/* lzo1a.c -- implementation of the LZO1A algorithm
This file is part of the LZO real-time data compression library.
Copyright (C) 1996-2002 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.,
59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
Markus F.X.J. Oberhumer
<markus@oberhumer.com>
*/
#include <lzo1a.h>
#include "lzo_conf.h"
/***********************************************************************
// The next two defines can be changed to customize LZO1A.
// The default version is LZO1A-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
/* Collect statistics */
#if 0 && !defined(LZO_COLLECT_STATS)
# define LZO_COLLECT_STATS
#endif
/***********************************************************************
// You should not have to change anything below this line.
************************************************************************/
/* check configuration */
#if (RBITS < 3 || RBITS > 5)
# error "invalid RBITS"
#endif
#if (CLEVEL < 1 || CLEVEL > 9)
# error "invalid CLEVEL"
#endif
/***********************************************************************
// internal configuration
// all of these affect compression only
************************************************************************/
/* return -1 instead of copying if the data cannot be compressed */
#undef LZO_RETURN_IF_NOT_COMPRESSIBLE
/* choose the hashing strategy */
#ifndef LZO_HASH
#define LZO_HASH LZO_HASH_LZO_INCREMENTAL_A
#endif
#define D_INDEX1(d,p) d = DM((0x21*DX2(p,5,5)) >> 5)
#define D_INDEX2(d,p) d = d ^ D_MASK
#include "lzo1a_de.h"
#include "stats1a.h"
#include "lzo_util.h"
/* check other constants */
#if (LBITS < 5 || LBITS > 8)
# error "invalid LBITS"
#endif
#if defined(LZO_COLLECT_STATS)
static lzo1a_stats_t lzo_statistics;
lzo1a_stats_t *lzo1a_stats = &lzo_statistics;
# define lzo_stats lzo1a_stats
#endif
/***********************************************************************
// get algorithm info, return memory required for compression
************************************************************************/
LZO_EXTERN(lzo_uint) lzo1a_info ( int *rbits, int *clevel );
LZO_PUBLIC(lzo_uint)
lzo1a_info ( int *rbits, int *clevel )
{
if (rbits)
*rbits = RBITS;
if (clevel)
*clevel = CLEVEL;
return D_SIZE * lzo_sizeof(lzo_byte *);
}
/***********************************************************************
// LZO1A decompress a block of data.
//
// Could be easily translated into assembly code.
************************************************************************/
LZO_PUBLIC(int)
lzo1a_decompress ( const lzo_byte *in , lzo_uint in_len,
lzo_byte *out, lzo_uintp out_len,
lzo_voidp wrkmem )
{
#if defined(LZO_OPTIMIZE_GNUC_i386)
register lzo_byte *op __asm__("%edi");
register const lzo_byte *ip __asm__("%esi");
register lzo_uint t __asm__("%ecx");
register const lzo_byte *m_pos __asm__("%ebx");
#else
register lzo_byte *op;
register const lzo_byte *ip;
register lzo_uint t;
register const lzo_byte *m_pos;
#endif
const lzo_byte * const ip_end = in + in_len;
LZO_UNUSED(wrkmem);
#if defined(__LZO_QUERY_DECOMPRESS)
if (__LZO_IS_DECOMPRESS_QUERY(in,in_len,out,out_len,wrkmem))
return __LZO_QUERY_DECOMPRESS(in,in_len,out,out_len,wrkmem,0,0);
#endif
op = out;
ip = in;
while (ip < ip_end)
{
t = *ip++; /* get marker */
LZO_STATS(lzo_stats->marker[t]++);
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;
goto literal;
}
else if (t < R0MIN) /* a short literal run */
{
literal:
MEMCPY_DS(op,ip,t);
