; GIF LITE v2.0 by Willow ; Written in pure assembler by Ivushkin Andrey aka Willow ; ; This include file will contain functions to handle GIF image format ; ; Created: August 15, 2004 ; Last changed: September 9, 2004 ; Change COLOR_ORDER in your program ; if colors are displayed improperly if ~ (COLOR_ORDER in <MENUETOS,OTHER>) ; This message may not appear under MenuetOS, so watch... display 'Please define COLOR_ORDER: MENUETOS or OTHER',13,10 end if struc GIF_info { ; .NextImg rd 1 ; used internally .Left rw 1 .Top rw 1 .Width rw 1 .Height rw 1 } _null fix 0x1000 ; **************************************** ; FUNCTION GetGIFinfo - retrieve Nth image info ; **************************************** ; in: ; esi - pointer to image list header ; ecx - image_index (0...img_count-1) ; edi - pointer to GIF_info structure to be filled ; out: ; eax - pointer to RAW data, or 0, if error GetGIFinfo: push esi ecx edi xor eax,eax jecxz .eloop .lp: mov esi,[esi] test esi,esi jz .error loop .lp .eloop: add esi,4 movsd movsd mov eax,esi .error: pop edi ecx esi ret ; **************************************** ; FUNCTION ReadGIF - unpacks GIF image ; **************************************** ; in: ; esi - pointer to GIF file in memory ; edi - pointer to output image list ; eax - pointer to work area (MIN 16 KB!) ; out: ; eax - 0, all OK; ; eax - 1, invalid signature; ; eax >=8, unsupported image attributes ; ; ecx - number of images ReadGIF: push esi edi mov [.table_ptr],eax mov [.cur_info],edi xor eax,eax mov [.globalColor],eax mov [.img_count],eax inc eax cmp dword[esi],'GIF8' jne .er ; signature mov ecx,[esi+0xa] inc eax add esi,0xd mov edi,esi bt ecx,7 jnc .nextblock mov [.globalColor],esi call .Gif_skipmap .nextblock: cmp byte[edi],0x21 jne .noextblock inc edi cmp byte[edi],0xf9 ; Graphic Control Ext jne .no_gc add edi,7 jmp .nextblock .no_gc: cmp byte[edi],0xfe ; Comment Ext jne .no_comm inc edi .block_skip: movzx eax,byte[edi] lea edi,[edi+eax+1] cmp byte[edi],0 jnz .block_skip inc edi jmp .nextblock .no_comm: cmp byte[edi],0xff ; Application Ext jne .nextblock add edi,13 jmp .block_skip .noextblock: cmp byte[edi],0x2c ; image beginning jne .er inc [.img_count] inc edi mov esi,[.cur_info] add esi,4 xchg esi,edi movsd movsd push edi movzx ecx,word[esi] inc esi bt ecx,7 jc .uselocal push [.globalColor] mov edi,esi jmp .setPal .uselocal: call .Gif_skipmap push esi .setPal: movzx ecx,byte[edi] inc ecx mov [.codesize],ecx dec ecx pop [.Palette] lea esi,[edi+1] mov edi,[.table_ptr] xor eax,eax cld lodsb ; eax - block_count add eax,esi mov [.block_ofs],eax mov [.bit_count],8 mov eax,1 shl eax,cl mov [.CC],eax inc eax mov [.EOI],eax lea ecx,[eax-1] mov eax, _null shl 16 .filltable: stosd inc eax loop .filltable pop edi mov [.img_start],edi .reinit: mov edx,[.EOI] inc edx push [.codesize] pop [.compsize] call .Gif_get_sym cmp eax,[.CC] je .reinit call .Gif_output .cycle: movzx ebx,ax call .Gif_get_sym cmp eax,edx jae .notintable cmp eax,[.CC] je .reinit cmp eax,[.EOI] je .end call .Gif_output .add: push eax mov eax,[.table_ptr] mov [eax+edx*4],ebx pop eax cmp edx,0xFFF jae .cycle inc edx bsr ebx,edx cmp ebx,[.compsize] jne .noinc inc [.compsize] .noinc: jmp .cycle .notintable: push eax mov eax,ebx call .Gif_output push ebx movzx eax,bx call .Gif_output pop ebx eax jmp .add .er: pop edi jmp .ex .end: mov eax,[.cur_info] mov [eax],edi mov [.cur_info],edi add esi,2 xchg esi,edi .nxt: cmp byte[edi],0 jnz .continue inc edi jmp .nxt .continue: cmp byte[edi],0x3b jne .nextblock xor eax,eax stosd mov ecx,[.img_count] .ex: pop edi esi ret .Gif_skipmap: ; in: ecx - image descriptor, esi - pointer to colormap ; out: edi - pointer to area after colormap and ecx,111b inc ecx ; color map size mov ebx,1 shl ebx,cl lea ebx,[ebx*2+ebx] lea edi,[esi+ebx] ret .Gif_get_sym: mov ecx,[.compsize] push ecx xor eax,eax .shift: ror byte[esi],1 rcr eax,1 dec [.bit_count] jnz .loop1 inc esi cmp esi,[.block_ofs] jb .noblock push eax xor eax,eax lodsb test eax,eax jnz .nextbl mov eax,[.EOI] sub esi,2 add esp,8 jmp .exx .nextbl: add eax,esi mov [.block_ofs],eax pop eax .noblock: mov [.bit_count],8 .loop1: loop .shift pop ecx rol eax,cl .exx: xor ecx,ecx ret .Gif_output: push esi eax edx mov edx,[.table_ptr] .next: push word[edx+eax*4] mov ax,word[edx+eax*4+2] inc ecx cmp ax,_null jnz .next shl ebx,16 mov bx,[esp] .loop2: pop ax lea esi,[eax+eax*2] add esi,[.Palette] if COLOR_ORDER eq MENUETOS mov esi,[esi] bswap esi shr esi,8 mov [edi],esi add edi,3 else movsw movsb end if loop .loop2 pop edx eax esi ret .globalColor rd 1 .img_count rd 1 .cur_info rd 1 ; image table pointer .img_start rd 1 .codesize rd 1 .compsize rd 1 .bit_count rd 1 .CC rd 1 .EOI rd 1 .Palette rd 1 .block_ofs rd 1 .table_ptr rd 1