sharpetronics/zstd
1
0
Fork 0
mirror of https://github.com/facebook/zstd.git synced 2025-12-06 00:02:05 -05:00
Code Issues Projects Releases Wiki Activity

bits.h refactor and bugfix

Browse Source
This commit is contained in:
Elliot Gorokhovsky 2022-02-14 16:08:00 -05:00
parent 529cd7b821
commit 6994a9f99c
1 changed files with 23 additions and 47 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

70
lib/common/bits.h
View File

@ -13,44 +13,6 @@
#include "mem.h"
MEM_STATIC unsigned ZSTD_highbit32_fallback(U32 val) {
assert(val != 0);
{
static const U32 DeBruijnClz[32] = {0, 9, 1, 10, 13, 21, 2, 29,
11, 14, 16, 18, 22, 25, 3, 30,
8, 12, 20, 28, 15, 17, 24, 7,
19, 27, 23, 6, 26, 5, 4, 31};
val |= val >> 1;
val |= val >> 2;
val |= val >> 4;
val |= val >> 8;
val |= val >> 16;
return DeBruijnClz[(val * 0x07C4ACDDU) >> 27];
}
}
MEM_STATIC unsigned ZSTD_highbit32(U32 val) /* compress, dictBuilder, decodeCorpus */
{
assert(val != 0);
{
# if defined(_MSC_VER) /* Visual */
# if STATIC_BMI2 == 1
return _lzcnt_u32(val)^31;
# else
unsigned long r;
_BitScanReverse(&r, val);
return (unsigned)r;
# endif
# elif defined(__GNUC__) && (__GNUC__ >= 4) /* GCC Intrinsic */
return (unsigned)__builtin_clz (val) ^ 31;
# elif defined(__ICCARM__) /* IAR Intrinsic */
return 31 - __CLZ(val);
# else /* Software version */
return ZSTD_highbit32_fallback(val);
# endif
}
}
MEM_STATIC unsigned ZSTD_countTrailingZeros32_fallback(U32 val)
{
assert(val != 0);
@ -67,9 +29,13 @@ MEM_STATIC unsigned ZSTD_countTrailingZeros32(U32 val)
{
assert(val != 0);
# if defined(_MSC_VER)
unsigned long r;
_BitScanForward(&r, val);
return (unsigned)r;
# if STATIC_BMI2 == 1
return _tzcnt_u32(val);
# else
unsigned long r;
_BitScanForward(&r, val);
return (unsigned)r;
# endif
# elif defined(__GNUC__) && (__GNUC__ >= 4)
return (unsigned)__builtin_ctz(val);
# else
@ -93,9 +59,13 @@ MEM_STATIC unsigned ZSTD_countLeadingZeros32(U32 val)
{
assert(val != 0);
# if defined(_MSC_VER)
unsigned long r;
_BitScanReverse(&r, val);
return (unsigned)r;
# if STATIC_BMI2 == 1
return _lzcnt_u32(val);
# else
unsigned long r;
_BitScanReverse(&r, val);
return (unsigned)(r ^ 31);
# endif
# elif defined(__GNUC__) && (__GNUC__ >= 4)
return (unsigned)__builtin_clz(val);
# else
@ -107,7 +77,7 @@ MEM_STATIC unsigned ZSTD_countTrailingZeros64(U64 val)
{
assert(val != 0);
# if defined(_MSC_VER) && defined(_WIN64)
# if STATIC_BMI2
# if STATIC_BMI2 == 1
return _tzcnt_u64(val);
# else
unsigned long r;
@ -133,12 +103,12 @@ MEM_STATIC unsigned ZSTD_countLeadingZeros64(U64 val)
{
assert(val != 0);
# if defined(_MSC_VER) && defined(_WIN64)
# if STATIC_BMI2
# if STATIC_BMI2 == 1
return _lzcnt_u64(val);
# else
unsigned long r;
_BitScanReverse64(&r, val);
return (unsigned)r;
return (unsigned)(r ^ 63);
# endif
# elif defined(__GNUC__) && (__GNUC__ >= 4)
return (unsigned)(__builtin_clzll(val));
@ -172,4 +142,10 @@ MEM_STATIC unsigned ZSTD_NbCommonBytes(size_t val)
}
}
MEM_STATIC unsigned ZSTD_highbit32(U32 val) /* compress, dictBuilder, decodeCorpus */
{
assert(val != 0);
return ZSTD_countLeadingZeros32(val) ^ 31;
}
#endif /* ZSTD_BITS_H */