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https://github.com/HDFGroup/hdf5.git
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311 lines
9.2 KiB
C
311 lines
9.2 KiB
C
/*
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* Copyright (C) 2001 National Center for Supercomputing Applications
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* All rights reserved.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include "gif.h"
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#define NEXTBYTE (*ptr++)
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#define IMAGESEP 0x2c
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#define INTERLACEMASK 0x40
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#define COLORMAPMASK 0x80
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WORD iWIDE, iHIGH, eWIDE, eHIGH, expand, numcols, strip, nostrip;
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unsigned long cols[256];
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char *cmd;
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FILE *fp;
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static int
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BitOffset = 0, /* Bit Offset of next code */
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XC = 0, YC = 0, /* Output X and Y coords of current pixel */
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Pass = 0, /* Used by output routine if WORDerlaced pic */
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OutCount = 0, /* Decompressor output 'stack count' */
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IWidth, IHeight, /* image dimensions */
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BytesPerScanline, /* Bytes per scanline in output raster */
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CodeSize, /* Code size, read from GIF header */
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InitCodeSize, /* Starting code size, used during Clear */
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Code, /* Value returned by ReadCode */
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MaxCode, /* limiting value for current code size */
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ClearCode, /* GIF clear code */
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EOFCode, /* GIF end-of-information code */
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CurCode, OldCode, InCode, /* Decompressor variables */
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FirstFree, /* First free code, generated per GIF spec */
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FreeCode, /* Decompressor, next free slot in hash table */
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FinChar, /* Decompressor variable */
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DataMask, /* AND mask for data size */
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ReadMask; /* Code AND mask for current code size */
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/*MODIFICATIONS*/
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BYTE tempbyte[10];
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BYTE * tempBYTEptr[10];
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WORD tempint[10];
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WORD ImageCount = 0;
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/*END MODIFICATION*/
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boolean Interlace, HasColormap;
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BYTE *Image; /* The result array */
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BYTE *RawGIF; /* The heap array to hold it, raw */
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BYTE *Raster; /* The raster data stream, unblocked */
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/* The hash table used by the decompressor */
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int Prefix[4096];
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int Suffix[4096];
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/* An output array used by the decompressor */
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int OutCode[1025];
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/* The color map, read from the GIF header */
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int numused;
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/*
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* Fetch the next code from the raster data stream. The codes can be any
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* length from 3 to 12 bits, packed WORDo 8-bit BYTEs, so we have to maWORDain
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* our location in the Raster array as a BIT Offset. We compute the BYTE
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* Offset WORDo the raster array by dividing this by 8, pick up three BYTEs,
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* compute the bit Offset WORDo our 24-bit chunk, shift to bring the desired
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* code to the bottom, then mask it off and return it.
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*/
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static int
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ReadCode(void)
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{
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int RawCode, ByteOffset;
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ByteOffset = BitOffset / 8;
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RawCode = Raster[ByteOffset] + (0x100 * Raster[ByteOffset + 1]);
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if (CodeSize >= 8)
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RawCode += (0x10000 * Raster[ByteOffset + 2]);
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RawCode >>= (BitOffset % 8);
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BitOffset += CodeSize;
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return (RawCode & ReadMask);
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}
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static void
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AddToPixel(BYTE Index)
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{
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if (YC<IHeight)
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*(Image + YC * BytesPerScanline + XC) = Index;
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/* Update the X-coordinate, and if it overflows, update the
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* Y-coordinate */
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if (++XC == IWidth) {
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/*
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* If a non-WORDerlaced picture, just increment YC to the next scan
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* line. If it's WORDerlaced, deal with the WORDerlace as described
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* in the GIF spec. Put the decoded scan line out to the screen if we
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* haven't gone past the bottom of it.
