diff options
Diffstat (limited to 'sys/contrib/openzfs/module/zstd/lib/common/bitstream.h')
| -rw-r--r-- | sys/contrib/openzfs/module/zstd/lib/common/bitstream.h | 210 |
1 files changed, 105 insertions, 105 deletions
diff --git a/sys/contrib/openzfs/module/zstd/lib/common/bitstream.h b/sys/contrib/openzfs/module/zstd/lib/common/bitstream.h index 11b660adb3cb..7e4cc2f0cabf 100644 --- a/sys/contrib/openzfs/module/zstd/lib/common/bitstream.h +++ b/sys/contrib/openzfs/module/zstd/lib/common/bitstream.h @@ -2,7 +2,7 @@ /* ****************************************************************** * bitstream * Part of FSE library - * Copyright (c) 2013-2020, Yann Collet, Facebook, Inc. + * Copyright (c) Meta Platforms, Inc. and affiliates. * * You can contact the author at : * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy @@ -15,10 +15,6 @@ #ifndef BITSTREAM_H_MODULE #define BITSTREAM_H_MODULE -#if defined (__cplusplus) -extern "C" { -#endif - /* * This API consists of small unitary functions, which must be inlined for best performance. * Since link-time-optimization is not available for all compilers, @@ -32,15 +28,17 @@ extern "C" { #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 =========================================*/ -#if defined(__BMI__) && defined(__GNUC__) -# include <immintrin.h> /* support for bextr (experimental) */ -#elif defined(__ICCARM__) -# include <intrinsics.h> +#ifndef ZSTD_NO_INTRINSICS +# if (defined(__BMI__) || defined(__BMI2__)) && defined(__GNUC__) +# include <immintrin.h> /* support for bextr (experimental)/bzhi */ +# elif defined(__ICCARM__) +# include <intrinsics.h> +# endif #endif #define STREAM_ACCUMULATOR_MIN_32 25 @@ -51,12 +49,13 @@ extern "C" { /*-****************************************** * bitStream encoding API (write forward) ********************************************/ +typedef size_t BitContainerType; /* bitStream can mix input from multiple sources. * 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 { - size_t bitContainer; + BitContainerType bitContainer; unsigned bitPos; char* startPtr; char* ptr; @@ -64,7 +63,7 @@ typedef struct { } BIT_CStream_t; MEM_STATIC size_t BIT_initCStream(BIT_CStream_t* bitC, void* dstBuffer, size_t dstCapacity); -MEM_STATIC void BIT_addBits(BIT_CStream_t* bitC, size_t value, unsigned nbBits); +MEM_STATIC void BIT_addBits(BIT_CStream_t* bitC, BitContainerType value, unsigned nbBits); MEM_STATIC void BIT_flushBits(BIT_CStream_t* bitC); MEM_STATIC size_t BIT_closeCStream(BIT_CStream_t* bitC); @@ -73,7 +72,7 @@ MEM_STATIC size_t BIT_closeCStream(BIT_CStream_t* bitC); * `dstCapacity` must be >= sizeof(bitD->bitContainer), otherwise @return will be an error code. * * bits are first added to a local register. -* Local register is size_t, hence 64-bits on 64-bits systems, or 32-bits on 32-bits systems. +* Local register is BitContainerType, 64-bits on 64-bits systems, or 32-bits on 32-bits systems. * Writing data into memory is an explicit operation, performed by the flushBits function. * Hence keep track how many bits are potentially stored into local register to avoid register overflow. * After a flushBits, a maximum of 7 bits might still be stored into local register. @@ -90,28 +89,28 @@ MEM_STATIC size_t BIT_closeCStream(BIT_CStream_t* bitC); * bitStream decoding API (read backward) **********************************************/ typedef struct { - size_t bitContainer; + BitContainerType bitContainer; unsigned bitsConsumed; const char* ptr; const char* start; const char* limitPtr; } BIT_DStream_t; -typedef enum { BIT_DStream_unfinished = 0, - BIT_DStream_endOfBuffer = 1, - BIT_DStream_completed = 2, - BIT_DStream_overflow = 3 } BIT_DStream_status; /* result of BIT_reloadDStream() */ - /* 1,2,4,8 would be better for bitmap combinations, but slows down performance a bit ... :( */ +typedef enum { BIT_DStream_unfinished = 0, /* fully refilled */ + BIT_DStream_endOfBuffer = 1, /* still some bits left in bitstream */ + BIT_DStream_completed = 2, /* bitstream entirely consumed, bit-exact */ + BIT_DStream_overflow = 3 /* user requested more bits than present in bitstream */ + } BIT_DStream_status; /* result of BIT_reloadDStream() */ MEM_STATIC size_t BIT_initDStream(BIT_DStream_t* bitD, const void* srcBuffer, size_t srcSize); -MEM_STATIC size_t BIT_readBits(BIT_DStream_t* bitD, unsigned nbBits); -MEM_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD); +FORCE_INLINE_TEMPLATE BitContainerType BIT_readBits(BIT_DStream_t* bitD, unsigned nbBits); +FORCE_INLINE_TEMPLATE BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD); MEM_STATIC unsigned BIT_endOfDStream(const BIT_DStream_t* bitD); /* Start by invoking BIT_initDStream(). * A chunk of the bitStream is then stored into a local register. -* Local register size is 64-bits on 64-bits systems, 32-bits on 32-bits systems (size_t). +* Local register size is 64-bits on 64-bits systems, 32-bits on 32-bits systems (BitContainerType). * You can then retrieve bitFields stored into the local register, **in reverse order**. * Local register is explicitly reloaded from memory by the BIT_reloadDStream() method. * A reload guarantee a minimum of ((8*sizeof(bitD->bitContainer))-7) bits when its result is BIT_DStream_unfinished. @@ -123,7 +122,7 @@ MEM_STATIC unsigned BIT_endOfDStream(const BIT_DStream_t* bitD); /*-**************************************** * unsafe API ******************************************/ -MEM_STATIC void BIT_addBitsFast(BIT_CStream_t* bitC, size_t value, unsigned nbBits); +MEM_STATIC void BIT_addBitsFast(BIT_CStream_t* bitC, BitContainerType value, unsigned nbBits); /* faster, but works only if value is "clean", meaning all high bits above nbBits are 0 */ MEM_STATIC void BIT_flushBitsFast(BIT_CStream_t* bitC); @@ -132,38 +131,6 @@ MEM_STATIC void BIT_flushBitsFast(BIT_CStream_t* bitC); 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 */ - unsigned long r=0; - return _BitScanReverse ( &r, val ) ? (unsigned)r : 0; -# 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, @@ -193,16 +160,31 @@ MEM_STATIC size_t BIT_initCStream(BIT_CStream_t* bitC, return 0; } +FORCE_INLINE_TEMPLATE BitContainerType BIT_getLowerBits(BitContainerType bitContainer, U32 const nbBits) +{ +#if STATIC_BMI2 && !defined(ZSTD_NO_INTRINSICS) +# if (defined(__x86_64__) || defined(_M_X64)) && !defined(__ILP32__) + return _bzhi_u64(bitContainer, nbBits); +# else + DEBUG_STATIC_ASSERT(sizeof(bitContainer) == sizeof(U32)); + return _bzhi_u32(bitContainer, nbBits); +# endif +#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) + BitContainerType value, unsigned nbBits) { - MEM_STATIC_ASSERT(BIT_MASK_SIZE == 32); + 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; } @@ -210,7 +192,7 @@ MEM_STATIC void BIT_addBits(BIT_CStream_t* bitC, * 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) + BitContainerType value, unsigned nbBits) { assert((value>>nbBits) == 0); assert(nbBits + bitC->bitPos < sizeof(bitC->bitContainer) * 8); @@ -257,7 +239,7 @@ MEM_STATIC size_t BIT_closeCStream(BIT_CStream_t* bitC) BIT_addBitsFast(bitC, 1, 1); /* endMark */ BIT_flushBits(bitC); if (bitC->ptr >= bitC->endPtr) return 0; /* overflow detected */ - return (bitC->ptr - bitC->startPtr) + (bitC->bitPos > 0); + return (size_t)(bitC->ptr - bitC->startPtr) + (bitC->bitPos > 0); } @@ -272,7 +254,7 @@ MEM_STATIC size_t BIT_closeCStream(BIT_CStream_t* bitC) */ MEM_STATIC size_t BIT_initDStream(BIT_DStream_t* bitD, const void* srcBuffer, size_t srcSize) { - if (srcSize < 1) { memset(bitD, 0, sizeof(*bitD)); return ERROR(srcSize_wrong); } + if (srcSize < 1) { ZSTD_memset(bitD, 0, sizeof(*bitD)); return ERROR(srcSize_wrong); } bitD->start = (const char*)srcBuffer; bitD->limitPtr = bitD->start + sizeof(bitD->bitContainer); @@ -281,35 +263,35 @@ MEM_STATIC size_t BIT_initDStream(BIT_DStream_t* bitD, const