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;;================================================================================================;;

;;//// png.asm //// (c) diamond, 2009 ////////////////////////////////////////////////////////////;;

;;================================================================================================;;

;;                                                                                                ;;

;; This file is part of Common development libraries (Libs-Dev).                                  ;;

;;                                                                                                ;;

;; Libs-Dev is free software: you can redistribute it and/or modify it under the terms of the GNU ;;

;; Lesser General Public License as published by the Free Software Foundation, either version 2.1 ;;

;; of the License, or (at your option) any later version.                                         ;;

;;                                                                                                ;;

;; Libs-Dev is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without  ;;

;; even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU  ;;

;; Lesser General Public License for more details.                                                ;;

;;                                                                                                ;;

;; You should have received a copy of the GNU Lesser General Public License along with Libs-Dev.  ;;

;; If not, see .                                                    ;;

;;                                                                                                ;;

;;================================================================================================;;

;;================================================================================================;;

;;proc img.is.png _data, _length ;////////////////////////////////////////////////////////////////;;

img.is.png:

;;------------------------------------------------------------------------------------------------;;

;? Determine if raw data could be decoded (is in PNG format)                                      ;;

;;------------------------------------------------------------------------------------------------;;

;> _data = raw data as read from file/stream                                                      ;;

;> _length = data length                                                                          ;;

;;------------------------------------------------------------------------------------------------;;

;< eax = false / true                                                                             ;;

;;================================================================================================;;

; test 1 (length of data)

	cmp	dword [esp+8], 8

	jb	.nope

; test 2: signature

	mov	eax, [esp+4]

	cmp	dword [eax], 0x474E5089

	jne	.nope

	cmp	dword [eax+4], 0x0A1A0A0D

	je	.yep

  .nope:

	xor	eax, eax

	ret	8

  .yep:

	xor	eax, eax

	inc	eax

	ret	8

;endp

;;================================================================================================;;

;;proc img.decode.png _data, _length, _options ;//////////////////////////////////////////////////;;

img.decode.png:

	xor	eax, eax	; .image = 0

	pushad

	mov	ebp, esp

.localsize = 29*4

virtual at ebp - .localsize

.width		dd	?

.height		dd	?

.bit_depth	dd	?

.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	?

	rd	1

.data		dd	?

.length		dd	?

.options	dd	?

end virtual

	push	eax	; .idat_read = 0

	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

@@:

	push	1

	pop	eax

	xchg	[deflate_loader_mutex], eax	; 'xchg' has an implicit 'lock' prefix

	test	eax, eax

	jz	@f

	mcall	5, 1

	jmp	@b

@@:

	cmp	[deflate_unpack2], __deflate_unpack2_import_name__

	jnz	.deflate_loaded

; do loading

	invoke	dll.load, @IMPORT

	test	eax, eax

	jz	.deflate_loaded

	add	esp, .localsize

	popad

	mov	[deflate_loader_mutex], eax

	ret	12

.deflate_loaded:

; release mutex

	mov	[deflate_loader_mutex], 0

; ok, continue

	mov	esi, [.data]		; esi -> data

	mov	ecx, [.length]		; ecx = length

; the signature has been already checked in img.is.png

	lodsd

	lodsd

	sub	ecx, 8

	xor	ebx, ebx	; no image allocated

.chunks_loop:

	sub	ecx, 12

	jc	.eof

	lodsd	; chunk length

	bswap	eax

	sub	ecx, eax

	jc	.eof

	push	ecx	; save length of data rest

	xchg	eax, ecx	; ecx = size of data in the chunk

	lodsd	; chunk type

	cmp	eax, 'IHDR'

	jz	.ihdr

	cmp	eax, 'IDAT'

	jz	.idat

	cmp	eax, 'IEND'

	jz	.iend

	cmp	eax, 'PLTE'

	jz	.palette

; unrecognized chunk, ignore

	lea	esi, [esi+ecx+4]

	pop	ecx

	jmp	.chunks_loop

; IHDR chunk

.ihdr:

