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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 .
*/
/*-*************************************
* Dependencies
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
# include "zstd_compress_sequences.h"
/**
* - log2 ( x / 256 ) lookup table for x in [ 0 , 256 ) .
* If x = = 0 : Return 0
* Else : Return floor ( - log2 ( x / 256 ) * 256 )
*/
static unsigned const kInverseProbabilityLog256 [ 256 ] = {
0 , 2048 , 1792 , 1642 , 1536 , 1453 , 1386 , 1329 , 1280 , 1236 , 1197 , 1162 ,
1130 , 1100 , 1073 , 1047 , 1024 , 1001 , 980 , 960 , 941 , 923 , 906 , 889 ,
874 , 859 , 844 , 830 , 817 , 804 , 791 , 779 , 768 , 756 , 745 , 734 ,
724 , 714 , 704 , 694 , 685 , 676 , 667 , 658 , 650 , 642 , 633 , 626 ,
618 , 610 , 603 , 595 , 588 , 581 , 574 , 567 , 561 , 554 , 548 , 542 ,
535 , 529 , 523 , 517 , 512 , 506 , 500 , 495 , 489 , 484 , 478 , 473 ,
468 , 463 , 458 , 453 , 448 , 443 , 438 , 434 , 429 , 424 , 420 , 415 ,
411 , 407 , 402 , 398 , 394 , 390 , 386 , 382 , 377 , 373 , 370 , 366 ,
362 , 358 , 354 , 350 , 347 , 343 , 339 , 336 , 332 , 329 , 325 , 322 ,
318 , 315 , 311 , 308 , 305 , 302 , 298 , 295 , 292 , 289 , 286 , 282 ,
279 , 276 , 273 , 270 , 267 , 264 , 261 , 258 , 256 , 253 , 250 , 247 ,
244 , 241 , 239 , 236 , 233 , 230 , 228 , 225 , 222 , 220 , 217 , 215 ,
212 , 209 , 207 , 204 , 202 , 199 , 197 , 194 , 192 , 190 , 187 , 185 ,
182 , 180 , 178 , 175 , 173 , 171 , 168 , 166 , 164 , 162 , 159 , 157 ,
155 , 153 , 151 , 149 , 146 , 144 , 142 , 140 , 138 , 136 , 134 , 132 ,
130 , 128 , 126 , 123 , 121 , 119 , 117 , 115 , 114 , 112 , 110 , 108 ,
106 , 104 , 102 , 100 , 98 , 96 , 94 , 93 , 91 , 89 , 87 , 85 ,
83 , 82 , 80 , 78 , 76 , 74 , 73 , 71 , 69 , 67 , 66 , 64 ,
62 , 61 , 59 , 57 , 55 , 54 , 52 , 50 , 49 , 47 , 46 , 44 ,
42 , 41 , 39 , 37 , 36 , 34 , 33 , 31 , 30 , 28 , 26 , 25 ,
23 , 22 , 20 , 19 , 17 , 16 , 14 , 13 , 11 , 10 , 8 , 7 ,
5 , 4 , 2 , 1 ,
} ;
static unsigned ZSTD_getFSEMaxSymbolValue ( FSE_CTable const * ctable ) {
void const * ptr = ctable ;
U16 const * u16ptr = ( U16 const * ) ptr ;
U32 const maxSymbolValue = MEM_read16 ( u16ptr + 1 ) ;
return maxSymbolValue ;
}
/**
* Returns the cost in bytes of encoding the normalized count header .
* Returns an error if any of the helper functions return an error .
*/
static size_t ZSTD_NCountCost ( unsigned const * count , unsigned const max ,
size_t const nbSeq , unsigned const FSELog )
{
BYTE wksp [ FSE_NCOUNTBOUND ] ;
S16 norm [ MaxSeq + 1 ] ;
const U32 tableLog = FSE_optimalTableLog ( FSELog , nbSeq , max ) ;
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FORWARD_IF_ERROR ( FSE_normalizeCount ( norm , tableLog , count , nbSeq , max ) , " " ) ;
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return FSE_writeNCount ( wksp , sizeof ( wksp ) , norm , max , tableLog ) ;
}
/**
* Returns the cost in bits of encoding the distribution described by count
* using the entropy bound .
