libimg: interlaced PNG

git-svn-id: svn://kolibrios.org@1308 a494cfbc-eb01-0410-851d-a64ba20cac60

programs/develop/libraries/libs-dev/libimg/png/png.asm

@@ -54,7 +54,7 @@ img.decode.png:
 	xor	eax, eax	; .image = 0
 	pushad
 	mov	ebp, esp
-.localsize = 15*4
+.localsize = 29*4
 virtual at ebp - .localsize
 .width		dd	?
 .height		dd	?
@@ -62,14 +62,32 @@ virtual at ebp - .localsize
 .color_type	dd	?
 .bytes_per_pixel dd	?
 .scanline_len	dd	?
+.bits_per_pixel dd	?
+.size_rest	dd	?
 .cur_chunk_ptr	dd	?
 .cur_chunk_size	dd	?
+.allocated	dd	?
 .paeth_a	dd	?
 .paeth_b	dd	?
 .paeth_c	dd	?
 .paeth_pa	dd	?
 .paeth_pb	dd	?
 .paeth_pc	dd	?
+.i		dd	?
+.j		dd	?
+; variables to handle interlace
+.row_distance	dd	?	; diff between two consecutives rows in destination
+.col_distance	dd	?	; summand for moving to next row in source
+.row_increment	dd	?
+.col_increment	dd	?
+.block_height	dd	?
+.block_width	dd	?
+.interlace	db	?	; 0 if not interlaced, 1 if interlaced
+.row_increment_shift db	?
+.col_increment_shift db	?
+.shift		db	?	; shift for current src byte
+.starting_row	dd	?
+.starting_col	dd	?
 .idat_read	dd	?
 	rb	1Ch
 .image		dd	?
@@ -78,8 +96,16 @@ virtual at ebp - .localsize
 .length		dd	?
 .options	dd	?
 end virtual
-	push	0	; .idat_read = 0
+	push	eax	; .idat_read = 0
-	sub	esp, .localsize-4
+	push	eax	; .starting_col = 0
+	push	eax	; .starting_row = 0
+	push	eax	; .col_increment_shift, .row_increment_shift
+	inc	eax
+	push	eax	; .block_width
+	push	eax	; .block_height
+	push	eax	; .col_increment
+	push	eax	; .row_increment
+	sub	esp, .localsize-32
 ; load deflate unpacker, if not yet
 ; acquire mutex
 @@:
@@ -169,8 +195,9 @@ end virtual
 	test	al, al
 	jnz	.invalid_chunk	; only filtering method 0 is defined
 	lodsb
-	test	al, al
+	cmp	al, 1
-	jnz	.invalid_chunk	; progressive PNGs are not supported yet
+	ja	.invalid_chunk	; only interlacing methods 0 and 1 are defined
+	mov	[.interlace], al
 ; check for correctness and calculate bytes_per_pixel and scanline_len
 	mov	eax, [.bit_depth]
 	mov	edx, [.color_type]
@@ -200,15 +227,10 @@ end virtual
 .grayscale1:
 @@:
 	mul	ebx
-	push	eax
+	mov	[.bits_per_pixel], eax
 	add	eax, 7
 	shr	eax, 3
 	mov	[.bytes_per_pixel], eax
-	pop	eax
-	mul	[.width]
-	add	eax, 7
-	shr	eax, 3
-	mov	[.scanline_len], eax
 ; allocate image
 	push	Image.bpp24
 	pop	eax
@@ -300,15 +322,49 @@ end virtual
 	jz	.invalid_chunk
 ; convert PNG unpacked data to RAW data
 	mov	esi, eax
-	push	eax ecx
+	mov	[.allocated], eax
-; unfilter
+	mov	[.size_rest], ecx
+; unfilter and deinterlace
+; .interlace_pass, .starting_row and .starting_col have been already set to 0
