
endp
;end if /* WARNINGS */

;void png_benign_error(png_const_structrp png_ptr, charp error_message)
;{
;   if ((png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN) != 0)
;   {
;#     ifdef PNG_READ_SUPPORTED
;         if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
;            png_ptr->chunk_name != 0)
;            png_chunk_warning(png_ptr, error_message);
;         else
;#     endif
;      png_warning(png_ptr, error_message);
;   }

;   else
;   {
;#     ifdef PNG_READ_SUPPORTED
;         if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
;            png_ptr->chunk_name != 0)
;            png_chunk_error(png_ptr, error_message);
;         else
;#     endif
;      png_error(png_ptr, error_message);
;   }
;}

;void png_app_warning(png_const_structrp png_ptr, charp error_message)
;{
;   if ((png_ptr->flags & PNG_FLAG_APP_WARNINGS_WARN) != 0)
;      png_warning(png_ptr, error_message);
;   else
;      png_error(png_ptr, error_message);
;}

;void (png_structrp png_ptr, charp error_message)
align 4
proc png_app_error uses eax edi, png_ptr:dword, error_message:dword
	mov edi,[png_ptr]
	mov eax,[edi+png_struct.flags]
	and eax,PNG_FLAG_APP_ERRORS_WARN
	cmp eax,0
	je @f ;if (..!=0)
		png_warning edi, [error_message]
		jmp .end0
	@@: ;else
		png_error edi, [error_message]
	.end0:
	ret
endp

PNG_MAX_ERROR_TEXT equ 196 ;Currently limited by profile_error in png.asm
if (PNG_WARNINGS_SUPPORTED eq 1) | \
	((PNG_READ_SUPPORTED eq 1) & (PNG_ERROR_TEXT_SUPPORTED eq 1))
; These utilities are used internally to build an error message that relates
; to the current chunk.  The chunk name comes from png_ptr->chunk_name,
; which is used to prefix the message.  The message is limited in length
; to 63 bytes. The name characters are output as hex digits wrapped in []
; if the character is invalid.

;#define isnonalpha(c) ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
align 4
png_digit db \ ;char[16]
	'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', \
	'A', 'B', 'C', 'D', 'E', 'F'

;void (png_const_structrp png_ptr, charp buffer, charp error_message)
align 4
proc png_format_buffer, png_ptr:dword, buffer:dword, error_message:dword
;   uint_32 chunk_name = png_ptr->chunk_name;
;   int iout = 0, ishift = 24;

;   while (ishift >= 0)
;   {
;      int c = (int)(chunk_name >> ishift) & 0xff;

;      ishift -= 8;
;      if (isnonalpha(c) != 0)
;      {
;         buffer[iout++] = PNG_LITERAL_LEFT_SQUARE_BRACKET;
;         buffer[iout++] = png_digit[(c & 0xf0) >> 4];
;         buffer[iout++] = png_digit[c & 0x0f];
;         buffer[iout++] = PNG_LITERAL_RIGHT_SQUARE_BRACKET;
;      }

;      else
;      {
;         buffer[iout++] = (char)c;
;      }
;   }

;   if (error_message == NULL)
;      buffer[iout] = '\0';

;   else
;   {
;      int iin = 0;

;      buffer[iout++] = ':';
;      buffer[iout++] = ' ';

;      while (iin < PNG_MAX_ERROR_TEXT-1 && error_message[iin] != '\0')
;         buffer[iout++] = error_message[iin++];

		;iin < PNG_MAX_ERROR_TEXT, so the following is safe:
;      buffer[iout] = '\0';
;   }
	ret
endp
end if ;WARNINGS || ERROR_TEXT

;void (png_const_structrp png_ptr, charp error_message)
align 4
proc png_chunk_error, png_ptr:dword, error_message:dword
;   char msg[18+PNG_MAX_ERROR_TEXT];
;   if (png_ptr == NULL)
;      png_error(png_ptr, error_message);

;   else
;   {
;      png_format_buffer(png_ptr, msg, error_message);
;      png_error(png_ptr, msg);
;   }
	ret
endp

;void (png_const_structrp png_ptr, charp warning_message)
align 4
proc png_chunk_warning, png_ptr:dword, warning_message:dword
;   char msg[18+PNG_MAX_ERROR_TEXT];
;   if (png_ptr == NULL)
;      png_warning(png_ptr, warning_message);

;   else
;   {
;      png_format_buffer(png_ptr, msg, warning_message);
;      png_warning(png_ptr, msg);
;   }
	ret
endp

;void (png_const_structrp png_ptr, charp error_message)
align 4
proc png_chunk_benign_error, png_ptr:dword, error_message:dword
;   if ((png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN) != 0)
;      png_chunk_warning(png_ptr, error_message);

;   else
;      png_chunk_error(png_ptr, error_message);
	ret
endp

;void (png_const_structrp png_ptr, charp message, int error)
align 4
proc png_chunk_report, png_ptr:dword, message:dword, error:dword
	; This is always supported, but for just read or just write it
	; unconditionally does the right thing.

