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85 lines
2.0 KiB
85 lines
2.0 KiB
/* Ppmd.h -- PPMD codec common code |
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2013-01-18 : Igor Pavlov : Public domain |
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This code is based on PPMd var.H (2001): Dmitry Shkarin : Public domain */ |
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#ifndef __PPMD_H |
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#define __PPMD_H |
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#include "CpuArch.h" |
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EXTERN_C_BEGIN |
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#ifdef MY_CPU_32BIT |
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#define PPMD_32BIT |
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#endif |
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#define PPMD_INT_BITS 7 |
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#define PPMD_PERIOD_BITS 7 |
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#define PPMD_BIN_SCALE (1 << (PPMD_INT_BITS + PPMD_PERIOD_BITS)) |
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#define PPMD_GET_MEAN_SPEC(summ, shift, round) (((summ) + (1 << ((shift) - (round)))) >> (shift)) |
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#define PPMD_GET_MEAN(summ) PPMD_GET_MEAN_SPEC((summ), PPMD_PERIOD_BITS, 2) |
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#define PPMD_UPDATE_PROB_0(prob) ((prob) + (1 << PPMD_INT_BITS) - PPMD_GET_MEAN(prob)) |
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#define PPMD_UPDATE_PROB_1(prob) ((prob) - PPMD_GET_MEAN(prob)) |
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#define PPMD_N1 4 |
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#define PPMD_N2 4 |
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#define PPMD_N3 4 |
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#define PPMD_N4 ((128 + 3 - 1 * PPMD_N1 - 2 * PPMD_N2 - 3 * PPMD_N3) / 4) |
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#define PPMD_NUM_INDEXES (PPMD_N1 + PPMD_N2 + PPMD_N3 + PPMD_N4) |
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#pragma pack(push, 1) |
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/* Most compilers works OK here even without #pragma pack(push, 1), but some GCC compilers need it. */ |
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/* SEE-contexts for PPM-contexts with masked symbols */ |
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typedef struct |
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{ |
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UInt16 Summ; /* Freq */ |
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Byte Shift; /* Speed of Freq change; low Shift is for fast change */ |
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Byte Count; /* Count to next change of Shift */ |
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} CPpmd_See; |
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#define Ppmd_See_Update(p) if ((p)->Shift < PPMD_PERIOD_BITS && --(p)->Count == 0) \ |
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{ (p)->Summ <<= 1; (p)->Count = (Byte)(3 << (p)->Shift++); } |
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typedef struct |
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{ |
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Byte Symbol; |
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Byte Freq; |
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UInt16 SuccessorLow; |
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UInt16 SuccessorHigh; |
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} CPpmd_State; |
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#pragma pack(pop) |
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typedef |
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#ifdef PPMD_32BIT |
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CPpmd_State * |
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#else |
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UInt32 |
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#endif |
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CPpmd_State_Ref; |
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typedef |
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#ifdef PPMD_32BIT |
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void * |
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#else |
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UInt32 |
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#endif |
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CPpmd_Void_Ref; |
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typedef |
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#ifdef PPMD_32BIT |
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Byte * |
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#else |
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UInt32 |
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#endif |
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CPpmd_Byte_Ref; |
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#define PPMD_SetAllBitsIn256Bytes(p) \ |
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{ unsigned i; for (i = 0; i < 256 / sizeof(p[0]); i += 8) { \ |
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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; }} |
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EXTERN_C_END |
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#endif
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