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/*
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* Copyright ( c ) 2016 - 2020 , Yann Collet , Facebook , Inc .
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* All rights reserved .
*
* 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 .
*/
/* zstd_decompress_block :
* this module takes care of decompressing _compressed_ block */
/*-*******************************************************
* Dependencies
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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# include "zstd_deps.h" /* ZSTD_memcpy, ZSTD_memmove, ZSTD_memset */
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# include "compiler.h" /* prefetch */
# include "cpu.h" /* bmi2 */
# include "mem.h" /* low level memory routines */
# define FSE_STATIC_LINKING_ONLY
# include "fse.h"
# define HUF_STATIC_LINKING_ONLY
# include "huf.h"
# include "zstd_internal.h"
# include "zstd_decompress_internal.h" /* ZSTD_DCtx */
# include "zstd_ddict.h" /* ZSTD_DDictDictContent */
# include "zstd_decompress_block.h"
/*_*******************************************************
* Macros
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/* These two optional macros force the use one way or another of the two
* ZSTD_decompressSequences implementations . You can ' t force in both directions
* at the same time .
*/
# if defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
defined ( ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG )
# error "Cannot force the use of the short and the long ZSTD_decompressSequences variants!"
# endif
/*_*******************************************************
* Memory operations
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
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static void ZSTD_copy4 ( void * dst , const void * src ) { ZSTD_memcpy ( dst , src , 4 ) ; }
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/*-*************************************************************
* Block decoding
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*! ZSTD_getcBlockSize() :
* Provides the size of compressed block from block header ` src ` */
size_t ZSTD_getcBlockSize ( const void * src , size_t srcSize ,
blockProperties_t * bpPtr )
{
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RETURN_ERROR_IF ( srcSize < ZSTD_blockHeaderSize , srcSize_wrong , " " ) ;
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{ U32 const cBlockHeader = MEM_readLE24 ( src ) ;
U32 const cSize = cBlockHeader > > 3 ;
bpPtr - > lastBlock = cBlockHeader & 1 ;
bpPtr - > blockType = ( blockType_e ) ( ( cBlockHeader > > 1 ) & 3 ) ;
bpPtr - > origSize = cSize ; /* only useful for RLE */
if ( bpPtr - > blockType = = bt_rle ) return 1 ;
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RETURN_ERROR_IF ( bpPtr - > blockType = = bt_reserved , corruption_detected , " " ) ;
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return cSize ;
}
}
/* Hidden declaration for fullbench */
size_t ZSTD_decodeLiteralsBlock ( ZSTD_DCtx * dctx ,
const void * src , size_t srcSize ) ;
/*! ZSTD_decodeLiteralsBlock() :
* @ return : nb of bytes read from src ( < srcSize )
* note : symbol not declared but exposed for fullbench */
size_t ZSTD_decodeLiteralsBlock ( ZSTD_DCtx * dctx ,
const void * src , size_t srcSize ) /* note : srcSize < BLOCKSIZE */
{
DEBUGLOG ( 5 , " ZSTD_decodeLiteralsBlock " ) ;
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RETURN_ERROR_IF ( srcSize < MIN_CBLOCK_SIZE , corruption_detected , " " ) ;
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{ const BYTE * const istart = ( const BYTE * ) src ;
symbolEncodingType_e const litEncType = ( symbolEncodingType_e ) ( istart [ 0 ] & 3 ) ;
switch ( litEncType )
{
case set_repeat :
DEBUGLOG ( 5 , " set_repeat flag : re-using stats from previous compressed literals block " ) ;
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RETURN_ERROR_IF ( dctx - > litEntropy = = 0 , dictionary_corrupted , " " ) ;
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/* fall-through */
case set_compressed :
RETURN_ERROR_IF ( srcSize < 5 , corruption_detected , " srcSize >= MIN_CBLOCK_SIZE == 3; here we need up to 5 for case 3 " ) ;
{ size_t lhSize , litSize , litCSize ;
U32 singleStream = 0 ;
U32 const lhlCode = ( istart [ 0 ] > > 2 ) & 3 ;
U32 const lhc = MEM_readLE32 ( istart ) ;
size_t hufSuccess ;
switch ( lhlCode )
{
case 0 : case 1 : default : /* note : default is impossible, since lhlCode into [0..3] */
/* 2 - 2 - 10 - 10 */
singleStream = ! lhlCode ;
lhSize = 3 ;
litSize = ( lhc > > 4 ) & 0x3FF ;
litCSize = ( lhc > > 14 ) & 0x3FF ;
break ;
case 2 :
/* 2 - 2 - 14 - 14 */
lhSize = 4 ;
litSize = ( lhc > > 4 ) & 0x3FFF ;
litCSize = lhc > > 18 ;
break ;
case 3 :
/* 2 - 2 - 18 - 18 */
lhSize = 5 ;
litSize = ( lhc > > 4 ) & 0x3FFFF ;
litCSize = ( lhc > > 22 ) + ( ( size_t ) istart [ 4 ] < < 10 ) ;
break ;
}
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RETURN_ERROR_IF ( litSize > ZSTD_BLOCKSIZE_MAX , corruption_detected , " " ) ;
RETURN_ERROR_IF ( litCSize + lhSize > srcSize , corruption_detected , " " ) ;
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/* prefetch huffman table if cold */
if ( dctx - > ddictIsCold & & ( litSize > 768 /* heuristic */ ) ) {
PREFETCH_AREA ( dctx - > HUFptr , sizeof ( dctx - > entropy . hufTable ) ) ;
}
if ( litEncType = = set_repeat ) {
if ( singleStream ) {
hufSuccess = HUF_decompress1X_usingDTable_bmi2 (
dctx - > litBuffer , litSize , istart + lhSize , litCSize ,
dctx - > HUFptr , dctx - > bmi2 ) ;
} else {
hufSuccess = HUF_decompress4X_usingDTable_bmi2 (
dctx - > litBuffer , litSize , istart + lhSize , litCSize ,
dctx - > HUFptr , dctx - > bmi2 ) ;
}
} else {
if ( singleStream ) {
# if defined(HUF_FORCE_DECOMPRESS_X2)
hufSuccess = HUF_decompress1X_DCtx_wksp (
dctx - > entropy . hufTable , dctx - > litBuffer , litSize ,
istart + lhSize , litCSize , dctx - > workspace ,
sizeof ( dctx - > workspace ) ) ;
# else
hufSuccess = HUF_decompress1X1_DCtx_wksp_bmi2 (
dctx - > entropy . hufTable , dctx - > litBuffer , litSize ,
istart + lhSize , litCSize , dctx - > workspace ,
sizeof ( dctx - > workspace ) , dctx - > bmi2 ) ;
# endif
} else {
hufSuccess = HUF_decompress4X_hufOnly_wksp_bmi2 (
dctx - > entropy . hufTable , dctx - > litBuffer , litSize ,
istart + lhSize , litCSize , dctx - > workspace ,
sizeof ( dctx - > workspace ) , dctx - > bmi2 ) ;
}
}
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RETURN_ERROR_IF ( HUF_isError ( hufSuccess ) , corruption_detected , " " ) ;
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dctx - > litPtr = dctx - > litBuffer ;
dctx - > litSize = litSize ;
dctx - > litEntropy = 1 ;
if ( litEncType = = set_compressed ) dctx - > HUFptr = dctx - > entropy . hufTable ;
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ZSTD_memset ( dctx - > litBuffer + dctx - > litSize , 0 , WILDCOPY_OVERLENGTH ) ;
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return litCSize + lhSize ;
}
case set_basic :
{ size_t litSize , lhSize ;
U32 const lhlCode = ( ( istart [ 0 ] ) > > 2 ) & 3 ;
switch ( lhlCode )
{
case 0 : case 2 : default : /* note : default is impossible, since lhlCode into [0..3] */
lhSize = 1 ;
litSize = istart [ 0 ] > > 3 ;
break ;
case 1 :
lhSize = 2 ;
litSize = MEM_readLE16 ( istart ) > > 4 ;
break ;
case 3 :
lhSize = 3 ;
litSize = MEM_readLE24 ( istart ) > > 4 ;
break ;
}
if ( lhSize + litSize + WILDCOPY_OVERLENGTH > srcSize ) { /* risk reading beyond src buffer with wildcopy */
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RETURN_ERROR_IF ( litSize + lhSize > srcSize , corruption_detected , " " ) ;
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ZSTD_memcpy ( dctx - > litBuffer , istart + lhSize , litSize ) ;
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dctx - > litPtr = dctx - > litBuffer ;
dctx - > litSize = litSize ;
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ZSTD_memset ( dctx - > litBuffer + dctx - > litSize , 0 , WILDCOPY_OVERLENGTH ) ;
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return lhSize + litSize ;
}
/* direct reference into compressed stream */
dctx - > litPtr = istart + lhSize ;
dctx - > litSize = litSize ;
return lhSize + litSize ;
}
case set_rle :
{ U32 const lhlCode = ( ( istart [ 0 ] ) > > 2 ) & 3 ;
size_t litSize , lhSize ;
switch ( lhlCode )
{
case 0 : case 2 : default : /* note : default is impossible, since lhlCode into [0..3] */
lhSize = 1 ;
litSize = istart [ 0 ] > > 3 ;
break ;
case 1 :
lhSize = 2 ;
litSize = MEM_readLE16 ( istart ) > > 4 ;
break ;
case 3 :
lhSize = 3 ;
litSize = MEM_readLE24 ( istart ) > > 4 ;
RETURN_ERROR_IF ( srcSize < 4 , corruption_detected , " srcSize >= MIN_CBLOCK_SIZE == 3; here we need lhSize+1 = 4 " ) ;
break ;
}
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RETURN_ERROR_IF ( litSize > ZSTD_BLOCKSIZE_MAX , corruption_detected , " " ) ;
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ZSTD_memset ( dctx - > litBuffer , istart [ lhSize ] , litSize + WILDCOPY_OVERLENGTH ) ;
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dctx - > litPtr = dctx - > litBuffer ;
dctx - > litSize = litSize ;
return lhSize + 1 ;
}
default :
RETURN_ERROR ( corruption_detected , " impossible " ) ;
}
}
}
/* Default FSE distribution tables.
