Rev 3811 | Details | Compare with Previous | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 10 | reyssat | 1 | /* |
| 2 | * gifdecode.c |
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| 3 | * |
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| 4 | * Copyright (c) 1997,1998,1999 by Hans Dinsen-Hansen |
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| 5 | * Partly inspired by Helene Schulerud's inversrl_imageb.c of 13.2.1991. |
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| 6 | * Copyright (c) 1995,1996 by Kevin Kadow |
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| 7 | * Copyright (c) 1990,1991,1992,1993 by Mark Podlipec |
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| 8 | * All rights reserved. |
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| 9 | * |
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| 10 | * This software may be freely copied, modified and redistributed |
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| 11 | * without fee provided that this copyright notice is preserved |
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| 12 | * intact on all copies and modified copies. |
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| 13 | * |
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| 14 | * There is no warranty or other guarantee of fitness of this software. |
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| 15 | * It is provided solely "as is". The author(s) disclaim(s) all |
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| 16 | * responsibility and liability with respect to this software's usage |
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| 17 | * or its effect upon hardware or computer systems. |
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| 18 | * |
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| 19 | * The Graphics Interchange format (c) is the Copyright property of |
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| 20 | * Compuserve Incorporated. Gif(sm) is a Service Mark property of |
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| 21 | * Compuserve Incorporated. |
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| 22 | * |
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| 23 | */ |
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| 24 | |||
| 25 | #include <stdio.h> |
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| 26 | #include "whirlgif.h" |
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| 27 | |||
| 28 | extern unsigned int debugFlag, verbose; |
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| 29 | extern int count; |
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| 30 | |||
| 31 | ULONG codeSize, expected, imgsize, mask, old, picI, rootCodeSize, first[MAXVAL]; |
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| 32 | UBYTE *topGifBuff, *picture, gifBuff[MAXVAL], last[MAXVAL]; |
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| 33 | int imgheight, imgwidth, interlaced, pass, |
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| 34 | step[5]={7,7,3,1,0}, start[5]= {0,4,2,1,0}; |
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| 35 | |||
| 36 | void GifDecode(FILE *fp, UBYTE *pix, GifImageHdr gifimage) |
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| 37 | { UBYTE *chPos, firstCodeOut = 0, charBuff[256]; |
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| 38 | ULONG CLEAR, EOI, bits = 0, code = 0, codeFeched, buffCount = 0; |
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| 39 | int need = 0; |
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| 40 | |||
| 41 | interlaced = gifimage.i; |
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| 42 | imgwidth = gifimage.width; |
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| 43 | imgheight = gifimage.height; |
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| 44 | imgsize = imgwidth * imgheight; |
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| 45 | picture = pix; |
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| 46 | pass = picI = 0; |
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| 47 | if ( debugFlag > 1 ) |
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| 48 | fprintf(stderr, "(interlaced,imgwidth,imgheight,imgsize)=(%d,%d,%d,%d)\n", |
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| 49 | interlaced, imgwidth, imgheight, imgsize); |
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| 50 | |||
| 51 | rootCodeSize = Xgetc(fp); |
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| 52 | CLEAR = 1 << rootCodeSize; |
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| 53 | EOI = CLEAR + 1; |
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| 54 | |||
| 55 | GifClearTable(); |
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| 56 | |||
| 57 | if ( (buffCount = Xgetc(fp)) == 0 ) { |
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| 3811 | kbelabas | 58 | sprintf((char*)charBuff, "End of image # %d before it began!\n", count); |
| 59 | TheEnd1((char*)charBuff); |
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| 10 | reyssat | 60 | } |
| 61 | |||
| 62 | while(buffCount > 0) { |
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| 63 | if ( fread(charBuff, 1, buffCount, fp) != buffCount ) { |
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| 3811 | kbelabas | 64 | sprintf((char*)charBuff, "Premature end of file; Image # %d\n", count); |
| 65 | TheEnd1((char*)charBuff); |
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| 10 | reyssat | 66 | } |
| 67 | for(chPos = charBuff; buffCount-- > 0; chPos++) { |
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| 68 | need += (int) *chPos << bits; |
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| 69 | bits += 8; |
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| 70 | while (bits >= codeSize) { |
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| 71 | code = need & mask; |
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| 72 | need >>= codeSize; |
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| 73 | bits -= codeSize; |
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| 74 | if(code > expected) |
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| 75 | TheEnd1("Neither LZW nor RunLength (new code != expected)\n"); |
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| 76 | if (code == EOI) { |
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| 77 | if (debugFlag > 1) fprintf(stderr, "Image # %d ends; buffCount=%d\n", |
