1 files changed, 79 insertions, 0 deletions
diff --git a/tkagif/tkagif.h b/tkagif/tkagif.h
index 66a71a0..3bf7836 100644
--- a/tkagif/tkagif.h
+++ b/tkagif/tkagif.h
@@ -5,6 +5,74 @@
 #ifndef __tkagif_h__
 #define __tkagif_h__
 
+#define HSIZE		5003	/* 80% occupancy */
+typedef struct {
+  unsigned char* pict;
+  long pictCount;
+  
+  int numBits;		/* Number of bits/code. */
+  long maxCode;		/* Maximum code, given numBits. */
+  int hashTable[HSIZE];
+  unsigned int codeTable[HSIZE];
+  long hSize;			/* For dynamic table sizing. */
+
+  /*
+   * To save much memory, we overlay the table used by compress() with those
+   * used by decompress(). The tab_prefix table is the same size and type as
+   * the codeTable. The tab_suffix table needs 2**GIFBITS characters. We get
+   * this from the beginning of hashTable. The output stack uses the rest of
+   * hashTable, and contains characters. There is plenty of room for any
+   * possible stack (stack used to be 8000 characters).
+   */
+
+  int freeEntry;		/* First unused entry. */
+
+  /*
+   * Block compression parameters.  After all codes are used up, and
+   * compression rate changes, start over.
+   */
+
+  int clearFlag;
+
+  int offset;
+  unsigned int inCount;	/* Length of input */
+  unsigned int outCount;	/* # of codes output (for debugging) */
+
+  /*
+   * Algorithm: use open addressing double hashing (no chaining) on the
+   * prefix code / next character combination. We do a variant of Knuth's
+   * algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime
+   * secondary probe. Here, the modular division first probe is gives way to
+   * a faster exclusive-or manipulation. Also do block compression with an
+   * adaptive reset, whereby the code table is cleared when the compression
+   * ratio decreases, but after the table fills. The variable-length output
+   * codes are re-sized at this point, and a special CLEAR code is generated
+   * for the decompressor. Late addition: construct the table according to
+   * file size for noticeable speed improvement on small files. Please
+   * direct questions about this implementation to ames!jaw.
+   */
+
+  int initialBits;
+
+  int clearCode;
+  int eofCode;
+
+  unsigned long currentAccumulated;
+  int currentBits;
+
+  /*
+   * Number of characters so far in this 'packet'
+   */
+
+  int accumulatedByteCount;
+
+  /*
+   * Define the storage for the packet accumulator
+   */
+
+  unsigned char packetAccumulator[256];
+} GIFState_t;
+
 class TkAGIF {
 private:
   Tcl_Interp* interp_;
@@ -15,9 +83,20 @@ private:
   int nbitsPerPixel_;
   int colorTableSize_;
   
+  GIFState_t state_;
+
 private:
   void noCompress(unsigned char*);
 
+  void compress(unsigned char*);
+  int input();
+  void output(long);
+  void clearForBlock();
+  void clearHashTable(int);
+  void charInit();
+  void charOut(int);
+  void flushChar();
+
  public:
   TkAGIF(Tcl_Interp*);