	cmp	ecx, 13

	jnz	.invalid_chunk

	cmp	[.image], 0

	jnz	.invalid_chunk

; read image characteristics

	lodsd

	bswap	eax

	mov	[.width], eax

	lodsd

	bswap	eax

	mov	[.height], eax

	xor	eax, eax

	lea	ebx, [eax+1]

	lodsb

	cmp	al, 16

	ja	.invalid_chunk

	test	al, al

	jz	.invalid_chunk

	lea	edx, [eax-1]

	test	al, dl

	jnz	.invalid_chunk

	mov	[.bit_depth], eax

	lodsb

	test	al, not 7

	jnz	.invalid_chunk

	mov	[.color_type], eax

	lodsb

	test	al, al

	jnz	.invalid_chunk	; only compression method 0 is defined

	lodsb

	test	al, al

	jnz	.invalid_chunk	; only filtering method 0 is defined

	lodsb

	cmp	al, 1

	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]

	dec	edx

	js	.grayscale1

	dec	edx

	jz	.rgb1

	dec	edx

	jz	.palette1

	dec	edx

	jz	.grayscale_alpha1

	dec	edx

	dec	edx

	jnz	.invalid_chunk

.rgb_alpha1:

	inc	ebx

.rgb1:

	inc	ebx

.grayscale_alpha1:

	inc	ebx

	cmp	al, 8

	jb	.invalid_chunk

	jmp	@f

.palette1:

	cmp	al, 8

	ja	.invalid_chunk

.grayscale1:

@@:

	mul	ebx

	mov	[.bits_per_pixel], eax

	add	eax, 7

	shr	eax, 3

	mov	[.bytes_per_pixel], eax

; allocate image

	push	Image.bpp24

	pop	eax

	cmp	[.color_type], 2

	jz	@f

	mov	al, Image.bpp32

	cmp	[.color_type], 6

	jz	@f

	mov	al, Image.bpp8

@@:

	stdcall	img.create, [.width], [.height], eax

	test	eax, eax

	jz	.invalid_chunk

	mov	[.image], eax

	jmp	.next_chunk

.invalid_chunk:

.iend:

	pop	ecx

.eof:

	add	esp, .localsize

	popad

	ret	12

; PLTE chunk

.palette:

	mov	eax, [.image]

	test	eax, eax

	jz	.invalid_chunk

	cmp	[.color_type], 3

	jz	.copy_palette

.ignore_chunk:

	add	esi, ecx

.next_chunk:

	lodsd

	pop	ecx

	jmp	.chunks_loop

.copy_palette:

	mov	edi, [eax + Image.Palette]

	xor	eax, eax

	cmp	ecx, 256*3

	ja	.next_chunk

@@:

	sub	ecx, 3

	jz	@f

	js	.invalid_chunk

	lodsd

	dec	esi

	bswap	eax

	shr	eax, 8

	stosd

	jmp	@b

@@:

	lodsd

	dec	esi

	bswap	eax

	shr	eax, 8

	stosd

	jmp	.next_chunk

.idat:

	jecxz	.next_chunk

	cmp	[.idat_read], 0

	jnz	@f

	lodsb

	inc	[.idat_read]

	and	al, 0xF

	cmp	al, 8

	jnz	.invalid_chunk

	dec	ecx

	jz	.next_chunk

@@:

	cmp	[.idat_read], 1

	jnz	@f

	lodsb

	inc	[.idat_read]

	test	al, 20h

	jnz	.invalid_chunk

	dec	ecx

	jz	.next_chunk

@@:

	mov	[.cur_chunk_ptr], esi

	mov	[.cur_chunk_size], ecx

	pop	[.length]

	push	eax

	push	esp

	push	ebp

	push	.deflate_callback

	call	[deflate_unpack2]

	pop	ecx

	test	eax, eax

	jz	.invalid_chunk

; convert PNG unpacked data to RAW data

	mov	esi, eax

	mov	[.allocated], eax

	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_abort

	sub	ecx, ebx

	jc	.unfilter_abort

	movzx	eax, byte [esi]

