ddidderr/zstd-rs
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Move bitwise builtins into bits.h

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This commit is contained in:
Elliot Gorokhovsky
2022-02-14 11:16:03 -05:00
parent 970460f67d
commit db2f4a6532
16 changed files with 250 additions and 400 deletions
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lib/dictBuilder/cover.c
+1
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@@ -34,6 +34,7 @@
#include "../common/pool.h"
#include "../common/threading.h"
#include "../common/zstd_internal.h" /* includes zstd.h */
#include "../common/bits.h" /* ZSTD_highbit32 */
#include "../zdict.h"
#include "cover.h"
lib/dictBuilder/zdict.c
+2 -80
View File
@@ -54,6 +54,7 @@
#include "../compress/zstd_compress_internal.h" /* ZSTD_loadCEntropy() */
#include "../zdict.h"
#include "divsufsort.h"
#include "../common/bits.h" /* ZSTD_NbCommonBytes */
/*-*************************************
@@ -130,85 +131,6 @@ size_t ZDICT_getDictHeaderSize(const void* dictBuffer, size_t dictSize)
/*-********************************************************
* Dictionary training functions
**********************************************************/
static unsigned ZDICT_NbCommonBytes (size_t val)
{
if (MEM_isLittleEndian()) {
if (MEM_64bits()) {
# if defined(_MSC_VER) && defined(_WIN64)
if (val != 0) {
unsigned long r;
_BitScanForward64(&r, (U64)val);
return (unsigned)(r >> 3);
} else {
/* Should not reach this code path */
__assume(0);
}
# elif defined(__GNUC__) && (__GNUC__ >= 3)
return (unsigned)(__builtin_ctzll((U64)val) >> 3);
# else
static const int DeBruijnBytePos[64] = { 0, 0, 0, 0, 0, 1, 1, 2, 0, 3, 1, 3, 1, 4, 2, 7, 0, 2, 3, 6, 1, 5, 3, 5, 1, 3, 4, 4, 2, 5, 6, 7, 7, 0, 1, 2, 3, 3, 4, 6, 2, 6, 5, 5, 3, 4, 5, 6, 7, 1, 2, 4, 6, 4, 4, 5, 7, 2, 6, 5, 7, 6, 7, 7 };
return DeBruijnBytePos[((U64)((val & -(long long)val) * 0x0218A392CDABBD3FULL)) >> 58];
# endif
} else { /* 32 bits */
# if defined(_MSC_VER)
if (val != 0) {
unsigned long r;
_BitScanForward(&r, (U32)val);
return (unsigned)(r >> 3);
} else {
/* Should not reach this code path */
__assume(0);
}
# elif defined(__GNUC__) && (__GNUC__ >= 3)
return (unsigned)(__builtin_ctz((U32)val) >> 3);
# else
static const int DeBruijnBytePos[32] = { 0, 0, 3, 0, 3, 1, 3, 0, 3, 2, 2, 1, 3, 2, 0, 1, 3, 3, 1, 2, 2, 2, 2, 0, 3, 1, 2, 0, 1, 0, 1, 1 };
return DeBruijnBytePos[((U32)((val & -(S32)val) * 0x077CB531U)) >> 27];
# endif
}
} else { /* Big Endian CPU */
if (MEM_64bits()) {
# if defined(_MSC_VER) && defined(_WIN64)
if (val != 0) {
unsigned long r;
_BitScanReverse64(&r, val);
return (unsigned)(r >> 3);
} else {
/* Should not reach this code path */
__assume(0);
}
# elif defined(__GNUC__) && (__GNUC__ >= 3)
return (unsigned)(__builtin_clzll(val) >> 3);
# else
unsigned r;
const unsigned n32 = sizeof(size_t)*4; /* calculate this way due to compiler complaining in 32-bits mode */
if (!(val>>n32)) { r=4; } else { r=0; val>>=n32; }
if (!(val>>16)) { r+=2; val>>=8; } else { val>>=24; }
r += (!val);
return r;
# endif
} else { /* 32 bits */
# if defined(_MSC_VER)
if (val != 0) {
unsigned long r;
_BitScanReverse(&r, (unsigned long)val);
return (unsigned)(r >> 3);
} else {
/* Should not reach this code path */
__assume(0);
}
# elif defined(__GNUC__) && (__GNUC__ >= 3)
return (unsigned)(__builtin_clz((U32)val) >> 3);
# else
unsigned r;
if (!(val>>16)) { r=2; val>>=8; } else { r=0; val>>=24; }
r += (!val);
return r;
# endif
} }
}
/*! ZDICT_count() :
Count the nb of common bytes between 2 pointers.
Note : this function presumes end of buffer followed by noisy guard band.
@@ -223,7 +145,7 @@ static size_t ZDICT_count(const void* pIn, const void* pMatch)
pMatch = (const char*)pMatch+sizeof(size_t);
continue;
}
pIn = (const char*)pIn+ZDICT_NbCommonBytes(diff);
pIn = (const char*)pIn+ZSTD_NbCommonBytes(diff);
return (size_t)((const char*)pIn - pStart);
}
}