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Diffstat (limited to 'lib/zstd/common/bitstream.h')
| -rw-r--r-- | lib/zstd/common/bitstream.h | 437 |
1 files changed, 0 insertions, 437 deletions
diff --git a/lib/zstd/common/bitstream.h b/lib/zstd/common/bitstream.h deleted file mode 100644 index 28248abe86..0000000000 --- a/lib/zstd/common/bitstream.h +++ /dev/null @@ -1,437 +0,0 @@ -/* ****************************************************************** - * bitstream - * Part of FSE library - * Copyright (c) Yann Collet, Facebook, Inc. - * - * 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 - * LICENSE file in the root directory of this source tree) and the GPLv2 (found - * in the COPYING file in the root directory of this source tree). - * You may select, at your option, one of the above-listed licenses. -****************************************************************** */ -#ifndef BITSTREAM_H_MODULE -#define BITSTREAM_H_MODULE - -/* -* This API consists of small unitary functions, which must be inlined for best performance. -* Since link-time-optimization is not available for all compilers, -* these functions are defined into a .h to be included. -*/ - -/*-**************************************** -* Dependencies -******************************************/ -#include "mem.h" /* unaligned access routines */ -#include "compiler.h" /* UNLIKELY() */ -#include "debug.h" /* assert(), DEBUGLOG(), RAWLOG() */ -#include "error_private.h" /* error codes and messages */ - - -/*========================================= -* Target specific -=========================================*/ - -#define STREAM_ACCUMULATOR_MIN_32 25 -#define STREAM_ACCUMULATOR_MIN_64 57 -#define STREAM_ACCUMULATOR_MIN ((U32)(MEM_32bits() ? STREAM_ACCUMULATOR_MIN_32 : STREAM_ACCUMULATOR_MIN_64)) - - -/*-****************************************** -* bitStream encoding API (write forward) -********************************************/ -/* 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; - unsigned bitPos; - char* startPtr; - char* ptr; - char* endPtr; -} 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_flushBits(BIT_CStream_t* bitC); -MEM_STATIC size_t BIT_closeCStream(BIT_CStream_t* bitC); - -/* Start with initCStream, providing the size of buffer to write into. -* bitStream will never write outside of this buffer. -* `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. -* 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. -* -* Avoid storing elements of more than 24 bits if you want compatibility with 32-bits bitstream readers. -* -* Last operation is to close the bitStream. -* The function returns the final size of CStream in bytes. -* If data couldn't fit into `dstBuffer`, it will return a 0 ( == not storable) -*/ - - -/*-******************************************** -* bitStream decoding API (read backward) -**********************************************/ -typedef struct { - size_t 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 ... :( */ - -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); -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). -* 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. -* Otherwise, it can be less than that, so proceed accordingly. -* Checking if DStream has reached its end can be performed with BIT_endOfDStream(). -*/ - - -/*-**************************************** -* unsafe API -******************************************/ -MEM_STATIC void BIT_addBitsFast(BIT_CStream_t* bitC, size_t 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); -/* 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 (__GNUC__ >= 3) /* Use GCC Intrinsic */ - return __builtin_clz (val) ^ 31; -# 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, - 0x3FFFF, 0x7FFFF, 0xFFFFF, 0x1FFFFF, 0x3FFFFF, 0x7FFFFF, - 0xFFFFFF, 0x1FFFFFF, 0x3FFFFFF, 0x7FFFFFF, 0xFFFFFFF, 0x1FFFFFFF, - 0x3FFFFFFF, 0x7FFFFFFF}; /* up to 31 bits */ -#define BIT_MASK_SIZE (sizeof(BIT_mask) / sizeof(BIT_mask[0])) - -/*-************************************************************** -* bitStream encoding -****************************************************************/ -/*! BIT_initCStream() : - * `dstCapacity` must be > sizeof(size_t) - * @return : 0 if success, - * otherwise an error code (can be tested using ERR_isError()) */ -MEM_STATIC size_t BIT_initCStream(BIT_CStream_t* bitC, - void* startPtr, size_t dstCapacity) -{ - bitC->bitContainer = 0; - bitC->bitPos = 0; - bitC->startPtr = (char*)startPtr; - bitC->ptr = bitC->startPtr; - bitC->endPtr = bitC->startPtr + dstCapacity - sizeof(bitC->bitContainer); - if (dstCapacity <= sizeof(bitC->bitContainer)) return ERROR(dstSize_tooSmall); - return 0; -} - -/*! 