;#  if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)
;      if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
;#  endif

if PNG_READ_SUPPORTED eq 1
;      {
;         if (error < PNG_CHUNK_ERROR)
;            png_chunk_warning(png_ptr, message);

;         else
;            png_chunk_benign_error(png_ptr, message);
;      }
end if

;#  if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)
;      else if ((png_ptr->mode & PNG_IS_READ_STRUCT) == 0)
;#  endif

if PNG_WRITE_SUPPORTED eq 1
;      {
;         if (error < PNG_CHUNK_WRITE_ERROR)
;            png_app_warning(png_ptr, message);
;
;         else
;            png_app_error(png_ptr, message);
;      }
end if
	ret
endp

;void (png_const_structrp png_ptr, charp name)
align 4
proc png_fixed_error, png_ptr:dword, name:dword
;#  define fixed_message "fixed point overflow in "
;#  define fixed_message_ln ((sizeof fixed_message)-1)
;   int  iin;
;   char msg[fixed_message_ln+PNG_MAX_ERROR_TEXT];
;   memcpy(msg, fixed_message, fixed_message_ln);
;   iin = 0;
;   if (name != NULL)
;      while (iin < (PNG_MAX_ERROR_TEXT-1) && name[iin] != 0)
;      {
;         msg[fixed_message_ln + iin] = name[iin];
;         ++iin;
;      }
;   msg[fixed_message_ln + iin] = 0;
;   png_error(png_ptr, msg);
	ret
endp

; This API only exists if ANSI-C style error handling is used,
; otherwise it is necessary for png_default_error to be overridden.

;jmp_buf* (png_structrp png_ptr, png_longjmp_ptr longjmp_fn,
;    size_t jmp_buf_size)
align 4
proc png_set_longjmp_fn, png_ptr:dword, longjmp_fn:dword, jmp_buf_size:dword
	; From libpng 1.6.0 the app gets one chance to set a 'jmpbuf_size' value
	; and it must not change after that.  Libpng doesn't care how big the
	; buffer is, just that it doesn't change.

	; If the buffer size is no *larger* than the size of jmp_buf when libpng is
	; compiled a built in jmp_buf is returned; this preserves the pre-1.6.0
	; semantics that this call will not fail.  If the size is larger, however,
	; the buffer is allocated and this may fail, causing the function to return
	; NULL.

;   if (png_ptr == NULL)
;      return NULL;

;   if (png_ptr->jmp_buf_ptr == NULL)
;   {
;      png_ptr->jmp_buf_size = 0; /* not allocated */

;      if (jmp_buf_size <= (sizeof png_ptr->jmp_buf_local))
;         png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local;

;      else
;      {
;         png_ptr->jmp_buf_ptr = png_malloc_warn(png_ptr, jmp_buf_size);

;         if (png_ptr->jmp_buf_ptr == NULL)
;            return NULL; /* new NULL return on OOM */

;         png_ptr->jmp_buf_size = jmp_buf_size;
;      }
;   }

;   else /* Already allocated: check the size */
;   {
;      size_t size = png_ptr->jmp_buf_size;

;      if (size == 0)
;      {
;         size = (sizeof png_ptr->jmp_buf_local);
;         if (png_ptr->jmp_buf_ptr != &png_ptr->jmp_buf_local)
;         {
	; This is an internal error in libpng: somehow we have been left
	; with a stack allocated jmp_buf when the application regained
	; control.  It's always possible to fix this up, but for the moment
	; this is a png_error because that makes it easy to detect.

;            png_error(png_ptr, "Libpng jmp_buf still allocated");
;            /* png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local; */
;         }
;      }

;      if (size != jmp_buf_size)
;      {
;         png_warning(png_ptr, "Application jmp_buf size changed");
;         return NULL; /* caller will probably crash: no choice here */
;      }
;   }

	; Finally fill in the function, now we have a satisfactory buffer. It is
	; valid to change the function on every call.