*/
static size_t ZSTD_entropyCost ( unsigned const * count , unsigned const max , size_t const total )
{
unsigned cost = 0 ;
unsigned s ;
for ( s = 0 ; s < = max ; + + s ) {
unsigned norm = ( unsigned ) ( ( 256 * count [ s ] ) / total ) ;
if ( count [ s ] ! = 0 & & norm = = 0 )
norm = 1 ;
assert ( count [ s ] < total ) ;
cost + = count [ s ] * kInverseProbabilityLog256 [ norm ] ;
}
return cost > > 8 ;
}
/**
* Returns the cost in bits of encoding the distribution in count using ctable .
* Returns an error if ctable cannot represent all the symbols in count .
*/
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size_t ZSTD_fseBitCost (
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FSE_CTable const * ctable ,
unsigned const * count ,
unsigned const max )
{
unsigned const kAccuracyLog = 8 ;
size_t cost = 0 ;
unsigned s ;
FSE_CState_t cstate ;
FSE_initCState ( & cstate , ctable ) ;
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if ( ZSTD_getFSEMaxSymbolValue ( ctable ) < max ) {
DEBUGLOG ( 5 , " Repeat FSE_CTable has maxSymbolValue %u < %u " ,
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ZSTD_getFSEMaxSymbolValue ( ctable ) , max ) ;
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return ERROR ( GENERIC ) ;
}
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for ( s = 0 ; s < = max ; + + s ) {
unsigned const tableLog = cstate . stateLog ;
unsigned const badCost = ( tableLog + 1 ) < < kAccuracyLog ;
unsigned const bitCost = FSE_bitCost ( cstate . symbolTT , tableLog , s , kAccuracyLog ) ;
if ( count [ s ] = = 0 )
continue ;
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if ( bitCost > = badCost ) {
DEBUGLOG ( 5 , " Repeat FSE_CTable has Prob[%u] == 0 " , s ) ;
return ERROR ( GENERIC ) ;
}
cost + = ( size_t ) count [ s ] * bitCost ;
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}
return cost > > kAccuracyLog ;
}
/**
* Returns the cost in bits of encoding the distribution in count using the
* table described by norm . The max symbol support by norm is assumed > = max .
* norm must be valid for every symbol with non - zero probability in count .
*/
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size_t ZSTD_crossEntropyCost ( short const * norm , unsigned accuracyLog ,
unsigned const * count , unsigned const max )
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{
unsigned const shift = 8 - accuracyLog ;
size_t cost = 0 ;
unsigned s ;
assert ( accuracyLog < = 8 ) ;
for ( s = 0 ; s < = max ; + + s ) {
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unsigned const normAcc = ( norm [ s ] ! = - 1 ) ? ( unsigned ) norm [ s ] : 1 ;
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unsigned const norm256 = normAcc < < shift ;
assert ( norm256 > 0 ) ;
assert ( norm256 < 256 ) ;
cost + = count [ s ] * kInverseProbabilityLog256 [ norm256 ] ;
}
return cost > > 8 ;
}
symbolEncodingType_e
ZSTD_selectEncodingType (
FSE_repeat * repeatMode , unsigned const * count , unsigned const max ,
size_t const mostFrequent , size_t nbSeq , unsigned const FSELog ,
FSE_CTable const * prevCTable ,
short const * defaultNorm , U32 defaultNormLog ,
ZSTD_defaultPolicy_e const isDefaultAllowed ,
ZSTD_strategy const strategy )
{
ZSTD_STATIC_ASSERT ( ZSTD_defaultDisallowed = = 0 & & ZSTD_defaultAllowed ! = 0 ) ;
if ( mostFrequent = = nbSeq ) {
* repeatMode = FSE_repeat_none ;
if ( isDefaultAllowed & & nbSeq < = 2 ) {
/* Prefer set_basic over set_rle when there are 2 or less symbols,
* since RLE uses 1 byte , but set_basic uses 5 - 6 bits per symbol .
