Upgrading lzma_sdk to version 9.20.

third_party/lzma_sdk/C/Ppmd7Dec.c

+/* 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);
+  }
+}