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

;;//// tga.asm //// (c) Nable, 2007-2008 /////////////////////////////////////////////////////////;;

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

;;                                                                                                ;;

;; 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 .                                                    ;;

;;                                                                                                ;;

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

;;                                                                                                ;;

;; References:                                                                                    ;;

;;   1. Hiview 1.2 by Mohammad A. REZAEI                                                          ;;

;;                                                                                                ;;

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

include 'tga.inc'

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

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

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

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

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

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

;> _length = data length                                                                          ;;

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

;< eax = false / true                                                                             ;;

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

	cmp	[_length], 18

	jbe	.nope

	mov	eax, [_data]

	push ebx

	mov	ebx,[eax+1] ;bl=cmatype,bh=subtype

	cmp	bl,1		;cmatype is in [0..1]

	ja	.nope

	cmp	bh,11		;subtype is in [1..3] (non-rle) or in [9..11] (rle)

	ja	.nope

	cmp	bh,9

	jae	.cont1

	cmp	bh,3

	ja	.nope

.cont1: 			;continue testing

	mov	ebx,[eax+16] ;bl=bpp, bh=flags //image descriptor

	test ebx,111b	;bpp must be 8, 15, 16, 24 or 32

	jnz	.maybe15

	shr	bl,3

	cmp	bl,4

	ja	.nope

	jmp	.cont2

.maybe15:

	cmp	bl,15

	jne	.nope

.cont2: 			;continue testing

	test bh,tga.flags.interlace_type ;deinterlacing is not supported yet

	jnz	.nope

	cmp	byte[eax+7],24	;test palette bpp - only 24 and 32 are supported

	je	.yep

	cmp	byte[eax+7],32	;test palette bpp - only 24 and 32 are supported

	je	.yep

.nope:

	xor	eax, eax

	pop ebx

	ret

.yep:

	xor	eax, eax

	inc	eax

	pop ebx

	ret

endp

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

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

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

;? Decode data into image if it contains correctly formed raw data in Targa format                ;;

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

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

;> _length = data length                                                                          ;;

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

;< eax = 0 (error) or pointer to image                                                            ;;

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

locals

  IMGwidth		dd ?

  IMGheight		dd ?

  IMGbpp		dd ?

  DupPixelCount dd ?

  TgaBlockCount dd ?

endl

	pushad

	cld						;paranoia

	and	[DupPixelCount],0	;prepare variables

	and	[TgaBlockCount],0	;prepare variables

	mov	eax,[_data]

	movzx esi,byte[eax]

	lea	esi,[esi+eax+18]	;skip comment and header

	mov	ebx,[eax+12]

	movzx ecx,bx		       ;ecx=width

	shr	ebx,16				;ebx=height

	mov	[IMGwidth],ecx

	mov	[IMGheight],ebx

	movzx edx,byte[eax+16]

	cmp	edx,16

	jnz	@f

	dec	edx					;16bpp tga images are really 15bpp ARGB

@@:

	sub	edx, 16 - Image.bpp16	; 15 -> Image.bpp15, 16 -> Image.bpp16

	mov	[IMGbpp],edx

	stdcall img.create,ecx,ebx,edx

	mov	[esp+28],eax		;save return value

	test eax,eax			;failed to allocate?

	jz	.locret 			;then exit

	cmp	edx,8

	jne	.palette_parsed

	mov edi,[eax+Image.Palette]

	mov	ecx,[_data]

	cmp	byte[ecx+2],3		;we also have grayscale subtype

	jz	.write_grayscale_palette ;that don't hold palette in file

	cmp	byte[ecx+2],11

	jz	.write_grayscale_palette

	mov dh,[ecx+7]			;size of colormap entries in bits

	movzx ecx,word[ecx+5]	;number of colormap entries

	cmp	dh,24

	jz	.skip_24bpp_palette	;test if colormap entries are 24bpp

	rep	movsd				;else they are 32 bpp

	jmp	.palette_parsed

.write_grayscale_palette:

	push eax

	mov	ecx,0x100

	xor	eax,eax

@@:

	stosd

	add	eax,0x010101

	loop @b

	pop	eax

	jmp	.palette_parsed

.skip_24bpp_palette:

	push eax

@@:

	lodsd

	dec esi

	and	eax,0xFFFFFF

;	bswap eax

;	shr	eax,8

	stosd

	loop @b

	pop	eax

.palette_parsed:

	mov	edi,[eax+Image.Data]

	imul ebx,[IMGwidth]		;ebx=width*height

	mov	edx,[IMGbpp]

	add	edx,7

	shr	edx,3				;edx=bytes per pixel

	mov	dh,dl				;dh=dl=bytes per pixel

	mov	eax,[_data]

	cmp	byte[eax+2],9

	jb	.not_an_rle

.tga_read_rle_pixel:

    cmp  [DupPixelCount],0	;Duplicate previously read pixel?

    jg	 .duplicate_previously_read_pixel

    dec  [TgaBlockCount]	;Decrement pixels remaining in block

    jns  .read_non_rle_pixel

    xor  eax,eax

    lodsb

    test al,al				;Start of duplicate-pixel block?

    jns  .2

    and  al,0x7f

    mov  [DupPixelCount],eax ;Number of duplications after this one

    and  [TgaBlockCount],0	;Then read new block header

    jmp  .read_non_rle_pixel

.2:

    mov  dword[TgaBlockCount],eax

.read_non_rle_pixel:

    xor  eax,eax

    mov  dl,dh

@@:

    shl  eax,8

    lodsb

    dec  dl

    jnz  @b

    cmp  dh,3

    jne  .put_pixel

    bswap eax

    shr  eax,8

	jmp	.put_pixel

.duplicate_previously_read_pixel:

    dec  [DupPixelCount]

.put_pixel:

	mov	dl,dh

	push eax

@@:

    stosb

    shr eax,8

    dec dl

    jnz @b

	pop	eax

	dec	ebx

	jnz	.tga_read_rle_pixel

	jmp	.locret

.not_an_rle:

	movzx edx,dl			;dh contains bpp too (for decoding needs)

	imul edx,ebx

	mov	ecx,edx

	rep	movsb				;just copy the image

.locret:

	popad

	ret

endp

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

proc img.encode.tga _img, _p_length, _options ;///////////////////////////////////////////////////;;

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

;? Encode image into raw data in Targa format                                                     ;;

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

;> _img = pointer to image                                                                        ;;

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

;< eax = 0 (error) or pointer to encoded data                                                     ;;

;< _p_length = encoded data length                                                                ;;

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

	xor	eax, eax

	ret

endp

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

;;////////////////////////////////////////////////////////////////////////////////////////////////;;

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

;! Below are private procs you should never call directly from your code                          ;;

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

;;////////////////////////////////////////////////////////////////////////////////////////////////;;

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

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

;;////////////////////////////////////////////////////////////////////////////////////////////////;;

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

;! Below is private data you should never use directly from your code                             ;;

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

;;////////////////////////////////////////////////////////////////////////////////////////////////;;

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;