repo sync | baa3858 | 2013-07-26 17:53:31 -0700 | [diff] [blame] | 1 | /* Ppmd7Dec.c -- PPMdH Decoder
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| 2 | 2010-03-12 : Igor Pavlov : Public domain
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| 3 | This code is based on PPMd var.H (2001): Dmitry Shkarin : Public domain */
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| 4 |
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| 5 | #include "Ppmd7.h"
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| 6 |
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| 7 | #define kTopValue (1 << 24)
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| 8 |
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| 9 | Bool Ppmd7z_RangeDec_Init(CPpmd7z_RangeDec *p)
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| 10 | {
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| 11 | unsigned i;
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| 12 | p->Code = 0;
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| 13 | p->Range = 0xFFFFFFFF;
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| 14 | if (p->Stream->Read((void *)p->Stream) != 0)
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| 15 | return False;
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| 16 | for (i = 0; i < 4; i++)
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| 17 | p->Code = (p->Code << 8) | p->Stream->Read((void *)p->Stream);
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| 18 | return (p->Code < 0xFFFFFFFF);
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| 19 | }
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| 20 |
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| 21 | static UInt32 Range_GetThreshold(void *pp, UInt32 total)
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| 22 | {
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| 23 | CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;
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| 24 | return (p->Code) / (p->Range /= total);
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| 25 | }
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| 26 |
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| 27 | static void Range_Normalize(CPpmd7z_RangeDec *p)
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| 28 | {
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| 29 | if (p->Range < kTopValue)
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| 30 | {
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| 31 | p->Code = (p->Code << 8) | p->Stream->Read((void *)p->Stream);
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| 32 | p->Range <<= 8;
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| 33 | if (p->Range < kTopValue)
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| 34 | {
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| 35 | p->Code = (p->Code << 8) | p->Stream->Read((void *)p->Stream);
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| 36 | p->Range <<= 8;
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| 37 | }
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| 38 | }
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| 39 | }
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| 40 |
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| 41 | static void Range_Decode(void *pp, UInt32 start, UInt32 size)
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| 42 | {
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| 43 | CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;
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| 44 | p->Code -= start * p->Range;
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| 45 | p->Range *= size;
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| 46 | Range_Normalize(p);
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| 47 | }
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| 48 |
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| 49 | static UInt32 Range_DecodeBit(void *pp, UInt32 size0)
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| 50 | {
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| 51 | CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;
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| 52 | UInt32 newBound = (p->Range >> 14) * size0;
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| 53 | UInt32 symbol;
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| 54 | if (p->Code < newBound)
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| 55 | {
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| 56 | symbol = 0;
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| 57 | p->Range = newBound;
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| 58 | }
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| 59 | else
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| 60 | {
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| 61 | symbol = 1;
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| 62 | p->Code -= newBound;
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| 63 | p->Range -= newBound;
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| 64 | }
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| 65 | Range_Normalize(p);
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| 66 | return symbol;
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| 67 | }
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| 68 |
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| 69 | void Ppmd7z_RangeDec_CreateVTable(CPpmd7z_RangeDec *p)
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| 70 | {
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| 71 | p->p.GetThreshold = Range_GetThreshold;
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| 72 | p->p.Decode = Range_Decode;
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| 73 | p->p.DecodeBit = Range_DecodeBit;
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| 74 | }
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| 75 |
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| 76 |
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| 77 | #define MASK(sym) ((signed char *)charMask)[sym]
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| 78 |
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| 79 | int Ppmd7_DecodeSymbol(CPpmd7 *p, IPpmd7_RangeDec *rc)
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| 80 | {
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| 81 | size_t charMask[256 / sizeof(size_t)];
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| 82 | if (p->MinContext->NumStats != 1)
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| 83 | {
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| 84 | CPpmd_State *s = Ppmd7_GetStats(p, p->MinContext);
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| 85 | unsigned i;
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| 86 | UInt32 count, hiCnt;
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| 87 | if ((count = rc->GetThreshold(rc, p->MinContext->SummFreq)) < (hiCnt = s->Freq))
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| 88 | {
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| 89 | Byte symbol;
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| 90 | rc->Decode(rc, 0, s->Freq);
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| 91 | p->FoundState = s;
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| 92 | symbol = s->Symbol;
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| 93 | Ppmd7_Update1_0(p);
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| 94 | return symbol;
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| 95 | }