* These are pre - calculated FSE decoding tables using default distributions as defined in specification :
* https : //github.com/facebook/zstd/blob/master/doc/zstd_compression_format.md#default-distributions
* They were generated programmatically with following method :
* - start from default distributions , present in / lib / common / zstd_internal . h
* - generate tables normally , using ZSTD_buildFSETable ( )
* - printout the content of tables
* - pretify output , report below , test with fuzzer to ensure it ' s correct */
/* Default FSE distribution table for Literal Lengths */
static const ZSTD_seqSymbol LL_defaultDTable [ ( 1 < < LL_DEFAULTNORMLOG ) + 1 ] = {
{ 1 , 1 , 1 , LL_DEFAULTNORMLOG } , /* header : fastMode, tableLog */
/* nextState, nbAddBits, nbBits, baseVal */
{ 0 , 0 , 4 , 0 } , { 16 , 0 , 4 , 0 } ,
{ 32 , 0 , 5 , 1 } , { 0 , 0 , 5 , 3 } ,
{ 0 , 0 , 5 , 4 } , { 0 , 0 , 5 , 6 } ,
{ 0 , 0 , 5 , 7 } , { 0 , 0 , 5 , 9 } ,
{ 0 , 0 , 5 , 10 } , { 0 , 0 , 5 , 12 } ,
{ 0 , 0 , 6 , 14 } , { 0 , 1 , 5 , 16 } ,
{ 0 , 1 , 5 , 20 } , { 0 , 1 , 5 , 22 } ,
{ 0 , 2 , 5 , 28 } , { 0 , 3 , 5 , 32 } ,
{ 0 , 4 , 5 , 48 } , { 32 , 6 , 5 , 64 } ,
{ 0 , 7 , 5 , 128 } , { 0 , 8 , 6 , 256 } ,
{ 0 , 10 , 6 , 1024 } , { 0 , 12 , 6 , 4096 } ,
{ 32 , 0 , 4 , 0 } , { 0 , 0 , 4 , 1 } ,
{ 0 , 0 , 5 , 2 } , { 32 , 0 , 5 , 4 } ,
{ 0 , 0 , 5 , 5 } , { 32 , 0 , 5 , 7 } ,
{ 0 , 0 , 5 , 8 } , { 32 , 0 , 5 , 10 } ,
{ 0 , 0 , 5 , 11 } , { 0 , 0 , 6 , 13 } ,
{ 32 , 1 , 5 , 16 } , { 0 , 1 , 5 , 18 } ,
{ 32 , 1 , 5 , 22 } , { 0 , 2 , 5 , 24 } ,
{ 32 , 3 , 5 , 32 } , { 0 , 3 , 5 , 40 } ,
{ 0 , 6 , 4 , 64 } , { 16 , 6 , 4 , 64 } ,
{ 32 , 7 , 5 , 128 } , { 0 , 9 , 6 , 512 } ,
{ 0 , 11 , 6 , 2048 } , { 48 , 0 , 4 , 0 } ,
{ 16 , 0 , 4 , 1 } , { 32 , 0 , 5 , 2 } ,
{ 32 , 0 , 5 , 3 } , { 32 , 0 , 5 , 5 } ,
{ 32 , 0 , 5 , 6 } , { 32 , 0 , 5 , 8 } ,
{ 32 , 0 , 5 , 9 } , { 32 , 0 , 5 , 11 } ,
{ 32 , 0 , 5 , 12 } , { 0 , 0 , 6 , 15 } ,
{ 32 , 1 , 5 , 18 } , { 32 , 1 , 5 , 20 } ,
{ 32 , 2 , 5 , 24 } , { 32 , 2 , 5 , 28 } ,
{ 32 , 3 , 5 , 40 } , { 32 , 4 , 5 , 48 } ,
{ 0 , 16 , 6 , 65536 } , { 0 , 15 , 6 , 32768 } ,
{ 0 , 14 , 6 , 16384 } , { 0 , 13 , 6 , 8192 } ,
} ; /* LL_defaultDTable */
/* Default FSE distribution table for Offset Codes */
static const ZSTD_seqSymbol OF_defaultDTable [ ( 1 < < OF_DEFAULTNORMLOG ) + 1 ] = {
{ 1 , 1 , 1 , OF_DEFAULTNORMLOG } , /* header : fastMode, tableLog */
/* nextState, nbAddBits, nbBits, baseVal */
{ 0 , 0 , 5 , 0 } , { 0 , 6 , 4 , 61 } ,
{ 0 , 9 , 5 , 509 } , { 0 , 15 , 5 , 32765 } ,
{ 0 , 21 , 5 , 2097149 } , { 0 , 3 , 5 , 5 } ,
{ 0 , 7 , 4 , 125 } , { 0 , 12 , 5 , 4093 } ,
{ 0 , 18 , 5 , 262141 } , { 0 , 23 , 5 , 8388605 } ,
{ 0 , 5 , 5 , 29 } , { 0 , 8 , 4 , 253 } ,
{ 0 , 14 , 5 , 16381 } , { 0 , 20 , 5 , 1048573 } ,
{ 0 , 2 , 5 , 1 } , { 16 , 7 , 4 , 125 } ,
{ 0 , 11 , 5 , 2045 } , { 0 , 17 , 5 , 131069 } ,
{ 0 , 22 , 5 , 4194301 } , { 0 , 4 , 5 , 13 } ,
{ 16 , 8 , 4 , 253 } , { 0 , 13 , 5 , 8189 } ,
{ 0 , 19 , 5 , 524285 } , { 0 , 1 , 5 , 1 } ,
{ 16 , 6 , 4 , 61 } , { 0 , 10 , 5 , 1021 } ,
{ 0 , 16 , 5 , 65533 } , { 0 , 28 , 5 , 268435453 } ,
{ 0 , 27 , 5 , 134217725 } , { 0 , 26 , 5 , 67108861 } ,
{ 0 , 25 , 5 , 33554429 } , { 0 , 24 , 5 , 16777213 } ,
} ; /* OF_defaultDTable */
/* Default FSE distribution table for Match Lengths */
static const ZSTD_seqSymbol ML_defaultDTable [ ( 1 < < ML_DEFAULTNORMLOG ) + 1 ] = {
{ 1 , 1 , 1 , ML_DEFAULTNORMLOG } , /* header : fastMode, tableLog */
/* nextState, nbAddBits, nbBits, baseVal */
{ 0 , 0 , 6 , 3 } , { 0 , 0 , 4 , 4 } ,
{ 32 , 0 , 5 , 5 } , { 0 , 0 , 5 , 6 } ,
{ 0 , 0 , 5 , 8 } , { 0 , 0 , 5 , 9 } ,
{ 0 , 0 , 5 , 11 } , { 0 , 0 , 6 , 13 } ,
{ 0 , 0 , 6 , 16 } , { 0 , 0 , 6 , 19 } ,
{ 0 , 0 , 6 , 22 } , { 0 , 0 , 6 , 25 } ,
{ 0 , 0 , 6 , 28 } , { 0 , 0 , 6 , 31 } ,
{ 0 , 0 , 6 , 34 } , { 0 , 1 , 6 , 37 } ,
{ 0 , 1 , 6 , 41 } , { 0 , 2 , 6 , 47 } ,
{ 0 , 3 , 6 , 59 } , { 0 , 4 , 6 , 83 } ,
{ 0 , 7 , 6 , 131 } , { 0 , 9 , 6 , 515 } ,
{ 16 , 0 , 4 , 4 } , { 0 , 0 , 4 , 5 } ,
{ 32 , 0 , 5 , 6 } , { 0 , 0 , 5 , 7 } ,
{ 32 , 0 , 5 , 9 } , { 0 , 0 , 5 , 10 } ,
{ 0 , 0 , 6 , 12 } , { 0 , 0 , 6 , 15 } ,
{ 0 , 0 , 6 , 18 } , { 0 , 0 , 6 , 21 } ,
{ 0 , 0 , 6 , 24 } , { 0 , 0 , 6 , 27 } ,
{ 0 , 0 , 6 , 30 } , { 0 , 0 , 6 , 33 } ,
{ 0 , 1 , 6 , 35 } , { 0 , 1 , 6 , 39 } ,
{ 0 , 2 , 6 , 43 } , { 0 , 3 , 6 , 51 } ,
{ 0 , 4 , 6 , 67 } , { 0 , 5 , 6 , 99 } ,
{ 0 , 8 , 6 , 259 } , { 32 , 0 , 4 , 4 } ,
{ 48 , 0 , 4 , 4 } , { 16 , 0 , 4 , 5 } ,
{ 32 , 0 , 5 , 7 } , { 32 , 0 , 5 , 8 } ,
{ 32 , 0 , 5 , 10 } , { 32 , 0 , 5 , 11 } ,
{ 0 , 0 , 6 , 14 } , { 0 , 0 , 6 , 17 } ,
{ 0 , 0 , 6 , 20 } , { 0 , 0 , 6 , 23 } ,
{ 0 , 0 , 6 , 26 } , { 0 , 0 , 6 , 29 } ,
{ 0 , 0 , 6 , 32 } , { 0 , 16 , 6 , 65539 } ,
{ 0 , 15 , 6 , 32771 } , { 0 , 14 , 6 , 16387 } ,
{ 0 , 13 , 6 , 8195 } , { 0 , 12 , 6 , 4099 } ,
{ 0 , 11 , 6 , 2051 } , { 0 , 10 , 6 , 1027 } ,
} ; /* ML_defaultDTable */
static void ZSTD_buildSeqTable_rle ( ZSTD_seqSymbol * dt , U32 baseValue , U32 nbAddBits )
{
void * ptr = dt ;
ZSTD_seqSymbol_header * const DTableH = ( ZSTD_seqSymbol_header * ) ptr ;
ZSTD_seqSymbol * const cell = dt + 1 ;
DTableH - > tableLog = 0 ;
DTableH - > fastMode = 0 ;
cell - > nbBits = 0 ;
cell - > nextState = 0 ;
assert ( nbAddBits < 255 ) ;
cell - > nbAdditionalBits = ( BYTE ) nbAddBits ;
cell - > baseValue = baseValue ;
}
/* ZSTD_buildFSETable() :
* generate FSE decoding table for one symbol ( ll , ml or off )
* cannot fail if input is valid = >
* all inputs are presumed validated at this stage */
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FORCE_INLINE_TEMPLATE
void ZSTD_buildFSETable_body ( ZSTD_seqSymbol * dt ,
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const short * normalizedCounter , unsigned maxSymbolValue ,
const U32 * baseValue , const U32 * nbAdditionalBits ,
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unsigned tableLog , void * wksp , size_t wkspSize )
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{
ZSTD_seqSymbol * const tableDecode = dt + 1 ;
U32 const maxSV1 = maxSymbolValue + 1 ;
U32 const tableSize = 1 < < tableLog ;
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U16 * symbolNext = ( U16 * ) wksp ;
BYTE * spread = ( BYTE * ) ( symbolNext + MaxSeq + 1 ) ;
U32 highThreshold = tableSize - 1 ;
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/* Sanity Checks */
assert ( maxSymbolValue < = MaxSeq ) ;
assert ( tableLog < = MaxFSELog ) ;
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assert ( wkspSize > = ZSTD_BUILD_FSE_TABLE_WKSP_SIZE ) ;
( void ) wkspSize ;
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/* Init, lay down lowprob symbols */
{ ZSTD_seqSymbol_header DTableH ;
DTableH . tableLog = tableLog ;
DTableH . fastMode = 1 ;
{ S16 const largeLimit = ( S16 ) ( 1 < < ( tableLog - 1 ) ) ;
U32 s ;
for ( s = 0 ; s < maxSV1 ; s + + ) {
if ( normalizedCounter [ s ] = = - 1 ) {
tableDecode [ highThreshold - - ] . baseValue = s ;
symbolNext [ s ] = 1 ;
} else {
if ( normalizedCounter [ s ] > = largeLimit ) DTableH . fastMode = 0 ;
assert ( normalizedCounter [ s ] > = 0 ) ;
symbolNext [ s ] = ( U16 ) normalizedCounter [ s ] ;
} } }
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ZSTD_memcpy ( dt , & DTableH , sizeof ( DTableH ) ) ;
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}
/* Spread symbols */
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assert ( tableSize < = 512 ) ;
/* Specialized symbol spreading for the case when there are
* no low probability ( - 1 count ) symbols . When compressing
* small blocks we avoid low probability symbols to hit this
* case , since header decoding speed matters more .
