;;================================================================================================;;
;;//// 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 <http://www.gnu.org/licenses/>. ;;
;; ;;
;;================================================================================================;;
;; ;;
;; 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 ;;
;;================================================================================================;;
;;////////////////////////////////////////////////////////////////////////////////////////////////;;
;;================================================================================================;;
;