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| 96 | p->PrevSuccess = 0;
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| 97 | i = p->MinContext->NumStats - 1;
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| 98 | do
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| 99 | {
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| 100 | if ((hiCnt += (++s)->Freq) > count)
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| 101 | {
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| 102 | Byte symbol;
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| 103 | rc->Decode(rc, hiCnt - s->Freq, s->Freq);
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| 104 | p->FoundState = s;
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| 105 | symbol = s->Symbol;
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| 106 | Ppmd7_Update1(p);
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| 107 | return symbol;
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| 108 | }
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| 109 | }
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| 110 | while (--i);
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| 111 | if (count >= p->MinContext->SummFreq)
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| 112 | return -2;
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| 113 | p->HiBitsFlag = p->HB2Flag[p->FoundState->Symbol];
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| 114 | rc->Decode(rc, hiCnt, p->MinContext->SummFreq - hiCnt);
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| 115 | PPMD_SetAllBitsIn256Bytes(charMask);
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| 116 | MASK(s->Symbol) = 0;
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| 117 | i = p->MinContext->NumStats - 1;
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| 118 | do { MASK((--s)->Symbol) = 0; } while (--i);
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| 119 | }
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| 120 | else
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| 121 | {
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| 122 | UInt16 *prob = Ppmd7_GetBinSumm(p);
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| 123 | if (rc->DecodeBit(rc, *prob) == 0)
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| 124 | {
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| 125 | Byte symbol;
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| 126 | *prob = (UInt16)PPMD_UPDATE_PROB_0(*prob);
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| 127 | symbol = (p->FoundState = Ppmd7Context_OneState(p->MinContext))->Symbol;
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| 128 | Ppmd7_UpdateBin(p);
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| 129 | return symbol;
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| 130 | }
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| 131 | *prob = (UInt16)PPMD_UPDATE_PROB_1(*prob);
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| 132 | p->InitEsc = PPMD7_kExpEscape[*prob >> 10];
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| 133 | PPMD_SetAllBitsIn256Bytes(charMask);
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| 134 | MASK(Ppmd7Context_OneState(p->MinContext)->Symbol) = 0;
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| 135 | p->PrevSuccess = 0;
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| 136 | }
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| 137 | for (;;)
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| 138 | {
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| 139 | CPpmd_State *ps[256], *s;
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| 140 | UInt32 freqSum, count, hiCnt;
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| 141 | CPpmd_See *see;
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| 142 | unsigned i, num, numMasked = p->MinContext->NumStats;
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| 143 | do
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| 144 | {
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| 145 | p->OrderFall++;
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| 146 | if (!p->MinContext->Suffix)
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| 147 | return -1;
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| 148 | p->MinContext = Ppmd7_GetContext(p, p->MinContext->Suffix);
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| 149 | }
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| 150 | while (p->MinContext->NumStats == numMasked);
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| 151 | hiCnt = 0;
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| 152 | s = Ppmd7_GetStats(p, p->MinContext);
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| 153 | i = 0;
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| 154 | num = p->MinContext->NumStats - numMasked;
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| 155 | do
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| 156 | {
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| 157 | int k = (int)(MASK(s->Symbol));
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| 158 | hiCnt += (s->Freq & k);
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| 159 | ps[i] = s++;
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| 160 | i -= k;
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| 161 | }
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| 162 | while (i != num);
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| 163 |
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| 164 | see = Ppmd7_MakeEscFreq(p, numMasked, &freqSum);
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| 165 | freqSum += hiCnt;
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| 166 | count = rc->GetThreshold(rc, freqSum);
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| 167 |
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| 168 | if (count < hiCnt)
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| 169 | {
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| 170 | Byte symbol;
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| 171 | CPpmd_State **pps = ps;
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| 172 | for (hiCnt = 0; (hiCnt += (*pps)->Freq) <= count; pps++);
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| 173 | s = *pps;
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| 174 | rc->Decode(rc, hiCnt - s->Freq, s->Freq);
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| 175 | Ppmd_See_Update(see);
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| 176 | p->FoundState = s;
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| 177 | symbol = s->Symbol;
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| 178 | Ppmd7_Update2(p);
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| 179 | return symbol;
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| 180 | }
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| 181 | if (count >= freqSum)
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| 182 | return -2;
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| 183 | rc->Decode(rc, hiCnt, freqSum - hiCnt);
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| 184 | see->Summ = (UInt16)(see->Summ + freqSum);
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| 185 | do { MASK(ps[--i]->Symbol) = 0; } while (i != 0);
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| 186 | }
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| 187 | }
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