*/
if ( highThreshold = = tableSize - 1 ) {
size_t const tableMask = tableSize - 1 ;
size_t const step = FSE_TABLESTEP ( tableSize ) ;
/* First lay down the symbols in order.
* We use a uint64_t to lay down 8 bytes at a time . This reduces branch
* misses since small blocks generally have small table logs , so nearly
* all symbols have counts < = 8. We ensure we have 8 bytes at the end of
* our buffer to handle the over - write .
*/
{
U64 const add = 0x0101010101010101ull ;
size_t pos = 0 ;
U64 sv = 0 ;
U32 s ;
for ( s = 0 ; s < maxSV1 ; + + s , sv + = add ) {
int i ;
int const n = normalizedCounter [ s ] ;
MEM_write64 ( spread + pos , sv ) ;
for ( i = 8 ; i < n ; i + = 8 ) {
MEM_write64 ( spread + pos + i , sv ) ;
}
pos + = n ;
}
}
/* Now we spread those positions across the table.
* The benefit of doing it in two stages is that we avoid the the
* variable size inner loop , which caused lots of branch misses .
* Now we can run through all the positions without any branch misses .
* We unroll the loop twice , since that is what emperically worked best .
*/
{
size_t position = 0 ;
size_t s ;
size_t const unroll = 2 ;
assert ( tableSize % unroll = = 0 ) ; /* FSE_MIN_TABLELOG is 5 */
for ( s = 0 ; s < ( size_t ) tableSize ; s + = unroll ) {
size_t u ;
for ( u = 0 ; u < unroll ; + + u ) {
size_t const uPosition = ( position + ( u * step ) ) & tableMask ;
tableDecode [ uPosition ] . baseValue = spread [ s + u ] ;
}
position = ( position + ( unroll * step ) ) & tableMask ;
}
assert ( position = = 0 ) ;
}
} else {
U32 const tableMask = tableSize - 1 ;
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U32 const step = FSE_TABLESTEP ( tableSize ) ;
U32 s , position = 0 ;
for ( s = 0 ; s < maxSV1 ; s + + ) {
int i ;
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int const n = normalizedCounter [ s ] ;
for ( i = 0 ; i < n ; i + + ) {
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tableDecode [ position ] . baseValue = s ;
position = ( position + step ) & tableMask ;
while ( position > highThreshold ) position = ( position + step ) & tableMask ; /* lowprob area */
} }
assert ( position = = 0 ) ; /* position must reach all cells once, otherwise normalizedCounter is incorrect */
}
/* Build Decoding table */
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{
U32 u ;
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for ( u = 0 ; u < tableSize ; u + + ) {
U32 const symbol = tableDecode [ u ] . baseValue ;
U32 const nextState = symbolNext [ symbol ] + + ;
tableDecode [ u ] . nbBits = ( BYTE ) ( tableLog - BIT_highbit32 ( nextState ) ) ;
tableDecode [ u ] . nextState = ( U16 ) ( ( nextState < < tableDecode [ u ] . nbBits ) - tableSize ) ;
assert ( nbAdditionalBits [ symbol ] < 255 ) ;
tableDecode [ u ] . nbAdditionalBits = ( BYTE ) nbAdditionalBits [ symbol ] ;
tableDecode [ u ] . baseValue = baseValue [ symbol ] ;
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}
}
}
/* Avoids the FORCE_INLINE of the _body() function. */
static void ZSTD_buildFSETable_body_default ( ZSTD_seqSymbol * dt ,
const short * normalizedCounter , unsigned maxSymbolValue ,
const U32 * baseValue , const U32 * nbAdditionalBits ,
unsigned tableLog , void * wksp , size_t wkspSize )
{
ZSTD_buildFSETable_body ( dt , normalizedCounter , maxSymbolValue ,
baseValue , nbAdditionalBits , tableLog , wksp , wkspSize ) ;
}
# if DYNAMIC_BMI2
TARGET_ATTRIBUTE ( " bmi2 " ) static void ZSTD_buildFSETable_body_bmi2 ( ZSTD_seqSymbol * dt ,
const short * normalizedCounter , unsigned maxSymbolValue ,
const U32 * baseValue , const U32 * nbAdditionalBits ,
unsigned tableLog , void * wksp , size_t wkspSize )
{
ZSTD_buildFSETable_body ( dt , normalizedCounter , maxSymbolValue ,
baseValue , nbAdditionalBits , tableLog , wksp , wkspSize ) ;
}
# endif
void ZSTD_buildFSETable ( ZSTD_seqSymbol * dt ,
const short * normalizedCounter , unsigned maxSymbolValue ,
const U32 * baseValue , const U32 * nbAdditionalBits ,
unsigned tableLog , void * wksp , size_t wkspSize , int bmi2 )
{
# if DYNAMIC_BMI2
if ( bmi2 ) {
ZSTD_buildFSETable_body_bmi2 ( dt , normalizedCounter , maxSymbolValue ,
baseValue , nbAdditionalBits , tableLog , wksp , wkspSize ) ;
return ;
}
# endif
( void ) bmi2 ;
ZSTD_buildFSETable_body_default ( dt , normalizedCounter , maxSymbolValue ,
baseValue , nbAdditionalBits , tableLog , wksp , wkspSize ) ;
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}
/*! ZSTD_buildSeqTable() :
* @ return : nb bytes read from src ,
* or an error code if it fails */
static size_t ZSTD_buildSeqTable ( ZSTD_seqSymbol * DTableSpace , const ZSTD_seqSymbol * * DTablePtr ,
symbolEncodingType_e type , unsigned max , U32 maxLog ,
const void * src , size_t srcSize ,
const U32 * baseValue , const U32 * nbAdditionalBits ,
const ZSTD_seqSymbol * defaultTable , U32 flagRepeatTable ,
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int ddictIsCold , int nbSeq , U32 * wksp , size_t wkspSize ,
int bmi2 )
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{
switch ( type )
{
case set_rle :
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RETURN_ERROR_IF ( ! srcSize , srcSize_wrong , " " ) ;
RETURN_ERROR_IF ( ( * ( const BYTE * ) src ) > max , corruption_detected , " " ) ;
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{ U32 const symbol = * ( const BYTE * ) src ;
U32 const baseline = baseValue [ symbol ] ;
U32 const nbBits = nbAdditionalBits [ symbol ] ;
ZSTD_buildSeqTable_rle ( DTableSpace , baseline , nbBits ) ;
}
* DTablePtr = DTableSpace ;
return 1 ;
case set_basic :
* DTablePtr = defaultTable ;
return 0 ;
case set_repeat :
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RETURN_ERROR_IF ( ! flagRepeatTable , corruption_detected , " " ) ;
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/* prefetch FSE table if used */
if ( ddictIsCold & & ( nbSeq > 24 /* heuristic */ ) ) {
const void * const pStart = * DTablePtr ;
size_t const pSize = sizeof ( ZSTD_seqSymbol ) * ( SEQSYMBOL_TABLE_SIZE ( maxLog ) ) ;
PREFETCH_AREA ( pStart , pSize ) ;
}
return 0 ;
case set_compressed :
{ unsigned tableLog ;
S16 norm [ MaxSeq + 1 ] ;
size_t const headerSize = FSE_readNCount ( norm , & max , & tableLog , src , srcSize ) ;
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RETURN_ERROR_IF ( FSE_isError ( headerSize ) , corruption_detected , " " ) ;
RETURN_ERROR_IF ( tableLog > maxLog , corruption_detected , " " ) ;
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ZSTD_buildFSETable ( DTableSpace , norm , max , baseValue , nbAdditionalBits , tableLog , wksp , wkspSize , bmi2 ) ;
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* DTablePtr = DTableSpace ;
return headerSize ;
}
default :
assert ( 0 ) ;
RETURN_ERROR ( GENERIC , " impossible " ) ;
}
}
size_t ZSTD_decodeSeqHeaders ( ZSTD_DCtx * dctx , int * nbSeqPtr ,
const void * src , size_t srcSize )
{
const BYTE * const istart = ( const BYTE * const ) src ;
const BYTE * const iend = istart + srcSize ;
