7zip/C/Ppmd8Enc.c

/* Ppmd8Enc.c -- Ppmd8 (PPMdI) Encoder
2021-04-13 : 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 "Precomp.h"

#include "Ppmd8.h"

#define kTop (1 << 24)
#define kBot (1 << 15)

#define WRITE_BYTE(p) IByteOut_Write(p->Stream.Out, (Byte)(p->Low >> 24))

void Ppmd8_Flush_RangeEnc(CPpmd8 *p)
{
  unsigned i;
  for (i = 0; i < 4; i++, p->Low <<= 8 )
    WRITE_BYTE(p);
}






#define RC_NORM(p) \
  while ((p->Low ^ (p->Low + p->Range)) < kTop \
    || (p->Range < kBot && ((p->Range = (0 - p->Low) & (kBot - 1)), 1))) \
    { WRITE_BYTE(p); p->Range <<= 8; p->Low <<= 8; }













// we must use only one type of Normalization from two: LOCAL or REMOTE
#define RC_NORM_LOCAL(p)    // RC_NORM(p)
#define RC_NORM_REMOTE(p)   RC_NORM(p)

// #define RC_PRE(total) p->Range /= total;
// #define RC_PRE(total)

#define R p




MY_FORCE_INLINE
// MY_NO_INLINE
static void RangeEnc_Encode(CPpmd8 *p, UInt32 start, UInt32 size, UInt32 total)
{
  R->Low += start * (R->Range /= total);
  R->Range *= size;
  RC_NORM_LOCAL(R);
}










#define RC_Encode(start, size, total) RangeEnc_Encode(p, start, size, total);
#define RC_EncodeFinal(start, size, total) RC_Encode(start, size, total); RC_NORM_REMOTE(p);

#define CTX(ref) ((CPpmd8_Context *)Ppmd8_GetContext(p, ref))

typedef CPpmd8_Context * CTX_PTR;
#define SUCCESSOR(p) Ppmd_GET_SUCCESSOR(p)

void Ppmd8_UpdateModel(CPpmd8 *p);

#define MASK(sym) ((unsigned char *)charMask)[sym]

// MY_FORCE_INLINE
// static
void Ppmd8_EncodeSymbol(CPpmd8 *p, int symbol)
{
  size_t charMask[256 / sizeof(size_t)];
  
  if (p->MinContext->NumStats != 0)
  {
    CPpmd_State *s = Ppmd8_GetStats(p, p->MinContext);
    UInt32 sum;
    unsigned i;
    UInt32 summFreq = p->MinContext->Union2.SummFreq;
    
    PPMD8_CORRECT_SUM_RANGE(p, summFreq)

    // RC_PRE(summFreq);

    if (s->Symbol == symbol)
    {

      RC_EncodeFinal(0, s->Freq, summFreq);
      p->FoundState = s;
      Ppmd8_Update1_0(p);
      return;
    }
    p->PrevSuccess = 0;
    sum = s->Freq;
    i = p->MinContext->NumStats;
    do
    {
      if ((++s)->Symbol == symbol)
      {

        RC_EncodeFinal(sum, s->Freq, summFreq);
        p->FoundState = s;
        Ppmd8_Update1(p);
        return;
      }
      sum += s->Freq;
    }
    while (--i);
    
    
    RC_Encode(sum, summFreq - sum, summFreq);
    
    
    PPMD_SetAllBitsIn256Bytes(charMask);
    // MASK(s->Symbol) = 0;
    // i = p->MinContext->NumStats;
    // do { MASK((--s)->Symbol) = 0; } while (--i);
    {
      CPpmd_State *s2 = Ppmd8_GetStats(p, p->MinContext);
      MASK(s->Symbol) = 0;
      do
      {
        unsigned sym0 = s2[0].Symbol;
        unsigned sym1 = s2[1].Symbol;
        s2 += 2;
        MASK(sym0) = 0;
        MASK(sym1) = 0;
      }
      while (s2 < s);
    }
  }
  else
  {
    UInt16 *prob = Ppmd8_GetBinSumm(p);
    CPpmd_State *s = Ppmd8Context_OneState(p->MinContext);
    UInt32 pr = *prob;
    UInt32 bound = (R->Range >> 14) * pr;
    pr = PPMD_UPDATE_PROB_1(pr);
    if (s->Symbol == symbol)
    {
      *prob = (UInt16)(pr + (1 << PPMD_INT_BITS));
      // RangeEnc_EncodeBit_0(p, bound);
      R->Range = bound;
      RC_NORM(R);

