Home | History | Annotate | Download | only in C 
      1 /* Ppmd7Enc.c -- PPMdH Encoder
      2 2010-03-12 : Igor Pavlov : Public domain
      3 This code is based on PPMd var.H (2001): Dmitry Shkarin : Public domain */
      4 
      5 #include "Ppmd7.h"
      6 
      7 #define kTopValue (1 << 24)
      8 
      9 void Ppmd7z_RangeEnc_Init(CPpmd7z_RangeEnc *p)
     10 {
     11   p->Low = 0;
     12   p->Range = 0xFFFFFFFF;
     13   p->Cache = 0;
     14   p->CacheSize = 1;
     15 }
     16 
     17 static void RangeEnc_ShiftLow(CPpmd7z_RangeEnc *p)
     18 {
     19   if ((UInt32)p->Low < (UInt32)0xFF000000 || (unsigned)(p->Low >> 32) != 0)
     20   {
     21     Byte temp = p->Cache;
     22     do
     23     {
     24       p->Stream->Write(p->Stream, (Byte)(temp + (Byte)(p->Low >> 32)));
     25       temp = 0xFF;
     26     }
     27     while(--p->CacheSize != 0);
     28     p->Cache = (Byte)((UInt32)p->Low >> 24);
     29   }
     30   p->CacheSize++;
     31   p->Low = (UInt32)p->Low << 8;
     32 }
     33 
     34 static void RangeEnc_Encode(CPpmd7z_RangeEnc *p, UInt32 start, UInt32 size, UInt32 total)
     35 {
     36   p->Low += start * (p->Range /= total);
     37   p->Range *= size;
     38   while (p->Range < kTopValue)
     39   {
     40     p->Range <<= 8;
     41     RangeEnc_ShiftLow(p);
     42   }
     43 }
     44 
     45 static void RangeEnc_EncodeBit_0(CPpmd7z_RangeEnc *p, UInt32 size0)
     46 {
     47   p->Range = (p->Range >> 14) * size0;
     48   while (p->Range < kTopValue)
     49   {
     50     p->Range <<= 8;
     51     RangeEnc_ShiftLow(p);
     52   }
     53 }
     54 
     55 static void RangeEnc_EncodeBit_1(CPpmd7z_RangeEnc *p, UInt32 size0)
     56 {
     57   UInt32 newBound = (p->Range >> 14) * size0;
     58   p->Low += newBound;
     59   p->Range -= newBound;
     60   while (p->Range < kTopValue)
     61   {
     62     p->Range <<= 8;
     63     RangeEnc_ShiftLow(p);
     64   }
     65 }
     66 
     67 void Ppmd7z_RangeEnc_FlushData(CPpmd7z_RangeEnc *p)
     68 {
     69   unsigned i;
     70   for (i = 0; i < 5; i++)
     71     RangeEnc_ShiftLow(p);
     72 }
     73 
     74 
     75 #define MASK(sym) ((signed char *)charMask)[sym]
     76 
     77 void Ppmd7_EncodeSymbol(CPpmd7 *p, CPpmd7z_RangeEnc *rc, int symbol)
     78 {
     79   size_t charMask[256 / sizeof(size_t)];
     80   if (p->MinContext->NumStats != 1)
     81   {
     82     CPpmd_State *s = Ppmd7_GetStats(p, p->MinContext);
     83     UInt32 sum;
     84     unsigned i;
     85     if (s->Symbol == symbol)
     86     {
     87       RangeEnc_Encode(rc, 0, s->Freq, p->MinContext->SummFreq);
     88       p->FoundState = s;
     89       Ppmd7_Update1_0(p);
     90       return;
     91     }
     92     p->PrevSuccess = 0;
     93     sum = s->Freq;
     94     i = p->MinContext->NumStats - 1;
     95     do
     96     {
     97       if ((++s)->Symbol == symbol)
     98       {
     99         RangeEnc_Encode(rc, sum, s->Freq, p->MinContext->SummFreq);
    100         p->FoundState = s;
    101         Ppmd7_Update1(p);
    102         return;
    103       }
    104       sum += s->Freq;
    105     }
    106     while (--i);
    107 
    108     p->HiBitsFlag = p->HB2Flag[p->FoundState->Symbol];
    109     PPMD_SetAllBitsIn256Bytes(charMask);
    110     MASK(s->Symbol) = 0;
    111     i = p->MinContext->NumStats - 1;
    112     do { MASK((--s)->Symbol) = 0; } while (--i);
    113     RangeEnc_Encode(rc, sum, p->MinContext->SummFreq - sum, p->MinContext->SummFreq);
    114   }
    115   else
    116   {
    117     UInt16 *prob = Ppmd7_GetBinSumm(p);
    118     CPpmd_State *s = Ppmd7Context_OneState(p->MinContext);
    119     if (s->Symbol == symbol)
    120     {
    121       RangeEnc_EncodeBit_0(rc, *prob);
    122       *prob = (UInt16)PPMD_UPDATE_PROB_0(*prob);
    123       p->FoundState = s;
    124       Ppmd7_UpdateBin(p);
    125       return;
    126     }
    127     else
    128     {
    129       RangeEnc_EncodeBit_1(rc, *prob);
    130       *prob = (UInt16)PPMD_UPDATE_PROB_1(*prob);
    131       p->InitEsc = PPMD7_kExpEscape[*prob >> 10];
    132       PPMD_SetAllBitsIn256Bytes(charMask);
    133       MASK(s->Symbol) = 0;
    134       p->PrevSuccess = 0;
    135     }
    136   }
    137   for (;;)
    138   {
    139     UInt32 escFreq;
    140     CPpmd_See *see;
    141     CPpmd_State *s;
    142     UInt32 sum;
    143     unsigned i, numMasked = p->MinContext->NumStats;
    144     do
    145     {
    146       p->OrderFall++;
    147       if (!p->MinContext->Suffix)
    148         return; /* EndMarker (symbol = -1) */
    149       p->MinContext = Ppmd7_GetContext(p, p->MinContext->Suffix);
    150     }
    151     while (p->MinContext->NumStats == numMasked);
    152 
    153     see = Ppmd7_MakeEscFreq(p, numMasked, &escFreq);
    154     s = Ppmd7_GetStats(p, p->MinContext);
    155     sum = 0;
    156     i = p->MinContext->NumStats;
    157     do
    158     {
    159       int cur = s->Symbol;
    160       if (cur == symbol)
    161       {
    162         UInt32 low = sum;
    163         CPpmd_State *s1 = s;
    164         do
    165         {
    166           sum += (s->Freq & (int)(MASK(s->Symbol)));
    167           s++;
    168         }
    169         while (--i);
    170         RangeEnc_Encode(rc, low, s1->Freq, sum + escFreq);
    171         Ppmd_See_Update(see);
    172         p->FoundState = s1;
    173         Ppmd7_Update2(p);
    174         return;
    175       }
    176       sum += (s->Freq & (int)(MASK(cur)));
    177       MASK(cur) = 0;
    178       s++;
    179     }
    180     while (--i);
    181 
    182     RangeEnc_Encode(rc, sum, escFreq, sum + escFreq);
    183     see->Summ = (UInt16)(see->Summ + sum + escFreq);
    184   }
    185 }
    186