;   png_ptr->longjmp_fn = longjmp_fn;
;   return png_ptr->jmp_buf_ptr;
.end_f:
	ret
endp

;void (png_structrp png_ptr)
align 4
proc png_free_jmpbuf, png_ptr:dword
;   if (png_ptr != NULL)
;   {
;      jmp_buf *jb = png_ptr->jmp_buf_ptr;

		; A size of 0 is used to indicate a local, stack, allocation of the
		; pointer; used here and in png.c

;      if (jb != NULL && png_ptr->jmp_buf_size > 0)
;      {

			; This stuff is so that a failure to free the error control structure
			; does not leave libpng in a state with no valid error handling: the
			; free always succeeds, if there is an error it gets ignored.

;         if (jb != &png_ptr->jmp_buf_local)
;         {
;            /* Make an internal, libpng, jmp_buf to return here */
;            jmp_buf free_jmp_buf;

;            if (!setjmp(free_jmp_buf))
;            {
;               png_ptr->jmp_buf_ptr = &free_jmp_buf; /* come back here */
;               png_ptr->jmp_buf_size = 0; /* stack allocation */
;               png_ptr->longjmp_fn = longjmp;
;               png_free(png_ptr, jb); /* Return to setjmp on error */
;            }
;         }
;      }

	; *Always* cancel everything out:
;      png_ptr->jmp_buf_size = 0;
;      png_ptr->jmp_buf_ptr = NULL;
;      png_ptr->longjmp_fn = 0;
;   }
	ret
endp

; This is the default error handling function.  Note that replacements for
; this function MUST NOT RETURN, or the program will likely crash.  This
; function is used by default, or if the program supplies NULL for the
; error function pointer in png_set_error_fn().

;void (png_const_structrp png_ptr, charp error_message)
align 4
proc png_default_error, png_ptr:dword, error_message:dword
if PNG_CONSOLE_IO_SUPPORTED eq 1
if PNG_ERROR_NUMBERS_SUPPORTED eq 1
	; Check on NULL only added in 1.5.4
;   if (error_message != NULL && *error_message == PNG_LITERAL_SHARP)
;   {
		; Strip "#nnnn " from beginning of error message.
;      int offset;
;      char error_number[16];
;      for (offset = 0; offset<15; offset++)
;      {
;         error_number[offset] = error_message[offset + 1];
;         if (error_message[offset] == ' ')
;            break;
;      }

;      if ((offset > 1) && (offset < 15))
;      {
;         error_number[offset - 1] = '\0';
;         fprintf(stderr, "libpng error no. %s: %s",
;             error_number, error_message + offset + 1);
;         fprintf(stderr, PNG_STRING_NEWLINE);
;      }

;      else
;      {
;         fprintf(stderr, "libpng error: %s, offset=%d",
;             error_message, offset);
;         fprintf(stderr, PNG_STRING_NEWLINE);
;      }
;   }
;   else
end if
;   {
;      fprintf(stderr, "libpng error: %s", error_message ? error_message :
;         "undefined");
;      fprintf(stderr, PNG_STRING_NEWLINE);
;   }
end if
;   png_longjmp(png_ptr, 1);
	ret
endp

; This function is called when there is a warning, but the library thinks
; it can continue anyway.  Replacement functions don't have to do anything
; here if you don't want them to.  In the default configuration, png_ptr is
; not used, but it is passed in case it may be useful.

;void (png_const_structrp png_ptr, charp warning_message)
align 4
proc png_default_warning, png_ptr:dword, warning_message:dword
if PNG_CONSOLE_IO_SUPPORTED eq 1
if PNG_ERROR_NUMBERS_SUPPORTED eq 1
;   if (*warning_message == PNG_LITERAL_SHARP)
;   {
;      int offset;
;      char warning_number[16];
;      for (offset = 0; offset < 15; offset++)
;      {
;         warning_number[offset] = warning_message[offset + 1];
;         if (warning_message[offset] == ' ')
;            break;
;      }

;      if ((offset > 1) && (offset < 15))
;      {
;         warning_number[offset + 1] = '\0';
;         fprintf(stderr, "libpng warning no. %s: %s",
;             warning_number, warning_message + offset);
;         fprintf(stderr, PNG_STRING_NEWLINE);
;      }

;      else
;      {
;         fprintf(stderr, "libpng warning: %s",
;             warning_message);
;         fprintf(stderr, PNG_STRING_NEWLINE);
;      }
;   }
;   else
end if
;   {
;      fprintf(stderr, "libpng warning: %s", warning_message);
;      fprintf(stderr, PNG_STRING_NEWLINE);
;   }
end if
	ret
endp

