diff options
Diffstat (limited to 'other-licenses/7zstub/src/C/Ppmd7Dec.c')
| -rw-r--r-- | other-licenses/7zstub/src/C/Ppmd7Dec.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/other-licenses/7zstub/src/C/Ppmd7Dec.c b/other-licenses/7zstub/src/C/Ppmd7Dec.c new file mode 100644 index 0000000000..3023b6776d --- /dev/null +++ b/other-licenses/7zstub/src/C/Ppmd7Dec.c @@ -0,0 +1,191 @@ +/* Ppmd7Dec.c -- PPMdH Decoder
+2017-04-03 : Igor Pavlov : Public domain
+This code is based on PPMd var.H (2001): Dmitry Shkarin : Public domain */
+
+#include "Precomp.h"
+
+#include "Ppmd7.h"
+
+#define kTopValue (1 << 24)
+
+Bool Ppmd7z_RangeDec_Init(CPpmd7z_RangeDec *p)
+{
+ unsigned i;
+ p->Code = 0;
+ p->Range = 0xFFFFFFFF;
+ if (IByteIn_Read(p->Stream) != 0)
+ return False;
+ for (i = 0; i < 4; i++)
+ p->Code = (p->Code << 8) | IByteIn_Read(p->Stream);
+ return (p->Code < 0xFFFFFFFF);
+}
+
+#define GET_Ppmd7z_RangeDec CPpmd7z_RangeDec *p = CONTAINER_FROM_VTBL(pp, CPpmd7z_RangeDec, vt);
+
+static UInt32 Range_GetThreshold(const IPpmd7_RangeDec *pp, UInt32 total)
+{
+ GET_Ppmd7z_RangeDec
+ return p->Code / (p->Range /= total);
+}
+
+static void Range_Normalize(CPpmd7z_RangeDec *p)
+{
+ if (p->Range < kTopValue)
+ {
+ p->Code = (p->Code << 8) | IByteIn_Read(p->Stream);
+ p->Range <<= 8;
+ if (p->Range < kTopValue)
+ {
+ p->Code = (p->Code << 8) | IByteIn_Read(p->Stream);
+ p->Range <<= 8;
+ }
+ }
+}
+
+static void Range_Decode(const IPpmd7_RangeDec *pp, UInt32 start, UInt32 size)
+{
+ GET_Ppmd7z_RangeDec
+ p->Code -= start * p->Range;
+ p->Range *= size;
+ Range_Normalize(p);
+}
+
+static UInt32 Range_DecodeBit(const IPpmd7_RangeDec *pp, UInt32 size0)
+{
+ GET_Ppmd7z_RangeDec
+ 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->vt.GetThreshold = Range_GetThreshold;
+ p->vt.Decode = Range_Decode;
+ p->vt.DecodeBit = Range_DecodeBit;
+}
+
+
+#define MASK(sym) ((signed char *)charMask)[sym]
+
+int Ppmd7_DecodeSymbol(CPpmd7 *p, const 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);
+ }
+}
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