const BYTE * ip = istart ;
int nbSeq ;
DEBUGLOG ( 5 , " ZSTD_decodeSeqHeaders " ) ;
/* check */
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RETURN_ERROR_IF ( srcSize < MIN_SEQUENCES_SIZE , srcSize_wrong , " " ) ;
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/* SeqHead */
nbSeq = * ip + + ;
if ( ! nbSeq ) {
* nbSeqPtr = 0 ;
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RETURN_ERROR_IF ( srcSize ! = 1 , srcSize_wrong , " " ) ;
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return 1 ;
}
if ( nbSeq > 0x7F ) {
if ( nbSeq = = 0xFF ) {
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RETURN_ERROR_IF ( ip + 2 > iend , srcSize_wrong , " " ) ;
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nbSeq = MEM_readLE16 ( ip ) + LONGNBSEQ ;
ip + = 2 ;
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} else {
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RETURN_ERROR_IF ( ip > = iend , srcSize_wrong , " " ) ;
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nbSeq = ( ( nbSeq - 0x80 ) < < 8 ) + * ip + + ;
}
}
* nbSeqPtr = nbSeq ;
/* FSE table descriptors */
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RETURN_ERROR_IF ( ip + 1 > iend , srcSize_wrong , " " ) ; /* minimum possible size: 1 byte for symbol encoding types */
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{ symbolEncodingType_e const LLtype = ( symbolEncodingType_e ) ( * ip > > 6 ) ;
symbolEncodingType_e const OFtype = ( symbolEncodingType_e ) ( ( * ip > > 4 ) & 3 ) ;
symbolEncodingType_e const MLtype = ( symbolEncodingType_e ) ( ( * ip > > 2 ) & 3 ) ;
ip + + ;
/* Build DTables */
{ size_t const llhSize = ZSTD_buildSeqTable ( dctx - > entropy . LLTable , & dctx - > LLTptr ,
LLtype , MaxLL , LLFSELog ,
ip , iend - ip ,
LL_base , LL_bits ,
LL_defaultDTable , dctx - > fseEntropy ,
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dctx - > ddictIsCold , nbSeq ,
dctx - > workspace , sizeof ( dctx - > workspace ) ,
dctx - > bmi2 ) ;
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RETURN_ERROR_IF ( ZSTD_isError ( llhSize ) , corruption_detected , " ZSTD_buildSeqTable failed " ) ;
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ip + = llhSize ;
}
{ size_t const ofhSize = ZSTD_buildSeqTable ( dctx - > entropy . OFTable , & dctx - > OFTptr ,
OFtype , MaxOff , OffFSELog ,
ip , iend - ip ,
OF_base , OF_bits ,
OF_defaultDTable , dctx - > fseEntropy ,
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dctx - > ddictIsCold , nbSeq ,
dctx - > workspace , sizeof ( dctx - > workspace ) ,
dctx - > bmi2 ) ;
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RETURN_ERROR_IF ( ZSTD_isError ( ofhSize ) , corruption_detected , " ZSTD_buildSeqTable failed " ) ;
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ip + = ofhSize ;
}
{ size_t const mlhSize = ZSTD_buildSeqTable ( dctx - > entropy . MLTable , & dctx - > MLTptr ,
MLtype , MaxML , MLFSELog ,
ip , iend - ip ,
ML_base , ML_bits ,
ML_defaultDTable , dctx - > fseEntropy ,
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dctx - > ddictIsCold , nbSeq ,
dctx - > workspace , sizeof ( dctx - > workspace ) ,
dctx - > bmi2 ) ;
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RETURN_ERROR_IF ( ZSTD_isError ( mlhSize ) , corruption_detected , " ZSTD_buildSeqTable failed " ) ;
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ip + = mlhSize ;
}
}
return ip - istart ;
}
typedef struct {
size_t litLength ;
size_t matchLength ;
size_t offset ;
const BYTE * match ;
} seq_t ;
typedef struct {
size_t state ;
const ZSTD_seqSymbol * table ;
} ZSTD_fseState ;
typedef struct {
BIT_DStream_t DStream ;
ZSTD_fseState stateLL ;
ZSTD_fseState stateOffb ;
ZSTD_fseState stateML ;
size_t prevOffset [ ZSTD_REP_NUM ] ;
const BYTE * prefixStart ;
const BYTE * dictEnd ;
size_t pos ;
} seqState_t ;
/*! ZSTD_overlapCopy8() :
* Copies 8 bytes from ip to op and updates op and ip where ip < = op .
* If the offset is < 8 then the offset is spread to at least 8 bytes .
*
* Precondition : * ip < = * op
* Postcondition : * op - * op > = 8
*/
HINT_INLINE void ZSTD_overlapCopy8 ( BYTE * * op , BYTE const * * ip , size_t offset ) {
assert ( * ip < = * op ) ;
if ( offset < 8 ) {
/* close range match, overlap */
static const U32 dec32table [ ] = { 0 , 1 , 2 , 1 , 4 , 4 , 4 , 4 } ; /* added */
static const int dec64table [ ] = { 8 , 8 , 8 , 7 , 8 , 9 , 10 , 11 } ; /* subtracted */
int const sub2 = dec64table [ offset ] ;
( * op ) [ 0 ] = ( * ip ) [ 0 ] ;
( * op ) [ 1 ] = ( * ip ) [ 1 ] ;
( * op ) [ 2 ] = ( * ip ) [ 2 ] ;
( * op ) [ 3 ] = ( * ip ) [ 3 ] ;
* ip + = dec32table [ offset ] ;
ZSTD_copy4 ( * op + 4 , * ip ) ;
* ip - = sub2 ;
} else {
ZSTD_copy8 ( * op , * ip ) ;
}
* ip + = 8 ;
* op + = 8 ;
assert ( * op - * ip > = 8 ) ;
}
/*! ZSTD_safecopy() :
* Specialized version of memcpy ( ) that is allowed to READ up to WILDCOPY_OVERLENGTH past the input buffer
* and write up to 16 bytes past oend_w ( op > = oend_w is allowed ) .
* This function is only called in the uncommon case where the sequence is near the end of the block . It
* should be fast for a single long sequence , but can be slow for several short sequences .
*
* @ param ovtype controls the overlap detection
* - ZSTD_no_overlap : The source and destination are guaranteed to be at least WILDCOPY_VECLEN bytes apart .
* - ZSTD_overlap_src_before_dst : The src and dst may overlap and may be any distance apart .
* The src buffer must be before the dst buffer .
*/
static void ZSTD_safecopy ( BYTE * op , BYTE * const oend_w , BYTE const * ip , ptrdiff_t length , ZSTD_overlap_e ovtype ) {
ptrdiff_t const diff = op - ip ;
BYTE * const oend = op + length ;
assert ( ( ovtype = = ZSTD_no_overlap & & ( diff < = - 8 | | diff > = 8 | | op > = oend_w ) ) | |
( ovtype = = ZSTD_overlap_src_before_dst & & diff > = 0 ) ) ;
if ( length < 8 ) {
/* Handle short lengths. */
while ( op < oend ) * op + + = * ip + + ;
return ;
}
if ( ovtype = = ZSTD_overlap_src_before_dst ) {
/* Copy 8 bytes and ensure the offset >= 8 when there can be overlap. */
assert ( length > = 8 ) ;
ZSTD_overlapCopy8 ( & op , & ip , diff ) ;
assert ( op - ip > = 8 ) ;
assert ( op < = oend ) ;
}
if ( oend < = oend_w ) {
/* No risk of overwrite. */
ZSTD_wildcopy ( op , ip , length , ovtype ) ;
return ;
}
if ( op < = oend_w ) {
/* Wildcopy until we get close to the end. */
assert ( oend > oend_w ) ;
ZSTD_wildcopy ( op , ip , oend_w - op , ovtype ) ;
ip + = oend_w - op ;
op = oend_w ;
}
/* Handle the leftovers. */
while ( op < oend ) * op + + = * ip + + ;
}
/* ZSTD_execSequenceEnd():
* This version handles cases that are near the end of the output buffer . It requires
* more careful checks to make sure there is no overflow . By separating out these hard
* and unlikely cases , we can speed up the common cases .
*
* NOTE : This function needs to be fast for a single long sequence , but doesn ' t need
* to be optimized for many small sequences , since those fall into ZSTD_execSequence ( ) .