* If basic encoding isn ' t possible , always choose RLE .
*/
DEBUGLOG ( 5 , " Selected set_basic " ) ;
return set_basic ;
}
DEBUGLOG ( 5 , " Selected set_rle " ) ;
return set_rle ;
}
if ( strategy < ZSTD_lazy ) {
if ( isDefaultAllowed ) {
size_t const staticFse_nbSeq_max = 1000 ;
size_t const mult = 10 - strategy ;
size_t const baseLog = 3 ;
size_t const dynamicFse_nbSeq_min = ( ( ( size_t ) 1 < < defaultNormLog ) * mult ) > > baseLog ; /* 28-36 for offset, 56-72 for lengths */
assert ( defaultNormLog > = 5 & & defaultNormLog < = 6 ) ; /* xx_DEFAULTNORMLOG */
assert ( mult < = 9 & & mult > = 7 ) ;
if ( ( * repeatMode = = FSE_repeat_valid )
& & ( nbSeq < staticFse_nbSeq_max ) ) {
DEBUGLOG ( 5 , " Selected set_repeat " ) ;
return set_repeat ;
}
if ( ( nbSeq < dynamicFse_nbSeq_min )
| | ( mostFrequent < ( nbSeq > > ( defaultNormLog - 1 ) ) ) ) {
DEBUGLOG ( 5 , " Selected set_basic " ) ;
/* The format allows default tables to be repeated, but it isn't useful.
* When using simple heuristics to select encoding type , we don ' t want
* to confuse these tables with dictionaries . When running more careful
* analysis , we don ' t need to waste time checking both repeating tables
* and default tables .
*/
* repeatMode = FSE_repeat_none ;
return set_basic ;
}
}
} else {
size_t const basicCost = isDefaultAllowed ? ZSTD_crossEntropyCost ( defaultNorm , defaultNormLog , count , max ) : ERROR ( GENERIC ) ;
size_t const repeatCost = * repeatMode ! = FSE_repeat_none ? ZSTD_fseBitCost ( prevCTable , count , max ) : ERROR ( GENERIC ) ;
size_t const NCountCost = ZSTD_NCountCost ( count , max , nbSeq , FSELog ) ;
size_t const compressedCost = ( NCountCost < < 3 ) + ZSTD_entropyCost ( count , max , nbSeq ) ;
if ( isDefaultAllowed ) {
assert ( ! ZSTD_isError ( basicCost ) ) ;
assert ( ! ( * repeatMode = = FSE_repeat_valid & & ZSTD_isError ( repeatCost ) ) ) ;
}
assert ( ! ZSTD_isError ( NCountCost ) ) ;
assert ( compressedCost < ERROR ( maxCode ) ) ;
DEBUGLOG ( 5 , " Estimated bit costs: basic=%u \t repeat=%u \t compressed=%u " ,
( unsigned ) basicCost , ( unsigned ) repeatCost , ( unsigned ) compressedCost ) ;
if ( basicCost < = repeatCost & & basicCost < = compressedCost ) {
DEBUGLOG ( 5 , " Selected set_basic " ) ;
assert ( isDefaultAllowed ) ;
* repeatMode = FSE_repeat_none ;
return set_basic ;
}
if ( repeatCost < = compressedCost ) {
DEBUGLOG ( 5 , " Selected set_repeat " ) ;
assert ( ! ZSTD_isError ( repeatCost ) ) ;
return set_repeat ;
}
assert ( compressedCost < basicCost & & compressedCost < repeatCost ) ;
}
DEBUGLOG ( 5 , " Selected set_compressed " ) ;
* repeatMode = FSE_repeat_check ;
return set_compressed ;
}
size_t
ZSTD_buildCTable ( void * dst , size_t dstCapacity ,
FSE_CTable * nextCTable , U32 FSELog , symbolEncodingType_e type ,
unsigned * count , U32 max ,
const BYTE * codeTable , size_t nbSeq ,
const S16 * defaultNorm , U32 defaultNormLog , U32 defaultMax ,
const FSE_CTable * prevCTable , size_t prevCTableSize ,
