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259 lines
8.0 KiB
C
259 lines
8.0 KiB
C
/*
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LZ4 Encoder - Part of LZ4 compression 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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/* lz4_encoder.h must be included into lz4.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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#ifdef COMPRESS_64K
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# define HASHLOG (MEMORY_USAGE-1)
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# define CURRENT_H_TYPE U16
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# define CURRENTBASE(base) const BYTE* const base = ip
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#else
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# define HASHLOG (MEMORY_USAGE-2)
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# define CURRENT_H_TYPE HTYPE
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# define CURRENTBASE(base) INITBASE(base)
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#endif
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#define HASHTABLE_NBCELLS (1U<<HASHLOG)
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#define LZ4_HASH(i) (((i) * 2654435761U) >> ((MINMATCH*8)-HASHLOG))
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#define LZ4_HASHVALUE(p) LZ4_HASH(A32(p))
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//****************************
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// Function code
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//****************************
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int FUNCTION_NAME(
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#ifdef USE_HEAPMEMORY
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void* ctx,
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#endif
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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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#ifdef USE_HEAPMEMORY
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CURRENT_H_TYPE* HashTable = (CURRENT_H_TYPE*)ctx;
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#else
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CURRENT_H_TYPE HashTable[HASHTABLE_NBCELLS] = {0};
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#endif
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const BYTE* ip = (BYTE*) source;
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CURRENTBASE(base);
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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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#define 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 length;
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const int skipStrength = SKIPSTRENGTH;
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U32 forwardH;
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// Init
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if (inputSize<MINLENGTH) goto _last_literals;
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#ifdef COMPRESS_64K
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if (inputSize>LZ4_64KLIMIT) return 0; // Size too large (not within 64K limit)
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#endif
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#ifdef USE_HEAPMEMORY
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memset((void*)HashTable, 0, HASHTABLESIZE);
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#endif
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// First Byte
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HashTable[LZ4_HASHVALUE(ip)] = (CURRENT_H_TYPE)(ip - base);
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ip++; forwardH = LZ4_HASHVALUE(ip);
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// Main Loop
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for ( ; ; )
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{
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int findMatchAttempts = (1U << skipStrength) + 3;
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const BYTE* forwardIp = ip;
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const BYTE* ref;
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BYTE* token;
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// Find a match
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do {
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U32 h = forwardH;
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int step = findMatchAttempts++ >> skipStrength;
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ip = forwardIp;
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forwardIp = ip + step;
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if unlikely(forwardIp > mflimit) { goto _last_literals; }
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forwardH = LZ4_HASHVALUE(forwardIp);
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ref = base + HashTable[h];
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HashTable[h] = (CURRENT_H_TYPE)(ip - base);
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} while ((ref < ip - MAX_DISTANCE) || (A32(ref) != A32(ip)));
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// Catch up
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while ((ip>anchor) && (ref>(BYTE*)source) && unlikely(ip[-1]==ref[-1])) { ip--; ref--; }
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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 unlikely(op + length + (2 + 1 + LASTLITERALS) + (length>>8) > oend) return 0; // Check output limit
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#endif
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if (length>=(int)RUN_MASK)
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{
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int len = length-RUN_MASK;
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*token=(RUN_MASK<<ML_BITS);
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for(; len >= 255 ; len-=255) *op++ = 255;
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*op++ = (BYTE)len;
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}
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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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_next_match:
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// Encode Offset
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LZ4_WRITE_LITTLEENDIAN_16(op,(U16)(ip-ref));
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// Start Counting
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ip+=MINMATCH; ref+=MINMATCH; // MinMatch already verified
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anchor = ip;
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while likely(ip<matchlimit-(STEPSIZE-1))
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{
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UARCH diff = AARCH(ref) ^ AARCH(ip);
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if (!diff) { ip+=STEPSIZE; ref+=STEPSIZE; continue; }
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ip += LZ4_NbCommonBytes(diff);
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goto _endCount;
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}
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if (LZ4_ARCH64) if ((ip<(matchlimit-3)) && (A32(ref) == A32(ip))) { ip+=4; ref+=4; }
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if ((ip<(matchlimit-1)) && (A16(ref) == A16(ip))) { ip+=2; ref+=2; }
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if ((ip<matchlimit) && (*ref == *ip)) ip++;
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_endCount:
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// Encode MatchLength
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length = (int)(ip - anchor);
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#ifdef LIMITED_OUTPUT
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if unlikely(op + (1 + LASTLITERALS) + (length>>8) > oend) return 0; // Check output limit
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#endif
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if (length>=(int)ML_MASK)
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{
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*token += ML_MASK;
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length -= ML_MASK;
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for (; length > 509 ; length-=510) { *op++ = 255; *op++ = 255; }
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if (length >= 255) { length-=255; *op++ = 255; }
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*op++ = (BYTE)length;
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}
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else *token += (BYTE)length;
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// Test end of chunk
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if (ip > mflimit) { anchor = ip; break; }
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// Fill table
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HashTable[LZ4_HASHVALUE(ip-2)] = (CURRENT_H_TYPE)(ip - 2 - base);
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// Test next position
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ref = base + HashTable[LZ4_HASHVALUE(ip)];
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HashTable[LZ4_HASHVALUE(ip)] = (CURRENT_H_TYPE)(ip - base);
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if ((ref >= ip - MAX_DISTANCE) && (A32(ref) == A32(ip))) { token = op++; *token=0; goto _next_match; }
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// Prepare next loop
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anchor = ip++;
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forwardH = LZ4_HASHVALUE(ip);
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}
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_last_literals:
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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 >= 255 ; 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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//****************************
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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 HASHLOG
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#undef HASHTABLE_NBCELLS
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#undef LZ4_HASH
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#undef LZ4_HASHVALUE
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#undef CURRENT_H_TYPE
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#undef CURRENTBASE
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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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#ifdef USE_HEAPMEMORY
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#undef USE_HEAPMEMORY
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#endif
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