/*! ReadBits() :
* Read (consume) next n bits from local register and update.
* Pay attention to not read more than nbBits contained into local register.
* @return : extracted value. */
public static size_t ReadBits(BIT_DStream_t bitD, U32 nbBits)
{
size_t value = LookBits(bitD, nbBits);
SkipBits(bitD, nbBits);
return(value);
}
/*! LookBitsFast() :
* unsafe version; only works if nbBits >= 1 */
public static size_t LookBitsFast(BIT_DStream_t bitD, U32 nbBits)
{
U32 regMask = sizeOfBitContainer * 8 - 1;
Debug.Assert(nbBits >= 1);
return((bitD.bitContainer << (int)(bitD.bitsConsumed & regMask)) >> (int)(((regMask + 1) - nbBits) & regMask));
}
/*! ReadBitsFast() :
* unsafe version; only works only if nbBits >= 1 */
public static size_t ReadBitsFast(BIT_DStream_t bitD, U32 nbBits)
{
size_t value = LookBitsFast(bitD, nbBits);
Debug.Assert(nbBits >= 1);
SkipBits(bitD, nbBits);
return(value);
}
} /* size == U32 */
public static void InitDState(FSE_DState_t DStatePtr, BIT_DStream_t bitD, FSE_DTable *dt)
{
void * ptr = dt;
FSE_DTableHeader *DTableH = (FSE_DTableHeader *)ptr;
DStatePtr.state = ReadBits(bitD, DTableH->tableLog);
ReloadDStream(bitD);
DStatePtr.table = dt + 1;
}
/*! DecodeSymbolFast() :
* unsafe, only works if no symbol has a probability > 50% */
public static BYTE DecodeSymbolFast(FSE_DState_t DStatePtr, BIT_DStream_t bitD)
{
FSE_decode_t DInfo = ((FSE_decode_t *)(DStatePtr.table))[DStatePtr.state];
U32 nbBits = DInfo.nbBits;
BYTE symbol = DInfo.symbol;
size_t lowBits = ReadBitsFast(bitD, nbBits);
DStatePtr.state = DInfo.newState + lowBits;
return(symbol);
}
/*! ReloadDStream() :
* Refill `bitD` from buffer previously set in InitDStream() .
* This function is safe, it guarantees it will not read beyond src buffer.
* @return : status of `BIT_DStream_t` internal register.
* when status == BIT_DStream_unfinished, internal register is filled with at least 25 or 57 bits */
public static BIT_DStream_status ReloadDStream(BIT_DStream_t bitD)
{
if (bitD.bitsConsumed > (sizeOfBitContainer * 8)) /* overflow detected, like end of stream */
{
return(BIT_DStream_status.BIT_DStream_overflow);
}
if (bitD.ptr >= bitD.limitPtr)
{
bitD.ptr -= bitD.bitsConsumed >> 3;
bitD.bitsConsumed &= 7;
bitD.bitContainer = MEM_readLEST(bitD.ptr);
return(BIT_DStream_status.BIT_DStream_unfinished);
}
if (bitD.ptr == bitD.start)
{
if (bitD.bitsConsumed < sizeOfBitContainer * 8)
{
return(BIT_DStream_status.BIT_DStream_endOfBuffer);
}
return(BIT_DStream_status.BIT_DStream_completed);
}
/* start < ptr < limitPtr */
{
U32 nbBytes = bitD.bitsConsumed >> 3;
BIT_DStream_status result = BIT_DStream_status.BIT_DStream_unfinished;
if (bitD.ptr - nbBytes < bitD.start)
{
nbBytes = (U32)(bitD.ptr - bitD.start); /* ptr > start */
result = BIT_DStream_status.BIT_DStream_endOfBuffer;
}
bitD.ptr -= nbBytes;
bitD.bitsConsumed -= nbBytes * 8;
bitD.bitContainer = MEM_readLEST(bitD.ptr); /* reminder : srcSize > sizeof(bitD->bitContainer), otherwise bitD->ptr == bitD->start */
return(result);
}
}
//#ifndef FSE_COMMONDEFS_ONLY
///*-*******************************************************
//* Decompression (Byte symbols)
//*********************************************************/
//size_t FSE_buildDTable_rle (FSE_DTable* dt, BYTE symbolValue)
//{
// void* ptr = dt;