*/
FORCE_NOINLINE
size_t ZSTD_execSequenceEnd ( BYTE * op ,
BYTE * const oend , seq_t sequence ,
const BYTE * * litPtr , const BYTE * const litLimit ,
const BYTE * const prefixStart , const BYTE * const virtualStart , const BYTE * const dictEnd )
{
BYTE * const oLitEnd = op + sequence . litLength ;
size_t const sequenceLength = sequence . litLength + sequence . matchLength ;
const BYTE * const iLitEnd = * litPtr + sequence . litLength ;
const BYTE * match = oLitEnd - sequence . offset ;
BYTE * const oend_w = oend - WILDCOPY_OVERLENGTH ;
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/* bounds checks : careful of address space overflow in 32-bit mode */
RETURN_ERROR_IF ( sequenceLength > ( size_t ) ( oend - op ) , dstSize_tooSmall , " last match must fit within dstBuffer " ) ;
RETURN_ERROR_IF ( sequence . litLength > ( size_t ) ( litLimit - * litPtr ) , corruption_detected , " try to read beyond literal buffer " ) ;
assert ( op < op + sequenceLength ) ;
assert ( oLitEnd < op + sequenceLength ) ;
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/* copy literals */
ZSTD_safecopy ( op , oend_w , * litPtr , sequence . litLength , ZSTD_no_overlap ) ;
op = oLitEnd ;
* litPtr = iLitEnd ;
/* copy Match */
if ( sequence . offset > ( size_t ) ( oLitEnd - prefixStart ) ) {
/* offset beyond prefix */
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RETURN_ERROR_IF ( sequence . offset > ( size_t ) ( oLitEnd - virtualStart ) , corruption_detected , " " ) ;
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match = dictEnd - ( prefixStart - match ) ;
if ( match + sequence . matchLength < = dictEnd ) {
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ZSTD_memmove ( oLitEnd , match , sequence . matchLength ) ;
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return sequenceLength ;
}
/* span extDict & currentPrefixSegment */
{ size_t const length1 = dictEnd - match ;
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ZSTD_memmove ( oLitEnd , match , length1 ) ;
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op = oLitEnd + length1 ;
sequence . matchLength - = length1 ;
match = prefixStart ;
} }
ZSTD_safecopy ( op , oend_w , match , sequence . matchLength , ZSTD_overlap_src_before_dst ) ;
return sequenceLength ;
}
HINT_INLINE
size_t ZSTD_execSequence ( BYTE * op ,
BYTE * const oend , seq_t sequence ,
const BYTE * * litPtr , const BYTE * const litLimit ,
const BYTE * const prefixStart , const BYTE * const virtualStart , const BYTE * const dictEnd )
{
BYTE * const oLitEnd = op + sequence . litLength ;
size_t const sequenceLength = sequence . litLength + sequence . matchLength ;
BYTE * const oMatchEnd = op + sequenceLength ; /* risk : address space overflow (32-bits) */
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BYTE * const oend_w = oend - WILDCOPY_OVERLENGTH ; /* risk : address space underflow on oend=NULL */
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const BYTE * const iLitEnd = * litPtr + sequence . litLength ;
const BYTE * match = oLitEnd - sequence . offset ;
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assert ( op ! = NULL /* Precondition */ ) ;
assert ( oend_w < oend /* No underflow */ ) ;
/* Handle edge cases in a slow path:
* - Read beyond end of literals
* - Match end is within WILDCOPY_OVERLIMIT of oend
* - 32 - bit mode and the match length overflows
*/
if ( UNLIKELY (
iLitEnd > litLimit | |
oMatchEnd > oend_w | |
( MEM_32bits ( ) & & ( size_t ) ( oend - op ) < sequenceLength + WILDCOPY_OVERLENGTH ) ) )
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return ZSTD_execSequenceEnd ( op , oend , sequence , litPtr , litLimit , prefixStart , virtualStart , dictEnd ) ;
/* Assumptions (everything else goes into ZSTD_execSequenceEnd()) */
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assert ( op < = oLitEnd /* No overflow */ ) ;
assert ( oLitEnd < oMatchEnd /* Non-zero match & no overflow */ ) ;
assert ( oMatchEnd < = oend /* No underflow */ ) ;
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assert ( iLitEnd < = litLimit /* Literal length is in bounds */ ) ;
assert ( oLitEnd < = oend_w /* Can wildcopy literals */ ) ;
assert ( oMatchEnd < = oend_w /* Can wildcopy matches */ ) ;
/* Copy Literals:
* Split out litLength < = 16 since it is nearly always true . + 1.6 % on gcc - 9.
* We likely don ' t need the full 32 - byte wildcopy .
*/
assert ( WILDCOPY_OVERLENGTH > = 16 ) ;
ZSTD_copy16 ( op , ( * litPtr ) ) ;
if ( UNLIKELY ( sequence . litLength > 16 ) ) {
ZSTD_wildcopy ( op + 16 , ( * litPtr ) + 16 , sequence . litLength - 16 , ZSTD_no_overlap ) ;
}
op = oLitEnd ;
* litPtr = iLitEnd ; /* update for next sequence */
/* Copy Match */
if ( sequence . offset > ( size_t ) ( oLitEnd - prefixStart ) ) {
/* offset beyond prefix -> go into extDict */
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RETURN_ERROR_IF ( UNLIKELY ( sequence . offset > ( size_t ) ( oLitEnd - virtualStart ) ) , corruption_detected , " " ) ;
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match = dictEnd + ( match - prefixStart ) ;
if ( match + sequence . matchLength < = dictEnd ) {
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ZSTD_memmove ( oLitEnd , match , sequence . matchLength ) ;
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return sequenceLength ;
}
/* span extDict & currentPrefixSegment */
{ size_t const length1 = dictEnd - match ;
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ZSTD_memmove ( oLitEnd , match , length1 ) ;
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op = oLitEnd + length1 ;
sequence . matchLength - = length1 ;
match = prefixStart ;
} }
/* Match within prefix of 1 or more bytes */
assert ( op < = oMatchEnd ) ;
assert ( oMatchEnd < = oend_w ) ;
assert ( match > = prefixStart ) ;
assert ( sequence . matchLength > = 1 ) ;
/* Nearly all offsets are >= WILDCOPY_VECLEN bytes, which means we can use wildcopy
* without overlap checking .
*/
if ( LIKELY ( sequence . offset > = WILDCOPY_VECLEN ) ) {
/* We bet on a full wildcopy for matches, since we expect matches to be
* longer than literals ( in general ) . In silesia , ~ 10 % of matches are longer
* than 16 bytes .
*/
ZSTD_wildcopy ( op , match , ( ptrdiff_t ) sequence . matchLength , ZSTD_no_overlap ) ;
return sequenceLength ;
}
assert ( sequence . offset < WILDCOPY_VECLEN ) ;
/* Copy 8 bytes and spread the offset to be >= 8. */
ZSTD_overlapCopy8 ( & op , & match , sequence . offset ) ;
/* If the match length is > 8 bytes, then continue with the wildcopy. */
if ( sequence . matchLength > 8 ) {
assert ( op < oMatchEnd ) ;
ZSTD_wildcopy ( op , match , ( ptrdiff_t ) sequence . matchLength - 8 , ZSTD_overlap_src_before_dst ) ;
}
return sequenceLength ;
}
static void
ZSTD_initFseState ( ZSTD_fseState * DStatePtr , BIT_DStream_t * bitD , const ZSTD_seqSymbol * dt )
{
const void * ptr = dt ;
const ZSTD_seqSymbol_header * const DTableH = ( const ZSTD_seqSymbol_header * ) ptr ;
DStatePtr - > state = BIT_readBits ( bitD , DTableH - > tableLog ) ;
DEBUGLOG ( 6 , " ZSTD_initFseState : val=%u using %u bits " ,
( U32 ) DStatePtr - > state , DTableH - > tableLog ) ;
BIT_reloadDStream ( bitD ) ;
DStatePtr - > table = dt + 1 ;
}
FORCE_INLINE_TEMPLATE void
ZSTD_updateFseState ( ZSTD_fseState * DStatePtr , BIT_DStream_t * bitD )
{
ZSTD_seqSymbol const DInfo = DStatePtr - > table [ DStatePtr - > state ] ;
U32 const nbBits = DInfo . nbBits ;
size_t const lowBits = BIT_readBits ( bitD , nbBits ) ;
DStatePtr - > state = DInfo . nextState + lowBits ;
}
FORCE_INLINE_TEMPLATE void
ZSTD_updateFseStateWithDInfo ( ZSTD_fseState * DStatePtr , BIT_DStream_t * bitD , ZSTD_seqSymbol const DInfo )
{
U32 const nbBits = DInfo . nbBits ;
size_t const lowBits = BIT_readBits ( bitD , nbBits ) ;
DStatePtr - > state = DInfo . nextState + lowBits ;
}
/* We need to add at most (ZSTD_WINDOWLOG_MAX_32 - 1) bits to read the maximum
* offset bits . But we can only read at most ( STREAM_ACCUMULATOR_MIN_32 - 1 )
* bits before reloading . This value is the maximum number of bytes we read
* after reloading when we are decoding long offsets .
