| /* Ppmd.h -- PPMD codec common code |
| 2010-03-12 : Igor Pavlov : Public domain |
| This code is based on PPMd var.H (2001): Dmitry Shkarin : Public domain */ |
| |
| #ifndef __PPMD_H |
| #define __PPMD_H |
| |
| #include "Types.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) |
| |
| /* 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) \ |
| { unsigned i; for (i = 0; i < 256 / sizeof(p[0]); i += 8) { \ |
| p[i+7] = p[i+6] = p[i+5] = p[i+4] = p[i+3] = p[i+2] = p[i+1] = p[i+0] = ~(size_t)0; }} |
| |
| EXTERN_C_END |
| |
| #endif |