1 /* Ppmd.h -- PPMD codec common code 2 2011-01-27 : 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 "Types.h" 9 #include "CpuArch.h" 10 11 EXTERN_C_BEGIN 12 13 #ifdef MY_CPU_32BIT 14 #define PPMD_32BIT 15 #endif 16 17 #define PPMD_INT_BITS 7 18 #define PPMD_PERIOD_BITS 7 19 #define PPMD_BIN_SCALE (1 << (PPMD_INT_BITS + PPMD_PERIOD_BITS)) 20 21 #define PPMD_GET_MEAN_SPEC(summ, shift, round) (((summ) + (1 << ((shift) - (round)))) >> (shift)) 22 #define PPMD_GET_MEAN(summ) PPMD_GET_MEAN_SPEC((summ), PPMD_PERIOD_BITS, 2) 23 #define PPMD_UPDATE_PROB_0(prob) ((prob) + (1 << PPMD_INT_BITS) - PPMD_GET_MEAN(prob)) 24 #define PPMD_UPDATE_PROB_1(prob) ((prob) - PPMD_GET_MEAN(prob)) 25 26 #define PPMD_N1 4 27 #define PPMD_N2 4 28 #define PPMD_N3 4 29 #define PPMD_N4 ((128 + 3 - 1 * PPMD_N1 - 2 * PPMD_N2 - 3 * PPMD_N3) / 4) 30 #define PPMD_NUM_INDEXES (PPMD_N1 + PPMD_N2 + PPMD_N3 + PPMD_N4) 31 32 #pragma pack(push, 1) 33 /* Most compilers works OK here even without #pragma pack(push, 1), but some GCC compilers need it. */ 34 35 /* SEE-contexts for PPM-contexts with masked symbols */ 36 typedef struct 37 { 38 UInt16 Summ; /* Freq */ 39 Byte Shift; /* Speed of Freq change; low Shift is for fast change */ 40 Byte Count; /* Count to next change of Shift */ 41 } CPpmd_See; 42 43 #define Ppmd_See_Update(p) if ((p)->Shift < PPMD_PERIOD_BITS && --(p)->Count == 0) \ 44 { (p)->Summ <<= 1; (p)->Count = (Byte)(3 << (p)->Shift++); } 45 46 typedef struct 47 { 48 Byte Symbol; 49 Byte Freq; 50 UInt16 SuccessorLow; 51 UInt16 SuccessorHigh; 52 } CPpmd_State; 53 54 #pragma pack(pop) 55 56 typedef 57 #ifdef PPMD_32BIT 58 CPpmd_State * 59 #else 60 UInt32 61 #endif 62 CPpmd_State_Ref; 63 64 typedef 65 #ifdef PPMD_32BIT 66 void * 67 #else 68 UInt32 69 #endif 70 CPpmd_Void_Ref; 71 72 typedef 73 #ifdef PPMD_32BIT 74 Byte * 75 #else 76 UInt32 77 #endif 78 CPpmd_Byte_Ref; 79 80 #define PPMD_SetAllBitsIn256Bytes(p) \ 81 { unsigned i; for (i = 0; i < 256 / sizeof(p[0]); i += 8) { \ 82 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; }} 83 84 EXTERN_C_END 85 86 #endif 87