*/
# define LONG_OFFSETS_MAX_EXTRA_BITS_32 \
( ZSTD_WINDOWLOG_MAX_32 > STREAM_ACCUMULATOR_MIN_32 \
? ZSTD_WINDOWLOG_MAX_32 - STREAM_ACCUMULATOR_MIN_32 \
: 0 )
typedef enum { ZSTD_lo_isRegularOffset , ZSTD_lo_isLongOffset = 1 } ZSTD_longOffset_e ;
typedef enum { ZSTD_p_noPrefetch = 0 , ZSTD_p_prefetch = 1 } ZSTD_prefetch_e ;
FORCE_INLINE_TEMPLATE seq_t
ZSTD_decodeSequence ( seqState_t * seqState , const ZSTD_longOffset_e longOffsets , const ZSTD_prefetch_e prefetch )
{
seq_t seq ;
ZSTD_seqSymbol const llDInfo = seqState - > stateLL . table [ seqState - > stateLL . state ] ;
ZSTD_seqSymbol const mlDInfo = seqState - > stateML . table [ seqState - > stateML . state ] ;
ZSTD_seqSymbol const ofDInfo = seqState - > stateOffb . table [ seqState - > stateOffb . state ] ;
U32 const llBase = llDInfo . baseValue ;
U32 const mlBase = mlDInfo . baseValue ;
U32 const ofBase = ofDInfo . baseValue ;
BYTE const llBits = llDInfo . nbAdditionalBits ;
BYTE const mlBits = mlDInfo . nbAdditionalBits ;
BYTE const ofBits = ofDInfo . nbAdditionalBits ;
BYTE const totalBits = llBits + mlBits + ofBits ;
/* sequence */
{ size_t offset ;
if ( ofBits > 1 ) {
ZSTD_STATIC_ASSERT ( ZSTD_lo_isLongOffset = = 1 ) ;
ZSTD_STATIC_ASSERT ( LONG_OFFSETS_MAX_EXTRA_BITS_32 = = 5 ) ;
assert ( ofBits < = MaxOff ) ;
if ( MEM_32bits ( ) & & longOffsets & & ( ofBits > = STREAM_ACCUMULATOR_MIN_32 ) ) {
U32 const extraBits = ofBits - MIN ( ofBits , 32 - seqState - > DStream . bitsConsumed ) ;
offset = ofBase + ( BIT_readBitsFast ( & seqState - > DStream , ofBits - extraBits ) < < extraBits ) ;
BIT_reloadDStream ( & seqState - > DStream ) ;
if ( extraBits ) offset + = BIT_readBitsFast ( & seqState - > DStream , extraBits ) ;
assert ( extraBits < = LONG_OFFSETS_MAX_EXTRA_BITS_32 ) ; /* to avoid another reload */
} else {
offset = ofBase + BIT_readBitsFast ( & seqState - > DStream , ofBits /*>0*/ ) ; /* <= (ZSTD_WINDOWLOG_MAX-1) bits */
if ( MEM_32bits ( ) ) BIT_reloadDStream ( & seqState - > DStream ) ;
}
seqState - > prevOffset [ 2 ] = seqState - > prevOffset [ 1 ] ;
seqState - > prevOffset [ 1 ] = seqState - > prevOffset [ 0 ] ;
seqState - > prevOffset [ 0 ] = offset ;
} else {
U32 const ll0 = ( llBase = = 0 ) ;
if ( LIKELY ( ( ofBits = = 0 ) ) ) {
if ( LIKELY ( ! ll0 ) )
offset = seqState - > prevOffset [ 0 ] ;
else {
offset = seqState - > prevOffset [ 1 ] ;
seqState - > prevOffset [ 1 ] = seqState - > prevOffset [ 0 ] ;
seqState - > prevOffset [ 0 ] = offset ;
}
} else {
offset = ofBase + ll0 + BIT_readBitsFast ( & seqState - > DStream , 1 ) ;
{ size_t temp = ( offset = = 3 ) ? seqState - > prevOffset [ 0 ] - 1 : seqState - > prevOffset [ offset ] ;
temp + = ! temp ; /* 0 is not valid; input is corrupted; force offset to 1 */
if ( offset ! = 1 ) seqState - > prevOffset [ 2 ] = seqState - > prevOffset [ 1 ] ;
seqState - > prevOffset [ 1 ] = seqState - > prevOffset [ 0 ] ;
seqState - > prevOffset [ 0 ] = offset = temp ;
} } }
seq . offset = offset ;
}
seq . matchLength = mlBase ;
if ( mlBits > 0 )
seq . matchLength + = BIT_readBitsFast ( & seqState - > DStream , mlBits /*>0*/ ) ;
if ( MEM_32bits ( ) & & ( mlBits + llBits > = STREAM_ACCUMULATOR_MIN_32 - LONG_OFFSETS_MAX_EXTRA_BITS_32 ) )
BIT_reloadDStream ( & seqState - > DStream ) ;
if ( MEM_64bits ( ) & & UNLIKELY ( totalBits > = STREAM_ACCUMULATOR_MIN_64 - ( LLFSELog + MLFSELog + OffFSELog ) ) )
BIT_reloadDStream ( & seqState - > DStream ) ;
/* Ensure there are enough bits to read the rest of data in 64-bit mode. */
ZSTD_STATIC_ASSERT ( 16 + LLFSELog + MLFSELog + OffFSELog < STREAM_ACCUMULATOR_MIN_64 ) ;
seq . litLength = llBase ;
if ( llBits > 0 )
seq . litLength + = BIT_readBitsFast ( & seqState - > DStream , llBits /*>0*/ ) ;
if ( MEM_32bits ( ) )
BIT_reloadDStream ( & seqState - > DStream ) ;
DEBUGLOG ( 6 , " seq: litL=%u, matchL=%u, offset=%u " ,
( U32 ) seq . litLength , ( U32 ) seq . matchLength , ( U32 ) seq . offset ) ;
if ( prefetch = = ZSTD_p_prefetch ) {
size_t const pos = seqState - > pos + seq . litLength ;
const BYTE * const matchBase = ( seq . offset > pos ) ? seqState - > dictEnd : seqState - > prefixStart ;
seq . match = matchBase + pos - seq . offset ; /* note : this operation can overflow when seq.offset is really too large, which can only happen when input is corrupted.
* No consequence though : no memory access will occur , offset is only used for prefetching */
seqState - > pos = pos + seq . matchLength ;
}
/* ANS state update
* gcc - 9.0 .0 does 2.5 % worse with ZSTD_updateFseStateWithDInfo ( ) .
* clang - 9.2 .0 does 7 % worse with ZSTD_updateFseState ( ) .
* Naturally it seems like ZSTD_updateFseStateWithDInfo ( ) should be the
* better option , so it is the default for other compilers . But , if you
* measure that it is worse , please put up a pull request .
*/
{
# if defined(__GNUC__) && !defined(__clang__)
const int kUseUpdateFseState = 1 ;
# else
const int kUseUpdateFseState = 0 ;
# endif
if ( kUseUpdateFseState ) {
ZSTD_updateFseState ( & seqState - > stateLL , & seqState - > DStream ) ; /* <= 9 bits */
ZSTD_updateFseState ( & seqState - > stateML , & seqState - > DStream ) ; /* <= 9 bits */
if ( MEM_32bits ( ) ) BIT_reloadDStream ( & seqState - > DStream ) ; /* <= 18 bits */
ZSTD_updateFseState ( & seqState - > stateOffb , & seqState - > DStream ) ; /* <= 8 bits */
} else {
ZSTD_updateFseStateWithDInfo ( & seqState - > stateLL , & seqState - > DStream , llDInfo ) ; /* <= 9 bits */
ZSTD_updateFseStateWithDInfo ( & seqState - > stateML , & seqState - > DStream , mlDInfo ) ; /* <= 9 bits */
if ( MEM_32bits ( ) ) BIT_reloadDStream ( & seqState - > DStream ) ; /* <= 18 bits */
ZSTD_updateFseStateWithDInfo ( & seqState - > stateOffb , & seqState - > DStream , ofDInfo ) ; /* <= 8 bits */
}
}
return seq ;
}
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# ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
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MEM_STATIC int ZSTD_dictionaryIsActive ( ZSTD_DCtx const * dctx , BYTE const * prefixStart , BYTE const * oLitEnd )
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{
size_t const windowSize = dctx - > fParams . windowSize ;
/* No dictionary used. */
if ( dctx - > dictContentEndForFuzzing = = NULL ) return 0 ;
/* Dictionary is our prefix. */
if ( prefixStart = = dctx - > dictContentBeginForFuzzing ) return 1 ;
/* Dictionary is not our ext-dict. */
if ( dctx - > dictEnd ! = dctx - > dictContentEndForFuzzing ) return 0 ;
/* Dictionary is not within our window size. */
if ( ( size_t ) ( oLitEnd - prefixStart ) > = windowSize ) return 0 ;
/* Dictionary is active. */
return 1 ;
}
MEM_STATIC void ZSTD_assertValidSequence (
ZSTD_DCtx const * dctx ,
BYTE const * op , BYTE const * oend ,
seq_t const seq ,
BYTE const * prefixStart , BYTE const * virtualStart )
{
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# if DEBUGLEVEL >= 1
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size_t const windowSize = dctx - > fParams . windowSize ;
size_t const sequenceSize = seq . litLength + seq . matchLength ;
BYTE const * const oLitEnd = op + seq . litLength ;
DEBUGLOG ( 6 , " Checking sequence: litL=%u matchL=%u offset=%u " ,
( U32 ) seq . litLength , ( U32 ) seq . matchLength , ( U32 ) seq . offset ) ;
assert ( op < = oend ) ;
assert ( ( size_t ) ( oend - op ) > = sequenceSize ) ;
assert ( sequenceSize < = ZSTD_BLOCKSIZE_MAX ) ;
if ( ZSTD_dictionaryIsActive ( dctx , prefixStart , oLitEnd ) ) {
size_t const dictSize = ( size_t ) ( ( char const * ) dctx - > dictContentEndForFuzzing - ( char const * ) dctx - > dictContentBeginForFuzzing ) ;
/* Offset must be within the dictionary. */
assert ( seq . offset < = ( size_t ) ( oLitEnd - virtualStart ) ) ;
assert ( seq . offset < = windowSize + dictSize ) ;
} else {
/* Offset must be within our window. */
assert ( seq . offset < = windowSize ) ;
}
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# else
( void ) dctx , ( void ) op , ( void ) oend , ( void ) seq , ( void ) prefixStart , ( void ) virtualStart ;
# endif
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}
# endif
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# ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG
FORCE_INLINE_TEMPLATE size_t
DONT_VECTORIZE
ZSTD_decompressSequences_body ( ZSTD_DCtx * dctx ,
void * dst , size_t maxDstSize ,
const void * seqStart , size_t seqSize , int nbSeq ,
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const ZSTD_longOffset_e isLongOffset ,
const int frame )
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{
const BYTE * ip = ( const BYTE * ) seqStart ;
const BYTE * const iend = ip + seqSize ;
BYTE * const ostart = ( BYTE * const ) dst ;
BYTE * const oend = ostart + maxDstSize ;
BYTE * op = ostart ;
const BYTE * litPtr = dctx - > litPtr ;
const BYTE * const litEnd = litPtr + dctx - > litSize ;
const BYTE * const prefixStart = ( const BYTE * ) ( dctx - > prefixStart ) ;
const BYTE * const vBase = ( const BYTE * ) ( dctx - > virtualStart ) ;
const BYTE * const dictEnd = ( const BYTE * ) ( dctx - > dictEnd ) ;
DEBUGLOG ( 5 , " ZSTD_decompressSequences_body " ) ;
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( void ) frame ;
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/* Regen sequences */
if ( nbSeq ) {
seqState_t seqState ;
size_t error = 0 ;
dctx - > fseEntropy = 1 ;
{ U32 i ; for ( i = 0 ; i < ZSTD_REP_NUM ; i + + ) seqState . prevOffset [ i ] = dctx - > entropy . rep [ i ] ; }
RETURN_ERROR_IF (
ERR_isError ( BIT_initDStream ( & seqState . DStream , ip , iend - ip ) ) ,
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corruption_detected , " " ) ;
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ZSTD_initFseState ( & seqState . stateLL , & seqState . DStream , dctx - > LLTptr ) ;
ZSTD_initFseState ( & seqState . stateOffb , & seqState . DStream , dctx - > OFTptr ) ;
ZSTD_initFseState ( & seqState . stateML , & seqState . DStream , dctx - > MLTptr ) ;
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assert ( dst ! = NULL ) ;
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ZSTD_STATIC_ASSERT (
BIT_DStream_unfinished < BIT_DStream_completed & &
BIT_DStream_endOfBuffer < BIT_DStream_completed & &
BIT_DStream_completed < BIT_DStream_overflow ) ;
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# if defined(__GNUC__) && defined(__x86_64__)
/* Align the decompression loop to 32 + 16 bytes.