; This function is called when the application wants to use another method
; of handling errors and warnings.  Note that the error function MUST NOT
; return to the calling routine or serious problems will occur.  The return
; method used in the default routine calls longjmp(png_ptr->jmp_buf_ptr, 1)

;void (png_structrp png_ptr, voidp error_ptr,
;    png_error_ptr error_fn, png_error_ptr warning_fn)
align 4
proc png_set_error_fn, png_ptr:dword, error_ptr:dword, error_fn:dword, warning_fn:dword
;   if (png_ptr == NULL)
;      return;

;   png_ptr->error_ptr = error_ptr;
;   png_ptr->error_fn = error_fn;
if PNG_WARNINGS_SUPPORTED eq 1
;   png_ptr->warning_fn = warning_fn;
end if
	ret
endp


; This function returns a pointer to the error_ptr associated with the user
; functions.  The application should free any memory associated with this
; pointer before png_write_destroy and png_read_destroy are called.

;voidp (png_const_structrp png_ptr)
align 4
proc png_get_error_ptr, png_ptr:dword
;   if (png_ptr == NULL)
;      return NULL;

;   return ((voidp)png_ptr->error_ptr);
	ret
endp

;void (png_structrp png_ptr, uint_32 strip_mode)
align 4
proc png_set_strip_error_numbers, png_ptr:dword, strip_mode:dword
;   if (png_ptr != NULL)
;   {
;      png_ptr->flags &=
;         ((~(PNG_FLAG_STRIP_ERROR_NUMBERS |
;         PNG_FLAG_STRIP_ERROR_TEXT))&strip_mode);
;   }
	ret
endp

; Currently the above both depend on SETJMP_SUPPORTED, however it would be
; possible to implement without setjmp support just so long as there is some
; way to handle the error return here:

;void (png_structp png_nonconst_ptr, charp error_message)
align 4
proc png_safe_error uses eax ebx, png_nonconst_ptr:dword, error_message:dword
	mov ebx,[png_nonconst_ptr]
	mov ebx,[ebx+png_struct.error_ptr]
	; An error is always logged here, overwriting anything (typically a warning)
	; that is already there:

	cmp ebx,0
	je .end0 ;if (..!=0)
		stdcall png_safecat, dword[ebx+png_image.message], sizeof.png_image.message, 0, [error_message]
		or dword[ebx+png_image.warning_or_error], PNG_IMAGE_ERROR

		; Retrieve the jmp_buf from within the png_control, making this work for
		; C++ compilation too is pretty tricky: C++ wants a pointer to the first
		; element of a jmp_buf, but C doesn't tell us the type of that.

;      if (image->opaque != NULL && image->opaque->error_buf != NULL)
;         longjmp(png_control_jmp_buf(image->opaque), 1);

		; Missing longjmp buffer, the following is to help debugging:
;      {
;         size_t pos = png_safecat(image->message, (sizeof image->message), 0,
;             "bad longjmp: ");
;         png_safecat(image->message, (sizeof image->message), pos,
;             error_message);
;      }
	.end0:

	; Here on an internal programming error.
;   abort();
	ret
endp

;void (png_structp png_nonconst_ptr, charp warning_message)
align 4
proc png_safe_warning uses eax ebx, png_nonconst_ptr:dword, warning_message:dword
	mov ebx,[png_nonconst_ptr]
	mov ebx,[ebx+png_struct.error_ptr]

	; A warning is only logged if there is no prior warning or error.
	cmp dword[ebx+png_image.warning_or_error],0
	jne @f ;if (..==0)
		stdcall png_safecat, dword[ebx+png_image.message], sizeof.png_image.message, 0, [warning_message]
		or dword[ebx+png_image.warning_or_error], PNG_IMAGE_WARNING
	@@:
	ret
endp

;int (png_imagep image_in, int (*function)(voidp), voidp arg)
align 4
proc png_safe_execute uses ebx, image_in:dword, function:dword, arg:dword
;   volatile png_imagep image = image_in;
;   volatile int result;
;   volatile voidp saved_error_buf;
;   jmp_buf safe_jmpbuf;

	; Safely execute function(arg) with png_error returning to this function.
	mov ebx,[image_in]
;   saved_error_buf = image->opaque->error_buf;
;   result = setjmp(safe_jmpbuf) == 0;

;   if (result != 0)
;   {
;      image->opaque->error_buf = safe_jmpbuf;
		stdcall [function], [arg]
;   }

;   image->opaque->error_buf = saved_error_buf;

	; And do the cleanup prior to any failure return.
	cmp eax,0
	jne @f ;if (..==0)
		stdcall png_image_free, ebx
	@@:
	ret
endp