code refactor
This commit is contained in:
Yann Collet
+64
-55
@@ -41,7 +41,7 @@ extern "C" {
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/*
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* This API consists of small unitary functions, which highly benefit from being inlined.
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* This API consists of small unitary functions, which must be inlined for best performance.
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* Since link-time-optimization is not available for all compilers,
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* these functions are defined into a .h to be included.
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*/
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@@ -74,21 +74,21 @@ MEM_STATIC void BIT_addBits(BIT_CStream_t* bitC, size_t value, unsigned nbBits
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MEM_STATIC void BIT_flushBits(BIT_CStream_t* bitC);
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MEM_STATIC size_t BIT_closeCStream(BIT_CStream_t* bitC);
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/*Start by initCStream, providing the size of buffer to write into.
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* bitStream will never write outside of this buffer.
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* `dstCapacity` must be >= sizeof(size_t), otherwise @return will be an error code.
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/* Start with initCStream, providing the size of buffer to write into.
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* bitStream will never write outside of this buffer.
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* `dstCapacity` must be >= sizeof(size_t), otherwise @return will be an error code.
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*
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* bits are first added to a local register.
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* Local register is size_t, hence 64-bits on 64-bits systems, or 32-bits on 32-bits systems.
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* Writing data into memory is an explicit operation, performed by the flushBits function.
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* Hence keep track how many bits are potentially stored into local register to avoid register overflow.
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* After a flushBits, a maximum of 7 bits might still be stored into local register.
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* bits are first added to a local register.
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* Local register is size_t, hence 64-bits on 64-bits systems, or 32-bits on 32-bits systems.
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* Writing data into memory is an explicit operation, performed by the flushBits function.
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* Hence keep track how many bits are potentially stored into local register to avoid register overflow.
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* After a flushBits, a maximum of 7 bits might still be stored into local register.
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*
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* Avoid storing elements of more than 24 bits if you want compatibility with 32-bits bitstream readers.
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* Avoid storing elements of more than 24 bits if you want compatibility with 32-bits bitstream readers.
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*
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* Last operation is to close the bitStream.
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* The function returns the final size of CStream in bytes.
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* If data couldn't fit into `dstBuffer`, it will return a 0 ( == not storable)
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* Last operation is to close the bitStream.
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* The function returns the final size of CStream in bytes.
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* If data couldn't fit into `dstBuffer`, it will return a 0 ( == not storable)
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*/
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@@ -115,14 +115,14 @@ MEM_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD);
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MEM_STATIC unsigned BIT_endOfDStream(const BIT_DStream_t* bitD);
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/*Start by invoking BIT_initDStream().
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* A chunk of the bitStream is then stored into a local register.
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* Local register size is 64-bits on 64-bits systems, 32-bits on 32-bits systems (size_t).
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* You can then retrieve bitFields stored into the local register, **in reverse order**.
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* Local register is explicitly reloaded from memory by the BIT_reloadDStream() method.
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* A reload guarantee a minimum of ((8*sizeof(size_t))-7) bits when its result is BIT_DStream_unfinished.
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* Otherwise, it can be less than that, so proceed accordingly.
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* Checking if DStream has reached its end can be performed with BIT_endOfDStream()
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/* Start by invoking BIT_initDStream().
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* A chunk of the bitStream is then stored into a local register.
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* Local register size is 64-bits on 64-bits systems, 32-bits on 32-bits systems (size_t).
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* You can then retrieve bitFields stored into the local register, **in reverse order**.
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* Local register is explicitly reloaded from memory by the BIT_reloadDStream() method.
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* A reload guarantee a minimum of ((8*sizeof(size_t))-7) bits when its result is BIT_DStream_unfinished.
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* Otherwise, it can be less than that, so proceed accordingly.