*
* zstd compiled with gcc - 9 on an Intel i9 - 9900 k shows 10 % decompression
* speed swings based on the alignment of the decompression loop . This
* performance swing is caused by parts of the decompression loop falling
* out of the DSB . The entire decompression loop should fit in the DSB ,
* when it can ' t we get much worse performance . You can measure if you ' ve
* hit the good case or the bad case with this perf command for some
* compressed file test . zst :
*
* perf stat - e cycles - e instructions - e idq . all_dsb_cycles_any_uops \
* - e idq . all_mite_cycles_any_uops - - . / zstd - tq test . zst
*
* If you see most cycles served out of the MITE you ' ve hit the bad case .
* If you see most cycles served out of the DSB you ' ve hit the good case .
* If it is pretty even then you may be in an okay case .
*
* I ' ve been able to reproduce this issue on the following CPUs :
* - Kabylake : Macbook Pro ( 15 - inch , 2019 ) 2.4 GHz Intel Core i9
* Use Instruments - > Counters to get DSB / MITE cycles .
* I never got performance swings , but I was able to
* go from the good case of mostly DSB to half of the
* cycles served from MITE .
* - Coffeelake : Intel i9 - 9900 k
*
* I haven ' t been able to reproduce the instability or DSB misses on any
* of the following CPUS :
* - Haswell
* - Broadwell : Intel ( R ) Xeon ( R ) CPU E5 - 2680 v4 @ 2.40 GH
* - Skylake
*
* If you are seeing performance stability this script can help test .
* It tests on 4 commits in zstd where I saw performance change .
*
* https : //gist.github.com/terrelln/9889fc06a423fd5ca6e99351564473f4
*/
__asm__ ( " .p2align 5 " ) ;
__asm__ ( " nop " ) ;
__asm__ ( " .p2align 4 " ) ;
# endif
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for ( ; ; ) {
seq_t const sequence = ZSTD_decodeSequence ( & seqState , isLongOffset , ZSTD_p_noPrefetch ) ;
size_t const oneSeqSize = ZSTD_execSequence ( op , oend , sequence , & litPtr , litEnd , prefixStart , vBase , dictEnd ) ;
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# if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
assert ( ! ZSTD_isError ( oneSeqSize ) ) ;
if ( frame ) ZSTD_assertValidSequence ( dctx , op , oend , sequence , prefixStart , vBase ) ;
# endif
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DEBUGLOG ( 6 , " regenerated sequence size : %u " , ( U32 ) oneSeqSize ) ;
BIT_reloadDStream ( & ( seqState . DStream ) ) ;
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op + = oneSeqSize ;
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/* gcc and clang both don't like early returns in this loop.
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* Instead break and check for an error at the end of the loop .
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*/
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if ( UNLIKELY ( ZSTD_isError ( oneSeqSize ) ) ) {
error = oneSeqSize ;
break ;
}
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if ( UNLIKELY ( ! - - nbSeq ) ) break ;
}
/* check if reached exact end */
DEBUGLOG ( 5 , " ZSTD_decompressSequences_body: after decode loop, remaining nbSeq : %i " , nbSeq ) ;
if ( ZSTD_isError ( error ) ) return error ;
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RETURN_ERROR_IF ( nbSeq , corruption_detected , " " ) ;
RETURN_ERROR_IF ( BIT_reloadDStream ( & seqState . DStream ) < BIT_DStream_completed , corruption_detected , " " ) ;
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/* save reps for next block */
{ U32 i ; for ( i = 0 ; i < ZSTD_REP_NUM ; i + + ) dctx - > entropy . rep [ i ] = ( U32 ) ( seqState . prevOffset [ i ] ) ; }
}
/* last literal segment */
{ size_t const lastLLSize = litEnd - litPtr ;
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RETURN_ERROR_IF ( lastLLSize > ( size_t ) ( oend - op ) , dstSize_tooSmall , " " ) ;
if ( op ! = NULL ) {
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ZSTD_memcpy ( op , litPtr , lastLLSize ) ;
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op + = lastLLSize ;
}
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}
return op - ostart ;
}
static size_t
ZSTD_decompressSequences_default ( ZSTD_DCtx * dctx ,
void * dst , size_t maxDstSize ,
const void * seqStart , size_t seqSize , int nbSeq ,
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const ZSTD_longOffset_e isLongOffset ,
const int frame )
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{
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return ZSTD_decompressSequences_body ( dctx , dst , maxDstSize , seqStart , seqSize , nbSeq , isLongOffset , frame ) ;
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}
# endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */
# ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT
FORCE_INLINE_TEMPLATE size_t
ZSTD_decompressSequencesLong_body (
ZSTD_DCtx * dctx ,
void * dst , size_t maxDstSize ,
const void * seqStart , size_t seqSize , int nbSeq ,
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const ZSTD_longOffset_e isLongOffset ,
const int frame )
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{
const BYTE * ip = ( const BYTE * ) seqStart ;
const BYTE * const iend = ip + seqSize ;
BYTE * const ostart = ( BYTE * const ) dst ;
BYTE * const oend = ostart + maxDstSize ;
BYTE * op = ostart ;
const BYTE * litPtr = dctx - > litPtr ;
const BYTE * const litEnd = litPtr + dctx - > litSize ;
const BYTE * const prefixStart = ( const BYTE * ) ( dctx - > prefixStart ) ;
const BYTE * const dictStart = ( const BYTE * ) ( dctx - > virtualStart ) ;
const BYTE * const dictEnd = ( const BYTE * ) ( dctx - > dictEnd ) ;
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( void ) frame ;
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/* Regen sequences */
if ( nbSeq ) {
# define STORED_SEQS 4
# define STORED_SEQS_MASK (STORED_SEQS-1)
# define ADVANCED_SEQS 4
seq_t sequences [ STORED_SEQS ] ;
int const seqAdvance = MIN ( nbSeq , ADVANCED_SEQS ) ;
seqState_t seqState ;
int seqNb ;
dctx - > fseEntropy = 1 ;
{ int i ; for ( i = 0 ; i < ZSTD_REP_NUM ; i + + ) seqState . prevOffset [ i ] = dctx - > entropy . rep [ i ] ; }
seqState . prefixStart = prefixStart ;
seqState . pos = ( size_t ) ( op - prefixStart ) ;
seqState . dictEnd = dictEnd ;
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assert ( dst ! = NULL ) ;
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assert ( iend > = ip ) ;
RETURN_ERROR_IF (
ERR_isError ( BIT_initDStream ( & seqState . DStream , ip , iend - ip ) ) ,
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corruption_detected , " " ) ;
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ZSTD_initFseState ( & seqState . stateLL , & seqState . DStream , dctx - > LLTptr ) ;
ZSTD_initFseState ( & seqState . stateOffb , & seqState . DStream , dctx - > OFTptr ) ;
ZSTD_initFseState ( & seqState . stateML , & seqState . DStream , dctx - > MLTptr ) ;
/* prepare in advance */
for ( seqNb = 0 ; ( BIT_reloadDStream ( & seqState . DStream ) < = BIT_DStream_completed ) & & ( seqNb < seqAdvance ) ; seqNb + + ) {
sequences [ seqNb ] = ZSTD_decodeSequence ( & seqState , isLongOffset , ZSTD_p_prefetch ) ;
PREFETCH_L1 ( sequences [ seqNb ] . match ) ; PREFETCH_L1 ( sequences [ seqNb ] . match + sequences [ seqNb ] . matchLength - 1 ) ; /* note : it's safe to invoke PREFETCH() on any memory address, including invalid ones */
}
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RETURN_ERROR_IF ( seqNb < seqAdvance , corruption_detected , " " ) ;
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/* decode and decompress */
for ( ; ( BIT_reloadDStream ( & ( seqState . DStream ) ) < = BIT_DStream_completed ) & & ( seqNb < nbSeq ) ; seqNb + + ) {
seq_t const sequence = ZSTD_decodeSequence ( & seqState , isLongOffset , ZSTD_p_prefetch ) ;
size_t const oneSeqSize = ZSTD_execSequence ( op , oend , sequences [ ( seqNb - ADVANCED_SEQS ) & STORED_SEQS_MASK ] , & litPtr , litEnd , prefixStart , dictStart , dictEnd ) ;
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# if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
assert ( ! ZSTD_isError ( oneSeqSize ) ) ;
if ( frame ) ZSTD_assertValidSequence ( dctx , op , oend , sequences [ ( seqNb - ADVANCED_SEQS ) & STORED_SEQS_MASK ] , prefixStart , dictStart ) ;
# endif
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if ( ZSTD_isError ( oneSeqSize ) ) return oneSeqSize ;
PREFETCH_L1 ( sequence . match ) ; PREFETCH_L1 ( sequence . match + sequence . matchLength - 1 ) ; /* note : it's safe to invoke PREFETCH() on any memory address, including invalid ones */
sequences [ seqNb & STORED_SEQS_MASK ] = sequence ;
op + = oneSeqSize ;
}
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RETURN_ERROR_IF ( seqNb < nbSeq , corruption_detected , " " ) ;
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/* finish queue */
seqNb - = seqAdvance ;
for ( ; seqNb < nbSeq ; seqNb + + ) {
size_t const oneSeqSize = ZSTD_execSequence ( op , oend , sequences [ seqNb & STORED_SEQS_MASK ] , & litPtr , litEnd , prefixStart , dictStart , dictEnd ) ;
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# if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE)
assert ( ! ZSTD_isError ( oneSeqSize ) ) ;
if ( frame ) ZSTD_assertValidSequence ( dctx , op , oend , sequences [ seqNb & STORED_SEQS_MASK ] , prefixStart , dictStart ) ;
# endif
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if ( ZSTD_isError ( oneSeqSize ) ) return oneSeqSize ;
op + = oneSeqSize ;
}
/* save reps for next block */
{ U32 i ; for ( i = 0 ; i < ZSTD_REP_NUM ; i + + ) dctx - > entropy . rep [ i ] = ( U32 ) ( seqState . prevOffset [ i ] ) ; }
}
/* last literal segment */
{ size_t const lastLLSize = litEnd - litPtr ;
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RETURN_ERROR_IF ( lastLLSize > ( size_t ) ( oend - op ) , dstSize_tooSmall , " " ) ;
if ( op ! = NULL ) {
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ZSTD_memcpy ( op , litPtr , lastLLSize ) ;
