1 /* Ppmd7Dec.c -- PPMdH Decoder
\r
2 2010-03-12 : Igor Pavlov : Public domain
\r
3 This code is based on PPMd var.H (2001): Dmitry Shkarin : Public domain */
\r
9 #define kTopValue (1 << 24)
\r
11 Bool Ppmd7z_RangeDec_Init(CPpmd7z_RangeDec *p)
\r
15 p->Range = 0xFFFFFFFF;
\r
16 if (p->Stream->Read((void *)p->Stream) != 0)
\r
18 for (i = 0; i < 4; i++)
\r
19 p->Code = (p->Code << 8) | p->Stream->Read((void *)p->Stream);
\r
20 return (p->Code < 0xFFFFFFFF);
\r
23 static UInt32 Range_GetThreshold(void *pp, UInt32 total)
\r
25 CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;
\r
26 return (p->Code) / (p->Range /= total);
\r
29 static void Range_Normalize(CPpmd7z_RangeDec *p)
\r
31 if (p->Range < kTopValue)
\r
33 p->Code = (p->Code << 8) | p->Stream->Read((void *)p->Stream);
\r
35 if (p->Range < kTopValue)
\r
37 p->Code = (p->Code << 8) | p->Stream->Read((void *)p->Stream);
\r
43 static void Range_Decode(void *pp, UInt32 start, UInt32 size)
\r
45 CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;
\r
46 p->Code -= start * p->Range;
\r
51 static UInt32 Range_DecodeBit(void *pp, UInt32 size0)
\r
53 CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;
\r
54 UInt32 newBound = (p->Range >> 14) * size0;
\r
56 if (p->Code < newBound)
\r
59 p->Range = newBound;
\r
64 p->Code -= newBound;
\r
65 p->Range -= newBound;
\r
71 void Ppmd7z_RangeDec_CreateVTable(CPpmd7z_RangeDec *p)
\r
73 p->p.GetThreshold = Range_GetThreshold;
\r
74 p->p.Decode = Range_Decode;
\r
75 p->p.DecodeBit = Range_DecodeBit;
\r
79 #define MASK(sym) ((signed char *)charMask)[sym]
\r
81 int Ppmd7_DecodeSymbol(CPpmd7 *p, IPpmd7_RangeDec *rc)
\r
83 size_t charMask[256 / sizeof(size_t)];
\r
84 if (p->MinContext->NumStats != 1)
\r
86 CPpmd_State *s = Ppmd7_GetStats(p, p->MinContext);
\r
88 UInt32 count, hiCnt;
\r
89 if ((count = rc->GetThreshold(rc, p->MinContext->SummFreq)) < (hiCnt = s->Freq))
\r
92 rc->Decode(rc, 0, s->Freq);
\r
99 i = p->MinContext->NumStats - 1;
\r
102 if ((hiCnt += (++s)->Freq) > count)
\r
105 rc->Decode(rc, hiCnt - s->Freq, s->Freq);
\r
107 symbol = s->Symbol;
\r
113 if (count >= p->MinContext->SummFreq)
\r
115 p->HiBitsFlag = p->HB2Flag[p->FoundState->Symbol];
\r
116 rc->Decode(rc, hiCnt, p->MinContext->SummFreq - hiCnt);
\r
117 PPMD_SetAllBitsIn256Bytes(charMask);
\r
118 MASK(s->Symbol) = 0;
\r
119 i = p->MinContext->NumStats - 1;
\r
120 do { MASK((--s)->Symbol) = 0; } while (--i);
\r
124 UInt16 *prob = Ppmd7_GetBinSumm(p);
\r
125 if (rc->DecodeBit(rc, *prob) == 0)
\r
128 *prob = (UInt16)PPMD_UPDATE_PROB_0(*prob);
\r
129 symbol = (p->FoundState = Ppmd7Context_OneState(p->MinContext))->Symbol;
\r
130 Ppmd7_UpdateBin(p);
\r
133 *prob = (UInt16)PPMD_UPDATE_PROB_1(*prob);
\r
134 p->InitEsc = PPMD7_kExpEscape[*prob >> 10];
\r
135 PPMD_SetAllBitsIn256Bytes(charMask);
\r
136 MASK(Ppmd7Context_OneState(p->MinContext)->Symbol) = 0;
\r
137 p->PrevSuccess = 0;
\r
141 CPpmd_State *ps[256], *s;
\r
142 UInt32 freqSum, count, hiCnt;
\r
144 unsigned i, num, numMasked = p->MinContext->NumStats;
\r
148 if (!p->MinContext->Suffix)
\r
150 p->MinContext = Ppmd7_GetContext(p, p->MinContext->Suffix);
\r
152 while (p->MinContext->NumStats == numMasked);
\r
154 s = Ppmd7_GetStats(p, p->MinContext);
\r
156 num = p->MinContext->NumStats - numMasked;
\r
159 int k = (int)(MASK(s->Symbol));
\r
160 hiCnt += (s->Freq & k);
\r
166 see = Ppmd7_MakeEscFreq(p, numMasked, &freqSum);
\r
168 count = rc->GetThreshold(rc, freqSum);
\r
173 CPpmd_State **pps = ps;
\r
174 for (hiCnt = 0; (hiCnt += (*pps)->Freq) <= count; pps++);
\r
176 rc->Decode(rc, hiCnt - s->Freq, s->Freq);
\r
177 Ppmd_See_Update(see);
\r
179 symbol = s->Symbol;
\r
183 if (count >= freqSum)
\r
185 rc->Decode(rc, hiCnt, freqSum - hiCnt);
\r
186 see->Summ = (UInt16)(see->Summ + freqSum);
\r
187 do { MASK(ps[--i]->Symbol) = 0; } while (i != 0);
\r