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-rw-r--r--trunk/src/lib/lib7z/Ppmd8Dec.c155
1 files changed, 155 insertions, 0 deletions
diff --git a/trunk/src/lib/lib7z/Ppmd8Dec.c b/trunk/src/lib/lib7z/Ppmd8Dec.c
new file mode 100644
index 00000000000..12fd7ec0d79
--- /dev/null
+++ b/trunk/src/lib/lib7z/Ppmd8Dec.c
@@ -0,0 +1,155 @@
+/* Ppmd8Dec.c -- PPMdI Decoder
+2010-04-16 : Igor Pavlov : Public domain
+This code is based on:
+ PPMd var.I (2002): Dmitry Shkarin : Public domain
+ Carryless rangecoder (1999): Dmitry Subbotin : Public domain */
+
+#include "Ppmd8.h"
+
+#define kTop (1 << 24)
+#define kBot (1 << 15)
+
+Bool Ppmd8_RangeDec_Init(CPpmd8 *p)
+{
+ unsigned i;
+ p->Low = 0;
+ p->Range = 0xFFFFFFFF;
+ p->Code = 0;
+ for (i = 0; i < 4; i++)
+ p->Code = (p->Code << 8) | p->Stream.In->Read(p->Stream.In);
+ return (p->Code < 0xFFFFFFFF);
+}
+
+static UInt32 RangeDec_GetThreshold(CPpmd8 *p, UInt32 total)
+{
+ return p->Code / (p->Range /= total);
+}
+
+static void RangeDec_Decode(CPpmd8 *p, UInt32 start, UInt32 size)
+{
+ start *= p->Range;
+ p->Low += start;
+ p->Code -= start;
+ p->Range *= size;
+
+ while ((p->Low ^ (p->Low + p->Range)) < kTop ||
+ (p->Range < kBot && ((p->Range = (0 - p->Low) & (kBot - 1)), 1)))
+ {
+ p->Code = (p->Code << 8) | p->Stream.In->Read(p->Stream.In);
+ p->Range <<= 8;
+ p->Low <<= 8;
+ }
+}
+
+#define MASK(sym) ((signed char *)charMask)[sym]
+
+int Ppmd8_DecodeSymbol(CPpmd8 *p)
+{
+ size_t charMask[256 / sizeof(size_t)];
+ if (p->MinContext->NumStats != 0)
+ {
+ CPpmd_State *s = Ppmd8_GetStats(p, p->MinContext);
+ unsigned i;
+ UInt32 count, hiCnt;
+ if ((count = RangeDec_GetThreshold(p, p->MinContext->SummFreq)) < (hiCnt = s->Freq))
+ {
+ Byte symbol;
+ RangeDec_Decode(p, 0, s->Freq);
+ p->FoundState = s;
+ symbol = s->Symbol;
+ Ppmd8_Update1_0(p);
+ return symbol;
+ }
+ p->PrevSuccess = 0;
+ i = p->MinContext->NumStats;
+ do
+ {
+ if ((hiCnt += (++s)->Freq) > count)
+ {
+ Byte symbol;
+ RangeDec_Decode(p, hiCnt - s->Freq, s->Freq);
+ p->FoundState = s;
+ symbol = s->Symbol;
+ Ppmd8_Update1(p);
+ return symbol;
+ }
+ }
+ while (--i);
+ if (count >= p->MinContext->SummFreq)
+ return -2;
+ RangeDec_Decode(p, hiCnt, p->MinContext->SummFreq - hiCnt);
+ PPMD_SetAllBitsIn256Bytes(charMask);
+ MASK(s->Symbol) = 0;
+ i = p->MinContext->NumStats;
+ do { MASK((--s)->Symbol) = 0; } while (--i);
+ }
+ else
+ {
+ UInt16 *prob = Ppmd8_GetBinSumm(p);
+ if (((p->Code / (p->Range >>= 14)) < *prob))
+ {
+ Byte symbol;
+ RangeDec_Decode(p, 0, *prob);
+ *prob = (UInt16)PPMD_UPDATE_PROB_0(*prob);
+ symbol = (p->FoundState = Ppmd8Context_OneState(p->MinContext))->Symbol;
+ Ppmd8_UpdateBin(p);
+ return symbol;
+ }
+ RangeDec_Decode(p, *prob, (1 << 14) - *prob);
+ *prob = (UInt16)PPMD_UPDATE_PROB_1(*prob);
+ p->InitEsc = PPMD8_kExpEscape[*prob >> 10];
+ PPMD_SetAllBitsIn256Bytes(charMask);
+ MASK(Ppmd8Context_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 = Ppmd8_GetContext(p, p->MinContext->Suffix);
+ }
+ while (p->MinContext->NumStats == numMasked);
+ hiCnt = 0;
+ s = Ppmd8_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 = Ppmd8_MakeEscFreq(p, numMasked, &freqSum);
+ freqSum += hiCnt;
+ count = RangeDec_GetThreshold(p, freqSum);
+
+ if (count < hiCnt)
+ {
+ Byte symbol;
+ CPpmd_State **pps = ps;
+ for (hiCnt = 0; (hiCnt += (*pps)->Freq) <= count; pps++);
+ s = *pps;
+ RangeDec_Decode(p, hiCnt - s->Freq, s->Freq);
+ Ppmd_See_Update(see);
+ p->FoundState = s;
+ symbol = s->Symbol;
+ Ppmd8_Update2(p);
+ return symbol;
+ }
+ if (count >= freqSum)
+ return -2;
+ RangeDec_Decode(p, hiCnt, freqSum - hiCnt);
+ see->Summ = (UInt16)(see->Summ + freqSum);
+ do { MASK(ps[--i]->Symbol) = 0; } while (i != 0);
+ }
+}