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op + = lastLLSize ;
}
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}
return op - ostart ;
}
static size_t
ZSTD_decompressSequencesLong_default ( ZSTD_DCtx * dctx ,
void * dst , size_t maxDstSize ,
const void * seqStart , size_t seqSize , int nbSeq ,
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const ZSTD_longOffset_e isLongOffset ,
const int frame )
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{
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return ZSTD_decompressSequencesLong_body ( dctx , dst , maxDstSize , seqStart , seqSize , nbSeq , isLongOffset , frame ) ;
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}
# endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */
# if DYNAMIC_BMI2
# ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG
static TARGET_ATTRIBUTE ( " bmi2 " ) size_t
DONT_VECTORIZE
ZSTD_decompressSequences_bmi2 ( ZSTD_DCtx * dctx ,
void * dst , size_t maxDstSize ,
const void * seqStart , size_t seqSize , int nbSeq ,
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const ZSTD_longOffset_e isLongOffset ,
const int frame )
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{
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return ZSTD_decompressSequences_body ( dctx , dst , maxDstSize , seqStart , seqSize , nbSeq , isLongOffset , frame ) ;
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}
# endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */
# ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT
static TARGET_ATTRIBUTE ( " bmi2 " ) size_t
ZSTD_decompressSequencesLong_bmi2 ( ZSTD_DCtx * dctx ,
void * dst , size_t maxDstSize ,
const void * seqStart , size_t seqSize , int nbSeq ,
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const ZSTD_longOffset_e isLongOffset ,
const int frame )
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{
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return ZSTD_decompressSequencesLong_body ( dctx , dst , maxDstSize , seqStart , seqSize , nbSeq , isLongOffset , frame ) ;
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}
# endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */
# endif /* DYNAMIC_BMI2 */
typedef size_t ( * ZSTD_decompressSequences_t ) (
ZSTD_DCtx * dctx ,
void * dst , size_t maxDstSize ,
const void * seqStart , size_t seqSize , int nbSeq ,
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const ZSTD_longOffset_e isLongOffset ,
const int frame ) ;
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# ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG
static size_t
ZSTD_decompressSequences ( ZSTD_DCtx * dctx , void * dst , size_t maxDstSize ,
const void * seqStart , size_t seqSize , int nbSeq ,
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const ZSTD_longOffset_e isLongOffset ,
const int frame )
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{
DEBUGLOG ( 5 , " ZSTD_decompressSequences " ) ;
# if DYNAMIC_BMI2
if ( dctx - > bmi2 ) {
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return ZSTD_decompressSequences_bmi2 ( dctx , dst , maxDstSize , seqStart , seqSize , nbSeq , isLongOffset , frame ) ;
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}
# endif
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return ZSTD_decompressSequences_default ( dctx , dst , maxDstSize , seqStart , seqSize , nbSeq , isLongOffset , frame ) ;
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}
# endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */
# ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT
/* ZSTD_decompressSequencesLong() :
* decompression function triggered when a minimum share of offsets is considered " long " ,
* aka out of cache .
* note : " long " definition seems overloaded here , sometimes meaning " wider than bitstream register " , and sometimes meaning " farther than memory cache distance " .
* This function will try to mitigate main memory latency through the use of prefetching */
static size_t
ZSTD_decompressSequencesLong ( ZSTD_DCtx * dctx ,
void * dst , size_t maxDstSize ,
const void * seqStart , size_t seqSize , int nbSeq ,
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const ZSTD_longOffset_e isLongOffset ,
const int frame )
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{
DEBUGLOG ( 5 , " ZSTD_decompressSequencesLong " ) ;
# if DYNAMIC_BMI2
if ( dctx - > bmi2 ) {
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return ZSTD_decompressSequencesLong_bmi2 ( dctx , dst , maxDstSize , seqStart , seqSize , nbSeq , isLongOffset , frame ) ;
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}
# endif
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return ZSTD_decompressSequencesLong_default ( dctx , dst , maxDstSize , seqStart , seqSize , nbSeq , isLongOffset , frame ) ;
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}
# endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */
# if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
! defined ( ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG )
/* ZSTD_getLongOffsetsShare() :
* condition : offTable must be valid
* @ return : " share " of long offsets ( arbitrarily defined as > ( 1 < < 23 ) )
* compared to maximum possible of ( 1 < < OffFSELog ) */
static unsigned
ZSTD_getLongOffsetsShare ( const ZSTD_seqSymbol * offTable )
{
const void * ptr = offTable ;
U32 const tableLog = ( ( const ZSTD_seqSymbol_header * ) ptr ) [ 0 ] . tableLog ;
const ZSTD_seqSymbol * table = offTable + 1 ;
U32 const max = 1 < < tableLog ;
U32 u , total = 0 ;
DEBUGLOG ( 5 , " ZSTD_getLongOffsetsShare: (tableLog=%u) " , tableLog ) ;
assert ( max < = ( 1 < < OffFSELog ) ) ; /* max not too large */
for ( u = 0 ; u < max ; u + + ) {
if ( table [ u ] . nbAdditionalBits > 22 ) total + = 1 ;
}
assert ( tableLog < = OffFSELog ) ;
total < < = ( OffFSELog - tableLog ) ; /* scale to OffFSELog */
return total ;
}
# endif
size_t
ZSTD_decompressBlock_internal ( ZSTD_DCtx * dctx ,
void * dst , size_t dstCapacity ,
const void * src , size_t srcSize , const int frame )
{ /* blockType == blockCompressed */
const BYTE * ip = ( const BYTE * ) src ;
/* isLongOffset must be true if there are long offsets.
* Offsets are long if they are larger than 2 ^ STREAM_ACCUMULATOR_MIN .
* We don ' t expect that to be the case in 64 - bit mode .
* In block mode , window size is not known , so we have to be conservative .
* ( note : but it could be evaluated from current - lowLimit )
*/
ZSTD_longOffset_e const isLongOffset = ( ZSTD_longOffset_e ) ( MEM_32bits ( ) & & ( ! frame | | ( dctx - > fParams . windowSize > ( 1ULL < < STREAM_ACCUMULATOR_MIN ) ) ) ) ;
DEBUGLOG ( 5 , " ZSTD_decompressBlock_internal (size : %u) " , ( U32 ) srcSize ) ;
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RETURN_ERROR_IF ( srcSize > = ZSTD_BLOCKSIZE_MAX , srcSize_wrong , " " ) ;
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/* Decode literals section */
{ size_t const litCSize = ZSTD_decodeLiteralsBlock ( dctx , src , srcSize ) ;
DEBUGLOG ( 5 , " ZSTD_decodeLiteralsBlock : %u " , ( U32 ) litCSize ) ;
if ( ZSTD_isError ( litCSize ) ) return litCSize ;
ip + = litCSize ;
srcSize - = litCSize ;
}
/* Build Decoding Tables */
{
/* These macros control at build-time which decompressor implementation
* we use . If neither is defined , we do some inspection and dispatch at
* runtime .
*/
# if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
! defined ( ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG )
int usePrefetchDecoder = dctx - > ddictIsCold ;
# endif
int nbSeq ;
size_t const seqHSize = ZSTD_decodeSeqHeaders ( dctx , & nbSeq , ip , srcSize ) ;
if ( ZSTD_isError ( seqHSize ) ) return seqHSize ;
ip + = seqHSize ;
srcSize - = seqHSize ;
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RETURN_ERROR_IF ( dst = = NULL & & nbSeq > 0 , dstSize_tooSmall , " NULL not handled " ) ;
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# if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
! defined ( ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG )
if ( ! usePrefetchDecoder
& & ( ! frame | | ( dctx - > fParams . windowSize > ( 1 < < 24 ) ) )
& & ( nbSeq > ADVANCED_SEQS ) ) { /* could probably use a larger nbSeq limit */
U32 const shareLongOffsets = ZSTD_getLongOffsetsShare ( dctx - > OFTptr ) ;
U32 const minShare = MEM_64bits ( ) ? 7 : 20 ; /* heuristic values, correspond to 2.73% and 7.81% */
usePrefetchDecoder = ( shareLongOffsets > = minShare ) ;
}
# endif
dctx - > ddictIsCold = 0 ;
# if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \
! defined ( ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG )
if ( usePrefetchDecoder )
# endif
# ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT
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return ZSTD_decompressSequencesLong ( dctx , dst , dstCapacity , ip , srcSize , nbSeq , isLongOffset , frame ) ;
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# endif
# ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG
/* else */
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return ZSTD_decompressSequences ( dctx , dst , dstCapacity , ip , srcSize , nbSeq , isLongOffset , frame ) ;
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# endif
}
}
void ZSTD_checkContinuity ( ZSTD_DCtx * dctx , const void * dst )
{
if ( dst ! = dctx - > previousDstEnd ) { /* not contiguous */
dctx - > dictEnd = dctx - > previousDstEnd ;
dctx - > virtualStart = ( const char * ) dst - ( ( const char * ) ( dctx - > previousDstEnd ) - ( const char * ) ( dctx - > prefixStart ) ) ;
dctx - > prefixStart = dst ;
dctx - > previousDstEnd = dst ;
}
}
size_t ZSTD_decompressBlock ( ZSTD_DCtx * dctx ,
void * dst , size_t dstCapacity ,
const void * src , size_t srcSize )
{
size_t dSize ;
ZSTD_checkContinuity ( dctx , dst ) ;
dSize = ZSTD_decompressBlock_internal ( dctx , dst , dstCapacity , src , srcSize , /* frame */ 0 ) ;
dctx - > previousDstEnd = ( char * ) dst + dSize ;
return dSize ;
}