+; .block_width, .block_height, .col_increment, .row_increment were set
+; to values for non-interlaced images; correct if necessary
+	cmp	[.interlace], 0
+	jz	.deinterlace_loop
+	push	8
+	pop	eax
+	mov	[.row_increment], eax
+	mov	[.col_increment], eax
+	mov	[.block_height], eax
+	mov	[.block_width], eax
+	mov	[.row_increment_shift], 3
+	mov	[.col_increment_shift], 3
+.deinterlace_loop:
 	mov	edx, [.height]
+	cmp	edx, [.starting_row]
+	jbe	.deinterlace_next
+	mov	ebx, [.width]
+	sub	ebx, [.starting_col]
+	jbe	.deinterlace_next
+	mov	cl, [.col_increment_shift]
+	add	ebx, [.col_increment]
+	dec	ebx
+	shr	ebx, cl
+	mov	eax, [.bits_per_pixel]
+	imul	eax, ebx
+	add	eax, 7
+	shr	eax, 3
+	mov	[.scanline_len], eax
+	shl	ebx, cl
+	mov	[.col_distance], ebx
+; Unfilter
+	mov	ecx, [.size_rest]
+	push	esi
 .unfilter_loop_e:
 	mov	ebx, [.scanline_len]
 	sub	ecx, 1
-	jc	.unfilter_done
+	jc	.unfilter_abort
 	sub	ecx, ebx
-	jc	.unfilter_done
+	jc	.unfilter_abort
 	movzx	eax, byte [esi]
 	add	esi, 1
 	cmp	eax, 4
@@ -480,15 +536,38 @@ align 4
 .unfilter_none:
 	add	esi, ebx
 .next_scanline:
-	sub	edx, 1
+	sub	edx, [.row_increment]
-	jnz	.unfilter_loop_e
+	jc	.unfilter_done
+	cmp	edx, [.starting_row]
+	jbe	.unfilter_done
+	jmp	.unfilter_loop_e
+.unfilter_abort:
+	xor	ecx, ecx
 .unfilter_done:
 ; unfiltering done, now convert to raw data
-	pop	ebx esi
+; with deinterlacing if needed
-	push	esi
+	pop	esi
+	mov	ebx, [.image]
+	mov	eax, [.width]
+	call	img._.get_scanline_len
+	mov	[.row_distance], eax
+	mov	eax, [.row_increment]
+	mul	[.width]
+	sub	eax, [.col_distance]
+	call	img._.get_scanline_len
+	mov	[.col_distance], eax
+	mov	edi, [ebx + Image.Data]
+	mov	eax, [.starting_row]
+	mul	[.width]
+	add	eax, [.starting_col]
+	call	img._.get_scanline_len
+	add	edi, eax
+	mov	eax, ebx
+	mov	ebx, [.size_rest]
+	mov	[.size_rest], ecx
 	mov	edx, [.height]
-	mov	eax, [.image]
+	sub	edx, [.starting_row]
-	mov	edi, [eax + Image.Data]
+	mov	[.j], edx
 	cmp	[.color_type], 0
 	jz	.grayscale2
 	cmp	[.color_type], 2
@@ -501,13 +580,39 @@ align 4
 	cmp	[.bit_depth], 16
 	jz	.rgb_alpha2_16bit
 .rgb_alpha2.next:
-	mov	ecx, [.scanline_len]
 	sub	ebx, 1
 	jc	.convert_done
 	add	esi, 1
-	sub	ebx, ecx
+	sub	ebx, [.scanline_len]
 	jc	.convert_done
+	mov	ecx, [.width]
+	sub	ecx, [.starting_col]
+	mov	[.i], ecx
+.rgb_alpha2.extloop:
+
+macro init_block
+{
+	push	ebx
+	mov	eax, [.col_increment]
+	mov	edx, [.j]
+	cmp	edx, [.block_height]
+	jb	@f
+	mov	edx, [.block_height]
 @@:
+	mov	ebx, [.i]
+	cmp	ebx, [.block_width]
+	jb	@f
+	mov	ebx, [.block_width]
+@@:
+}
+
+	init_block
+	lea	eax, [edi+eax*4]
+	push	eax
+.rgb_alpha2.innloop1:
+	push	edi
