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-rw-r--r--tools/gifconv/decompress.c299
1 files changed, 299 insertions, 0 deletions
diff --git a/tools/gifconv/decompress.c b/tools/gifconv/decompress.c
new file mode 100644
index 0000000..18dbb3e
--- /dev/null
+++ b/tools/gifconv/decompress.c
@@ -0,0 +1,299 @@
+#include <stdio.h>
+#include <stdlib.h>
+#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' */
+RWidth, RHeight, /* screen dimensions */
+IWidth, IHeight, /* image dimensions */
+LeftOfs, TopOfs, /* image offset */
+BitsPerPixel, /* Bits per pixel, read from GIF header */
+BytesPerScanline, /* Bytes per scanline in output raster */
+ColorMapSize, /* number of colors */
+Background, /* background color */
+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.
+*/
+ReadCode()
+{
+ 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);
+}
+
+
+AddToPixel(Index)
+BYTE Index;
+{
+ if (YC<IHeight)
+ *(Image + YC * BytesPerScanline + XC) = Index;
+
+
+
+ /* Update the X-coordinate, and if it overflows, update the Y-coordinate */
+ if (++XC == IWidth) {
+
+ /* If a non-WORDerlaced picture, just increment YC to the next scan line.
+ * If it's WORDerlaced, deal with the WORDerlace as described in the GIF
+ * spec. Put the decoded scan line out to the screen if we haven't gone
+ * past the bottom of it.
+ */
+
+ XC = 0;
+ if (!Interlace) YC++;
+ else {
+ switch (Pass) {
+ case 0:
+ YC += 8;
+ 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(IWidth*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;
+}
+
+
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