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void * entropyWorkspace , size_t entropyWorkspaceSize )
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{
BYTE * op = ( BYTE * ) dst ;
const BYTE * const oend = op + dstCapacity ;
DEBUGLOG ( 6 , " ZSTD_buildCTable (dstCapacity=%u) " , ( unsigned ) dstCapacity ) ;
switch ( type ) {
case set_rle :
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FORWARD_IF_ERROR ( FSE_buildCTable_rle ( nextCTable , ( BYTE ) max ) , " " ) ;
RETURN_ERROR_IF ( dstCapacity = = 0 , dstSize_tooSmall , " not enough space " ) ;
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* op = codeTable [ 0 ] ;
return 1 ;
case set_repeat :
memcpy ( nextCTable , prevCTable , prevCTableSize ) ;
return 0 ;
case set_basic :
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FORWARD_IF_ERROR ( FSE_buildCTable_wksp ( nextCTable , defaultNorm , defaultMax , defaultNormLog , entropyWorkspace , entropyWorkspaceSize ) , " " ) ; /* note : could be pre-calculated */
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return 0 ;
case set_compressed : {
S16 norm [ MaxSeq + 1 ] ;
size_t nbSeq_1 = nbSeq ;
const U32 tableLog = FSE_optimalTableLog ( FSELog , nbSeq , max ) ;
if ( count [ codeTable [ nbSeq - 1 ] ] > 1 ) {
count [ codeTable [ nbSeq - 1 ] ] - - ;
nbSeq_1 - - ;
}
assert ( nbSeq_1 > 1 ) ;
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FORWARD_IF_ERROR ( FSE_normalizeCount ( norm , tableLog , count , nbSeq_1 , max ) , " " ) ;
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{ size_t const NCountSize = FSE_writeNCount ( op , oend - op , norm , max , tableLog ) ; /* overflow protected */
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FORWARD_IF_ERROR ( NCountSize , " FSE_writeNCount failed " ) ;
FORWARD_IF_ERROR ( FSE_buildCTable_wksp ( nextCTable , norm , max , tableLog , entropyWorkspace , entropyWorkspaceSize ) , " " ) ;
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return NCountSize ;
}
}
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default : assert ( 0 ) ; RETURN_ERROR ( GENERIC , " impossible to reach " ) ;
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}
}
FORCE_INLINE_TEMPLATE size_t
ZSTD_encodeSequences_body (
void * dst , size_t dstCapacity ,
FSE_CTable const * CTable_MatchLength , BYTE const * mlCodeTable ,
FSE_CTable const * CTable_OffsetBits , BYTE const * ofCodeTable ,
FSE_CTable const * CTable_LitLength , BYTE const * llCodeTable ,
seqDef const * sequences , size_t nbSeq , int longOffsets )
{
BIT_CStream_t blockStream ;
FSE_CState_t stateMatchLength ;
FSE_CState_t stateOffsetBits ;
FSE_CState_t stateLitLength ;
RETURN_ERROR_IF (
ERR_isError ( BIT_initCStream ( & blockStream , dst , dstCapacity ) ) ,
dstSize_tooSmall , " not enough space remaining " ) ;
DEBUGLOG ( 6 , " available space for bitstream : %i (dstCapacity=%u) " ,
( int ) ( blockStream . endPtr - blockStream . startPtr ) ,
( unsigned ) dstCapacity ) ;
/* first symbols */