	add	esi, 1

	cmp	eax, 4

	ja	.next_scanline

	jmp	dword [@f + eax*4]

align 4

@@:

	dd	.unfilter_none

	dd	.unfilter_sub

	dd	.unfilter_up

	dd	.unfilter_average

	dd	.unfilter_paeth

.unfilter_sub:

	mov	edi, [.bytes_per_pixel]

	add	esi, edi

	sub	ebx, edi

	jbe	.next_scanline

	neg	edi

@@:

	mov	al, [esi+edi]

	add	[esi], al

	add	esi, 1

	sub	ebx, 1

	jnz	@b

	jmp	.next_scanline

.unfilter_up:

	cmp	edx, [.height]

	jz	.unfilter_none

	lea	edi, [ebx+1]

	neg	edi

@@:

	mov	al, [esi+edi]

	add	[esi], al

	add	esi, 1

	sub	ebx, 1

	jnz	@b

	jmp	.next_scanline

.unfilter_average:

	mov	edi, [.bytes_per_pixel]

	cmp	edx, [.height]

	jz	.unfilter_average_firstline

	push	edx

	lea	edx, [ebx+1]

	neg	edx

	sub	ebx, edi

@@:

	mov	al, [esi+edx]

	shr	al, 1

	add	[esi], al

	add	esi, 1

	sub	edi, 1

	jnz	@b

	mov	edi, [.bytes_per_pixel]

	neg	edi

	test	ebx, ebx

	jz	.unfilter_average_done

@@:

	mov	al, [esi+edx]

	add	al, [esi+edi]

	rcr	al, 1

	add	[esi], al

	add	esi, 1

	sub	ebx, 1

	jnz	@b

.unfilter_average_done:

	pop	edx

	jmp	.next_scanline

.unfilter_average_firstline:

	mov	edi, [.bytes_per_pixel]

	add	esi, edi

	sub	ebx, edi

	jbe	.next_scanline

	neg	edi

@@:

	mov	al, [esi+edi]

	shr	al, 1

	add	[esi], al

	add	esi, 1

	sub	ebx, 1

	jnz	@b

	jmp	.unfilter_none

.unfilter_paeth:

	cmp	edx, [.height]

	jz	.unfilter_sub

	push	edx

	lea	edx, [ebx+1]

	mov	edi, [.bytes_per_pixel]

	neg	edx

	sub	ebx, edi

@@:

	mov	al, [esi+edx]

	add	[esi], al

	add	esi, 1

	sub	edi, 1

	jnz	@b

	mov	edi, [.bytes_per_pixel]

	neg	edi

	test	ebx, ebx

	jz	.unfilter_paeth_done

	push	ecx

@@:

	push	ebx

; PaethPredictor(Raw(x-bpp) = a, Prior(x) = b, Prior(x-bpp) = c)

	movzx	eax, byte [esi+edi]

	mov	[.paeth_a], eax

	movzx	ecx, byte [esi+edx]

	add	edi, edx

	mov	[.paeth_b], ecx

	add	ecx, eax

	movzx	eax, byte [esi+edi]

	mov	[.paeth_c], eax

	sub	ecx, eax	; ecx = a + b - c = p

; calculate pa = abs(p-a), pb = abs(p-b), pc = abs(p-c)

	mov	ebx, ecx

	sub	ebx, eax	; ebx = p - c

	cmp	ebx, 80000000h

	sbb	eax, eax	; eax = (p < c) ? 0 : 0xFFFFFFF

	not	eax		; eax = (p < c) ? 0xFFFFFFFF : 0

	and	eax, ebx	; eax = (p < c) ? p - c : 0

	sub	ebx, eax

	sub	ebx, eax	; ebx = abs(p-c)

	mov	[.paeth_pc], ebx

	mov	ebx, ecx

	sub	ebx, [.paeth_a]

	cmp	ebx, 80000000h

	sbb	eax, eax

	not	eax

	and	eax, ebx

	sub	ebx, eax

	sub	ebx, eax

	mov	[.paeth_pa], ebx

	mov	ebx, ecx

	sub	ebx, [.paeth_b]

