ext/zstdruby/libzstd/common/bitstream.h in zstd-ruby-1.5.2.3 vs ext/zstdruby/libzstd/common/bitstream.h in zstd-ruby-1.5.4.0
- old
+ new
@@ -1,9 +1,9 @@
/* ******************************************************************
* bitstream
* Part of FSE library
- * Copyright (c) Yann Collet, Facebook, Inc.
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
*
* You can contact the author at :
* - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
*
* This source code is licensed under both the BSD-style license (found in the
@@ -28,18 +28,19 @@
******************************************/
#include "mem.h" /* unaligned access routines */
#include "compiler.h" /* UNLIKELY() */
#include "debug.h" /* assert(), DEBUGLOG(), RAWLOG() */
#include "error_private.h" /* error codes and messages */
+#include "bits.h" /* ZSTD_highbit32 */
/*=========================================
* Target specific
=========================================*/
#ifndef ZSTD_NO_INTRINSICS
-# if defined(__BMI__) && defined(__GNUC__)
-# include <immintrin.h> /* support for bextr (experimental) */
+# if (defined(__BMI__) || defined(__BMI2__)) && defined(__GNUC__)
+# include <immintrin.h> /* support for bextr (experimental)/bzhi */
# elif defined(__ICCARM__)
# include <intrinsics.h>
# endif
#endif
@@ -130,52 +131,10 @@
/* unsafe version; does not check buffer overflow */
MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, unsigned nbBits);
/* faster, but works only if nbBits >= 1 */
-
-
-/*-**************************************************************
-* Internal functions
-****************************************************************/
-MEM_STATIC unsigned BIT_highbit32 (U32 val)
-{
- assert(val != 0);
- {
-# if defined(_MSC_VER) /* Visual */
-# if STATIC_BMI2 == 1
- return _lzcnt_u32(val) ^ 31;
-# else
- if (val != 0) {
- unsigned long r;
- _BitScanReverse(&r, val);
- return (unsigned)r;
- } else {
- /* Should not reach this code path */
- __assume(0);
- }
-# endif
-# elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */
- return __builtin_clz (val) ^ 31;
-# elif defined(__ICCARM__) /* IAR Intrinsic */
- return 31 - __CLZ(val);
-# else /* Software version */
- static const unsigned 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 };
- U32 v = val;
- v |= v >> 1;
- v |= v >> 2;
- v |= v >> 4;
- v |= v >> 8;
- v |= v >> 16;
- return DeBruijnClz[ (U32) (v * 0x07C4ACDDU) >> 27];
-# endif
- }
-}
-
/*===== Local Constants =====*/
static const unsigned BIT_mask[] = {
0, 1, 3, 7, 0xF, 0x1F,
0x3F, 0x7F, 0xFF, 0x1FF, 0x3FF, 0x7FF,
0xFFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF, 0x1FFFF,
@@ -201,20 +160,30 @@
bitC->endPtr = bitC->startPtr + dstCapacity - sizeof(bitC->bitContainer);
if (dstCapacity <= sizeof(bitC->bitContainer)) return ERROR(dstSize_tooSmall);
return 0;
}
+MEM_STATIC FORCE_INLINE_ATTR size_t BIT_getLowerBits(size_t bitContainer, U32 const nbBits)
+{
+#if defined(STATIC_BMI2) && STATIC_BMI2 == 1 && !defined(ZSTD_NO_INTRINSICS)
+ return _bzhi_u64(bitContainer, nbBits);
+#else
+ assert(nbBits < BIT_MASK_SIZE);
+ return bitContainer & BIT_mask[nbBits];
+#endif
+}
+
/*! BIT_addBits() :
* can add up to 31 bits into `bitC`.
* Note : does not check for register overflow ! */
MEM_STATIC void BIT_addBits(BIT_CStream_t* bitC,
size_t value, unsigned nbBits)
{
DEBUG_STATIC_ASSERT(BIT_MASK_SIZE == 32);
assert(nbBits < BIT_MASK_SIZE);
assert(nbBits + bitC->bitPos < sizeof(bitC->bitContainer) * 8);
- bitC->bitContainer |= (value & BIT_mask[nbBits]) << bitC->bitPos;
+ bitC->bitContainer |= BIT_getLowerBits(value, nbBits) << bitC->bitPos;
bitC->bitPos += nbBits;
}
/*! BIT_addBitsFast() :
* works only if `value` is _clean_,
@@ -289,11 +258,11 @@
if (srcSize >= sizeof(bitD->bitContainer)) { /* normal case */
bitD->ptr = (const char*)srcBuffer + srcSize - sizeof(bitD->bitContainer);
bitD->bitContainer = MEM_readLEST(bitD->ptr);
{ BYTE const lastByte = ((const BYTE*)srcBuffer)[srcSize-1];
- bitD->bitsConsumed = lastByte ? 8 - BIT_highbit32(lastByte) : 0; /* ensures bitsConsumed is always set */
+ bitD->bitsConsumed = lastByte ? 8 - ZSTD_highbit32(lastByte) : 0; /* ensures bitsConsumed is always set */
if (lastByte == 0) return ERROR(GENERIC); /* endMark not present */ }
} else {
bitD->ptr = bitD->start;
bitD->bitContainer = *(const BYTE*)(bitD->start);
switch(srcSize)
@@ -317,11 +286,11 @@
ZSTD_FALLTHROUGH;
default: break;
}
{ BYTE const lastByte = ((const BYTE*)srcBuffer)[srcSize-1];
- bitD->bitsConsumed = lastByte ? 8 - BIT_highbit32(lastByte) : 0;
+ bitD->bitsConsumed = lastByte ? 8 - ZSTD_highbit32(lastByte) : 0;
if (lastByte == 0) return ERROR(corruption_detected); /* endMark not present */
}
bitD->bitsConsumed += (U32)(sizeof(bitD->bitContainer) - srcSize)*8;
}
@@ -348,20 +317,10 @@
#else
return (bitContainer >> (start & regMask)) & BIT_mask[nbBits];
#endif
}
-MEM_STATIC FORCE_INLINE_ATTR size_t BIT_getLowerBits(size_t bitContainer, U32 const nbBits)
-{
-#if defined(STATIC_BMI2) && STATIC_BMI2 == 1
- return _bzhi_u64(bitContainer, nbBits);
-#else
- assert(nbBits < BIT_MASK_SIZE);
- return bitContainer & BIT_mask[nbBits];
-#endif
-}
-
/*! BIT_lookBits() :
* Provides next n bits from local register.
* local register is not modified.
* On 32-bits, maxNbBits==24.
* On 64-bits, maxNbBits==56.
@@ -404,10 +363,10 @@
BIT_skipBits(bitD, nbBits);
return value;
}
/*! BIT_readBitsFast() :
- * unsafe version; only works only if nbBits >= 1 */
+ * unsafe version; only works if nbBits >= 1 */
MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, unsigned nbBits)
{
size_t const value = BIT_lookBitsFast(bitD, nbBits);
assert(nbBits >= 1);
BIT_skipBits(bitD, nbBits);