// FSE_DTableHeader* DTableH = (FSE_DTableHeader*)ptr;
// void* dPtr = dt + 1;
// FSE_decode_t* cell = (FSE_decode_t*)dPtr;
// DTableH->tableLog = 0;
// DTableH->fastMode = 0;
// cell->newState = 0;
// cell->symbol = symbolValue;
// cell->nbBits = 0;
// return 0;
//}
//size_t FSE_buildDTable_raw (FSE_DTable* dt, unsigned nbBits)
//{
// void* ptr = dt;
// FSE_DTableHeader* DTableH = (FSE_DTableHeader*)ptr;
// void* dPtr = dt + 1;
// FSE_decode_t* dinfo = (FSE_decode_t*)dPtr;
// unsigned tableSize = 1 << nbBits;
// unsigned tableMask = tableSize - 1;
// unsigned maxSV1 = tableMask+1;
// unsigned s;
// /* Sanity checks */
// if (nbBits < 1) return ERROR( Error.GENERIC); /* min size */
// /* Build Decoding Table */
// DTableH->tableLog = (U16)nbBits;
// DTableH->fastMode = 1;
// for (s=0; s<maxSV1; s++) {
// dinfo[s].newState = 0;
// dinfo[s].symbol = (BYTE)s;
// dinfo[s].nbBits = (BYTE)nbBits;
// }
// return 0;
//}
public static size_t FSE_decompress_usingDTable_generic(void *dst, size_t maxDstSize, void *cSrc, size_t cSrcSize, FSE_DTable *dt, uint fast)
{
BYTE *ostart = (BYTE *)dst;
BYTE *op = ostart;
BYTE *omax = op + maxDstSize;
BYTE *olimit = omax - 3;
BIT_DStream_t bitD = new BIT_DStream_t();
FSE_DState_t state1 = new FSE_DState_t();
FSE_DState_t state2 = new FSE_DState_t();
/* Init */
{ size_t errcod = InitDStream(bitD, cSrc, cSrcSize); if (IsError(errcod))
{
return(errcod);
}
}
Fse.InitDState(state1, bitD, dt);
Fse.InitDState(state2, bitD, dt);
//#define FSE_GETSYMBOL(statePtr) fast ? DecodeSymbolFast(statePtr, &bitD) : DecodeSymbol(statePtr, &bitD)
/* 4 symbols per loop */
for (; (ReloadDStream(bitD) == BIT_DStream_status.BIT_DStream_unfinished) & (op < olimit); op += 4)
{
op[0] = fast != 0 ? DecodeSymbolFast(state1, bitD) : DecodeSymbol(state1, bitD);
//if (FSE_MAX_TABLELOG * 2 + 7 > sizeOfBitContainer * 8) /* This test must be static */
// ReloadDStream(bitD);
op[1] = fast != 0 ? DecodeSymbolFast(state2, bitD) : DecodeSymbol(state2, bitD);
if (FSE_MAX_TABLELOG * 4 + 7 > sizeOfBitContainer * 8) /* This test must be static */
{
if (ReloadDStream(bitD) > BIT_DStream_status.BIT_DStream_unfinished)
{
op += 2; break;
}
}
op[2] = fast != 0 ? DecodeSymbolFast(state1, bitD) : DecodeSymbol(state1, bitD);
//if (FSE_MAX_TABLELOG * 2 + 7 > sizeOfBitContainer * 8) /* This test must be static */
// ReloadDStream(bitD);
op[3] = fast != 0 ? DecodeSymbolFast(state2, bitD) : DecodeSymbol(state2, bitD);
}
/* tail */
/* note : ReloadDStream(&bitD) >= FSE_DStream_partiallyFilled; Ends at exactly BIT_DStream_completed */
while (true)
{
if (op > (omax - 2))
{
return(ERROR(Error.dstSize_tooSmall));
}
*op++ = fast != 0 ? DecodeSymbolFast(state1, bitD) : DecodeSymbol(state1, bitD);
if (ReloadDStream(bitD) == BIT_DStream_status.BIT_DStream_overflow)
{
*op++ = fast != 0 ? DecodeSymbolFast(state2, bitD) : DecodeSymbol(state2, bitD);
break;
}
if (op > (omax - 2))
{
return(ERROR(Error.dstSize_tooSmall));
}
*op++ = fast != 0 ? DecodeSymbolFast(state2, bitD) : DecodeSymbol(state2, bitD);
if (ReloadDStream(bitD) == BIT_DStream_status.BIT_DStream_overflow)
{
*op++ = fast != 0 ? DecodeSymbolFast(state1, bitD) : DecodeSymbol(state1, bitD);
break;
}
}
return((size_t)(op - ostart));
}
/*! EndOfDStream() :
* @return : 1 if DStream has _exactly_ reached its end (all bits consumed).
