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340 lines
10 KiB
C
340 lines
10 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) ((LZ4HC_Data_Structure*)ctx, source, dest, inputSize, maxOutputSize);
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#else
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int result = COMBINED_NAME(FUNCTION_NAME,ctx) ((LZ4HC_Data_Structure*)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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