      // p->FoundState = s;
      // Ppmd8_UpdateBin(p);
      {
        unsigned freq = s->Freq;
        CTX_PTR c = CTX(SUCCESSOR(s));
        p->FoundState = s;
        p->PrevSuccess = 1;
        p->RunLength++;
        s->Freq = (Byte)(freq + (freq < 196)); // Ppmd8 (196)
        // NextContext(p);
        if (p->OrderFall == 0 && (const Byte *)c >= p->UnitsStart)
          p->MaxContext = p->MinContext = c;
        else
          Ppmd8_UpdateModel(p);
      }
      return;
    }

    *prob = (UInt16)pr;
    p->InitEsc = p->ExpEscape[pr >> 10];
    // RangeEnc_EncodeBit_1(p, bound);
    R->Low += bound;
    R->Range = (R->Range & ~((UInt32)PPMD_BIN_SCALE - 1)) - bound;
    RC_NORM_LOCAL(R)

    PPMD_SetAllBitsIn256Bytes(charMask);
    MASK(s->Symbol) = 0;
    p->PrevSuccess = 0;
  }

  for (;;)
  {
    CPpmd_See *see;
    CPpmd_State *s;
    UInt32 sum, escFreq;
    CPpmd8_Context *mc;
    unsigned i, numMasked;

    RC_NORM_REMOTE(p)

    mc = p->MinContext;
    numMasked = mc->NumStats;

    do
    {
      p->OrderFall++;
      if (!mc->Suffix)
        return; /* EndMarker (symbol = -1) */
      mc = Ppmd8_GetContext(p, mc->Suffix);

    }
    while (mc->NumStats == numMasked);
    
    p->MinContext = mc;

    see = Ppmd8_MakeEscFreq(p, numMasked, &escFreq);
    
    
    
    
    
    
    
    
    

    
    
    
    
    
    

    
    
    
    
    
    
    
    s = Ppmd8_GetStats(p, p->MinContext);
    sum = 0;
    i = (unsigned)p->MinContext->NumStats + 1;

    do
    {
      unsigned cur = s->Symbol;
      if ((int)cur == symbol)
      {
        UInt32 low = sum;
        UInt32 freq = s->Freq;
        unsigned num2;

        Ppmd_See_Update(see);
        p->FoundState = s;
        sum += escFreq;

        num2 = i / 2;
        i &= 1;
        sum += freq & (0 - (UInt32)i);
        if (num2 != 0)
        {
          s += i;
          for (;;)
          {
            unsigned sym0 = s[0].Symbol;
            unsigned sym1 = s[1].Symbol;
            s += 2;
            sum += (s[-2].Freq & (unsigned)(MASK(sym0)));
            sum += (s[-1].Freq & (unsigned)(MASK(sym1)));
            if (--num2 == 0)
              break;
          }
        }

        PPMD8_CORRECT_SUM_RANGE(p, sum);

        RC_EncodeFinal(low, freq, sum);
        Ppmd8_Update2(p);
        return;
      }
      sum += (s->Freq & (unsigned)(MASK(cur)));
      s++;
    }
    while (--i);
    
    {
      UInt32 total = sum + escFreq;
      see->Summ = (UInt16)(see->Summ + total);
      PPMD8_CORRECT_SUM_RANGE(p, total);

      RC_Encode(sum, total - sum, total);
    }

    {
      CPpmd_State *s2 = Ppmd8_GetStats(p, p->MinContext);
      s--;
      MASK(s->Symbol) = 0;
      do
      {
        unsigned sym0 = s2[0].Symbol;
        unsigned sym1 = s2[1].Symbol;
        s2 += 2;
        MASK(sym0) = 0;
        MASK(sym1) = 0;
      }
      while (s2 < s);
    }
  }
}