+	mov	ecx, ebx
+.rgb_alpha2.innloop2:
 	mov	al, [esi+2]
 	mov	[edi], al
 	mov	al, [esi+1]
@@ -516,21 +621,36 @@ align 4
 	mov	[edi+2], al
 	mov	al, [esi+3]
 	mov	[edi+3], al
-	add	esi, 4
 	add	edi, 4
-	sub	ecx, 4
+	dec	ecx
-	jnz	@b
+	jnz	.rgb_alpha2.innloop2
-	sub	edx, 1
+	pop	edi
-	jnz	.rgb_alpha2.next
+	add	edi, [.row_distance]
+	dec	edx
+	jnz	.rgb_alpha2.innloop1
+	pop	edi ebx
+	add	esi, 4
+	mov	eax, [.col_increment]
+	sub	[.i], eax
+	ja	.rgb_alpha2.extloop
+	add	edi, [.col_distance]
+	mov	eax, [.row_increment]
+	sub	[.j], eax
+	ja	.rgb_alpha2.next
 	jmp	.convert_done
 .rgb_alpha2_16bit:
-	mov	ecx, [.scanline_len]
 	sub	ebx, 1
 	jc	.convert_done
 	add	esi, 1
-	sub	ebx, ecx
+	sub	ebx, [.scanline_len]
 	jc	.convert_done
-.rgb_alpha2.loop:
+	mov	ecx, [.width]
+	sub	ecx, [.starting_col]
+	mov	[.i], ecx
+.rgb_alpha2_16bit.loop:
+	init_block
+	lea	eax, [edi+eax*4]
+	push	eax
 
 ; convert 16 bit sample to 8 bit sample
 macro convert_16_to_8
@@ -547,6 +667,10 @@ local .l1,.l2
 .l2:
 }
 
+.rgb_alpha2_16bit.innloop1:
+	push	edi
+	mov	ecx, ebx
+.rgb_alpha2_16bit.innloop2:
 	mov	ax, [esi+4]
 	convert_16_to_8
 	mov	[edi], al
@@ -559,42 +683,25 @@ local .l1,.l2
 	;mov	ax, [esi+6]
 	;convert_16_to_8
 	;mov	[edi+3], al
-	add	esi, 8
 	add	edi, 4
-	sub	ecx, 8
+	dec	ecx
-	jnz	.rgb_alpha2.loop
+	jnz	.rgb_alpha2_16bit.innloop2
-	sub	edx, 1
+	pop	edi
-	jnz	.rgb_alpha2_16bit
+	add	edi, [.row_distance]
+	dec	edx
+	jnz	.rgb_alpha2_16bit.innloop1
+	pop	edi ebx
+	add	esi, 8
+	mov	eax, [.col_increment]
+	sub	[.i], eax
+	ja	.rgb_alpha2_16bit.loop
+	add	edi, [.col_distance]
+	mov	eax, [.row_increment]
+	sub	[.j], eax
+	ja	.rgb_alpha2_16bit
 	jmp	.convert_done
 .grayscale2:
-	push	edi edx
+	call	.create_grayscale_palette
-	mov	edi, [eax + Image.Palette]
-	mov	ecx, [.bit_depth]
-	cmp	cl, 16
-	jnz	@f
-	mov	cl, 8
-@@:
-	push	1
-	pop	eax
-	shl	eax, cl
-	xchg	eax, ecx
-	mov	edx, 0x010101
-	cmp	al, 8
-	jz	.graypal_common
-	mov	edx, 0x111111
-	cmp	al, 4
-	jz	.graypal_common
-	mov	edx, 0x555555
-	cmp	al, 2
-	jz	.graypal_common
-	mov	edx, 0xFFFFFF
-.graypal_common:
-	xor	eax, eax
-@@:
-	stosd
-	add	eax, edx
-	loop	@b
-	pop	edx edi
 	cmp	[.bit_depth], 16
 	jz	.grayscale2_16bit
 .palette2:
@@ -605,20 +712,40 @@ local .l1,.l2
 	cmp	[.bit_depth], 4
 	jz	.palette2_4bit
 .palette2_8bit:
-	mov	ecx, [.scanline_len]
 	sub	ebx, 1
 	jc	.convert_done
 	add	esi, 1
-	sub	ebx, ecx
+	sub	ebx, [.scanline_len]
 	jc	.convert_done
-	push	ecx
+	mov	ecx, [.width]
-	shr	ecx, 2
+	sub	ecx, [.starting_col]
-	rep	movsd
+	mov	[.i], ecx
-	pop	ecx
+.palette2_8bit.extloop:
-	and	ecx, 3
+	init_block
-	rep	movsb
+	add	eax, edi
-	sub	edx, 1
+	push	eax