FSE_initCState2 ( & stateMatchLength , CTable_MatchLength , mlCodeTable [ nbSeq - 1 ] ) ;
FSE_initCState2 ( & stateOffsetBits , CTable_OffsetBits , ofCodeTable [ nbSeq - 1 ] ) ;
FSE_initCState2 ( & stateLitLength , CTable_LitLength , llCodeTable [ nbSeq - 1 ] ) ;
BIT_addBits ( & blockStream , sequences [ nbSeq - 1 ] . litLength , LL_bits [ llCodeTable [ nbSeq - 1 ] ] ) ;
if ( MEM_32bits ( ) ) BIT_flushBits ( & blockStream ) ;
BIT_addBits ( & blockStream , sequences [ nbSeq - 1 ] . matchLength , ML_bits [ mlCodeTable [ nbSeq - 1 ] ] ) ;
if ( MEM_32bits ( ) ) BIT_flushBits ( & blockStream ) ;
if ( longOffsets ) {
U32 const ofBits = ofCodeTable [ nbSeq - 1 ] ;
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unsigned const extraBits = ofBits - MIN ( ofBits , STREAM_ACCUMULATOR_MIN - 1 ) ;
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if ( extraBits ) {
BIT_addBits ( & blockStream , sequences [ nbSeq - 1 ] . offset , extraBits ) ;
BIT_flushBits ( & blockStream ) ;
}
BIT_addBits ( & blockStream , sequences [ nbSeq - 1 ] . offset > > extraBits ,
ofBits - extraBits ) ;
} else {
BIT_addBits ( & blockStream , sequences [ nbSeq - 1 ] . offset , ofCodeTable [ nbSeq - 1 ] ) ;
}
BIT_flushBits ( & blockStream ) ;
{ size_t n ;
for ( n = nbSeq - 2 ; n < nbSeq ; n - - ) { /* intentional underflow */
BYTE const llCode = llCodeTable [ n ] ;
BYTE const ofCode = ofCodeTable [ n ] ;
BYTE const mlCode = mlCodeTable [ n ] ;
U32 const llBits = LL_bits [ llCode ] ;
U32 const ofBits = ofCode ;
U32 const mlBits = ML_bits [ mlCode ] ;
DEBUGLOG ( 6 , " encoding: litlen:%2u - matchlen:%2u - offCode:%7u " ,
( unsigned ) sequences [ n ] . litLength ,
( unsigned ) sequences [ n ] . matchLength + MINMATCH ,
( unsigned ) sequences [ n ] . offset ) ;
/* 32b*/ /* 64b*/
/* (7)*/ /* (7)*/
FSE_encodeSymbol ( & blockStream , & stateOffsetBits , ofCode ) ; /* 15 */ /* 15 */
FSE_encodeSymbol ( & blockStream , & stateMatchLength , mlCode ) ; /* 24 */ /* 24 */
if ( MEM_32bits ( ) ) BIT_flushBits ( & blockStream ) ; /* (7)*/
FSE_encodeSymbol ( & blockStream , & stateLitLength , llCode ) ; /* 16 */ /* 33 */
if ( MEM_32bits ( ) | | ( ofBits + mlBits + llBits > = 64 - 7 - ( LLFSELog + MLFSELog + OffFSELog ) ) )
BIT_flushBits ( & blockStream ) ; /* (7)*/
BIT_addBits ( & blockStream , sequences [ n ] . litLength , llBits ) ;
if ( MEM_32bits ( ) & & ( ( llBits + mlBits ) > 24 ) ) BIT_flushBits ( & blockStream ) ;
BIT_addBits ( & blockStream , sequences [ n ] . matchLength , mlBits ) ;
if ( MEM_32bits ( ) | | ( ofBits + mlBits + llBits > 56 ) ) BIT_flushBits ( & blockStream ) ;
if ( longOffsets ) {
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unsigned const extraBits = ofBits - MIN ( ofBits , STREAM_ACCUMULATOR_MIN - 1 ) ;
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if ( extraBits ) {
BIT_addBits ( & blockStream , sequences [ n ] . offset , extraBits ) ;
BIT_flushBits ( & blockStream ) ; /* (7)*/
}