	cmp	ebx, 80000000h

	sbb	eax, eax

	not	eax

	and	eax, ebx

	sub	ebx, eax

	sub	ebx, eax

	;mov	[.paeth_pb], ebx

; select closest value

	push	edx

	mov	edx, [.paeth_b]

	sub	edx, [.paeth_a]

	sub	ebx, [.paeth_pa]

	sbb	ecx, ecx	; ecx = (pa > pb) ? 0xFFFFFFFF : 0

	sbb	eax, eax	; eax = (pa > pb) ? 0xFFFFFFFF : 0

	and	ecx, ebx	; ecx = (pa > pb) ? pb - pa : 0

	and	eax, edx	; eax = (pa > pb) ? b - a : 0

	add	ecx, [.paeth_pa]	; ecx = (pa > pb) ? pb : pa = min(pa,pb)

	add	eax, [.paeth_a]		; eax = (pa > pb) ? b : a

	mov	edx, [.paeth_c]

	sub	edx, eax

	sub	[.paeth_pc], ecx

	sbb	ebx, ebx	; ebx = (min(pa,pb) <= pc) ? 0 : 0xFFFFFFFF

	and	ebx, edx	; ebx = (min(pa,pb) <= pc) ? 0 : c - eax

	add	eax, ebx

	pop	edx

	add	[esi], al

	pop	ebx

	sub	edi, edx

	add	esi, 1

	sub	ebx, 1

	jnz	@b

	pop	ecx

.unfilter_paeth_done:

	pop	edx

	jmp	.next_scanline

.unfilter_none:

	add	esi, ebx

.next_scanline:

	sub	edx, [.row_increment]

	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

; with deinterlacing if needed

	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]

	sub	edx, [.starting_row]

	mov	[.j], edx

	cmp	[.color_type], 0

	jz	.grayscale2

	cmp	[.color_type], 2

	jz	.rgb2

	cmp	[.color_type], 3

	jz	.palette2

	cmp	[.color_type], 4

	jz	.grayscale_alpha2

.rgb_alpha2:

	cmp	[.bit_depth], 16

	jz	.rgb_alpha2_16bit

.rgb_alpha2.next:

	sub	ebx, 1

	jc	.convert_done

	add	esi, 1

	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]

	mov	[edi+1], al

	mov	al, [esi]

	mov	[edi+2], al

	mov	al, [esi+3]

	mov	[edi+3], al

	add	edi, 4

	dec	ecx

	jnz	.rgb_alpha2.innloop2

	pop	edi

	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:

	sub	ebx, 1

	jc	.convert_done

	add	esi, 1

	sub	ebx, [.scanline_len]

	jc	.convert_done

	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

{

local .l1,.l2

	xor	ah, 0x80

	js	.l1

	cmp	al, ah

	adc	al, 0

	jmp	.l2

.l1:

	cmp	ah, al

	sbb	al, 0

.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

	mov	ax, [esi+2]

	convert_16_to_8

	mov	[edi+1], al

	mov	ax, [esi]

	convert_16_to_8

	mov	[edi+2], al

	;mov	ax, [esi+6]

	;convert_16_to_8

	;mov	[edi+3], al

	add	edi, 4

	dec	ecx

	jnz	.rgb_alpha2_16bit.innloop2

	pop	edi

	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:

	call	.create_grayscale_palette

	cmp	[.bit_depth], 16

	jz	.grayscale2_16bit

.palette2:

	cmp	[.bit_depth], 1

	jz	.palette2_1bit

	cmp	[.bit_depth], 2

	jz	.palette2_2bit

	cmp	[.bit_depth], 4

	jz	.palette2_4bit

.palette2_8bit:

	sub	ebx, 1

	jc	.convert_done

	add	esi, 1

	sub	ebx, [.scanline_len]

	jc	.convert_done

	mov	ecx, [.width]

	sub	ecx, [.starting_col]

	mov	[.i], ecx

.palette2_8bit.extloop:

	init_block

	add	eax, edi

	push	eax

	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

	jc	.convert_done

	add	esi, 1

	sub	ebx, [.scanline_len]

	jc	.convert_done

	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]

	inc	esi

	shr	al, 4

	jmp	@f

.palette2_4bit.shifted:

	mov	al, [esi-1]

	and	al, 0xF

@@:

	block_byte_innerloop .palette2_4bit.extloop

	ja	.palette2_4bit

	jmp	.convert_done

.palette2_2bit:

	sub	ebx, 1

	jc	.convert_done

	add	esi, 1

	sub	ebx, [.scanline_len]

	jc	.convert_done

	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]

	inc	esi

	shr	al, cl

	jmp	@f

.palette2_2bit.shifted:

	mov	al, [esi-1]

	shr	al, cl

	and	al, 3

@@:

	mov	[.shift], cl

	block_byte_innerloop .palette2_2bit.extloop

	ja	.palette2_2bit

	jmp	.convert_done

.palette2_1bit:

	sub	ebx, 1

	jc	.convert_done

	add	esi, 1

	sub	ebx, [.scanline_len]

	jc	.convert_done

	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]

	inc	esi

	shr	al, cl

	jmp	@f

.palette2_1bit.shifted:

	mov	al, [esi-1]

	shr	al, cl

	and	al, 1

@@:

	mov	[.shift], cl

	block_byte_innerloop .palette2_1bit.extloop

	ja	.palette2_1bit

	jmp	.convert_done

.grayscale2_16bit:

	sub	ebx, 1

	jc	.convert_done

	add	esi, 1

	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

	block_byte_innerloop .grayscale2_16bit.extloop

	ja	.grayscale2_16bit

	jmp	.convert_done

.rgb2:

	cmp	[.bit_depth], 16

	jz	.rgb2_16bit

.rgb2.next:

	sub	ebx, 1

	jc	.convert_done

	add	esi, 1

	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	edi, 3

	dec	ecx

	jnz	.rgb2.innloop2

	pop	edi

	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:

	sub	ebx, 1

	jc	.convert_done

	add	esi, 1

	sub	ebx, [.scanline_len]

	jc	.convert_done

	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

	mov	ax, [esi+2]

	convert_16_to_8

	mov	[edi+1], al

	mov	ax, [esi]

	convert_16_to_8

	mov	[edi+2], al

	add	edi, 3

	dec	ecx

	jnz	.rgb2_16bit.innloop2

	pop	edi

	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:

	sub	ebx, 1

	jc	.convert_done

	add	esi, 1

	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]

	add	esi, 2

	block_byte_innerloop .grayscale_alpha2.extloop

	ja	.grayscale_alpha2.next

	jmp	.convert_done

.grayscale_alpha2_16bit:

	sub	ebx, 1

	jc	.convert_done

	add	esi, 1

	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

	block_byte_innerloop .grayscale_alpha2_16bit.extloop

	ja	.grayscale_alpha2_16bit

.convert_done:

; next interlace pass

.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]

	jmp	.next_chunk

.deflate_callback:

	mov	ebp, [esp+4]

	mov	ebx, [esp+8]

	xor	eax, eax

	mov	esi, [.cur_chunk_size]

	mov	[ebx], esi

	test	esi, esi

	jz	.deflate_callback.ret

	mov	eax, [.cur_chunk_ptr]

	mov	ecx, [.length]

	add	esi, eax

	mov	[.cur_chunk_ptr], esi

	and	[.cur_chunk_size], 0

@@:

	sub	ecx, 12

	jb	.deflate_callback.ret

	cmp	dword [esi+4+4], 'IDAT'

	jnz	.deflate_callback.ret

	mov	edx, [esi+4]

	bswap	edx

	sub	ecx, edx

	jb	.deflate_callback.ret

	add	esi, 4+8

	test	edx, edx

	jz	@b

	mov	[.cur_chunk_size], edx

	mov	[.cur_chunk_ptr], esi

	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:

	xor	eax, eax

	ret	12