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*/
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XC = 0;
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if (!Interlace) {
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YC++;
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} else {
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switch (Pass) {
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case 0:
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YC += 8;
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if (YC >= IHeight) {
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Pass++;
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YC = 4;
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}
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break;
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case 1:
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YC += 8;
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if (YC >= IHeight) {
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Pass++;
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YC = 2;
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}
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break;
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case 2:
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YC += 4;
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if (YC >= IHeight) {
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Pass++;
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YC = 1;
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}
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break;
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case 3:
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YC += 2;
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break;
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default:
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break;
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}
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}
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}
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}
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/* Main routine. Convert a GIF image to an HDF image */
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BYTE *
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Decompress(GIFIMAGEDESC *GifImageDesc, GIFHEAD *GifHead)
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{
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int i;
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XC = 0;
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YC = 0;
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Pass = 0;
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OutCount = 0;
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BitOffset = 0;
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DataMask = (1L << ((GifHead->PackedField & 0x07) +1)) -1;
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Raster = GifImageDesc->GIFImage;
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/* Check for image seperator */
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/* Now read in values from the image descriptor */
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IWidth = GifImageDesc->ImageWidth;
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IHeight = GifImageDesc->ImageHeight;
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Interlace = GifImageDesc->PackedField & 0x40;
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/*
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* Note that I ignore the possible existence of a local color map. I'm
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* told there aren't many files around that use them, and the spec says
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* it's defined for future use. This could lead to an error reading some
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* files.
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*/
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/*
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* Start reading the raster data. First we get the WORDial code size and
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* compute decompressor constant values, based on this code size.
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*/
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CodeSize = GifImageDesc->CodeSize;
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ClearCode = (1 << CodeSize);
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EOFCode = ClearCode + 1;
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FreeCode = FirstFree = ClearCode + 2;
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/*
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* The GIF spec has it that the code size is the code size used to compute
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* the above values is the code size given in the file, but the code size
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* used in compression/decompression is the code size given in the file
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* plus one. (thus the ++).
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*/
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CodeSize++;
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InitCodeSize = CodeSize;
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MaxCode = (1 << CodeSize);
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ReadMask = MaxCode - 1;
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/*
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* Read the raster data. Here we just transpose it from the GIF array to
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* the Raster array, turning it from a series of blocks WORDo one long
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* data stream, which makes life much easier for ReadCode().
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*/
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/* Allocate the Image */
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if (!(Image = (BYTE *)malloc((size_t)IWidth*(size_t)IHeight))) {
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printf("Out of memory");
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exit(-1);
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}
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BytesPerScanline = IWidth;
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/*
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* Decompress the file, continuing until you see the GIF EOF code. One
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* obvious enhancement is to add checking for corrupt files here.
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*/
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Code = ReadCode();
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while (Code != EOFCode) {
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/*
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* Clear code sets everything back to its initial value, then reads
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* the immediately subsequent code as uncompressed data.
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*/
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if (Code == ClearCode) {
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CodeSize = InitCodeSize;
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MaxCode = (1 << CodeSize);
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ReadMask = MaxCode - 1;
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FreeCode = FirstFree;
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CurCode = OldCode = Code = ReadCode();
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FinChar = CurCode & DataMask;
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AddToPixel((BYTE)FinChar);
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} else {
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/*
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* If not a clear code, then must be data: save same as CurCode
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* and InCode
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*/
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CurCode = InCode = Code;
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/*
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* If greater or equal to FreeCode, not in the hash table yet;
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* repeat the last character decoded
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*/
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if (CurCode >= FreeCode) {
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CurCode = OldCode;
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OutCode[OutCount++] = FinChar;
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}
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/*
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* Unless this code is raw data, pursue the chain poWORDed to by
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* CurCode through the hash table to its end; each code in the
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* chain puts its associated output code on the output queue.
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*/
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while (CurCode > DataMask) {
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if (OutCount > 1024) {
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/*return error message*/
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}
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OutCode[OutCount++] = Suffix[CurCode];
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CurCode = Prefix[CurCode];
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}
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/* The last code in the chain is treated as raw data. */
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FinChar = CurCode & DataMask;
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OutCode[OutCount++] = FinChar;
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/*
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* Now we put the data out to the Output routine. It's been
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* stacked LIFO, so deal with it that way...
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*/
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for (i = OutCount - 1; i >= 0; i--)
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AddToPixel((BYTE)OutCode[i]);
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OutCount = 0;
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/*
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* Build the hash table on-the-fly. No table is stored in the
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* file.
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*/
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Prefix[FreeCode] = OldCode;
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Suffix[FreeCode] = FinChar;
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OldCode = InCode;
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/*
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* PoWORD to the next slot in the table. If we exceed the current
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* MaxCode value, increment the code size unless it's already 12.
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* If it is, do nothing: the next code decompressed better be
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* CLEAR
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*/
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FreeCode++;
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if (FreeCode >= MaxCode)
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if (CodeSize < 12) {
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CodeSize++;
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MaxCode *= 2;
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ReadMask = (1 << CodeSize) - 1;
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}
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}
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Code = ReadCode();
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}
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return Image;
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}
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