BIT_addBits ( & blockStream , sequences [ n ] . offset > > extraBits ,
ofBits - extraBits ) ; /* 31 */
} else {
BIT_addBits ( & blockStream , sequences [ n ] . offset , ofBits ) ; /* 31 */
}
BIT_flushBits ( & blockStream ) ; /* (7)*/
DEBUGLOG ( 7 , " remaining space : %i " , ( int ) ( blockStream . endPtr - blockStream . ptr ) ) ;
} }
DEBUGLOG ( 6 , " ZSTD_encodeSequences: flushing ML state with %u bits " , stateMatchLength . stateLog ) ;
FSE_flushCState ( & blockStream , & stateMatchLength ) ;
DEBUGLOG ( 6 , " ZSTD_encodeSequences: flushing Off state with %u bits " , stateOffsetBits . stateLog ) ;
FSE_flushCState ( & blockStream , & stateOffsetBits ) ;
DEBUGLOG ( 6 , " ZSTD_encodeSequences: flushing LL state with %u bits " , stateLitLength . stateLog ) ;
FSE_flushCState ( & blockStream , & stateLitLength ) ;
{ size_t const streamSize = BIT_closeCStream ( & blockStream ) ;
RETURN_ERROR_IF ( streamSize = = 0 , dstSize_tooSmall , " not enough space " ) ;
return streamSize ;
}
}
static size_t
ZSTD_encodeSequences_default (
void * dst , size_t dstCapacity ,
FSE_CTable const * CTable_MatchLength , BYTE const * mlCodeTable ,
FSE_CTable const * CTable_OffsetBits , BYTE const * ofCodeTable ,
FSE_CTable const * CTable_LitLength , BYTE const * llCodeTable ,
seqDef const * sequences , size_t nbSeq , int longOffsets )
{
return ZSTD_encodeSequences_body ( dst , dstCapacity ,
CTable_MatchLength , mlCodeTable ,
CTable_OffsetBits , ofCodeTable ,
CTable_LitLength , llCodeTable ,
sequences , nbSeq , longOffsets ) ;
}
# if DYNAMIC_BMI2
static TARGET_ATTRIBUTE ( " bmi2 " ) size_t
ZSTD_encodeSequences_bmi2 (
void * dst , size_t dstCapacity ,
FSE_CTable const * CTable_MatchLength , BYTE const * mlCodeTable ,
FSE_CTable const * CTable_OffsetBits , BYTE const * ofCodeTable ,
FSE_CTable const * CTable_LitLength , BYTE const * llCodeTable ,
seqDef const * sequences , size_t nbSeq , int longOffsets )
{
return ZSTD_encodeSequences_body ( dst , dstCapacity ,
CTable_MatchLength , mlCodeTable ,
CTable_OffsetBits , ofCodeTable ,
CTable_LitLength , llCodeTable ,
sequences , nbSeq , longOffsets ) ;
}
# endif
size_t ZSTD_encodeSequences (
void * dst , size_t dstCapacity ,
FSE_CTable const * CTable_MatchLength , BYTE const * mlCodeTable ,
FSE_CTable const * CTable_OffsetBits , BYTE const * ofCodeTable ,
FSE_CTable const * CTable_LitLength , BYTE const * llCodeTable ,
seqDef const * sequences , size_t nbSeq , int longOffsets , int bmi2 )
{
DEBUGLOG ( 5 , " ZSTD_encodeSequences: dstCapacity = %u " , ( unsigned ) dstCapacity ) ;
# if DYNAMIC_BMI2
if ( bmi2 ) {
return ZSTD_encodeSequences_bmi2 ( dst , dstCapacity ,
CTable_MatchLength , mlCodeTable ,
CTable_OffsetBits , ofCodeTable ,
CTable_LitLength , llCodeTable ,
sequences , nbSeq , longOffsets ) ;
}
# endif
( void ) bmi2 ;
return ZSTD_encodeSequences_default ( dst , dstCapacity ,
CTable_MatchLength , mlCodeTable ,
CTable_OffsetBits , ofCodeTable ,
CTable_LitLength , llCodeTable ,
sequences , nbSeq , longOffsets ) ;
}