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 86