ddidderr/zstd-rs
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minor code refactor

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This commit is contained in:
Yann Collet
2016-03-19 12:12:07 +01:00
parent f3120413cc
commit d1d210f3fb
5 changed files with 109 additions and 154 deletions
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lib/bitstream.h
+27 -30
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@@ -56,10 +56,9 @@ extern "C" {
/*-******************************************
* bitStream encoding API (write forward)
********************************************/
/*!
* bitStream can mix input from multiple sources.
* A critical property of these streams is that they encode and decode in **reverse** direction.
* So the first bit sequence you add will be the last to be read, like a LIFO stack.
/* bitStream can mix input from multiple sources.
* A critical property of these streams is that they encode and decode in **reverse** direction.
* So the first bit sequence you add will be the last to be read, like a LIFO stack.
*/
typedef struct
{
@@ -75,10 +74,9 @@ MEM_STATIC void BIT_addBits(BIT_CStream_t* bitC, size_t value, unsigned nbBits
MEM_STATIC void BIT_flushBits(BIT_CStream_t* bitC);
MEM_STATIC size_t BIT_closeCStream(BIT_CStream_t* bitC);
/*!
* Start by initCStream, providing the size of buffer to write into.
/*Start by initCStream, providing the size of buffer to write into.
* bitStream will never write outside of this buffer.
* @dstCapacity must be >= sizeof(size_t), otherwise @return will be an error code.
* `dstCapacity` must be >= sizeof(size_t), otherwise @return will be an error code.
*
* bits are first added to a local register.
* Local register is size_t, hence 64-bits on 64-bits systems, or 32-bits on 32-bits systems.
@@ -90,7 +88,7 @@ MEM_STATIC size_t BIT_closeCStream(BIT_CStream_t* bitC);
*
* Last operation is to close the bitStream.
* The function returns the final size of CStream in bytes.
* If data couldn't fit into @dstBuffer, it will return a 0 ( == not storable)
* If data couldn't fit into `dstBuffer`, it will return a 0 ( == not storable)
*/
@@ -117,8 +115,7 @@ MEM_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD);
MEM_STATIC unsigned BIT_endOfDStream(const BIT_DStream_t* bitD);
/*!
* Start by invoking BIT_initDStream().
/*Start by invoking BIT_initDStream().
* A chunk of the bitStream is then stored into a local register.
* Local register size is 64-bits on 64-bits systems, 32-bits on 32-bits systems (size_t).
* You can then retrieve bitFields stored into the local register, **in reverse order**.
@@ -190,7 +187,7 @@ MEM_STATIC void BIT_addBits(BIT_CStream_t* bitC, size_t value, unsigned nbBits)
bitC->bitPos += nbBits;
}
/*! BIT_addBitsFast
/*! BIT_addBitsFast() :
* works only if `value` is _clean_, meaning all high bits above nbBits are 0 */
MEM_STATIC void BIT_addBitsFast(BIT_CStream_t* bitC, size_t value, unsigned nbBits)
{
@@ -198,7 +195,7 @@ MEM_STATIC void BIT_addBitsFast(BIT_CStream_t* bitC, size_t value, unsigned nbBi
bitC->bitPos += nbBits;
}
/*! BIT_flushBitsFast
/*! BIT_flushBitsFast() :
* unsafe version; does not check buffer overflow */
MEM_STATIC void BIT_flushBitsFast(BIT_CStream_t* bitC)
{
@@ -219,8 +216,8 @@ MEM_STATIC void BIT_flushBits(BIT_CStream_t* bitC)
bitC->bitContainer >>= nbBytes*8; /* if bitPos >= sizeof(bitContainer)*8 --> undefined behavior */
}
/*! BIT_closeCStream
* @result : size of CStream, in bytes, or 0 if it cannot fit into dstBuffer */
/*! BIT_closeCStream() :
* @return : size of CStream, in bytes, or 0 if it cannot fit into dstBuffer */
MEM_STATIC size_t BIT_closeCStream(BIT_CStream_t* bitC)
{
char* endPtr;
@@ -241,12 +238,12 @@ MEM_STATIC size_t BIT_closeCStream(BIT_CStream_t* bitC)
/*-********************************************************
* bitStream decoding
**********************************************************/
/*!BIT_initDStream
/*!BIT_initDStream() :
* Initialize a BIT_DStream_t.
* @bitD : a pointer to an already allocated BIT_DStream_t structure
* @srcBuffer must point at the beginning of a bitStream
* @srcSize must be the exact size of the bitStream
* @result : size of stream (== srcSize) or an errorCode if a problem is detected
* `bitD` : a pointer to an already allocated BIT_DStream_t structure.
* `srcBuffer` must point at the beginning of a bitStream.
* `srcSize` must be the exact size of the bitStream.
* @return : size of stream (== srcSize) or an errorCode if a problem is detected
*/
MEM_STATIC size_t BIT_initDStream(BIT_DStream_t* bitD, const void* srcBuffer, size_t srcSize)
{
@@ -284,24 +281,24 @@ MEM_STATIC size_t BIT_initDStream(BIT_DStream_t* bitD, const void* srcBuffer, si
return srcSize;
}
/*!BIT_lookBits
* Provides next n bits from local register
* local register is not modified (bits are still present for next read/look)
* On 32-bits, maxNbBits==25
* On 64-bits, maxNbBits==57
/*!BIT_lookBits() :
* Provides next n bits from local register.
* local register is not modified (bits are still present for next read/look).
* On 32-bits, maxNbBits==24.
* On 64-bits, maxNbBits==56.
* @return : value extracted
*/
MEM_STATIC size_t BIT_lookBits(BIT_DStream_t* bitD, U32 nbBits)
{
const U32 bitMask = sizeof(bitD->bitContainer)*8 - 1;
U32 const bitMask = sizeof(bitD->bitContainer)*8 - 1;
return ((bitD->bitContainer << (bitD->bitsConsumed & bitMask)) >> 1) >> ((bitMask-nbBits) & bitMask);
}
/*! BIT_lookBitsFast :
/*! BIT_lookBitsFast*() :
* unsafe version; only works only if nbBits >= 1 */
MEM_STATIC size_t BIT_lookBitsFast(BIT_DStream_t* bitD, U32 nbBits)
{
const U32 bitMask = sizeof(bitD->bitContainer)*8 - 1;
U32 const bitMask = sizeof(bitD->bitContainer)*8 - 1;
return (bitD->bitContainer << (bitD->bitsConsumed & bitMask)) >> (((bitMask+1)-nbBits) & bitMask);
}
@@ -310,7 +307,7 @@ MEM_STATIC void BIT_skipBits(BIT_DStream_t* bitD, U32 nbBits)
bitD->bitsConsumed += nbBits;
}
/*!BIT_readBits
/*!BIT_readBits() :
* Read next n bits from local register.
* pay attention to not read more than nbBits contained into local register.
* @return : extracted value.
@@ -322,7 +319,7 @@ MEM_STATIC size_t BIT_readBits(BIT_DStream_t* bitD, U32 nbBits)
return value;
}
/*!BIT_readBitsFast :
/*!BIT_readBitsFast() :
* unsafe version; only works only if nbBits >= 1 */
MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, U32 nbBits)
{
@@ -360,7 +357,7 @@ MEM_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD)
}
}
/*! BIT_endOfDStream
/*! BIT_endOfDStream() :
* @return Tells if DStream has reached its exact end
*/
MEM_STATIC unsigned BIT_endOfDStream(const BIT_DStream_t* DStream)