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->bitPos += nbBits; -} - -/*! BIT_addBitsFast() : - * 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) -{ - assert((value>>nbBits) == 0); - assert(nbBits + bitC->bitPos < sizeof(bitC->bitContainer) * 8); - bitC->bitContainer |= value << bitC->bitPos; - bitC->bitPos += nbBits; -} - -/*! BIT_flushBitsFast() : - * assumption : bitContainer has not overflowed - * unsafe version; does not check buffer overflow */ -MEM_STATIC void BIT_flushBitsFast(BIT_CStream_t* bitC) -{ - size_t const nbBytes = bitC->bitPos >> 3; - assert(bitC->bitPos < sizeof(bitC->bitContainer) * 8); - assert(bitC->ptr <= bitC->endPtr); - MEM_writeLEST(bitC->ptr, bitC->bitContainer); - bitC->ptr += nbBytes; - bitC->bitPos &= 7; - bitC->bitContainer >>= nbBytes*8; -} - -/*! BIT_flushBits() : - * assumption : bitContainer has not overflowed - * safe version; check for buffer overflow, and prevents it. - * note : does not signal buffer overflow. - * overflow will be revealed later on using BIT_closeCStream() */ -MEM_STATIC void BIT_flushBits(BIT_CStream_t* bitC) -{ - size_t const nbBytes = bitC->bitPos >> 3; - assert(bitC->bitPos < sizeof(bitC->bitContainer) * 8); - assert(bitC->ptr <= bitC->endPtr); - MEM_writeLEST(bitC->ptr, bitC->bitContainer); - bitC->ptr += nbBytes; - if (bitC->ptr > bitC->endPtr) bitC->ptr = bitC->endPtr; - bitC->bitPos &= 7; - bitC->bitContainer >>= nbBytes*8; -} - -/*! BIT_closeCStream() : - * @return : size of CStream, in bytes, - * or 0 if it could not fit into dstBuffer */ -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); -} - - -/*-******************************************************** -* bitStream decoding -**********************************************************/ -/*! BIT_initDStream() : - * Initialize a BIT_DStream_t. - * `bitD` : a pointer to an already allocated BIT_DStream_t structure. - * `srcSize` must be the *exact* size of the bitStream, in bytes. - * @return : size of stream (== srcSize), or an errorCode if a problem is detected - */ -MEM_STATIC size_t BIT_initDStream(BIT_DStream_t* bitD, const void* srcBuffer, size_t srcSize) -{ - 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); - - 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 */ - 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); - ZSTD_FALLTHROUGH; - - case 6: bitD->bitContainer += (size_t)(((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); - ZSTD_FALLTHROUGH; - - case 4: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[3]) << 24; - ZSTD_FALLTHROUGH; - - case 3: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[2]) << 16; - ZSTD_FALLTHROUGH; - - case 2: bitD->bitContainer += (size_t)(((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; - if (lastByte == 0) return ERROR(corruption_detected); /* endMark not present */ - } - bitD->bitsConsumed += (U32)(sizeof(bitD->bitContainer) - srcSize)*8; - } - - return srcSize; -} - -MEM_STATIC FORCE_INLINE_ATTR size_t BIT_getUpperBits(size_t bitContainer, U32 const start) -{ - return bitContainer >> start; -} - -MEM_STATIC FORCE_INLINE_ATTR size_t BIT_getMiddleBits(size_t 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); - return (bitContainer >> (start & regMask)) & BIT_mask[nbBits]; -} - -MEM_STATIC FORCE_INLINE_ATTR size_t BIT_getLowerBits(size_t bitContainer, U32 const nbBits) -{ - assert(nbBits < BIT_MASK_SIZE); - return bitContainer & BIT_mask[nbBits]; -} - -/*! BIT_lookBits() : - * Provides next n bits from local register. - * local register is not modified. - * On 32-bits, maxNbBits==24. - * On 64-bits, maxNbBits==56. - * @return : value extracted */ -MEM_STATIC FORCE_INLINE_ATTR size_t BIT_lookBits(const BIT_DStream_t* bitD, U32 nbBits) -{ - /* 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 -} - -/*! BIT_lookBitsFast() : - * unsafe version; only works if nbBits >= 1 */ -MEM_STATIC size_t 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 FORCE_INLINE_ATTR void BIT_skipBits(BIT_DStream_t* bitD, U32 nbBits) -{ - bitD->bitsConsumed += nbBits; -} - -/*! BIT_readBits() : - * 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 FORCE_INLINE_ATTR size_t BIT_readBits(BIT_DStream_t* bitD, unsigned nbBits) -{ - size_t 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) -{ - size_t const value = BIT_lookBitsFast(bitD, nbBits); - assert(nbBits >= 1); - BIT_skipBits(bitD, nbBits); - return value; -} - -/*! BIT_reloadDStreamFast() : - * Similar to BIT_reloadDStream(), but with two differences: - * 1. bitsConsumed <= sizeof(bitD->bitContainer)*8 must hold! - * 2. Returns BIT_DStream_overflow when bitD->ptr < bitD->limitPtr, at this - * point you must use BIT_reloadDStream() to reload. - */ -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; -} - -/*! BIT_reloadDStream() : - * Refill `bitD` from buffer previously set in BIT_initDStream() . - * This function is safe, it guarantees it will not read 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) -{ - if (bitD->bitsConsumed > (sizeof(bitD->bitContainer)*8)) /* overflow detected, like end of stream */ - return BIT_DStream_overflow; - - if (bitD->ptr >= bitD->limitPtr) { - return BIT_reloadDStreamFast(bitD); - } - if (bitD->ptr == bitD->start) { - if (bitD->bitsConsumed < sizeof(bitD->bitContainer)*8) return BIT_DStream_endOfBuffer; - return BIT_DStream_completed; - } - /* start < ptr < limitPtr */ - { U32 nbBytes = bitD->bitsConsumed >> 3; - BIT_DStream_status result = BIT_DStream_unfinished; - if (bitD->ptr - nbBytes < bitD->start) { - nbBytes = (U32)(bitD->ptr - bitD->start); /* ptr > start */ - result = BIT_DStream_endOfBuffer; - } - bitD->ptr -= nbBytes; - bitD->bitsConsumed -= nbBytes*8; - bitD->bitContainer = MEM_readLEST(bitD->ptr); /* reminder : srcSize > sizeof(bitD->bitContainer), otherwise bitD->ptr == bitD->start */ - return result; - } -} - -/*! BIT_endOfDStream() : - * @return : 1 if DStream has _exactly_ reached its end (all bits consumed). - */ -MEM_STATIC unsigned BIT_endOfDStream(const BIT_DStream_t* DStream) -{ - return ((DStream->ptr == DStream->start) && (DStream->bitsConsumed == sizeof(DStream->bitContainer)*8)); -} - - -#endif /* BITSTREAM_H_MODULE */ |