86 lines
2.1 KiB
C
Executable File
86 lines
2.1 KiB
C
Executable File
/* 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
|