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