/* lzo1.c -- implementation of the LZO1 algorithm This file is part of the LZO real-time data compression library. Copyright (C) 1996-2015 Markus Franz Xaver Johannes Oberhumer All Rights Reserved. The LZO library is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. The LZO library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with the LZO library; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. Markus F.X.J. Oberhumer http://www.oberhumer.com/opensource/lzo/ */ #include "lzo_conf.h" #include /*********************************************************************** // The next two defines can be changed to customize LZO1. // The default version is LZO1-5/1. ************************************************************************/ /* run bits (3 - 5) - the compressor and the decompressor * must use the same value. */ #if !defined(RBITS) # define RBITS 5 #endif /* compression level (1 - 9) - this only affects the compressor. * 1 is fastest, 9 is best compression ratio */ #if !defined(CLEVEL) # define CLEVEL 1 /* fastest by default */ #endif /* check configuration */ #if (RBITS < 3 || RBITS > 5) # error "invalid RBITS" #endif #if (CLEVEL < 1 || CLEVEL > 9) # error "invalid CLEVEL" #endif /*********************************************************************** // You should not have to change anything below this line. ************************************************************************/ /* Format of the marker byte 76543210 -------- 00000000 a long run (a 'R0' run) - there are short and long R0 runs 000rrrrr a short run with len r mmmooooo a short match (len = 2+m, o = offset low bits) 111ooooo a long match (o = offset low bits) */ #define RSIZE (1 << RBITS) #define RMASK (RSIZE - 1) #define OBITS RBITS /* offset and run-length use same bits */ #define OSIZE (1 << OBITS) #define OMASK (OSIZE - 1) #define MBITS (8 - OBITS) #define MSIZE (1 << MBITS) #define MMASK (MSIZE - 1) /* sanity checks */ #if (OBITS < 3 || OBITS > 5) # error "invalid OBITS" #endif #if (MBITS < 3 || MBITS > 5) # error "invalid MBITS" #endif /*********************************************************************** // some macros to improve readability ************************************************************************/ /* Minimum len of a match */ #define MIN_MATCH 3 #define THRESHOLD (MIN_MATCH - 1) /* Minimum len of match coded in 2 bytes */ #define MIN_MATCH_SHORT MIN_MATCH /* Maximum len of match coded in 2 bytes */ #define MAX_MATCH_SHORT (THRESHOLD + (MSIZE - 2)) /* MSIZE - 2: 0 is used to indicate runs, * MSIZE-1 is used to indicate a long match */ /* Minimum len of match coded in 3 bytes */ #define MIN_MATCH_LONG (MAX_MATCH_SHORT + 1) /* Maximum len of match coded in 3 bytes */ #define MAX_MATCH_LONG (MIN_MATCH_LONG + 255) /* Maximum offset of a match */ #define MAX_OFFSET (1 << (8 + OBITS)) /* RBITS | MBITS MIN THR. MSIZE MAXS MINL MAXL MAXO R0MAX R0FAST ======+=============================================================== 3 | 5 3 2 32 32 33 288 2048 263 256 4 | 4 3 2 16 16 17 272 4096 271 264 5 | 3 3 2 8 8 9 264 8192 287 280 */ /*********************************************************************** // internal configuration // all of these affect compression only ************************************************************************/ /* choose the hashing strategy */ #ifndef LZO_HASH #define LZO_HASH LZO_HASH_LZO_INCREMENTAL_A #endif #define D_INDEX1(d,p) d = DM(DMUL(0x21,DX2(p,5,5)) >> 5) #define D_INDEX2(d,p) d = d ^ D_MASK #define DBITS (8 + RBITS) #include "lzo_dict.h" #define DVAL_LEN DVAL_LOOKAHEAD /*********************************************************************** // get algorithm info, return memory required for compression ************************************************************************/ LZO_EXTERN(lzo_uint) lzo1_info(int* rbits, int* clevel); LZO_PUBLIC(lzo_uint) lzo1_info(int* rbits, int* clevel) { if (rbits) *rbits = RBITS; if (clevel) *clevel = CLEVEL; return D_SIZE * lzo_sizeof(lzo_bytep); } /*********************************************************************** // decode a R0 literal run (a long run) ************************************************************************/ #define R0MIN (RSIZE) /* Minimum len of R0 run of literals */ #define R0MAX (R0MIN + 255) /* Maximum len of R0 run of literals */ #define R0FAST (R0MAX & ~7u) /* R0MAX aligned to 8 byte boundary */ #if (R0MAX - R0FAST != 7) || ((R0FAST & 7) != 0) # error "something went wrong" #endif /* 7 special codes from R0FAST+1 .. R0MAX * these codes mean long R0 runs with lengths * 512, 1024, 2048, 4096, 8192, 16384, 32768 */ /*********************************************************************** // LZO1 decompress a block of data. // // Could be easily translated into assembly code. ************************************************************************/ LZO_PUBLIC(int) lzo1_decompress(const lzo_bytep in , lzo_uint in_len, lzo_bytep out, lzo_uintp out_len, lzo_voidp wrkmem) { lzo_bytep op; const lzo_bytep ip; const lzo_bytep const ip_end = in + in_len; lzo_uint t; LZO_UNUSED(wrkmem); op = out; ip = in; while (ip < ip_end) { t = *ip++; /* get marker */ if (t < R0MIN) /* a literal run */ { if (t == 0) /* a R0 literal run */ { t = *ip++; if (t >= R0FAST - R0MIN) /* a long R0 run */ { t -= R0FAST - R0MIN; if (t == 0) t = R0FAST; else { #if 0 t = 256u << ((unsigned) t); #else /* help the optimizer */ lzo_uint tt = 256; do tt <<= 1; while (--t > 0); t = tt; #endif } MEMCPY8_DS(op, ip, t); continue; } t += R0MIN; } MEMCPY_DS(op, ip, t); } else /* a match */ { lzo_uint tt; /* get match offset */ const lzo_bytep m_pos = op - 1; m_pos -= (lzo_uint)(t & OMASK) | (((lzo_uint) * ip++) << OBITS); /* get match len */ if (t >= ((MSIZE - 1) << OBITS)) /* all m-bits set */ tt = (MIN_MATCH_LONG - THRESHOLD) + *ip++; /* a long match */ else tt = t >> OBITS; /* a short match */ assert(m_pos >= out); assert(m_pos < op); /* a half unrolled loop */ *op++ = *m_pos++; *op++ = *m_pos++; MEMCPY_DS(op, m_pos, tt); } } *out_len = pd(op, out); /* the next line is the only check in the decompressor ! */ return (ip == ip_end ? LZO_E_OK : (ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN)); } /*********************************************************************** // code a literal run ************************************************************************/ static #if LZO_ARCH_AVR __lzo_noinline #endif lzo_bytep store_run(lzo_bytep op, const lzo_bytep ii, lzo_uint r_len) { assert(r_len > 0); /* code a long R0 run */ if (r_len >= 512) { unsigned r_bits = 7; /* 256 << 7 == 32768 */ do { while (r_len >= (256u << r_bits)) { r_len -= (256u << r_bits); *op++ = 0; *op++ = LZO_BYTE((R0FAST - R0MIN) + r_bits); MEMCPY8_DS(op, ii, (256u << r_bits)); } } while (--r_bits > 0); } while (r_len >= R0FAST) { r_len -= R0FAST; *op++ = 0; *op++ = R0FAST - R0MIN; MEMCPY8_DS(op, ii, R0FAST); } if (r_len >= R0MIN) { /* code a short R0 run */ *op++ = 0; *op++ = LZO_BYTE(r_len - R0MIN); MEMCPY_DS(op, ii, r_len); } else if (r_len > 0) { /* code a 'normal' run */ *op++ = LZO_BYTE(r_len); MEMCPY_DS(op, ii, r_len); } assert(r_len == 0); return op; } /*********************************************************************** // LZO1 compress a block of data. // // Could be translated into assembly code without too much effort. // // I apologize for the spaghetti code, but it really helps the optimizer. ************************************************************************/ static int do_compress(const lzo_bytep in , lzo_uint in_len, lzo_bytep out, lzo_uintp out_len, lzo_voidp wrkmem) { const lzo_bytep ip; #if defined(__LZO_HASH_INCREMENTAL) lzo_xint dv; #endif lzo_bytep op; const lzo_bytep m_pos; const lzo_bytep const ip_end = in + in_len - DVAL_LEN - MIN_MATCH_LONG; const lzo_bytep const in_end = in + in_len - DVAL_LEN; const lzo_bytep ii; lzo_dict_p const dict = (lzo_dict_p) wrkmem; #if !defined(NDEBUG) const lzo_bytep m_pos_sav; #endif op = out; ip = in; ii = ip; /* point to start of literal run */ if (in_len <= MIN_MATCH_LONG + DVAL_LEN + 1) goto the_end; /* init dictionary */ #if (LZO_DETERMINISTIC) BZERO8_PTR(wrkmem, sizeof(lzo_dict_t), D_SIZE); #endif DVAL_FIRST(dv, ip); UPDATE_D(dict, 0, dv, ip, in); ip++; DVAL_NEXT(dv, ip); do { LZO_DEFINE_UNINITIALIZED_VAR(lzo_uint, m_off, 0); lzo_uint dindex; DINDEX1(dindex, ip); GINDEX(m_pos, m_off, dict, dindex, in); if (LZO_CHECK_MPOS(m_pos, m_off, in, ip, MAX_OFFSET)) goto literal; if (m_pos[0] == ip[0] && m_pos[1] == ip[1] && m_pos[2] == ip[2]) goto match; DINDEX2(dindex, ip); GINDEX(m_pos, m_off, dict, dindex, in); if (LZO_CHECK_MPOS(m_pos, m_off, in, ip, MAX_OFFSET)) goto literal; if (m_pos[0] == ip[0] && m_pos[1] == ip[1] && m_pos[2] == ip[2]) goto match; goto literal; literal: UPDATE_I(dict, 0, dindex, ip, in); if (++ip >= ip_end) break; continue; match: UPDATE_I(dict, 0, dindex, ip, in); #if !defined(NDEBUG) && (LZO_DICT_USE_PTR) m_pos_sav = m_pos; #endif m_pos += 3; { /* we have found a match (of at least length 3) */ #if !defined(NDEBUG) && !(LZO_DICT_USE_PTR) assert((m_pos_sav = ip - m_off) == (m_pos - 3)); #endif /* 1) store the current literal run */ if (pd(ip, ii) > 0) { lzo_uint t = pd(ip, ii); #if 1 /* OPTIMIZED: inline the copying of a short run */ if (t < R0MIN) { *op++ = LZO_BYTE(t); MEMCPY_DS(op, ii, t); } else #endif op = store_run(op, ii, t); } /* 2a) compute match len */ ii = ip; /* point to start of current match */ /* we already matched MIN_MATCH bytes, * m_pos also already advanced MIN_MATCH bytes */ ip += MIN_MATCH; assert(m_pos < ip); /* try to match another MIN_MATCH_LONG - MIN_MATCH bytes * to see if we get a long match */ #define PS *m_pos++ != *ip++ #if (MIN_MATCH_LONG - MIN_MATCH == 2) /* MBITS == 2 */ if (PS || PS) #elif (MIN_MATCH_LONG - MIN_MATCH == 6) /* MBITS == 3 */ if (PS || PS || PS || PS || PS || PS) #elif (MIN_MATCH_LONG - MIN_MATCH == 14) /* MBITS == 4 */ if (PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS) #elif (MIN_MATCH_LONG - MIN_MATCH == 30) /* MBITS == 5 */ if (PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS || PS) #else # error "MBITS not yet implemented" #endif { lzo_uint m_len; /* 2b) code a short match */ assert(pd(ip, m_pos) == m_off); --ip; /* ran one too far, point back to non-match */ m_len = pd(ip, ii); assert(m_len >= MIN_MATCH_SHORT); assert(m_len <= MAX_MATCH_SHORT); assert(m_off > 0); assert(m_off <= MAX_OFFSET); assert(ii - m_off == m_pos_sav); assert(lzo_memcmp(m_pos_sav, ii, m_len) == 0); --m_off; /* code short match len + low offset bits */ *op++ = LZO_BYTE(((m_len - THRESHOLD) << OBITS) | (m_off & OMASK)); /* code high offset bits */ *op++ = LZO_BYTE(m_off >> OBITS); /* 2c) Insert phrases (beginning with ii+1) into the dictionary. */ #define SI /* nothing */ #define DI ++ii; DVAL_NEXT(dv,ii); UPDATE_D(dict,0,dv,ii,in); #define XI assert(ii < ip); ii = ip; DVAL_FIRST(dv,(ip)); #if (CLEVEL == 9) || (CLEVEL >= 7 && MBITS <= 4) || (CLEVEL >= 5 && MBITS <= 3) /* Insert the whole match (ii+1)..