-	jnz	.palette2_8bit
+	mov	al, [esi]
+	inc	esi
+macro block_byte_innerloop extloop
+{
+local .l1
+.l1:
+	mov	ecx, ebx
+	rep	stosb
+	sub	edi, ebx
+	add	edi, [.row_distance]
+	dec	edx
+	jnz	.l1
+	pop	edi ebx
+	mov	eax, [.col_increment]
+	sub	[.i], eax
+	ja	extloop
+	add	edi, [.col_distance]
+	mov	eax, [.row_increment]
+	sub	[.j], eax
+}
+	block_byte_innerloop .palette2_8bit.extloop
+	ja	.palette2_8bit
 	jmp	.convert_done
 .palette2_4bit:
 	sub	ebx, 1
@@ -626,27 +753,26 @@ local .l1,.l2
 	add	esi, 1
 	sub	ebx, [.scanline_len]
 	jc	.convert_done
-	push	edx
 	mov	ecx, [.width]
-@@:
+	sub	ecx, [.starting_col]
+	mov	[.i], ecx
+	mov	[.shift], 0
+.palette2_4bit.extloop:
+	init_block
+	add	eax, edi
+	push	eax
+	xor	[.shift], 1
+	jz	.palette2_4bit.shifted
 	mov	al, [esi]
-	add	esi, 1
+	inc	esi
-	mov	dl, al
 	shr	al, 4
-	and	dl, 0xF
+	jmp	@f
-	mov	[edi], al
+.palette2_4bit.shifted:
-	sub	ecx, 1
+	mov	al, [esi-1]
-	jz	@f
+	and	al, 0xF
-	mov	[edi+1], dl
-	add	edi, 2
-	sub	ecx, 1
-	jnz	@b
-	sub	edi, 1
 @@:
-	pop	edx
+	block_byte_innerloop .palette2_4bit.extloop
-	add	edi, 1
+	ja	.palette2_4bit
-	sub	edx, 1
-	jnz	.palette2_4bit
 	jmp	.convert_done
 .palette2_2bit:
 	sub	ebx, 1
@@ -654,40 +780,30 @@ local .l1,.l2
 	add	esi, 1
 	sub	ebx, [.scanline_len]
 	jc	.convert_done
-	push	edx
 	mov	ecx, [.width]
-@@:
+	sub	ecx, [.starting_col]
+	mov	[.i], ecx
+	mov	[.shift], 0
+.palette2_2bit.extloop:
+	init_block
+	add	eax, edi
+	push	eax
+	mov	cl, [.shift]
+	sub	cl, 2
+	jns	.palette2_2bit.shifted
+	mov	cl, 6
 	mov	al, [esi]
-	add	esi, 1
+	inc	esi
-	mov	dl, al
+	shr	al, cl
-	shr	al, 6
+	jmp	@f
-	and	dl, not 11000000b
+.palette2_2bit.shifted:
-	mov	[edi], al
+	mov	al, [esi-1]
-	add	edi, 1
+	shr	al, cl
-	sub	ecx, 1
+	and	al, 3
-	jz	@f
-	mov	al, dl
-	shr	dl, 4
-	and	al, not 00110000b
-	mov	[edi], dl
-	add	edi, 1
-	sub	ecx, 1
-	jz	@f
-	mov	dl, al
-	shr	al, 2
-	and	dl, not 00001100b
-	mov	[edi], al
-	add	edi, 1
-	sub	ecx, 1
-	jz	@f
-	mov	[edi], dl
-	add	edi, 1
-	sub	ecx, 1
-	jnz	@b
 @@:
-	pop	edx
+	mov	[.shift], cl
-	sub	edx, 1
+	block_byte_innerloop .palette2_2bit.extloop
-	jnz	.palette2_2bit
+	ja	.palette2_2bit
 	jmp	.convert_done
 .palette2_1bit:
 	sub	ebx, 1
@@ -695,93 +811,112 @@ local .l1,.l2
 	add	esi, 1
 	sub	ebx, [.scanline_len]
 	jc	.convert_done
-	push	edx
 	mov	ecx, [.width]
-@@:
+	sub	ecx, [.starting_col]
+	mov	[.i], ecx
+	mov	[.shift], 0
+.palette2_1bit.extloop:
+	init_block
+	add	eax, edi
+	push	eax
+	mov	cl, [.shift]
+	dec	cl
+	jns	.palette2_1bit.shifted
+	mov	cl, 7
 	mov	al, [esi]
-	add	esi, 1
+	inc	esi
-repeat 3
+	shr	al, cl
-	mov	dl, al
+	jmp	@f
-	shr	al, 9-%*2
+.palette2_1bit.shifted:
-	and	dl, not (1 shl (9-%*2))
+	mov	al, [esi-1]
-	mov	[edi], al
+	shr	al, cl
-	add	edi, 1
+	and	al, 1
-	sub	ecx, 1
-	jz	@f
-	mov	al, dl
-	shr	dl, 8-%*2
-	and	al, not (1 shl (8-%*2))
-	mov	[edi], dl
-	add	edi, 1
-	sub	ecx, 1
-	jz	@f
-end repeat
-	mov	dl, al
-	shr	al, 1
-	and	dl, not (1 shl 1)
-	mov	[edi], al
-	add	edi, 1
-	sub	ecx, 1
-	jz	@f
-	mov	[edi], dl
-	add	edi, 1
-	sub	ecx, 1
-	jnz	@b
 @@:
-	pop	edx
+	mov	[.shift], cl
-	sub	edx, 1
+	block_byte_innerloop .palette2_1bit.extloop
-	jnz	.palette2_1bit
+	ja	.palette2_1bit
 	jmp	.convert_done
 .grayscale2_16bit:
-	mov	ecx, [.scanline_len]
 	sub	ebx, 1
 	jc	.convert_done
 	add	esi, 1
-	sub	ebx, ecx
+	sub	ebx, [.scanline_len]
 	jc	.convert_done
-@@:
+	mov	ecx, [.width]
+	sub	ecx, [.starting_col]
+	mov	[.i], ecx
+.grayscale2_16bit.extloop:
+	init_block
+	add	eax, edi
+	push	eax
 	mov	ax, [esi]
 	add	esi, 2
 	convert_16_to_8
-	mov	[edi], al
+	block_byte_innerloop .grayscale2_16bit.extloop
-	add	edi, 1
+	ja	.grayscale2_16bit
-	sub	ecx, 2
-	jnz	@b
-	sub	edx, 1
-	jnz	.grayscale2_16bit
 	jmp	.convert_done
 .rgb2:
 	cmp	[.bit_depth], 16
 	jz	.rgb2_16bit
 .rgb2.next:
-	mov	ecx, [.scanline_len]
 	sub	ebx, 1
 	jc	.convert_done
 	add	esi, 1
-	sub	ebx, ecx
+	sub	ebx, [.scanline_len]
 	jc	.convert_done
-@@:
+	mov	ecx, [.width]
+	sub	ecx, [.starting_col]
+	mov	[.i], ecx
+.rgb2.extloop:
+	init_block
+	lea	eax, [eax*3]
+	add	eax, edi
+	push	eax
+.rgb2.innloop1:
+	push	edi
+	mov	ecx, ebx
+.rgb2.innloop2:
 	mov	al, [esi+2]
 	mov	[edi], al
 	mov	al, [esi+1]
 	mov	[edi+1], al
 	mov	al, [esi]
 	mov	[edi+2], al
-	add	esi, 3
 	add	edi, 3
-	sub	ecx, 3
+	dec	ecx
-	jnz	@b
+	jnz	.rgb2.innloop2
-	sub	edx, 1
+	pop	edi
-	jnz	.rgb2.next
+	add	edi, [.row_distance]
+	dec	edx
+	jnz	.rgb2.innloop1
+	pop	edi ebx
+	add	esi, 3
+	mov	eax, [.col_increment]
+	sub	[.i], eax
+	ja	.rgb2.extloop
+	add	edi, [.col_distance]
+	mov	eax, [.row_increment]
+	sub	[.j], eax
+	ja	.rgb2.next
 	jmp	.convert_done
 .rgb2_16bit:
-	mov	ecx, [.scanline_len]
 	sub	ebx, 1
 	jc	.convert_done
 	add	esi, 1
-	sub	ebx, ecx
+	sub	ebx, [.scanline_len]
 	jc	.convert_done
-.rgb2.loop:
+	mov	ecx, [.width]
+	sub	ecx, [.starting_col]
+	mov	[.i], ecx
+.rgb2_16bit.extloop:
+	init_block
+	lea	eax, [eax*3]
+	add	eax, edi
+	push	eax
+.rgb2_16bit.innloop1:
+	push	edi
+	mov	ecx, ebx
+.rgb2_16bit.innloop2:
 	mov	ax, [esi+4]
 	convert_16_to_8
 	mov	[edi], al
@@ -791,53 +926,88 @@ end repeat
 	mov	ax, [esi]
 	convert_16_to_8
 	mov	[edi+2], al
-	add	esi, 6
 	add	edi, 3
-	sub	ecx, 6
+	dec	ecx
-	jnz	.rgb2.loop
+	jnz	.rgb2_16bit.innloop2
-	sub	edx, 1
+	pop	edi
-	jnz	.rgb2_16bit
+	add	edi, [.row_distance]
+	dec	edx
+	jnz	.rgb2_16bit.innloop1
