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mirror of https://github.com/facebook/zstd.git synced 2025-10-31 16:47:48 +02:00

Don't initialize the first parameter of _BitScanReverse* functions

Like the document example, no need to initialize `r` to 0.
https://docs.microsoft.com/en-us/cpp/intrinsics/bitscanreverse-bitscanreverse64
This commit is contained in:
Ma Lin
2021-09-24 19:24:29 +08:00
parent cc22042da0
commit 95f492ea17
11 changed files with 21 additions and 30 deletions

View File

@@ -343,8 +343,7 @@ FORCE_INLINE unsigned FSE_highbit32 (U32 val)
{
# if defined(_MSC_VER) /* Visual */
unsigned long r;
_BitScanReverse ( &r, val );
return (unsigned) r;
return _BitScanReverse(&r, val) ? (unsigned)r : 0;
# elif defined(__GNUC__) && (GCC_VERSION >= 304) /* GCC Intrinsic */
return __builtin_clz (val) ^ 31;
# else /* Software version */

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@@ -353,9 +353,8 @@ MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, unsigned nbBits);
MEM_STATIC unsigned BIT_highbit32 (U32 val)
{
# if defined(_MSC_VER) /* Visual */
unsigned long r=0;
_BitScanReverse ( &r, val );
return (unsigned) r;
unsigned long r;
return _BitScanReverse(&r, val) ? (unsigned)r : 0;
# elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */
return __builtin_clz (val) ^ 31;
# else /* Software version */

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@@ -356,9 +356,8 @@ MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, unsigned nbBits);
MEM_STATIC unsigned BIT_highbit32 (U32 val)
{
# if defined(_MSC_VER) /* Visual */
unsigned long r=0;
_BitScanReverse ( &r, val );
return (unsigned) r;
unsigned long r;
return _BitScanReverse(&r, val) ? (unsigned)r : 0;
# elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */
return __builtin_clz (val) ^ 31;
# else /* Software version */

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@@ -627,9 +627,8 @@ MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, unsigned nbBits);
MEM_STATIC unsigned BIT_highbit32 (U32 val)
{
# if defined(_MSC_VER) /* Visual */
unsigned long r=0;
_BitScanReverse ( &r, val );
return (unsigned) r;
unsigned long r;
return _BitScanReverse(&r, val) ? (unsigned)r : 0;
# elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */
return __builtin_clz (val) ^ 31;
# else /* Software version */

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@@ -756,9 +756,8 @@ MEM_STATIC size_t BITv05_readBitsFast(BITv05_DStream_t* bitD, unsigned nbBits);
MEM_STATIC unsigned BITv05_highbit32 (U32 val)
{
# if defined(_MSC_VER) /* Visual */
unsigned long r=0;
_BitScanReverse ( &r, val );
return (unsigned) r;
unsigned long r;
return _BitScanReverse(&r, val) ? (unsigned)r : 0;
# elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */
return __builtin_clz (val) ^ 31;
# else /* Software version */

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@@ -860,9 +860,8 @@ MEM_STATIC size_t BITv06_readBitsFast(BITv06_DStream_t* bitD, unsigned nbBits);
MEM_STATIC unsigned BITv06_highbit32 ( U32 val)
{
# if defined(_MSC_VER) /* Visual */
unsigned long r=0;
_BitScanReverse ( &r, val );
return (unsigned) r;
unsigned long r;
return _BitScanReverse(&r, val) ? (unsigned)r : 0;
# elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */
return __builtin_clz (val) ^ 31;
# else /* Software version */

View File

@@ -530,9 +530,8 @@ MEM_STATIC size_t BITv07_readBitsFast(BITv07_DStream_t* bitD, unsigned nbBits);
MEM_STATIC unsigned BITv07_highbit32 (U32 val)
{
# if defined(_MSC_VER) /* Visual */
unsigned long r=0;
_BitScanReverse ( &r, val );
return (unsigned) r;
unsigned long r;
return _BitScanReverse(&r, val) ? (unsigned)r : 0;
# elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */
return __builtin_clz (val) ^ 31;
# else /* Software version */