| 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 |
| 4 | \r |
| 5 | #include "Precomp.h"\r |
| 6 | \r |
| 7 | #include "Ppmd7.h"\r |
| 8 | \r |
| 9 | #define kTopValue (1 << 24)\r |
| 10 | \r |
| 11 | Bool Ppmd7z_RangeDec_Init(CPpmd7z_RangeDec *p)\r |
| 12 | {\r |
| 13 | unsigned i;\r |
| 14 | p->Code = 0;\r |
| 15 | p->Range = 0xFFFFFFFF;\r |
| 16 | if (p->Stream->Read((void *)p->Stream) != 0)\r |
| 17 | return False;\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 |
| 21 | }\r |
| 22 | \r |
| 23 | static UInt32 Range_GetThreshold(void *pp, UInt32 total)\r |
| 24 | {\r |
| 25 | CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;\r |
| 26 | return (p->Code) / (p->Range /= total);\r |
| 27 | }\r |
| 28 | \r |
| 29 | static void Range_Normalize(CPpmd7z_RangeDec *p)\r |
| 30 | {\r |
| 31 | if (p->Range < kTopValue)\r |
| 32 | {\r |
| 33 | p->Code = (p->Code << 8) | p->Stream->Read((void *)p->Stream);\r |
| 34 | p->Range <<= 8;\r |
| 35 | if (p->Range < kTopValue)\r |
| 36 | {\r |
| 37 | p->Code = (p->Code << 8) | p->Stream->Read((void *)p->Stream);\r |
| 38 | p->Range <<= 8;\r |
| 39 | }\r |
| 40 | }\r |
| 41 | }\r |
| 42 | \r |
| 43 | static void Range_Decode(void *pp, UInt32 start, UInt32 size)\r |
| 44 | {\r |
| 45 | CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;\r |
| 46 | p->Code -= start * p->Range;\r |
| 47 | p->Range *= size;\r |
| 48 | Range_Normalize(p);\r |
| 49 | }\r |
| 50 | \r |
| 51 | static UInt32 Range_DecodeBit(void *pp, UInt32 size0)\r |
| 52 | {\r |
| 53 | CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;\r |
| 54 | UInt32 newBound = (p->Range >> 14) * size0;\r |
| 55 | UInt32 symbol;\r |
| 56 | if (p->Code < newBound)\r |
| 57 | {\r |
| 58 | symbol = 0;\r |
| 59 | p->Range = newBound;\r |
| 60 | }\r |
| 61 | else\r |
| 62 | {\r |
| 63 | symbol = 1;\r |
| 64 | p->Code -= newBound;\r |
| 65 | p->Range -= newBound;\r |
| 66 | }\r |
| 67 | Range_Normalize(p);\r |
| 68 | return symbol;\r |
| 69 | }\r |
| 70 | \r |
| 71 | void Ppmd7z_RangeDec_CreateVTable(CPpmd7z_RangeDec *p)\r |
| 72 | {\r |
| 73 | p->p.GetThreshold = Range_GetThreshold;\r |
| 74 | p->p.Decode = Range_Decode;\r |
| 75 | p->p.DecodeBit = Range_DecodeBit;\r |
| 76 | }\r |
| 77 | \r |
| 78 | \r |
| 79 | #define MASK(sym) ((signed char *)charMask)[sym]\r |
| 80 | \r |
| 81 | int Ppmd7_DecodeSymbol(CPpmd7 *p, IPpmd7_RangeDec *rc)\r |
| 82 | {\r |
| 83 | size_t charMask[256 / sizeof(size_t)];\r |
| 84 | if (p->MinContext->NumStats != 1)\r |
| 85 | {\r |
| 86 | CPpmd_State *s = Ppmd7_GetStats(p, p->MinContext);\r |
| 87 | unsigned i;\r |
| 88 | UInt32 count, hiCnt;\r |
| 89 | if ((count = rc->GetThreshold(rc, p->MinContext->SummFreq)) < (hiCnt = s->Freq))\r |
