e185b252f0
Cleaner C99 detection, thanks to Elad Modified Basic Types, as recommended by Wayne Scott Simplified compression function Corrected : warning on missing #undef in lz4hc, thanks Arseny Kapoulkine Modified length loops as suggested by Wouter Vermaelen Modified pragma pack directive for older versions of GCC, as reported by Peter Costello Updated xxHash to r29 Indent lz4hc.c with spaces git-svn-id: https://lz4.googlecode.com/svn/trunk@95 650e7d94-2a16-8b24-b05c-7c0b3f6821cd
343 lines
11 KiB
C
343 lines
11 KiB
C
/*
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LZ4 HC Encoder - Part of LZ4 HC algorithm
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Copyright (C) 2011-2013, Yann Collet.
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BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are
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met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above
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copyright notice, this list of conditions and the following disclaimer
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in the documentation and/or other materials provided with the
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distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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You can contact the author at :
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- LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
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- LZ4 source repository : http://code.google.com/p/lz4/
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*/
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/* lz4hc_encoder.h must be included into lz4hc.c
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The objective of this file is to create a single LZ4 compression function source
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which will be instanciated multiple times with minor variations
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depending on a set of #define.
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*/
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//****************************
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// Check required defines
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//****************************
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#ifndef FUNCTION_NAME
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# error "FUNTION_NAME is not defined"
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#endif
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//****************************
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// Local definitions
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//****************************
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#define COMBINED_NAME_RAW(n1,n2) n1 ## n2
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#define COMBINED_NAME(n1,n2) COMBINED_NAME_RAW(n1,n2)
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#define ENCODE_SEQUENCE_NAME COMBINED_NAME(FUNCTION_NAME,_encodeSequence)
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#ifdef LIMITED_OUTPUT
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# define ENCODE_SEQUENCE(i,o,a,m,r,d) if (ENCODE_SEQUENCE_NAME(i,o,a,m,r,d)) return 0;
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#else
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# define ENCODE_SEQUENCE(i,o,a,m,r,d) ENCODE_SEQUENCE_NAME(i,o,a,m,r)
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#endif
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//****************************
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// Function code
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//****************************
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forceinline static int ENCODE_SEQUENCE_NAME (
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const BYTE** ip,
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BYTE** op,
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const BYTE** anchor,
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int matchLength,
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const BYTE* ref
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#ifdef LIMITED_OUTPUT
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,BYTE* oend
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#endif
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)
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{
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int length, len;
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BYTE* token;
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// Encode Literal length
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length = (int)(*ip - *anchor);
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token = (*op)++;
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#ifdef LIMITED_OUTPUT
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if ((*op + length + (2 + 1 + LASTLITERALS) + (length>>8)) > oend) return 1; // Check output limit
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#endif
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if (length>=(int)RUN_MASK) { *token=(RUN_MASK<<ML_BITS); len = length-RUN_MASK; for(; len > 254 ; len-=255) *(*op)++ = 255; *(*op)++ = (BYTE)len; }
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else *token = (BYTE)(length<<ML_BITS);
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// Copy Literals
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LZ4_BLINDCOPY(*anchor, *op, length);
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// Encode Offset
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LZ4_WRITE_LITTLEENDIAN_16(*op,(U16)(*ip-ref));
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// Encode MatchLength
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length = (int)(matchLength-MINMATCH);
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#ifdef LIMITED_OUTPUT
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if (*op + (1 + LASTLITERALS) + (length>>8) > oend) return 1; // Check output limit
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#endif
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if (length>=(int)ML_MASK) { *token+=ML_MASK; length-=ML_MASK; for(; length > 509 ; length-=510) { *(*op)++ = 255; *(*op)++ = 255; } if (length > 254) { length-=255; *(*op)++ = 255; } *(*op)++ = (BYTE)length; }
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else *token += (BYTE)length;
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// Prepare next loop
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*ip += matchLength;
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*anchor = *ip;
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return 0;
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}
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int COMBINED_NAME(FUNCTION_NAME,ctx) (
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LZ4HC_Data_Structure* ctx,
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const char* source,
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char* dest,
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int inputSize
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#ifdef LIMITED_OUTPUT
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,int maxOutputSize
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#endif
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)
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{
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const BYTE* ip = (const BYTE*) source;
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const BYTE* anchor = ip;
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const BYTE* const iend = ip + inputSize;
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const BYTE* const mflimit = iend - MFLIMIT;
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const BYTE* const matchlimit = (iend - LASTLITERALS);
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BYTE* op = (BYTE*) dest;
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#ifdef LIMITED_OUTPUT
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BYTE* const oend = op + maxOutputSize;
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#endif
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int ml, ml2, ml3, ml0;
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const BYTE* ref=NULL;
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const BYTE* start2=NULL;
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const BYTE* ref2=NULL;
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const BYTE* start3=NULL;
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const BYTE* ref3=NULL;
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const BYTE* start0;
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const BYTE* ref0;
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ip++;
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// Main Loop
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while (ip < mflimit)
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{
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ml = LZ4HC_InsertAndFindBestMatch (ctx, ip, matchlimit, (&ref));
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if (!ml) { ip++; continue; }
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// saved, in case we would skip too much
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start0 = ip;
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ref0 = ref;
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ml0 = ml;
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_Search2:
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if (ip+ml < mflimit)
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ml2 = LZ4HC_InsertAndGetWiderMatch(ctx, ip + ml - 2, ip + 1, matchlimit, ml, &ref2, &start2);
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else ml2 = ml;
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if (ml2 == ml) // No better match
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{
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ENCODE_SEQUENCE(&ip, &op, &anchor, ml, ref, oend);
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continue;
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}
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if (start0 < ip)
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{
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if (start2 < ip + ml0) // empirical
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{
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ip = start0;
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ref = ref0;
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ml = ml0;
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}
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}
