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312 lines
7 KiB
C
312 lines
7 KiB
C
/* Ppmd7Dec.c -- Ppmd7z (PPMdH with 7z Range Coder) Decoder
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2023-04-02 : Igor Pavlov : Public domain
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This code is based on:
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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 ((UInt32)1 << 24)
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#define READ_BYTE(p) IByteIn_Read((p)->Stream)
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BoolInt Ppmd7z_RangeDec_Init(CPpmd7_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 (READ_BYTE(p) != 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) | READ_BYTE(p);
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return (p->Code < 0xFFFFFFFF);
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}
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#define RC_NORM_BASE(p) if ((p)->Range < kTopValue) \
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{ (p)->Code = ((p)->Code << 8) | READ_BYTE(p); (p)->Range <<= 8;
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#define RC_NORM_1(p) RC_NORM_BASE(p) }
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#define RC_NORM(p) RC_NORM_BASE(p) RC_NORM_BASE(p) }}
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// we must use only one type of Normalization from two: LOCAL or REMOTE
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#define RC_NORM_LOCAL(p) // RC_NORM(p)
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#define RC_NORM_REMOTE(p) RC_NORM(p)
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#define R (&p->rc.dec)
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Z7_FORCE_INLINE
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// Z7_NO_INLINE
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static void Ppmd7z_RD_Decode(CPpmd7 *p, UInt32 start, UInt32 size)
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{
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R->Code -= start * R->Range;
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R->Range *= size;
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RC_NORM_LOCAL(R)
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}
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#define RC_Decode(start, size) Ppmd7z_RD_Decode(p, start, size);
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#define RC_DecodeFinal(start, size) RC_Decode(start, size) RC_NORM_REMOTE(R)
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#define RC_GetThreshold(total) (R->Code / (R->Range /= (total)))
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#define CTX(ref) ((CPpmd7_Context *)Ppmd7_GetContext(p, ref))
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// typedef CPpmd7_Context * CTX_PTR;
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#define SUCCESSOR(p) Ppmd_GET_SUCCESSOR(p)
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void Ppmd7_UpdateModel(CPpmd7 *p);
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#define MASK(sym) ((unsigned char *)charMask)[sym]
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// Z7_FORCE_INLINE
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// static
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int Ppmd7z_DecodeSymbol(CPpmd7 *p)
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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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const UInt32 summFreq = p->MinContext->Union2.SummFreq;
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count = RC_GetThreshold(summFreq);
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hiCnt = count;
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if ((Int32)(count -= s->Freq) < 0)
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{
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Byte sym;
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RC_DecodeFinal(0, s->Freq)
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p->FoundState = s;
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sym = s->Symbol;
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Ppmd7_Update1_0(p);
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return sym;
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}
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p->PrevSuccess = 0;
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i = (unsigned)p->MinContext->NumStats - 1;
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do
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{
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if ((Int32)(count -= (++s)->Freq) < 0)
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{
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Byte sym;
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RC_DecodeFinal((hiCnt - count) - s->Freq, s->Freq)
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p->FoundState = s;
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sym = s->Symbol;
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Ppmd7_Update1(p);
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return sym;
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}
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}
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while (--i);
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if (hiCnt >= summFreq)
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return PPMD7_SYM_ERROR;
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hiCnt -= count;
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RC_Decode(hiCnt, summFreq - hiCnt)
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p->HiBitsFlag = PPMD7_HiBitsFlag_3(p->FoundState->Symbol);
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PPMD_SetAllBitsIn256Bytes(charMask)
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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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CPpmd_State *s2 = Ppmd7_GetStats(p, p->MinContext);
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MASK(s->Symbol) = 0;
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do
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{
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unsigned sym0 = s2[0].Symbol;
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unsigned sym1 = s2[1].Symbol;
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s2 += 2;
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MASK(sym0) = 0;
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MASK(sym1) = 0;
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}
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while (s2 < s);
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}
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}
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else
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{
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CPpmd_State *s = Ppmd7Context_OneState(p->MinContext);
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UInt16 *prob = Ppmd7_GetBinSumm(p);
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UInt32 pr = *prob;
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UInt32 size0 = (R->Range >> 14) * pr;
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pr = PPMD_UPDATE_PROB_1(pr);
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if (R->Code < size0)
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{
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Byte sym;
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*prob = (UInt16)(pr + (1 << PPMD_INT_BITS));
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// RangeDec_DecodeBit0(size0);
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R->Range = size0;
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RC_NORM_1(R)
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/* we can use single byte normalization here because of
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(min(BinSumm[][]) = 95) > (1 << (14 - 8)) */
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// sym = (p->FoundState = Ppmd7Context_OneState(p->MinContext))->Symbol;
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// Ppmd7_UpdateBin(p);
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{
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unsigned freq = s->Freq;
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CPpmd7_Context *c = CTX(SUCCESSOR(s));
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sym = s->Symbol;
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p->FoundState = s;
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p->PrevSuccess = 1;
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p->RunLength++;
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s->Freq = (Byte)(freq + (freq < 128));