+	pop	edi ebx
+	add	esi, 6
+	mov	eax, [.col_increment]
+	sub	[.i], eax
+	ja	.rgb2_16bit.extloop
+	add	edi, [.col_distance]
+	mov	eax, [.row_increment]
+	sub	[.j], eax
+	ja	.rgb2_16bit
 	jmp	.convert_done
 .grayscale_alpha2:
+	call	.create_grayscale_palette
 	cmp	[.bit_depth], 16
 	jz	.grayscale_alpha2_16bit
 .grayscale_alpha2.next:
-	mov	ecx, [.scanline_len]
 	sub	ebx, 1
 	jc	.convert_done
 	add	esi, 1
-	sub	ebx, ecx
+	sub	ebx, [.scanline_len]
 	jc	.convert_done
-@@:
+	mov	ecx, [.width]
+	sub	ecx, [.starting_col]
+	mov	[.i], ecx
+.grayscale_alpha2.extloop:
+	init_block
+	add	eax, edi
+	push	eax
 	mov	al, [esi]
-	mov	[edi], al
 	add	esi, 2
-	add	edi, 1
+	block_byte_innerloop .grayscale_alpha2.extloop
-	sub	ecx, 2
+	ja	.grayscale_alpha2.next
-	jnz	@b
-	sub	edx, 1
-	jnz	.grayscale_alpha2.next
 	jmp	.convert_done
 .grayscale_alpha2_16bit:
-	mov	ecx, [.scanline_len]
 	sub	ebx, 1
 	jc	.convert_done
 	add	esi, 1
-	sub	ebx, ecx
+	sub	ebx, [.scanline_len]
 	jc	.convert_done
-@@:
+	mov	ecx, [.width]
+	sub	ecx, [.starting_col]
+	mov	[.i], ecx
+.grayscale_alpha2_16bit.extloop:
+	init_block
+	add	eax, edi
+	push	eax
 	mov	ax, [esi]
 	add	esi, 4
 	convert_16_to_8
-	mov	[edi], al
+	block_byte_innerloop .grayscale_alpha2_16bit.extloop
-	add	edi, 1
+	ja	.grayscale_alpha2_16bit
-	sub	ecx, 4
-	jnz	@b
-	sub	edx, 1
-	jnz	.grayscale_alpha2_16bit
 .convert_done:
-	pop	ecx
+; next interlace pass
-	mcall	68, 13
+.deinterlace_next:
+	mov	eax, [.block_width]
+	cmp	eax, [.block_height]
+	jz	.deinterlace_dec_width
+	mov	[.block_height], eax
+	mov	[.col_increment], eax
+	dec	[.col_increment_shift]
+	mov	[.starting_row], eax
+	and	[.starting_col], 0
+	jmp	.deinterlace_loop
+.deinterlace_dec_width:
+	shr	eax, 1
+	jz	.deinterlace_done
+	mov	[.block_width], eax
+	mov	[.starting_col], eax
+	add	eax, eax
+	and	[.starting_row], 0
+	mov	[.row_increment], eax
+	bsf	eax, eax
+	mov	[.row_increment_shift], al
+	jmp	.deinterlace_loop
+.deinterlace_done:
+	mcall	68, 13, [.allocated]
 	mov	esi, [.cur_chunk_ptr]
 	add	esi, [.cur_chunk_size]
 	push	[.length]
@@ -873,6 +1043,37 @@ end repeat
 	mov	[.length], ecx
 .deflate_callback.ret:
 	ret	8
+
+.create_grayscale_palette:
+	push	edi edx
+	mov	edi, [eax + Image.Palette]
+	mov	ecx, [.bit_depth]
+	cmp	cl, 16
+	jnz	@f
+	mov	cl, 8
+@@:
+	push	1
+	pop	eax
+	shl	eax, cl
+	xchg	eax, ecx
+	mov	edx, 0x010101
+	cmp	al, 8
+	jz	.graypal_common
+	mov	edx, 0x111111
+	cmp	al, 4
+	jz	.graypal_common
+	mov	edx, 0x555555
+	cmp	al, 2
+	jz	.graypal_common
+	mov	edx, 0xFFFFFF
+.graypal_common:
+	xor	eax, eax
+@@:
+	stosd
+	add	eax, edx
+	loop	@b
+	pop	edx edi
+	ret
 ;endp
 
 img.encode.png: