diff options
Diffstat (limited to 'thirdparty/zstd/common/bitstream.h')
| -rw-r--r-- | thirdparty/zstd/common/bitstream.h | 48 |
1 files changed, 16 insertions, 32 deletions
diff --git a/thirdparty/zstd/common/bitstream.h b/thirdparty/zstd/common/bitstream.h index f7f389fe0f..d955bd677b 100644 --- a/thirdparty/zstd/common/bitstream.h +++ b/thirdparty/zstd/common/bitstream.h @@ -1,8 +1,7 @@ /* ****************************************************************** bitstream Part of FSE library - header file (to include) - Copyright (C) 2013-2017, Yann Collet. + Copyright (C) 2013-present, Yann Collet. BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php) @@ -49,21 +48,10 @@ extern "C" { * Dependencies ******************************************/ #include "mem.h" /* unaligned access routines */ +#include "debug.h" /* assert(), DEBUGLOG(), RAWLOG() */ #include "error_private.h" /* error codes and messages */ -/*-************************************* -* Debug -***************************************/ -#if defined(BIT_DEBUG) && (BIT_DEBUG>=1) -# include <assert.h> -#else -# ifndef assert -# define assert(condition) ((void)0) -# endif -#endif - - /*========================================= * Target specific =========================================*/ @@ -83,8 +71,7 @@ extern "C" { * A critical property of these streams is that they encode and decode in **reverse** direction. * So the first bit sequence you add will be the last to be read, like a LIFO stack. */ -typedef struct -{ +typedef struct { size_t bitContainer; unsigned bitPos; char* startPtr; @@ -118,8 +105,7 @@ MEM_STATIC size_t BIT_closeCStream(BIT_CStream_t* bitC); /*-******************************************** * bitStream decoding API (read backward) **********************************************/ -typedef struct -{ +typedef struct { size_t bitContainer; unsigned bitsConsumed; const char* ptr; @@ -236,7 +222,8 @@ MEM_STATIC void BIT_addBits(BIT_CStream_t* bitC, } /*! BIT_addBitsFast() : - * works only if `value` is _clean_, meaning all high bits above nbBits are 0 */ + * works only if `value` is _clean_, + * meaning all high bits above nbBits are 0 */ MEM_STATIC void BIT_addBitsFast(BIT_CStream_t* bitC, size_t value, unsigned nbBits) { @@ -352,17 +339,10 @@ MEM_STATIC size_t BIT_getUpperBits(size_t bitContainer, U32 const start) MEM_STATIC size_t BIT_getMiddleBits(size_t bitContainer, U32 const start, U32 const nbBits) { -#if defined(__BMI__) && defined(__GNUC__) && __GNUC__*1000+__GNUC_MINOR__ >= 4008 /* experimental */ -# if defined(__x86_64__) - if (sizeof(bitContainer)==8) - return _bextr_u64(bitContainer, start, nbBits); - else -# endif - return _bextr_u32(bitContainer, start, nbBits); -#else + U32 const regMask = sizeof(bitContainer)*8 - 1; + /* if start > regMask, bitstream is corrupted, and result is undefined */ assert(nbBits < BIT_MASK_SIZE); - return (bitContainer >> start) & BIT_mask[nbBits]; -#endif + return (bitContainer >> (start & regMask)) & BIT_mask[nbBits]; } MEM_STATIC size_t BIT_getLowerBits(size_t bitContainer, U32 const nbBits) @@ -379,9 +359,13 @@ MEM_STATIC size_t BIT_getLowerBits(size_t bitContainer, U32 const nbBits) * @return : value extracted */ MEM_STATIC size_t BIT_lookBits(const BIT_DStream_t* bitD, U32 nbBits) { -#if defined(__BMI__) && defined(__GNUC__) /* experimental; fails if bitD->bitsConsumed + nbBits > sizeof(bitD->bitContainer)*8 */ + /* arbitrate between double-shift and shift+mask */ +#if 1 + /* if bitD->bitsConsumed + nbBits > sizeof(bitD->bitContainer)*8, + * bitstream is likely corrupted, and result is undefined */ return BIT_getMiddleBits(bitD->bitContainer, (sizeof(bitD->bitContainer)*8) - bitD->bitsConsumed - nbBits, nbBits); #else + /* this code path is slower on my os-x laptop */ U32 const regMask = sizeof(bitD->bitContainer)*8 - 1; return ((bitD->bitContainer << (bitD->bitsConsumed & regMask)) >> 1) >> ((regMask-nbBits) & regMask); #endif @@ -405,7 +389,7 @@ MEM_STATIC void BIT_skipBits(BIT_DStream_t* bitD, U32 nbBits) * Read (consume) next n bits from local register and update. * Pay attention to not read more than nbBits contained into local register. * @return : extracted value. */ -MEM_STATIC size_t BIT_readBits(BIT_DStream_t* bitD, U32 nbBits) +MEM_STATIC size_t BIT_readBits(BIT_DStream_t* bitD, unsigned nbBits) { size_t const value = BIT_lookBits(bitD, nbBits); BIT_skipBits(bitD, nbBits); @@ -414,7 +398,7 @@ MEM_STATIC size_t BIT_readBits(BIT_DStream_t* bitD, U32 nbBits) /*! BIT_readBitsFast() : * unsafe version; only works only if nbBits >= 1 */ -MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, U32 nbBits) +MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, unsigned nbBits) { size_t const value = BIT_lookBitsFast(bitD, nbBits); assert(nbBits >= 1); |