/* Ppmd7Dec.c -- PPMdH Decoder | |
2018-07-04 : Igor Pavlov : Public domain | |
This code is based on PPMd var.H (2001): Dmitry Shkarin : Public domain */ | |
#include "Precomp.h" | |
#include "Ppmd7.h" | |
#define kTopValue (1 << 24) | |
BoolInt Ppmd7z_RangeDec_Init(CPpmd7z_RangeDec *p) | |
{ | |
unsigned i; | |
p->Code = 0; | |
p->Range = 0xFFFFFFFF; | |
if (IByteIn_Read(p->Stream) != 0) | |
return False; | |
for (i = 0; i < 4; i++) | |
p->Code = (p->Code << 8) | IByteIn_Read(p->Stream); | |
return (p->Code < 0xFFFFFFFF); | |
} | |
#define GET_Ppmd7z_RangeDec CPpmd7z_RangeDec *p = CONTAINER_FROM_VTBL(pp, CPpmd7z_RangeDec, vt); | |
static UInt32 Range_GetThreshold(const IPpmd7_RangeDec *pp, UInt32 total) | |
{ | |
GET_Ppmd7z_RangeDec | |
return p->Code / (p->Range /= total); | |
} | |
static void Range_Normalize(CPpmd7z_RangeDec *p) | |
{ | |
if (p->Range < kTopValue) | |
{ | |
p->Code = (p->Code << 8) | IByteIn_Read(p->Stream); | |
p->Range <<= 8; | |
if (p->Range < kTopValue) | |
{ | |
p->Code = (p->Code << 8) | IByteIn_Read(p->Stream); | |
p->Range <<= 8; | |
} | |
} | |
} | |
static void Range_Decode(const IPpmd7_RangeDec *pp, UInt32 start, UInt32 size) | |
{ | |
GET_Ppmd7z_RangeDec | |
p->Code -= start * p->Range; | |
p->Range *= size; | |
Range_Normalize(p); | |
} | |
static UInt32 Range_DecodeBit(const IPpmd7_RangeDec *pp, UInt32 size0) | |
{ | |
GET_Ppmd7z_RangeDec | |
UInt32 newBound = (p->Range >> 14) * size0; | |
UInt32 symbol; | |
if (p->Code < newBound) | |
{ | |
symbol = 0; | |
p->Range = newBound; | |
} | |
else | |
{ | |
symbol = 1; | |
p->Code -= newBound; | |
p->Range -= newBound; | |
} | |
Range_Normalize(p); | |
return symbol; | |
} | |
void Ppmd7z_RangeDec_CreateVTable(CPpmd7z_RangeDec *p) | |
{ | |
p->vt.GetThreshold = Range_GetThreshold; | |
p->vt.Decode = Range_Decode; | |
p->vt.DecodeBit = Range_DecodeBit; | |
} | |
#define MASK(sym) ((signed char *)charMask)[sym] | |
int Ppmd7_DecodeSymbol(CPpmd7 *p, const IPpmd7_RangeDec *rc) | |
{ | |
size_t charMask[256 / sizeof(size_t)]; | |
if (p->MinContext->NumStats != 1) | |
{ | |
CPpmd_State *s = Ppmd7_GetStats(p, p->MinContext); | |
unsigned i; | |
UInt32 count, hiCnt; | |
if ((count = rc->GetThreshold(rc, p->MinContext->SummFreq)) < (hiCnt = s->Freq)) | |
{ | |
Byte symbol; | |
rc->Decode(rc, 0, s->Freq); | |
p->FoundState = s; | |
symbol = s->Symbol; | |
Ppmd7_Update1_0(p); | |
return symbol; | |
} | |
p->PrevSuccess = 0; | |
i = p->MinContext->NumStats - 1; | |
do | |
{ | |
if ((hiCnt += (++s)->Freq) > count) | |
{ | |
Byte symbol; | |
rc->Decode(rc, hiCnt - s->Freq, s->Freq); | |
p->FoundState = s; | |
symbol = s->Symbol; | |
Ppmd7_Update1(p); | |
return symbol; | |
} | |
} | |
while (--i); | |
if (count >= p->MinContext->SummFreq) | |
return -2; | |
p->HiBitsFlag = p->HB2Flag[p->FoundState->Symbol]; | |
rc->Decode(rc, hiCnt, p->MinContext->SummFreq - hiCnt); | |
PPMD_SetAllBitsIn256Bytes(charMask); | |
MASK(s->Symbol) = 0; | |
i = p->MinContext->NumStats - 1; | |
do { MASK((--s)->Symbol) = 0; } while (--i); | |
} | |
else | |
{ | |
UInt16 *prob = Ppmd7_GetBinSumm(p); | |
if (rc->DecodeBit(rc, *prob) == 0) | |
{ | |
Byte symbol; | |
*prob = (UInt16)PPMD_UPDATE_PROB_0(*prob); | |
symbol = (p->FoundState = Ppmd7Context_OneState(p->MinContext))->Symbol; | |
Ppmd7_UpdateBin(p); | |
return symbol; | |
} | |
*prob = (UInt16)PPMD_UPDATE_PROB_1(*prob); | |
p->InitEsc = PPMD7_kExpEscape[*prob >> 10]; | |
PPMD_SetAllBitsIn256Bytes(charMask); | |
MASK(Ppmd7Context_OneState(p->MinContext)->Symbol) = 0; | |
p->PrevSuccess = 0; | |
} | |
for (;;) | |
{ | |
CPpmd_State *ps[256], *s; | |
UInt32 freqSum, count, hiCnt; | |
CPpmd_See *see; | |
unsigned i, num, numMasked = p->MinContext->NumStats; | |
do | |
{ | |
p->OrderFall++; | |
if (!p->MinContext->Suffix) | |
return -1; | |
p->MinContext = Ppmd7_GetContext(p, p->MinContext->Suffix); | |
} | |
while (p->MinContext->NumStats == numMasked); | |
hiCnt = 0; | |
s = Ppmd7_GetStats(p, p->MinContext); | |
i = 0; | |
num = p->MinContext->NumStats - numMasked; | |
do | |
{ | |
int k = (int)(MASK(s->Symbol)); | |
hiCnt += (s->Freq & k); | |
ps[i] = s++; | |
i -= k; | |
} | |
while (i != num); | |
see = Ppmd7_MakeEscFreq(p, numMasked, &freqSum); | |
freqSum += hiCnt; | |
count = rc->GetThreshold(rc, freqSum); | |
if (count < hiCnt) | |
{ | |
Byte symbol; | |
CPpmd_State **pps = ps; | |
for (hiCnt = 0; (hiCnt += (*pps)->Freq) <= count; pps++); | |
s = *pps; | |
rc->Decode(rc, hiCnt - s->Freq, s->Freq); | |
Ppmd_See_Update(see); | |
p->FoundState = s; | |
symbol = s->Symbol; | |
Ppmd7_Update2(p); | |
return symbol; | |
} | |
if (count >= freqSum) | |
return -2; | |
rc->Decode(rc, hiCnt, freqSum - hiCnt); | |
see->Summ = (UInt16)(see->Summ + freqSum); | |
do { MASK(ps[--i]->Symbol) = 0; } while (i != 0); | |
} | |
} |