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// Here, start0==ip
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if ((start2 - ip) < 3) // First Match too small : removed
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{
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ml = ml2;
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ip = start2;
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ref =ref2;
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goto _Search2;
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}
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_Search3:
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// Currently we have :
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// ml2 > ml1, and
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// ip1+3 <= ip2 (usually < ip1+ml1)
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if ((start2 - ip) < OPTIMAL_ML)
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{
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int correction;
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int new_ml = ml;
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if (new_ml > OPTIMAL_ML) new_ml = OPTIMAL_ML;
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if (ip+new_ml > start2 + ml2 - MINMATCH) new_ml = (int)(start2 - ip) + ml2 - MINMATCH;
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correction = new_ml - (int)(start2 - ip);
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if (correction > 0)
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{
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start2 += correction;
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ref2 += correction;
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ml2 -= correction;
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}
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}
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// Now, we have start2 = ip+new_ml, with new_ml = min(ml, OPTIMAL_ML=18)
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if (start2 + ml2 < mflimit)
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ml3 = LZ4HC_InsertAndGetWiderMatch(ctx, start2 + ml2 - 3, start2, matchlimit, ml2, &ref3, &start3);
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else ml3 = ml2;
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if (ml3 == ml2) // No better match : 2 sequences to encode
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{
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// ip & ref are known; Now for ml
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if (start2 < ip+ml) ml = (int)(start2 - ip);
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// Now, encode 2 sequences
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ENCODE_SEQUENCE(&ip, &op, &anchor, ml, ref, oend);
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ip = start2;
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ENCODE_SEQUENCE(&ip, &op, &anchor, ml2, ref2, oend);
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continue;
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}
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if (start3 < ip+ml+3) // Not enough space for match 2 : remove it
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{
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if (start3 >= (ip+ml)) // can write Seq1 immediately ==> Seq2 is removed, so Seq3 becomes Seq1
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{
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if (start2 < ip+ml)
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{
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int correction = (int)(ip+ml - start2);
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start2 += correction;
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ref2 += correction;
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ml2 -= correction;
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if (ml2 < MINMATCH)
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{
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start2 = start3;
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ref2 = ref3;
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ml2 = ml3;
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}
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}
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ENCODE_SEQUENCE(&ip, &op, &anchor, ml, ref, oend);
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ip = start3;
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ref = ref3;
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ml = ml3;
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start0 = start2;
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ref0 = ref2;
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ml0 = ml2;
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goto _Search2;
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}
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start2 = start3;
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ref2 = ref3;
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ml2 = ml3;
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goto _Search3;
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}
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// OK, now we have 3 ascending matches; let's write at least the first one
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// ip & ref are known; Now for ml
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if (start2 < ip+ml)
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{
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if ((start2 - ip) < (int)ML_MASK)
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{
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int correction;
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if (ml > OPTIMAL_ML) ml = OPTIMAL_ML;
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if (ip + ml > start2 + ml2 - MINMATCH) ml = (int)(start2 - ip) + ml2 - MINMATCH;
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correction = ml - (int)(start2 - ip);
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if (correction > 0)
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{
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start2 += correction;
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ref2 += correction;
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ml2 -= correction;
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}
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}
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else
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{
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ml = (int)(start2 - ip);
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}
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}
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ENCODE_SEQUENCE(&ip, &op, &anchor, ml, ref, oend);
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ip = start2;
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ref = ref2;
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ml = ml2;
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start2 = start3;
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ref2 = ref3;
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ml2 = ml3;
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goto _Search3;
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}
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// Encode Last Literals
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{
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int lastRun = (int)(iend - anchor);
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#ifdef LIMITED_OUTPUT
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if (((char*)op - dest) + lastRun + 1 + ((lastRun+255-RUN_MASK)/255) > (U32)maxOutputSize) return 0; // Check output limit
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#endif
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if (lastRun>=(int)RUN_MASK) { *op++=(RUN_MASK<<ML_BITS); lastRun-=RUN_MASK; for(; lastRun > 254 ; lastRun-=255) *op++ = 255; *op++ = (BYTE) lastRun; }
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else *op++ = (BYTE)(lastRun<<ML_BITS);
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memcpy(op, anchor, iend - anchor);
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op += iend-anchor;
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}
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// End
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return (int) (((char*)op)-dest);
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}
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int FUNCTION_NAME (const char* source,
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char* dest,
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int inputSize
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#ifdef LIMITED_OUTPUT
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,int maxOutputSize
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#endif
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)
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{
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void* ctx = LZ4HC_create((const BYTE*)source);
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#ifdef LIMITED_OUTPUT
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int result = COMBINED_NAME(FUNCTION_NAME,ctx) (ctx, source, dest, inputSize, maxOutputSize);
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#else
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int result = COMBINED_NAME(FUNCTION_NAME,ctx) (ctx, source, dest, inputSize);
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#endif
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LZ4HC_free (&ctx);
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return result;
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}
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//****************************
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// Clean defines
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//****************************
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// Required defines
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#undef FUNCTION_NAME
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// Locally Generated
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#undef ENCODE_SEQUENCE
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#undef ENCODE_SEQUENCE_NAME
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// Optional defines
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#ifdef LIMITED_OUTPUT
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#undef LIMITED_OUTPUT
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#endif
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