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| 78 | count, buffCount); |
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| 79 | goto skipRest; |
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| 80 | } |
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| 81 | |||
| 82 | if(code == CLEAR) { |
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| 83 | GifClearTable(); |
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| 84 | continue; |
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| 85 | } |
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| 86 | if(old == MAXVAL) { /* i.e. first code after clear table */ |
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| 87 | pix = GifSendData(pix, 1, &last[code]); |
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| 88 | firstCodeOut = last[code]; |
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| 89 | old = code; |
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| 90 | continue; |
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| 91 | } |
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| 92 | codeFeched = code; |
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| 93 | if(code == expected) { |
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| 94 | *topGifBuff++ = firstCodeOut; |
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| 95 | code = old; |
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| 96 | } |
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| 97 | while(code > CLEAR) { |
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| 98 | *topGifBuff++ = last[code]; |
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| 99 | code = first[code]; |
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| 100 | } |
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| 101 | |||
| 102 | *topGifBuff++ = firstCodeOut = last[code]; |
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| 103 | first[expected] = old; |
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| 104 | last[expected] = firstCodeOut; |
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| 105 | if(expected < MAXVAL) expected++; |
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| 106 | if(((expected & mask) == 0) && (expected < MAXVAL)) { |
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| 107 | codeSize++; |
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| 108 | mask += expected; |
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| 109 | } |
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| 110 | old = codeFeched; |
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| 111 | pix = GifSendData(pix, topGifBuff - gifBuff, gifBuff); |
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| 112 | topGifBuff = gifBuff; |
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| 113 | |||
| 114 | } /* end of extracting codes */ |
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| 115 | } /* end of reading a block of data */ |
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| 116 | if ( (buffCount = Xgetc(fp)) == 0 ) { |
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| 3811 | kbelabas | 117 | sprintf((char*)charBuff, "End of image # %d without EOI\n", count); |
| 118 | TheEnd1((char*)charBuff); |
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| 10 | reyssat | 119 | } |
| 120 | } |
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| 121 | |||
| 122 | skipRest: |
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| 3814 | kbelabas | 123 | if (debugFlag) fprintf(stderr, "Ending GifDecode, written: %d=%d\n", |
| 124 | interlaced && (pix-picture == 0) ? imgsize : (int)(pix - picture), imgsize); |
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| 10 | reyssat | 125 | return ; |
| 126 | } |
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| 127 | |||
| 128 | UBYTE *GifSendData(UBYTE *pix, int bytes, UBYTE source[]) |
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| 129 | |||
| 130 | { int j=0; |
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| 131 | for(j = bytes - 1; j >= 0; j--) { |
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| 132 | picI++; |
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| 133 | *pix = source[j]; pix++; |
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| 134 | if ( interlaced && (picI % imgwidth == 0) ) { |
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| 135 | picI += ( imgwidth * step[pass]); |
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| 136 | if (picI >= imgsize) { |
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| 137 | picI = start[++pass] * imgwidth; |
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| 138 | if ( debugFlag > 1 ) |
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| 139 | fprintf(stderr, "De-interlacing: (picI,pass,start[pass])=(%d,%d,%d)\n", |
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| 140 | picI, pass, start[pass]); |
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| 141 | } |
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| 142 | pix = &picture[picI]; |
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| 143 | } |
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| 144 | } |
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| 145 | return(pix); |
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| 146 | } |
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| 147 | |||
| 148 | void GifClearTable() |
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| 149 | { int i, maxi; |
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| 150 | maxi = 1 << rootCodeSize; |
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| 151 | expected = maxi + 2; |
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| 152 | if (debugFlag > 1 ) fprintf(stderr, "Initing Table..."); |
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| 153 | old = MAXVAL; |
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| 154 | codeSize = rootCodeSize + 1; |
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| 155 | mask = (1<<codeSize) - 1; |
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| 156 | |||
| 157 | for(i = 0; i < maxi; i++) { |
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| 158 | first[i] = MAXVAL; |
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| 159 | last[i] = i & 0xff; |
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| 160 | } |
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| 161 | topGifBuff = gifBuff; |
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| 162 | } |