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// NextContext(p);
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if (p->OrderFall == 0 && (const Byte *)c > p->Text)
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p->MaxContext = p->MinContext = c;
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else
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Ppmd7_UpdateModel(p);
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}
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return sym;
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}
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*prob = (UInt16)pr;
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p->InitEsc = p->ExpEscape[pr >> 10];
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// RangeDec_DecodeBit1(size0);
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R->Code -= size0;
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R->Range -= size0;
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RC_NORM_LOCAL(R)
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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 *s, *s2;
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UInt32 freqSum, count, hiCnt;
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CPpmd_See *see;
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CPpmd7_Context *mc;
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unsigned numMasked;
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RC_NORM_REMOTE(R)
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mc = p->MinContext;
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numMasked = mc->NumStats;
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do
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{
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p->OrderFall++;
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if (!mc->Suffix)
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return PPMD7_SYM_END;
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mc = Ppmd7_GetContext(p, mc->Suffix);
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}
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while (mc->NumStats == numMasked);
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s = Ppmd7_GetStats(p, mc);
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{
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unsigned num = mc->NumStats;
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unsigned num2 = num / 2;
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num &= 1;
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hiCnt = (s->Freq & (unsigned)(MASK(s->Symbol))) & (0 - (UInt32)num);
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s += num;
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p->MinContext = mc;
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do
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{
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unsigned sym0 = s[0].Symbol;
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unsigned sym1 = s[1].Symbol;
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s += 2;
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hiCnt += (s[-2].Freq & (unsigned)(MASK(sym0)));
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hiCnt += (s[-1].Freq & (unsigned)(MASK(sym1)));
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}
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while (--num2);
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}
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see = Ppmd7_MakeEscFreq(p, numMasked, &freqSum);
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freqSum += hiCnt;
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count = RC_GetThreshold(freqSum);
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if (count < hiCnt)
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{
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Byte sym;
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s = Ppmd7_GetStats(p, p->MinContext);
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hiCnt = count;
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// count -= s->Freq & (unsigned)(MASK(s->Symbol));
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// if ((Int32)count >= 0)
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{
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for (;;)
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{
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count -= s->Freq & (unsigned)(MASK((s)->Symbol)); s++; if ((Int32)count < 0) break;
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// count -= s->Freq & (unsigned)(MASK((s)->Symbol)); s++; if ((Int32)count < 0) break;
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}
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}
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s--;
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RC_DecodeFinal((hiCnt - count) - s->Freq, s->Freq)
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// new (see->Summ) value can overflow over 16-bits in some rare cases
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Ppmd_See_UPDATE(see)
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p->FoundState = s;
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sym = s->Symbol;
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Ppmd7_Update2(p);
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return sym;
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}
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if (count >= freqSum)
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return PPMD7_SYM_ERROR;
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RC_Decode(hiCnt, freqSum - hiCnt)
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// We increase (see->Summ) for sum of Freqs of all non_Masked symbols.
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// new (see->Summ) value can overflow over 16-bits in some rare cases
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see->Summ = (UInt16)(see->Summ + freqSum);
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s = Ppmd7_GetStats(p, p->MinContext);
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s2 = s + p->MinContext->NumStats;
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do
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{
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MASK(s->Symbol) = 0;
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s++;
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}
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while (s != s2);
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}
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}
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/*
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Byte *Ppmd7z_DecodeSymbols(CPpmd7 *p, Byte *buf, const Byte *lim)
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{
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int sym = 0;
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if (buf != lim)
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do
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{
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sym = Ppmd7z_DecodeSymbol(p);
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if (sym < 0)
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break;
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*buf = (Byte)sym;
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}
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while (++buf < lim);
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p->LastSymbol = sym;
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return buf;
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}
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*/
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#undef kTopValue
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#undef READ_BYTE
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#undef RC_NORM_BASE
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#undef RC_NORM_1
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#undef RC_NORM
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#undef RC_NORM_LOCAL
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#undef RC_NORM_REMOTE
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#undef R
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#undef RC_Decode
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#undef RC_DecodeFinal
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#undef RC_GetThreshold
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#undef CTX
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#undef SUCCESSOR
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#undef MASK
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