diff options
Diffstat (limited to 'src/libs/7zip/unix/CPP/7zip/Compress/PpmdDecode.h')
-rw-r--r-- | src/libs/7zip/unix/CPP/7zip/Compress/PpmdDecode.h | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/src/libs/7zip/unix/CPP/7zip/Compress/PpmdDecode.h b/src/libs/7zip/unix/CPP/7zip/Compress/PpmdDecode.h new file mode 100644 index 000000000..fe6927bf8 --- /dev/null +++ b/src/libs/7zip/unix/CPP/7zip/Compress/PpmdDecode.h @@ -0,0 +1,156 @@ +// PpmdDecode.h +// 2009-05-30 : Igor Pavlov : Public domain +// This code is based on Dmitry Shkarin's PPMdH code (public domain) + +#ifndef __COMPRESS_PPMD_DECODE_H +#define __COMPRESS_PPMD_DECODE_H + +#include "PpmdContext.h" + +namespace NCompress { +namespace NPpmd { + +class CRangeDecoderVirt +{ +public: + virtual ~CRangeDecoderVirt() {} + virtual UInt32 GetThreshold(UInt32 total) = 0; + virtual void Decode(UInt32 start, UInt32 size) = 0; + virtual UInt32 DecodeBit(UInt32 size0, UInt32 numTotalBits) = 0; +}; + +typedef NRangeCoder::CDecoder CRangeDecoderMy; + +class CRangeDecoder:public CRangeDecoderVirt, public CRangeDecoderMy +{ + UInt32 GetThreshold(UInt32 total) { return CRangeDecoderMy::GetThreshold(total); } + void Decode(UInt32 start, UInt32 size) { CRangeDecoderMy::Decode(start, size); } + UInt32 DecodeBit(UInt32 size0, UInt32 numTotalBits) { return CRangeDecoderMy::DecodeBit(size0, numTotalBits); } +}; + +struct CDecodeInfo: public CInfo +{ + void DecodeBinSymbol(CRangeDecoderVirt *rangeDecoder) + { + PPM_CONTEXT::STATE& rs = MinContext->oneState(); + UInt16& bs = GetBinSumm(rs, GetContextNoCheck(MinContext->Suffix)->NumStats); + if (rangeDecoder->DecodeBit(bs, TOT_BITS) == 0) + { + FoundState = &rs; + rs.Freq = (Byte)(rs.Freq + (rs.Freq < 128 ? 1: 0)); + bs = (UInt16)(bs + INTERVAL - GET_MEAN(bs, PERIOD_BITS, 2)); + PrevSuccess = 1; + RunLength++; + } + else + { + bs = (UInt16)(bs - GET_MEAN(bs, PERIOD_BITS, 2)); + InitEsc = ExpEscape[bs >> 10]; + NumMasked = 1; + CharMask[rs.Symbol] = EscCount; + PrevSuccess = 0; + FoundState = NULL; + } + } + + void DecodeSymbol1(CRangeDecoderVirt *rangeDecoder) + { + PPM_CONTEXT::STATE* p = GetStateNoCheck(MinContext->Stats); + int i, count, hiCnt; + if ((count = rangeDecoder->GetThreshold(MinContext->SummFreq)) < (hiCnt = p->Freq)) + { + PrevSuccess = (2 * hiCnt > MinContext->SummFreq); + RunLength += PrevSuccess; + rangeDecoder->Decode(0, p->Freq); // MinContext->SummFreq); + (FoundState = p)->Freq = (Byte)(hiCnt += 4); + MinContext->SummFreq += 4; + if (hiCnt > MAX_FREQ) + rescale(); + return; + } + PrevSuccess = 0; + i = MinContext->NumStats - 1; + while ((hiCnt += (++p)->Freq) <= count) + if (--i == 0) + { + HiBitsFlag = HB2Flag[FoundState->Symbol]; + rangeDecoder->Decode(hiCnt, MinContext->SummFreq - hiCnt); // , MinContext->SummFreq); + CharMask[p->Symbol] = EscCount; + i = (NumMasked = MinContext->NumStats)-1; + FoundState = NULL; + do { CharMask[(--p)->Symbol] = EscCount; } while ( --i ); + return; + } + rangeDecoder->Decode(hiCnt - p->Freq, p->Freq); // , MinContext->SummFreq); + update1(p); + } + + + void DecodeSymbol2(CRangeDecoderVirt *rangeDecoder) + { + int count, hiCnt, i = MinContext->NumStats - NumMasked; + UInt32 freqSum; + SEE2_CONTEXT* psee2c = makeEscFreq2(i, freqSum); + PPM_CONTEXT::STATE* ps[256], ** pps = ps, * p = GetStateNoCheck(MinContext->Stats)-1; + hiCnt = 0; + do + { + do { p++; } while (CharMask[p->Symbol] == EscCount); + hiCnt += p->Freq; + *pps++ = p; + } + while ( --i ); + + freqSum += hiCnt; + count = rangeDecoder->GetThreshold(freqSum); + + p = *(pps = ps); + if (count < hiCnt) + { + hiCnt = 0; + while ((hiCnt += p->Freq) <= count) + p=*++pps; + rangeDecoder->Decode(hiCnt - p->Freq, p->Freq); // , freqSum); + + psee2c->update(); + update2(p); + } + else + { + rangeDecoder->Decode(hiCnt, freqSum - hiCnt); // , freqSum); + + i = MinContext->NumStats - NumMasked; + pps--; + do { CharMask[(*++pps)->Symbol] = EscCount; } while ( --i ); + psee2c->Summ = (UInt16)(psee2c->Summ + freqSum); + NumMasked = MinContext->NumStats; + } + } + + int DecodeSymbol(CRangeDecoderVirt *rangeDecoder) + { + if (MinContext->NumStats != 1) + DecodeSymbol1(rangeDecoder); + else + DecodeBinSymbol(rangeDecoder); + while ( !FoundState ) + { + do + { + OrderFall++; + MinContext = GetContext(MinContext->Suffix); + if (MinContext == 0) + return -1; + } + while (MinContext->NumStats == NumMasked); + DecodeSymbol2(rangeDecoder); + } + Byte symbol = FoundState->Symbol; + NextContext(); + return symbol; + } +}; + +}} + +#endif |