1 /****************************************************************************
   2 
   3 gif_lib_private.h - internal giflib routines and structures
   4 
   5 ****************************************************************************/
   6 
   7 #ifndef _GIF_LIB_PRIVATE_H
   8 #define _GIF_LIB_PRIVATE_H
   9 
  10 #include "gif_lib.h"
  11 #include "gif_hash.h"
  12 
  13 #define EXTENSION_INTRODUCER      0x21
  14 #define DESCRIPTOR_INTRODUCER     0x2c
  15 #define TERMINATOR_INTRODUCER     0x3b
  16 
  17 #define LZ_MAX_CODE         4095    /* Biggest code possible in 12 bits. */
  18 #define LZ_BITS             12
  19 
  20 #define FLUSH_OUTPUT        4096    /* Impossible code, to signal flush. */
  21 #define FIRST_CODE          4097    /* Impossible code, to signal first. */
  22 #define NO_SUCH_CODE        4098    /* Impossible code, to signal empty. */
  23 
  24 #define FILE_STATE_WRITE    0x01
  25 #define FILE_STATE_SCREEN   0x02
  26 #define FILE_STATE_IMAGE    0x04
  27 #define FILE_STATE_READ     0x08
  28 
  29 #define IS_READABLE(Private)    (Private->FileState & FILE_STATE_READ)
  30 #define IS_WRITEABLE(Private)   (Private->FileState & FILE_STATE_WRITE)
  31 
  32 typedef struct GifFilePrivateType {
  33     GifWord FileState, FileHandle,  /* Where all this data goes to! */
  34       BitsPerPixel,     /* Bits per pixel (Codes uses at least this + 1). */
  35       ClearCode,   /* The CLEAR LZ code. */
  36       EOFCode,     /* The EOF LZ code. */
  37       RunningCode, /* The next code algorithm can generate. */
  38       RunningBits, /* The number of bits required to represent RunningCode. */
  39       MaxCode1,    /* 1 bigger than max. possible code, in RunningBits bits. */
  40       LastCode,    /* The code before the current code. */
  41       CrntCode,    /* Current algorithm code. */
  42       StackPtr,    /* For character stack (see below). */
  43       CrntShiftState;    /* Number of bits in CrntShiftDWord. */
  44     unsigned long CrntShiftDWord;   /* For bytes decomposition into codes. */
  45     unsigned long PixelCount;   /* Number of pixels in image. */
  46     FILE *File;    /* File as stream. */
  47     InputFunc Read;     /* function to read gif input (TVT) */
  48     OutputFunc Write;   /* function to write gif output (MRB) */
  49     GifByteType Buf[256];   /* Compressed input is buffered here. */
  50     GifByteType Stack[LZ_MAX_CODE]; /* Decoded pixels are stacked here. */
  51     GifByteType Suffix[LZ_MAX_CODE + 1];    /* So we can trace the codes. */
  52     GifPrefixType Prefix[LZ_MAX_CODE + 1];
  53     GifHashTableType *HashTable;
  54     bool gif89;
  55 } GifFilePrivateType;
  56 
  57 #endif /* _GIF_LIB_PRIVATE_H */
  58 
  59 /* end */
--- EOF ---