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* Checking if DStream has reached its end can be performed with BIT_endOfDStream()
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*/
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@@ -169,17 +169,24 @@ MEM_STATIC unsigned BIT_highbit32 (register U32 val)
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/*-**************************************************************
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* bitStream encoding
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****************************************************************/
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MEM_STATIC size_t BIT_initCStream(BIT_CStream_t* bitC, void* startPtr, size_t maxSize)
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/*! BIT_initCStream() :
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* `dstCapacity` must be > sizeof(void*)
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* @return : 0 if success,
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otherwise an error code (can be tested using ERR_isError() ) */
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MEM_STATIC size_t BIT_initCStream(BIT_CStream_t* bitC, void* startPtr, size_t dstCapacity)
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{
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bitC->bitContainer = 0;
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bitC->bitPos = 0;
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bitC->startPtr = (char*)startPtr;
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bitC->ptr = bitC->startPtr;
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bitC->endPtr = bitC->startPtr + maxSize - sizeof(bitC->ptr);
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if (maxSize < sizeof(bitC->ptr)) return ERROR(dstSize_tooSmall);
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bitC->endPtr = bitC->startPtr + dstCapacity - sizeof(bitC->ptr);
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if (dstCapacity <= sizeof(bitC->ptr)) return ERROR(dstSize_tooSmall);
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return 0;
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}
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/*! BIT_addBits() :
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can add up to 26 bits into `bitC`.
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Does not check for register overflow ! */
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MEM_STATIC void BIT_addBits(BIT_CStream_t* bitC, size_t value, unsigned nbBits)
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{
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static const unsigned mask[] = { 0, 1, 3, 7, 0xF, 0x1F, 0x3F, 0x7F, 0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF, 0x1FFFF, 0x3FFFF, 0x7FFFF, 0xFFFFF, 0x1FFFFF, 0x3FFFFF, 0x7FFFFF, 0xFFFFFF, 0x1FFFFFF, 0x3FFFFFF }; /* up to 26 bits */
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@@ -206,6 +213,9 @@ MEM_STATIC void BIT_flushBitsFast(BIT_CStream_t* bitC)
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bitC->bitContainer >>= nbBytes*8; /* if bitPos >= sizeof(bitContainer)*8 --> undefined behavior */
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}
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/*! BIT_flushBits() :
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* safe version; check for buffer overflow, and prevents it.
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* note : does not signal buffer overflow. This will be revealed later on using BIT_closeCStream() */
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MEM_STATIC void BIT_flushBits(BIT_CStream_t* bitC)
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{
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size_t nbBytes = bitC->bitPos >> 3;
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@@ -217,33 +227,28 @@ MEM_STATIC void BIT_flushBits(BIT_CStream_t* bitC)
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}
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/*! BIT_closeCStream() :
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* @return : size of CStream, in bytes, or 0 if it cannot fit into dstBuffer */
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* @return : size of CStream, in bytes,
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or 0 if it could not fit into dstBuffer */
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MEM_STATIC size_t BIT_closeCStream(BIT_CStream_t* bitC)
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{
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char* endPtr;
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BIT_addBitsFast(bitC, 1, 1); /* endMark */
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BIT_flushBits(bitC);
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if (bitC->ptr >= bitC->endPtr) /* too close to buffer's end */
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return 0; /* not storable */
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if (bitC->ptr >= bitC->endPtr) return 0; /* doesn't fit within authorized budget : cancel */
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endPtr = bitC->ptr;
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endPtr += bitC->bitPos > 0; /* remaining bits (incomplete byte) */
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return (endPtr - bitC->startPtr);
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return (bitC->ptr - bitC->startPtr) + (bitC->bitPos > 0);
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}
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/*-********************************************************
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* bitStream decoding
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**********************************************************/
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/*!BIT_initDStream() :
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* Initialize a BIT_DStream_t.
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* `bitD` : a pointer to an already allocated BIT_DStream_t structure.
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* `srcBuffer` must point at the beginning of a bitStream.
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* `srcSize` must be the exact size of the bitStream.
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* @return : size of stream (== srcSize) or an errorCode if a problem is detected
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/*! BIT_initDStream() :
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* Initialize a BIT_DStream_t.
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* `bitD` : a pointer to an already allocated BIT_DStream_t structure.
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* `srcBuffer` must point at the beginning of a bitStream.
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* `srcSize` must be the exact size of the bitStream, in bytes.