void* srcBuffer, si 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) { - case 7: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[6]) << (sizeof(bitD->bitContainer)*8 - 16); - /* fall-through */ + case 7: bitD->bitContainer += (BitContainerType)(((const BYTE*)(srcBuffer))[6]) << (sizeof(bitD->bitContainer)*8 - 16); + ZSTD_FALLTHROUGH; - case 6: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[5]) << (sizeof(bitD->bitContainer)*8 - 24); - /* fall-through */ + case 6: bitD->bitContainer += (BitContainerType)(((const BYTE*)(srcBuffer))[5]) << (sizeof(bitD->bitContainer)*8 - 24); + ZSTD_FALLTHROUGH; - case 5: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[4]) << (sizeof(bitD->bitContainer)*8 - 32); - /* fall-through */ + case 5: bitD->bitContainer += (BitContainerType)(((const BYTE*)(srcBuffer))[4]) << (sizeof(bitD->bitContainer)*8 - 32); + ZSTD_FALLTHROUGH; - case 4: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[3]) << 24; - /* fall-through */ + case 4: bitD->bitContainer += (BitContainerType)(((const BYTE*)(srcBuffer))[3]) << 24; + ZSTD_FALLTHROUGH; - case 3: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[2]) << 16; - /* fall-through */ + case 3: bitD->bitContainer += (BitContainerType)(((const BYTE*)(srcBuffer))[2]) << 16; + ZSTD_FALLTHROUGH; - case 2: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[1]) << 8; - /* fall-through */ + case 2: bitD->bitContainer += (BitContainerType)(((const BYTE*)(srcBuffer))[1]) << 8; + 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; @@ -318,23 +300,26 @@ MEM_STATIC size_t BIT_initDStream(BIT_DStream_t* bitD, const void* srcBuffer, si return srcSize; } -MEM_STATIC size_t BIT_getUpperBits(size_t bitContainer, U32 const start) +FORCE_INLINE_TEMPLATE BitContainerType BIT_getUpperBits(BitContainerType bitContainer, U32 const start) { return bitContainer >> start; } -MEM_STATIC size_t BIT_getMiddleBits(size_t bitContainer, U32 const start, U32 const nbBits) +FORCE_INLINE_TEMPLATE BitContainerType BIT_getMiddleBits(BitContainerType bitContainer, U32 const start, U32 const nbBits) { U32 const regMask = sizeof(bitContainer)*8 - 1; /* if start > regMask, bitstream is corrupted, and result is undefined */ assert(nbBits < BIT_MASK_SIZE); + /* x86 transform & ((1 << nbBits) - 1) to bzhi instruction, it is better + * than accessing memory. When bmi2 instruction is not present, we consider + * such cpus old (pre-Haswell, 2013) and their performance is not of that + * importance. + */ +#if defined(__x86_64__) || defined(_M_X64) + return (bitContainer >> (start & regMask)) & ((((U64)1) << nbBits) - 1); +#else return (bitContainer >> (start & regMask)) & BIT_mask[nbBits]; -} - -MEM_STATIC size_t BIT_getLowerBits(size_t bitContainer, U32 const nbBits) -{ - assert(nbBits < BIT_MASK_SIZE); - return bitContainer & BIT_mask[nbBits]; +#endif } /*! BIT_lookBits() : @@ -343,7 +328,7 @@ MEM_STATIC size_t BIT_getLowerBits(size_t bitContainer, U32 const nbBits) * On 32-bits, maxNbBits==24. * On 64-bits, maxNbBits==56. * @return : value extracted */ -MEM_STATIC size_t BIT_lookBits(const BIT_DStream_t* bitD, U32 nbBits) +FORCE_INLINE_TEMPLATE BitContainerType BIT_lookBits(const BIT_DStream_t* bitD, U32 nbBits) { /* arbitrate between double-shift and shift+mask */ #if 1 @@ -359,14 +344,14 @@ MEM_STATIC size_t BIT_lookBits(const BIT_DStream_t* bitD, U32 nbBits) /*! BIT_lookBitsFast() : * unsafe version; only works if nbBits >= 1 */ -MEM_STATIC size_t BIT_lookBitsFast(const BIT_DStream_t* bitD, U32 nbBits) +MEM_STATIC BitContainerType BIT_lookBitsFast(const BIT_DStream_t* bitD, U32 nbBits) { U32 const regMask = sizeof(bitD->bitContainer)*8 - 1; assert(nbBits >= 1); return (bitD->bitContainer << (bitD->bitsConsumed & regMask)) >> (((regMask+1)-nbBits) & regMask); } -MEM_STATIC void BIT_skipBits(BIT_DStream_t* bitD, U32 nbBits) +FORCE_INLINE_TEMPLATE void BIT_skipBits(BIT_DStream_t* bitD, U32 