ddidderr/zstd-rs
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minor variables isolation

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This commit is contained in:
Yann Collet
2016-03-24 02:02:32 +01:00
parent 7cbe79ab25
commit b21ce15efe
2 changed files with 56 additions and 64 deletions
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lib/bitstream.h
+11 -14
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@@ -122,7 +122,7 @@ MEM_STATIC unsigned BIT_endOfDStream(const BIT_DStream_t* bitD);
* Local register is explicitly reloaded from memory by the BIT_reloadDStream() method.
* A reload guarantee a minimum of ((8*sizeof(size_t))-7) bits when its result is BIT_DStream_unfinished.
* Otherwise, it can be less than that, so proceed accordingly.
* Checking if DStream has reached its end can be performed with BIT_endOfDStream()
* Checking if DStream has reached its end can be performed with BIT_endOfDStream().
*/
@@ -256,15 +256,13 @@ MEM_STATIC size_t BIT_initDStream(BIT_DStream_t* bitD, const void* srcBuffer, si
if (srcSize < 1) { memset(bitD, 0, sizeof(*bitD)); return ERROR(srcSize_wrong); }
if (srcSize >= sizeof(size_t)) { /* normal case */
U32 contain32;
bitD->start = (const char*)srcBuffer;
bitD->ptr = (const char*)srcBuffer + srcSize - sizeof(size_t);
bitD->bitContainer = MEM_readLEST(bitD->ptr);
contain32 = ((const BYTE*)srcBuffer)[srcSize-1];
if (contain32 == 0) return ERROR(GENERIC); /* endMark not present */
bitD->bitsConsumed = 8 - BIT_highbit32(contain32);
{ BYTE const lastByte = ((const BYTE*)srcBuffer)[srcSize-1];
if (lastByte == 0) return ERROR(GENERIC); /* endMark not present */
bitD->bitsConsumed = 8 - BIT_highbit32(lastByte); }
} else {
U32 contain32;
bitD->start = (const char*)srcBuffer;
bitD->ptr = bitD->start;
bitD->bitContainer = *(const BYTE*)(bitD->start);
@@ -278,9 +276,9 @@ MEM_STATIC size_t BIT_initDStream(BIT_DStream_t* bitD, const void* srcBuffer, si
case 2: bitD->bitContainer += (size_t)(((const BYTE*)(bitD->start))[1]) << 8;
default:;
}
contain32 = ((const BYTE*)srcBuffer)[srcSize-1];
if (contain32 == 0) return ERROR(GENERIC); /* endMark not present */
bitD->bitsConsumed = 8 - BIT_highbit32(contain32);
{ BYTE const lastByte = ((const BYTE*)srcBuffer)[srcSize-1];
if (lastByte == 0) return ERROR(GENERIC); /* endMark not present */
bitD->bitsConsumed = 8 - BIT_highbit32(lastByte); }
bitD->bitsConsumed += (U32)(sizeof(size_t) - srcSize)*8;
}
@@ -295,7 +293,7 @@ MEM_STATIC size_t BIT_getUpperBits(size_t bitD, U32 const start)
#include <immintrin.h>
MEM_STATIC size_t BIT_getMiddleBits(size_t bitD, U32 const nbBits, U32 const start)
{
#if defined(__BMI__) && defined(__GNUC__)
#if defined(__BMI__) && defined(__GNUC__) /* experimental */
return __builtin_ia32_bextr_u64(bitD, (nbBits<<8) | start );
#else
return (bitD >> start) & BIT_mask[nbBits];
@@ -316,12 +314,11 @@ MEM_STATIC size_t BIT_getLowerBits(size_t bitD, U32 const nbBits)
*/
MEM_STATIC size_t BIT_lookBits(const BIT_DStream_t* bitD, U32 nbBits)
{
#if defined(__BMI__) && defined(__GNUC__)
#if defined(__BMI__) && defined(__GNUC__) /* experimental */
return __builtin_ia32_bextr_u64(bitD->bitContainer, (nbBits<<8) | (64 - bitD->bitsConsumed - nbBits) );
#else
U32 const bitMask = sizeof(bitD->bitContainer)*8 - 1;
return ((bitD->bitContainer << (bitD->bitsConsumed & bitMask)) >> 1) >> ((bitMask-nbBits) & bitMask);
//return (bitD->bitContainer >> (64 - bitD->bitsConsumed - nbBits)) & BIT_mask[nbBits];
#endif
}
@@ -339,8 +336,8 @@ MEM_STATIC void BIT_skipBits(BIT_DStream_t* bitD, U32 nbBits)
}
/*! BIT_readBits() :
* Read next n bits from local register.
* pay attention to not read more than nbBits contained into local register.
* 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.
*/
MEM_STATIC size_t BIT_readBits(BIT_DStream_t* bitD, U32 nbBits)