nel/3rdparty/seven_zip/Ppmd.h

   1 /* Ppmd.h -- PPMD codec common code
   2 2017-04-03 : Igor Pavlov : Public domain
   3 This code is based on PPMd var.H (2001): Dmitry Shkarin : Public domain */
   4
   5 #ifndef __PPMD_H
   6 #define __PPMD_H
   7
   8 #include "CpuArch.h"
   9
  10 EXTERN_C_BEGIN
  11
  12 #ifdef MY_CPU_32BIT
  13   #define PPMD_32BIT
  14 #endif
  15
  16 #define PPMD_INT_BITS 7
  17 #define PPMD_PERIOD_BITS 7
  18 #define PPMD_BIN_SCALE (1 << (PPMD_INT_BITS + PPMD_PERIOD_BITS))
  19
  20 #define PPMD_GET_MEAN_SPEC(summ, shift, round) (((summ) + (1 << ((shift) - (round)))) >> (shift))
  21 #define PPMD_GET_MEAN(summ) PPMD_GET_MEAN_SPEC((summ), PPMD_PERIOD_BITS, 2)
  22 #define PPMD_UPDATE_PROB_0(prob) ((prob) + (1 << PPMD_INT_BITS) - PPMD_GET_MEAN(prob))
  23 #define PPMD_UPDATE_PROB_1(prob) ((prob) - PPMD_GET_MEAN(prob))
  24
  25 #define PPMD_N1 4
  26 #define PPMD_N2 4
  27 #define PPMD_N3 4
  28 #define PPMD_N4 ((128 + 3 - 1 * PPMD_N1 - 2 * PPMD_N2 - 3 * PPMD_N3) / 4)
  29 #define PPMD_NUM_INDEXES (PPMD_N1 + PPMD_N2 + PPMD_N3 + PPMD_N4)
  30
  31 #pragma pack(push, 1)
  32 /* Most compilers works OK here even without #pragma pack(push, 1), but some GCC compilers need it. */
  33
  34 /* SEE-contexts for PPM-contexts with masked symbols */
  35 typedef struct
  36 {
  37   UInt16 Summ; /* Freq */
  38   Byte Shift;  /* Speed of Freq change; low Shift is for fast change */
  39   Byte Count;  /* Count to next change of Shift */
  40 } CPpmd_See;
  41
  42 #define Ppmd_See_Update(p)  if ((p)->Shift < PPMD_PERIOD_BITS && --(p)->Count == 0) \
  43     { (p)->Summ <<= 1; (p)->Count = (Byte)(3 << (p)->Shift++); }
  44
  45 typedef struct
  46 {
  47   Byte Symbol;
  48   Byte Freq;
  49   UInt16 SuccessorLow;
  50   UInt16 SuccessorHigh;
  51 } CPpmd_State;
  52
  53 #pragma pack(pop)
  54
  55 typedef
  56   #ifdef PPMD_32BIT
  57     CPpmd_State *
  58   #else
  59     UInt32
  60   #endif
  61   CPpmd_State_Ref;
  62
  63 typedef
  64   #ifdef PPMD_32BIT
  65     void *
  66   #else
  67     UInt32
  68   #endif
  69   CPpmd_Void_Ref;
  70
  71 typedef
  72   #ifdef PPMD_32BIT
  73     Byte *
  74   #else
  75     UInt32
  76   #endif
  77   CPpmd_Byte_Ref;
  78
  79 #define PPMD_SetAllBitsIn256Bytes(p) \
  80   { size_t z; for (z = 0; z < 256 / sizeof(p[0]); z += 8) { \
  81   p[z+7] = p[z+6] = p[z+5] = p[z+4] = p[z+3] = p[z+2] = p[z+1] = p[z+0] = ~(size_t)0; }}
  82
  83 EXTERN_C_END
  84
  85 #endif