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192 lines
4.8 KiB
C
192 lines
4.8 KiB
C
/* Ppmd7Dec.c -- PPMdH Decoder
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2018-07-04 : 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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#include "Precomp.h"
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#include "Ppmd7.h"
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#define kTopValue (1 << 24)
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BoolInt Ppmd7z_RangeDec_Init(CPpmd7z_RangeDec *p)
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{
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unsigned i;
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p->Code = 0;
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p->Range = 0xFFFFFFFF;
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if (IByteIn_Read(p->Stream) != 0)
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return False;
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for (i = 0; i < 4; i++)
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p->Code = (p->Code << 8) | IByteIn_Read(p->Stream);
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return (p->Code < 0xFFFFFFFF);
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}
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#define GET_Ppmd7z_RangeDec CPpmd7z_RangeDec *p = CONTAINER_FROM_VTBL(pp, CPpmd7z_RangeDec, vt);
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static UInt32 Range_GetThreshold(const IPpmd7_RangeDec *pp, UInt32 total)
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{
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GET_Ppmd7z_RangeDec
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return p->Code / (p->Range /= total);
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}
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static void Range_Normalize(CPpmd7z_RangeDec *p)
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{
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if (p->Range < kTopValue)
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{
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p->Code = (p->Code << 8) | IByteIn_Read(p->Stream);
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p->Range <<= 8;
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if (p->Range < kTopValue)
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{
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p->Code = (p->Code << 8) | IByteIn_Read(p->Stream);
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p->Range <<= 8;
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}
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}
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}
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static void Range_Decode(const IPpmd7_RangeDec *pp, UInt32 start, UInt32 size)
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{
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GET_Ppmd7z_RangeDec
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p->Code -= start * p->Range;
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p->Range *= size;
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Range_Normalize(p);
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}
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static UInt32 Range_DecodeBit(const IPpmd7_RangeDec *pp, UInt32 size0)
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{
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GET_Ppmd7z_RangeDec
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UInt32 newBound = (p->Range >> 14) * size0;
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UInt32 symbol;
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if (p->Code < newBound)
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{
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symbol = 0;
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p->Range = newBound;
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}
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else
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{
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symbol = 1;
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p->Code -= newBound;
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p->Range -= newBound;
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}
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Range_Normalize(p);
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return symbol;
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}
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void Ppmd7z_RangeDec_CreateVTable(CPpmd7z_RangeDec *p)
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{
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p->vt.GetThreshold = Range_GetThreshold;
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p->vt.Decode = Range_Decode;
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p->vt.DecodeBit = Range_DecodeBit;
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}
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#define MASK(sym) ((signed char *)charMask)[sym]
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int Ppmd7_DecodeSymbol(CPpmd7 *p, const IPpmd7_RangeDec *rc)
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{
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size_t charMask[256 / sizeof(size_t)];
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if (p->MinContext->NumStats != 1)
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{
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CPpmd_State *s = Ppmd7_GetStats(p, p->MinContext);
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unsigned i;
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UInt32 count, hiCnt;
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if ((count = rc->GetThreshold(rc, p->MinContext->SummFreq)) < (hiCnt = s->Freq))
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{
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Byte symbol;
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rc->Decode(rc, 0, s->Freq);
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p->FoundState = s;
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symbol = s->Symbol;
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Ppmd7_Update1_0(p);
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return symbol;
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}
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p->PrevSuccess = 0;
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i = p->MinContext->NumStats - 1;
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do
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{
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if ((hiCnt += (++s)->Freq) > count)
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{
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Byte symbol;
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rc->Decode(rc, hiCnt - s->Freq, s->Freq);
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p->FoundState = s;
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symbol = s->Symbol;
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Ppmd7_Update1(p);
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return symbol;
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}
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}
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while (--i);
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if (count >= p->MinContext->SummFreq)
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return -2;
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p->HiBitsFlag = p->HB2Flag[p->FoundState->Symbol];
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rc->Decode(rc, hiCnt, p->MinContext->SummFreq - hiCnt);
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PPMD_SetAllBitsIn256Bytes(charMask);
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MASK(s->Symbol) = 0;
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i = p->MinContext->NumStats - 1;
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do { MASK((--s)->Symbol) = 0; } while (--i);
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}
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else
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{
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UInt16 *prob = Ppmd7_GetBinSumm(p);
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if (rc->DecodeBit(rc, *prob) == 0)
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{
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Byte symbol;
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*prob = (UInt16)PPMD_UPDATE_PROB_0(*prob);
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symbol = (p->FoundState = Ppmd7Context_OneState(p->MinContext))->Symbol;
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Ppmd7_UpdateBin(p);
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return symbol;
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}
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*prob = (UInt16)PPMD_UPDATE_PROB_1(*prob);
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p->InitEsc = PPMD7_kExpEscape[*prob >> 10];
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PPMD_SetAllBitsIn256Bytes(charMask);
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MASK(Ppmd7Context_OneState(p->MinContext)->Symbol) = 0;
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p->PrevSuccess = 0;
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}
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for (;;)
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{
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CPpmd_State *ps[256], *s;
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UInt32 freqSum, count, hiCnt;
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CPpmd_See *see;
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unsigned i, num, numMasked = p->MinContext->NumStats;
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do
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{
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p->OrderFall++;
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if (!p->MinContext->Suffix)
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return -1;
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p->MinContext = Ppmd7_GetContext(p, p->MinContext->Suffix);
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}
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while (p->MinContext->NumStats == numMasked);
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hiCnt = 0;
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s = Ppmd7_GetStats(p, p->MinContext);
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i = 0;
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num = p->MinContext->NumStats - numMasked;
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do
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{
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int k = (int)(MASK(s->Symbol));
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hiCnt += (s->Freq & k);
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ps[i] = s++;
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i -= k;
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}
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while (i != num);
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see = Ppmd7_MakeEscFreq(p, numMasked, &freqSum);
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freqSum += hiCnt;
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count = rc->GetThreshold(rc, freqSum);
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if (count < hiCnt)
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{
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Byte symbol;
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CPpmd_State **pps = ps;
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for (hiCnt = 0; (hiCnt += (*pps)->Freq) <= count; pps++);
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s = *pps;
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rc->Decode(rc, hiCnt - s->Freq, s->Freq);
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Ppmd_See_Update(see);
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p->FoundState = s;
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symbol = s->Symbol;
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Ppmd7_Update2(p);
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return symbol;
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}
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if (count >= freqSum)
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return -2;
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rc->Decode(rc, hiCnt, freqSum - hiCnt);
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see->Summ = (UInt16)(see->Summ + freqSum);
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do { MASK(ps[--i]->Symbol) = 0; } while (i != 0);
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}
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}
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