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/* Ppmd.h -- PPMD codec common code↩
2017-04-03 : Igor Pavlov : Public domain↩
This code is based on PPMd var.H (2001): Dmitry Shkarin : Public domain */↩
↩
#ifndef __PPMD_H↩
#define __PPMD_H↩
↩
#include "CpuArch.h"↩
↩
EXTERN_C_BEGIN↩
↩
#ifdef MY_CPU_32BIT↩
#define PPMD_32BIT↩
#endif↩
↩
#define PPMD_INT_BITS 7↩
#define PPMD_PERIOD_BITS 7↩
#define PPMD_BIN_SCALE (1 << (PPMD_INT_BITS + PPMD_PERIOD_BITS))↩
↩
#define PPMD_GET_MEAN_SPEC(summ, shift, round) (((summ) + (1 << ((shift) - (round)))) >> (shift))↩
#define PPMD_GET_MEAN(summ) PPMD_GET_MEAN_SPEC((summ), PPMD_PERIOD_BITS, 2)↩
#define PPMD_UPDATE_PROB_0(prob) ((prob) + (1 << PPMD_INT_BITS) - PPMD_GET_MEAN(prob))↩
#define PPMD_UPDATE_PROB_1(prob) ((prob) - PPMD_GET_MEAN(prob))↩
↩
#define PPMD_N1 4↩
#define PPMD_N2 4↩
#define PPMD_N3 4↩
#define PPMD_N4 ((128 + 3 - 1 * PPMD_N1 - 2 * PPMD_N2 - 3 * PPMD_N3) / 4)↩
#define PPMD_NUM_INDEXES (PPMD_N1 + PPMD_N2 + PPMD_N3 + PPMD_N4)↩
↩
#pragma pack(push, 1)↩
/* Most compilers works OK here even without #pragma pack(push, 1), but some GCC compilers need it. */↩
↩
/* SEE-contexts for PPM-contexts with masked symbols */↩
typedef struct↩
{↩
UInt16 Summ; /* Freq */↩
Byte Shift; /* Speed of Freq change; low Shift is for fast change */↩
Byte Count; /* Count to next change of Shift */↩
} CPpmd_See;↩
↩
#define Ppmd_See_Update(p) if ((p)->Shift < PPMD_PERIOD_BITS && --(p)->Count == 0) \↩
{ (p)->Summ <<= 1; (p)->Count = (Byte)(3 << (p)->Shift++); }↩
↩
typedef struct↩
{↩
Byte Symbol;↩
Byte Freq;↩
UInt16 SuccessorLow;↩
UInt16 SuccessorHigh;↩
} CPpmd_State;↩
↩
#pragma pack(pop)↩
↩
typedef↩
#ifdef PPMD_32BIT↩
CPpmd_State *↩
#else↩
UInt32↩
#endif↩
CPpmd_State_Ref;↩
↩
typedef↩
#ifdef PPMD_32BIT↩
void *↩
#else↩
UInt32↩
#endif↩
CPpmd_Void_Ref;↩
↩
typedef↩
#ifdef PPMD_32BIT↩
Byte *↩
#else↩
UInt32↩
#endif↩
CPpmd_Byte_Ref;↩
↩
#define PPMD_SetAllBitsIn256Bytes(p) \↩
{ size_t z; for (z = 0; z < 256 / sizeof(p[0]); z += 8) { \↩
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; }}↩
↩
EXTERN_C_END↩
↩
#endif↩