diff options
Diffstat (limited to 'src/libs/7zip/win/C/Ppmd7Dec.c')
| -rw-r--r-- | src/libs/7zip/win/C/Ppmd7Dec.c | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/src/libs/7zip/win/C/Ppmd7Dec.c b/src/libs/7zip/win/C/Ppmd7Dec.c new file mode 100644 index 000000000..68438d5ce --- /dev/null +++ b/src/libs/7zip/win/C/Ppmd7Dec.c @@ -0,0 +1,187 @@ +/* Ppmd7Dec.c -- PPMdH Decoder +2010-03-12 : Igor Pavlov : Public domain +This code is based on PPMd var.H (2001): Dmitry Shkarin : Public domain */ + +#include "Ppmd7.h" + +#define kTopValue (1 << 24) + +Bool Ppmd7z_RangeDec_Init(CPpmd7z_RangeDec *p) +{ + unsigned i; + p->Code = 0; + p->Range = 0xFFFFFFFF; + if (p->Stream->Read((void *)p->Stream) != 0) + return False; + for (i = 0; i < 4; i++) + p->Code = (p->Code << 8) | p->Stream->Read((void *)p->Stream); + return (p->Code < 0xFFFFFFFF); +} + +static UInt32 Range_GetThreshold(void *pp, UInt32 total) +{ + CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp; + return (p->Code) / (p->Range /= total); +} + +static void Range_Normalize(CPpmd7z_RangeDec *p) +{ + if (p->Range < kTopValue) + { + p->Code = (p->Code << 8) | p->Stream->Read((void *)p->Stream); + p->Range <<= 8; + if (p->Range < kTopValue) + { + p->Code = (p->Code << 8) | p->Stream->Read((void *)p->Stream); + p->Range <<= 8; + } + } +} + +static void Range_Decode(void *pp, UInt32 start, UInt32 size) +{ + CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp; + p->Code -= start * p->Range; + p->Range *= size; + Range_Normalize(p); +} + +static UInt32 Range_DecodeBit(void *pp, UInt32 size0) +{ + CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp; + UInt32 newBound = (p->Range >> 14) * size0; + UInt32 symbol; + if (p->Code < newBound) + { + symbol = 0; + p->Range = newBound; + } + else + { + symbol = 1; + p->Code -= newBound; + p->Range -= newBound; + } + Range_Normalize(p); + return symbol; +} + +void Ppmd7z_RangeDec_CreateVTable(CPpmd7z_RangeDec *p) +{ + p->p.GetThreshold = Range_GetThreshold; + p->p.Decode = Range_Decode; + p->p.DecodeBit = Range_DecodeBit; +} + + +#define MASK(sym) ((signed char *)charMask)[sym] + +int Ppmd7_DecodeSymbol(CPpmd7 *p, IPpmd7_RangeDec *rc) +{ + size_t charMask[256 / sizeof(size_t)]; + if (p->MinContext->NumStats != 1) + { + CPpmd_State *s = Ppmd7_GetStats(p, p->MinContext); + unsigned i; + UInt32 count, hiCnt; + if ((count = rc->GetThreshold(rc, p->MinContext->SummFreq)) < (hiCnt = s->Freq)) + { + Byte symbol; + rc->Decode(rc, 0, s->Freq); + p->FoundState = s; + symbol = s->Symbol; + Ppmd7_Update1_0(p); + return symbol; + } + p->PrevSuccess = 0; + i = p->MinContext->NumStats - 1; + do + { + if ((hiCnt += (++s)->Freq) > count) + { + Byte symbol; + rc->Decode(rc, hiCnt - s->Freq, s->Freq); + p->FoundState = s; + symbol = s->Symbol; + Ppmd7_Update1(p); + return symbol; + } + } + while (--i); + if (count >= p->MinContext->SummFreq) + return -2; + p->HiBitsFlag = p->HB2Flag[p->FoundState->Symbol]; + rc->Decode(rc, hiCnt, p->MinContext->SummFreq - hiCnt); + PPMD_SetAllBitsIn256Bytes(charMask); + MASK(s->Symbol) = 0; + i = p->MinContext->NumStats - 1; + do { MASK((--s)->Symbol) = 0; } while (--i); + } + else + { + UInt16 *prob = Ppmd7_GetBinSumm(p); + if (rc->DecodeBit(rc, *prob) == 0) + { + Byte symbol; + *prob = (UInt16)PPMD_UPDATE_PROB_0(*prob); + symbol = (p->FoundState = Ppmd7Context_OneState(p->MinContext))->Symbol; + Ppmd7_UpdateBin(p); + return symbol; + } + *prob = (UInt16)PPMD_UPDATE_PROB_1(*prob); + p->InitEsc = PPMD7_kExpEscape[*prob >> 10]; + PPMD_SetAllBitsIn256Bytes(charMask); + MASK(Ppmd7Context_OneState(p->MinContext)->Symbol) = 0; + p->PrevSuccess = 0; + } + for (;;) + { + CPpmd_State *ps[256], *s; + UInt32 freqSum, count, hiCnt; + CPpmd_See *see; + unsigned i, num, numMasked = p->MinContext->NumStats; + do + { + p->OrderFall++; + if (!p->MinContext->Suffix) + return -1; + p->MinContext = Ppmd7_GetContext(p, p->MinContext->Suffix); + } + while (p->MinContext->NumStats == numMasked); + hiCnt = 0; + s = Ppmd7_GetStats(p, p->MinContext); + i = 0; + num = p->MinContext->NumStats - numMasked; + do + { + int k = (int)(MASK(s->Symbol)); + hiCnt += (s->Freq & k); + ps[i] = s++; + i -= k; + } + while (i != num); + + see = Ppmd7_MakeEscFreq(p, numMasked, &freqSum); + freqSum += hiCnt; + count = rc->GetThreshold(rc, freqSum); + + if (count < hiCnt) + { + Byte symbol; + CPpmd_State **pps = ps; + for (hiCnt = 0; (hiCnt += (*pps)->Freq) <= count; pps++); + s = *pps; + rc->Decode(rc, hiCnt - s->Freq, s->Freq); + Ppmd_See_Update(see); + p->FoundState = s; + symbol = s->Symbol; + Ppmd7_Update2(p); + return symbol; + } + if (count >= freqSum) + return -2; + rc->Decode(rc, hiCnt, freqSum - hiCnt); + see->Summ = (UInt16)(see->Summ + freqSum); + do { MASK(ps[--i]->Symbol) = 0; } while (i != 0); + } +} |