1 /* Ppmd.h -- PPMD codec common code 2 2010-03-12 : 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 /* SEE-contexts for PPM-contexts with masked symbols */ 33 typedef struct 34 { 35 UInt16 Summ; /* Freq */ 36 Byte Shift; /* Speed of Freq change; low Shift is for fast change */ 37 Byte Count; /* Count to next change of Shift */ 38 } CPpmd_See; 39 40 #define Ppmd_See_Update(p) if ((p)->Shift < PPMD_PERIOD_BITS && --(p)->Count == 0) \ 41 { (p)->Summ <<= 1; (p)->Count = (Byte)(3 << (p)->Shift++); } 42 43 typedef struct 44 { 45 Byte Symbol; 46 Byte Freq; 47 UInt16 SuccessorLow; 48 UInt16 SuccessorHigh; 49 } CPpmd_State; 50 51 typedef 52 #ifdef PPMD_32BIT 53 CPpmd_State * 54 #else 55 UInt32 56 #endif 57 CPpmd_State_Ref; 58 59 typedef 60 #ifdef PPMD_32BIT 61 void * 62 #else 63 UInt32 64 #endif 65 CPpmd_Void_Ref; 66 67 typedef 68 #ifdef PPMD_32BIT 69 Byte * 70 #else 71 UInt32 72 #endif 73 CPpmd_Byte_Ref; 74 75 #define PPMD_SetAllBitsIn256Bytes(p) \ 76 { unsigned i; for (i = 0; i < 256 / sizeof(p[0]); i += 8) { \ 77 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; }} 78 79 EXTERN_C_END 80 81 #endif 82