*/
public static uint EndOfDStream(BIT_DStream_t DStream)
{
return(((DStream.ptr == DStream.start) && (DStream.bitsConsumed == sizeOfBitContainer * 8)) ? (uint)1 : 0);
}
public static void SkipBits(BIT_DStream_t bitD, U32 nbBits)
{
bitD.bitsConsumed += nbBits;
}
//MEM_STATIC size_t GetUpperBits(size_t bitContainer, U32 start)
//{
// return bitContainer >> start;
//}
//MEM_STATIC size_t GetMiddleBits(size_t bitContainer, U32 start, U32 nbBits)
//{
//#if defined(__BMI__) && defined(__GNUC__) && __GNUC__*1000+__GNUC_MINOR__ >= 4008 /* experimental */
//# if defined(__x86_64__)
// if (sizeof(bitContainer)==8)
// return _bextr_u64(bitContainer, start, nbBits);
// else
//# endif
// return _bextr_u32(bitContainer, start, nbBits);
//#else
// Debug.Assert(nbBits < BIT_MASK_SIZE);
// return (bitContainer >> start) & BIT_mask[nbBits];
//#endif
//}
//MEM_STATIC size_t GetLowerBits(size_t bitContainer, U32 nbBits)
//{
// Debug.Assert(nbBits < BIT_MASK_SIZE);
// return bitContainer & BIT_mask[nbBits];
//}
/*! LookBits() :
* Provides next n bits from local register.
* local register is not modified.
* On 32-bits, maxNbBits==24.
* On 64-bits, maxNbBits==56.
* @return : value extracted */
public static size_t LookBits(BIT_DStream_t bitD, U32 nbBits)
{
U32 regMask = sizeOfBitContainer * 8 - 1;
return(((bitD.bitContainer << (int)(bitD.bitsConsumed & regMask)) >> 1) >> (int)((regMask - nbBits) & regMask));
}
public const uint sizeOfBitContainer = 4; //sizeof(BIT_DStream_t.bitContainer)
/*-********************************************************
* bitStream decoding
**********************************************************/
/*! InitDStream() :
* Initialize a BIT_DStream_t.
* `bitD` : a pointer to an already allocated BIT_DStream_t structure.
* `srcSize` must be the *exact* size of the bitStream, in bytes.
* @return : size of stream (== srcSize), or an errorCode if a problem is detected
*/
public static size_t InitDStream(BIT_DStream_t bitD, void *srcBuffer, size_t srcSize)
{
if (srcSize < 1)
{
bitD.Reset(); return(ERROR(Error.srcSize_wrong));
}
bitD.start = (sbyte *)srcBuffer;
bitD.limitPtr = bitD.start + sizeOfBitContainer;
if (srcSize >= sizeOfBitContainer)
{ /* normal case */
bitD.ptr = (sbyte *)srcBuffer + srcSize - sizeOfBitContainer;
bitD.bitContainer = MEM_readLEST(bitD.ptr);
{
BYTE lastByte = ((BYTE *)srcBuffer)[srcSize - 1];
bitD.bitsConsumed = lastByte != 0 ? 8 - BIT_highbit32(lastByte) : 0; /* ensures bitsConsumed is always set */
if (lastByte == 0)
{
return(ERROR(Error.GENERIC)); /* endMark not present */
}
}
}
else
{
bitD.ptr = bitD.start;
bitD.bitContainer = *(BYTE *)(bitD.start);
{
if (srcSize >= 7)
{
bitD.bitContainer += (size_t)(((BYTE *)(srcBuffer))[6]) << (int)(sizeOfBitContainer * 8 - 16);
}
/* fall-through */
if (srcSize >= 6)
{
bitD.bitContainer += (size_t)(((BYTE *)(srcBuffer))[5]) << (int)(sizeOfBitContainer * 8 - 24);
}
/* fall-through */
if (srcSize >= 5)
{
bitD.bitContainer += (size_t)(((BYTE *)(srcBuffer))[4]) << (int)(sizeOfBitContainer * 8 - 32);
}
/* fall-through */
if (srcSize >= 4)
{
bitD.bitContainer += (size_t)(((BYTE *)(srcBuffer))[3]) << 24;
}
/* fall-through */
if (srcSize >= 3)
{
bitD.bitContainer += (size_t)(((BYTE *)(srcBuffer))[2]) << 16;
}
/* fall-through */
if (srcSize >= 2)
{
bitD.bitContainer += (size_t)(((BYTE *)(srcBuffer))[1]) << 8;
}
/* fall-through */
/*default: break;*/
}
{
BYTE lastByte = ((BYTE *)srcBuffer)[srcSize - 1];
bitD.bitsConsumed = lastByte != 0 ? 8 - BIT_highbit32(lastByte) : 0;
if (lastByte == 0)
{
return(ERROR(Error.corruption_detected)); /* endMark not present */
}
}
bitD.bitsConsumed += (U32)(sizeOfBitContainer - srcSize) * 8;
}
return(srcSize);
}