| 90 | {\r |
| 91 | Byte symbol;\r |
| 92 | rc->Decode(rc, 0, s->Freq);\r |
| 93 | p->FoundState = s;\r |
| 94 | symbol = s->Symbol;\r |
| 95 | Ppmd7_Update1_0(p);\r |
| 96 | return symbol;\r |
| 97 | }\r |
| 98 | p->PrevSuccess = 0;\r |
| 99 | i = p->MinContext->NumStats - 1;\r |
| 100 | do\r |
| 101 | {\r |
| 102 | if ((hiCnt += (++s)->Freq) > count)\r |
| 103 | {\r |
| 104 | Byte symbol;\r |
| 105 | rc->Decode(rc, hiCnt - s->Freq, s->Freq);\r |
| 106 | p->FoundState = s;\r |
| 107 | symbol = s->Symbol;\r |
| 108 | Ppmd7_Update1(p);\r |
| 109 | return symbol;\r |
| 110 | }\r |
| 111 | }\r |
| 112 | while (--i);\r |
| 113 | if (count >= p->MinContext->SummFreq)\r |
| 114 | return -2;\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 |
| 121 | }\r |
| 122 | else\r |
| 123 | {\r |
| 124 | UInt16 *prob = Ppmd7_GetBinSumm(p);\r |
| 125 | if (rc->DecodeBit(rc, *prob) == 0)\r |
| 126 | {\r |
| 127 | Byte symbol;\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 |
| 131 | return symbol;\r |
| 132 | }\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 |
| 138 | }\r |
| 139 | for (;;)\r |
| 140 | {\r |
| 141 | CPpmd_State *ps[256], *s;\r |
| 142 | UInt32 freqSum, count, hiCnt;\r |
| 143 | CPpmd_See *see;\r |
| 144 | unsigned i, num, numMasked = p->MinContext->NumStats;\r |
| 145 | do\r |
| 146 | {\r |
| 147 | p->OrderFall++;\r |
| 148 | if (!p->MinContext->Suffix)\r |
| 149 | return -1;\r |
| 150 | p->MinContext = Ppmd7_GetContext(p, p->MinContext->Suffix);\r |
| 151 | }\r |
| 152 | while (p->MinContext->NumStats == numMasked);\r |
| 153 | hiCnt = 0;\r |
| 154 | s = Ppmd7_GetStats(p, p->MinContext);\r |
| 155 | i = 0;\r |
| 156 | num = p->MinContext->NumStats - numMasked;\r |
| 157 | do\r |
| 158 | {\r |
| 159 | int k = (int)(MASK(s->Symbol));\r |
| 160 | hiCnt += (s->Freq & k);\r |
| 161 | ps[i] = s++;\r |
| 162 | i -= k;\r |
| 163 | }\r |
| 164 | while (i != num);\r |
| 165 | \r |
| 166 | see = Ppmd7_MakeEscFreq(p, numMasked, &freqSum);\r |
| 167 | freqSum += hiCnt;\r |
| 168 | count = rc->GetThreshold(rc, freqSum);\r |
| 169 | \r |
| 170 | if (count < hiCnt)\r |
| 171 | {\r |
| 172 | Byte symbol;\r |
| 173 | CPpmd_State **pps = ps;\r |
| 174 | for (hiCnt = 0; (hiCnt += (*pps)->Freq) <= count; pps++);\r |
| 175 | s = *pps;\r |
| 176 | rc->Decode(rc, hiCnt - s->Freq, s->Freq);\r |
| 177 | Ppmd_See_Update(see);\r |
| 178 | p->FoundState = s;\r |
| 179 | symbol = s->Symbol;\r |
| 180 | Ppmd7_Update2(p);\r |
| 181 | return symbol;\r |
| 182 | }\r |
| 183 | if (count >= freqSum)\r |
| 184 | return -2;\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 |
| 188 | }\r |
| 189 | }\r |