nbBits) { bitD->bitsConsumed += nbBits; } @@ -375,23 +360,38 @@ 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, unsigned nbBits) +FORCE_INLINE_TEMPLATE BitContainerType BIT_readBits(BIT_DStream_t* bitD, unsigned nbBits) { - size_t const value = BIT_lookBits(bitD, nbBits); + BitContainerType const value = BIT_lookBits(bitD, nbBits); BIT_skipBits(bitD, nbBits); return value; } /*! BIT_readBitsFast() : - * unsafe version; only works only if nbBits >= 1 */ -MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, unsigned nbBits) + * unsafe version; only works if nbBits >= 1 */ +MEM_STATIC BitContainerType BIT_readBitsFast(BIT_DStream_t* bitD, unsigned nbBits) { - size_t const value = BIT_lookBitsFast(bitD, nbBits); + BitContainerType const value = BIT_lookBitsFast(bitD, nbBits); assert(nbBits >= 1); BIT_skipBits(bitD, nbBits); return value; } +/*! BIT_reloadDStream_internal() : + * Simple variant of BIT_reloadDStream(), with two conditions: + * 1. bitstream is valid : bitsConsumed <= sizeof(bitD->bitContainer)*8 + * 2. look window is valid after shifted down : bitD->ptr >= bitD->start + */ +MEM_STATIC BIT_DStream_status BIT_reloadDStream_internal(BIT_DStream_t* bitD) +{ + assert(bitD->bitsConsumed <= sizeof(bitD->bitContainer)*8); + bitD->ptr -= bitD->bitsConsumed >> 3; + assert(bitD->ptr >= bitD->start); + bitD->bitsConsumed &= 7; + bitD->bitContainer = MEM_readLEST(bitD->ptr); + return BIT_DStream_unfinished; +} + /*! BIT_reloadDStreamFast() : * Similar to BIT_reloadDStream(), but with two differences: * 1. bitsConsumed <= sizeof(bitD->bitContainer)*8 must hold! @@ -402,31 +402,35 @@ MEM_STATIC BIT_DStream_status BIT_reloadDStreamFast(BIT_DStream_t* bitD) { if (UNLIKELY(bitD->ptr < bitD->limitPtr)) return BIT_DStream_overflow; - assert(bitD->bitsConsumed <= sizeof(bitD->bitContainer)*8); - bitD->ptr -= bitD->bitsConsumed >> 3; - bitD->bitsConsumed &= 7; - bitD->bitContainer = MEM_readLEST(bitD->ptr); - return BIT_DStream_unfinished; + return BIT_reloadDStream_internal(bitD); } /*! BIT_reloadDStream() : * Refill `bitD` from buffer previously set in BIT_initDStream() . - * This function is safe, it guarantees it will not read beyond src buffer. + * This function is safe, it guarantees it will not never beyond src buffer. * @return : status of `BIT_DStream_t` internal register. * when status == BIT_DStream_unfinished, internal register is filled with at least 25 or 57 bits */ -MEM_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD) +FORCE_INLINE_TEMPLATE BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD) { - if (bitD->bitsConsumed > (sizeof(bitD->bitContainer)*8)) /* overflow detected, like end of stream */ + /* note : once in overflow mode, a bitstream remains in this mode until it's reset */ + if (UNLIKELY(bitD->bitsConsumed > (sizeof(bitD->bitContainer)*8))) { + static const BitContainerType zeroFilled = 0; + bitD->ptr = (const char*)&zeroFilled; /* aliasing is allowed for char */ + /* overflow detected, erroneous scenario or end of stream: no update */ return BIT_DStream_overflow; + } + + assert(bitD->ptr >= bitD->start); if (bitD->ptr >= bitD->limitPtr) { - return BIT_reloadDStreamFast(bitD); + return BIT_reloadDStream_internal(bitD); } if (bitD->ptr == bitD->start) { + /* reached end of bitStream => no update */ if (bitD->bitsConsumed < sizeof(bitD->bitContainer)*8) return BIT_DStream_endOfBuffer; return BIT_DStream_completed; } - /* start < ptr < limitPtr */ + /* start < ptr < limitPtr => cautious update */ { U32 nbBytes = bitD->bitsConsumed >> 3; BIT_DStream_status result = BIT_DStream_unfinished; if (bitD->ptr - nbBytes < bitD->start) { @@ -448,8 +452,4 @@ MEM_STATIC unsigned BIT_endOfDStream(const BIT_DStream_t* DStream) return ((DStream->ptr == DStream->start) && (DStream->bitsConsumed == sizeof(DStream->bitContainer)*8)); } -#if defined (__cplusplus) -} -#endif - #endif /* BITSTREAM_H_MODULE */ |