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718112a8fe
Currently none of these is being used, but eventually they will, once more code gets ported over. So it's better to have them right away and avoid editing the project file too much, only to revert that later.
85 lines
2 KiB
C
85 lines
2 KiB
C
/* Ppmd.h -- PPMD codec common code
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2017-04-03 : 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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{ size_t z; for (z = 0; z < 256 / sizeof(p[0]); z += 8) { \
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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; }}
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EXTERN_C_END
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#endif
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