(ip-1) into dictionary. */ ++ii; do { DVAL_NEXT(dv, ii); UPDATE_D(dict, 0, dv, ii, in); } while (++ii < ip); DVAL_NEXT(dv, ii); assert(ii == ip); DVAL_ASSERT(dv, ip); #elif (CLEVEL >= 3) SI DI DI XI #elif (CLEVEL >= 2) SI DI XI #else XI #endif } else { /* we've found a long match - see how far we can still go */ const lzo_bytep end; lzo_uint m_len; assert(ip <= in_end); assert(ii == ip - MIN_MATCH_LONG); if (pd(in_end, ip) <= (MAX_MATCH_LONG - MIN_MATCH_LONG)) end = in_end; else { end = ip + (MAX_MATCH_LONG - MIN_MATCH_LONG); assert(end < in_end); } while (ip < end && *m_pos == *ip) m_pos++, ip++; assert(ip <= in_end); /* 2b) code the long match */ m_len = pd(ip, ii); assert(m_len >= MIN_MATCH_LONG); assert(m_len <= MAX_MATCH_LONG); assert(m_off > 0); assert(m_off <= MAX_OFFSET); assert(ii - m_off == m_pos_sav); assert(lzo_memcmp(m_pos_sav, ii, m_len) == 0); assert(pd(ip, m_pos) == m_off); --m_off; /* code long match flag + low offset bits */ *op++ = LZO_BYTE(((MSIZE - 1) << OBITS) | (m_off & OMASK)); /* code high offset bits */ *op++ = LZO_BYTE(m_off >> OBITS); /* code match len */ *op++ = LZO_BYTE(m_len - MIN_MATCH_LONG); /* 2c) Insert phrases (beginning with ii+1) into the dictionary. */ #if (CLEVEL == 9) /* Insert the whole match (ii+1)..(ip-1) into dictionary. */ /* This is not recommended because it is slow. */ ++ii; do { DVAL_NEXT(dv, ii); UPDATE_D(dict, 0, dv, ii, in); } while (++ii < ip); DVAL_NEXT(dv, ii); assert(ii == ip); DVAL_ASSERT(dv, ip); #elif (CLEVEL >= 8) SI DI DI DI DI DI DI DI DI XI #elif (CLEVEL >= 7) SI DI DI DI DI DI DI DI XI #elif (CLEVEL >= 6) SI DI DI DI DI DI DI XI #elif (CLEVEL >= 5) SI DI DI DI DI XI #elif (CLEVEL >= 4) SI DI DI DI XI #elif (CLEVEL >= 3) SI DI DI XI #elif (CLEVEL >= 2) SI DI XI #else XI #endif } /* ii now points to the start of next literal run */ assert(ii == ip); } } while (ip < ip_end); the_end: assert(ip <= in_end); #if defined(LZO_RETURN_IF_NOT_COMPRESSIBLE) /* return -1 if op == out to indicate that we * couldn't compress and didn't copy anything. */ if (op == out) { *out_len = 0; return LZO_E_NOT_COMPRESSIBLE; } #endif /* store the final literal run */ if (pd(in_end + DVAL_LEN, ii) > 0) op = store_run(op, ii, pd(in_end + DVAL_LEN, ii)); *out_len = pd(op, out); return 0; /* compression went ok */ } /*********************************************************************** // compress public entry point. ************************************************************************/ LZO_PUBLIC(int) lzo1_compress(const lzo_bytep in , lzo_uint in_len, lzo_bytep out, lzo_uintp out_len, lzo_voidp wrkmem) { int r = LZO_E_OK; /* don't try to compress a block that's too short */ if (in_len == 0) *out_len = 0; else if (in_len <= MIN_MATCH_LONG + DVAL_LEN + 1) { #if defined(LZO_RETURN_IF_NOT_COMPRESSIBLE) r = LZO_E_NOT_COMPRESSIBLE; #else *out_len = pd(store_run(out, in, in_len), out); #endif } else r = do_compress(in, in_len, out, out_len, wrkmem); return r; } /* vim:set ts=4 sw=4 et: */