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* @return : size of stream (== srcSize) or an errorCode if a problem is detected
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*/
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MEM_STATIC size_t BIT_initDStream(BIT_DStream_t* bitD, const void* srcBuffer, size_t srcSize)
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{
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@@ -281,12 +286,12 @@ MEM_STATIC size_t BIT_initDStream(BIT_DStream_t* bitD, const void* srcBuffer, si
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return srcSize;
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}
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/*!BIT_lookBits() :
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* Provides next n bits from local register.
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* local register is not modified (bits are still present for next read/look).
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* On 32-bits, maxNbBits==24.
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* On 64-bits, maxNbBits==56.
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* @return : value extracted
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/*! BIT_lookBits() :
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* Provides next n bits from local register.
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* local register is not modified (bits are still present for next read/look).
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* On 32-bits, maxNbBits==24.
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* On 64-bits, maxNbBits==56.
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* @return : value extracted
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*/
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MEM_STATIC size_t BIT_lookBits(BIT_DStream_t* bitD, U32 nbBits)
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{
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@@ -294,7 +299,7 @@ MEM_STATIC size_t BIT_lookBits(BIT_DStream_t* bitD, U32 nbBits)
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return ((bitD->bitContainer << (bitD->bitsConsumed & bitMask)) >> 1) >> ((bitMask-nbBits) & bitMask);
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}
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/*! BIT_lookBitsFast*() :
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/*! BIT_lookBitsFast() :
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* unsafe version; only works only if nbBits >= 1 */
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MEM_STATIC size_t BIT_lookBitsFast(BIT_DStream_t* bitD, U32 nbBits)
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{
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@@ -307,10 +312,10 @@ MEM_STATIC void BIT_skipBits(BIT_DStream_t* bitD, U32 nbBits)
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bitD->bitsConsumed += nbBits;
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}
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/*!BIT_readBits() :
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* Read next n bits from local register.
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* pay attention to not read more than nbBits contained into local register.
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* @return : extracted value.
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/*! BIT_readBits() :
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* Read next n bits from local register.
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* pay attention to not read more than nbBits contained into local register.
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* @return : extracted value.
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*/
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MEM_STATIC size_t BIT_readBits(BIT_DStream_t* bitD, U32 nbBits)
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{
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@@ -319,8 +324,8 @@ MEM_STATIC size_t BIT_readBits(BIT_DStream_t* bitD, U32 nbBits)
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return value;
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}
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/*!BIT_readBitsFast() :
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* unsafe version; only works only if nbBits >= 1 */
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/*! BIT_readBitsFast() :
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* unsafe version; only works only if nbBits >= 1 */
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MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, U32 nbBits)
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{
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size_t value = BIT_lookBitsFast(bitD, nbBits);
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@@ -328,6 +333,11 @@ MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, U32 nbBits)
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return value;
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}
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/*! BIT_reloadDStream() :
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* Refill `BIT_DStream_t` from src buffer previously defined (see BIT_initDStream() ).
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* This function is safe, it guarantees it will not read beyond src buffer.
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* @return : status of `BIT_DStream_t` internal register.
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if status == unfinished, internal register is filled with >= (sizeof(size_t)*8 - 7) bits */
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MEM_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD)
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{
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if (bitD->bitsConsumed > (sizeof(bitD->bitContainer)*8)) /* should never happen */
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@@ -343,8 +353,7 @@ MEM_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD)
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if (bitD->bitsConsumed < sizeof(bitD->bitContainer)*8) return BIT_DStream_endOfBuffer;
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return BIT_DStream_completed;
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}
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{
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U32 nbBytes = bitD->bitsConsumed >> 3;
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{ U32 nbBytes = bitD->bitsConsumed >> 3;
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BIT_DStream_status result = BIT_DStream_unfinished;
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if (bitD->ptr - nbBytes < bitD->start) {
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nbBytes = (U32)(bitD->ptr - bitD->start); /* ptr > start */
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@@ -358,7 +367,7 @@ MEM_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD)
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}
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/*! BIT_endOfDStream() :
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* @return Tells if DStream has reached its exact end
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* @return Tells if DStream has exactly reached its end (all bits consumed).
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*/
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MEM_STATIC unsigned BIT_endOfDStream(const BIT_DStream_t* DStream)
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{
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