/* after a literal a match must follow */
while (ip < ip_end)
{
t = *ip++; /* get R1 marker */
if (t >= R0MIN)
goto match;
/* R1 match - a context sensitive 3 byte match + 1 byte literal */
assert((t & OMASK) == t);
m_pos = op - MIN_OFFSET;
m_pos -= t | (((lzo_uint) *ip++) << OBITS);
assert(m_pos >= out); assert(m_pos < op);
*op++ = *m_pos++;
*op++ = *m_pos++;
*op++ = *m_pos++;
*op++ = *ip++;
}
}
else /* a match */
{
match:
/* get match offset */
m_pos = op - MIN_OFFSET;
m_pos -= (t & OMASK) | (((lzo_uint) *ip++) << OBITS);
assert(m_pos >= out); assert(m_pos < op);
/* get match len */
if (t < ((MSIZE - 1) << OBITS)) /* a short match */
{
t >>= OBITS;
*op++ = *m_pos++;
*op++ = *m_pos++;
MEMMOVE_DS(op,m_pos,t);
}
else /* a long match */
{
#if (LBITS < 8)
t = (MIN_MATCH_LONG - THRESHOLD) + ((lzo_uint)(*ip++) & LMASK);
#else
t = (MIN_MATCH_LONG - THRESHOLD) + (lzo_uint)(*ip++);
#endif
*op++ = *m_pos++;
*op++ = *m_pos++;
MEMMOVE_DS(op,m_pos,t);
#if (LBITS < 8)
/* a very short literal following a long match */
t = ip[-1] >> LBITS;
if (t) do
*op++ = *ip++;
while (--t);
#endif
}
}
}
*out_len = 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));
}
/***********************************************************************
// LZO1A compress a block of data.
//
// I apologize for the spaghetti code, but it really helps the optimizer.
************************************************************************/
#include "lzo1a_cr.ch"
static int
do_compress ( const lzo_byte *in , lzo_uint in_len,
lzo_byte *out, lzo_uintp out_len,
lzo_voidp wrkmem )
{
#if defined(LZO_OPTIMIZE_GNUC_i386)
register const lzo_byte *ip __asm__("%esi");
#else
register const lzo_byte *ip;
#endif
#if defined(__LZO_HASH_INCREMENTAL)
lzo_uint32 dv;
#endif
const lzo_byte *m_pos;
lzo_byte *op;
const lzo_byte * const ip_end = in+in_len - DVAL_LEN - MIN_MATCH_LONG;
const lzo_byte * const in_end = in+in_len - DVAL_LEN;
const lzo_byte *ii;
lzo_dict_p const dict = (lzo_dict_p) wrkmem;
const lzo_byte *r1 = ip_end; /* pointer for R1 match (none yet) */
#if (LBITS < 8)
const lzo_byte *im = ip_end; /* pointer to last match start */
#endif
#if !defined(NDEBUG)
const lzo_byte *m_pos_sav;
#endif
op = out;
ip = in;
ii = ip; /* point to start of current literal run */
/* init dictionary */
#if defined(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_moff_t m_off;
lzo_uint dindex;
DINDEX1(dindex,ip);
GINDEX(m_pos,m_off,dict,dindex,in);
if (LZO_CHECK_MPOS_NON_DET(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_NON_DET(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) && defined(LZO_DICT_USE_PTR)
assert(m_pos == NULL || m_pos >= in);
m_pos_sav = m_pos;
#endif
m_pos += 3;
{
/* we have found a match (of at least length 3) */
#if !defined(NDEBUG) && !defined(LZO_DICT_USE_PTR)
assert((m_pos_sav = ip - m_off) == (m_pos - 3));
#endif
assert(m_pos >= in);
assert(ip < ip_end);
/* 1) store the current literal run */
if (pd(ip,ii) > 0)
{
lzo_uint t = pd(ip,ii);
if (ip - r1 == MIN_MATCH + 1)
{
/* Code a context sensitive R1 match.
* This is tricky and somewhat difficult to explain:
* multiplex a literal run of length 1 into the previous
* short match of length MIN_MATCH.
* The key idea is:
* - after a short run a match MUST follow
* - therefore the value m = 000 in the mmmooooo marker is free
* - use 000ooooo to indicate a MIN_MATCH match (this
* is already coded) plus a 1 byte literal
*/
assert(t == 1);
/* modify marker byte */
assert((op[-2] >> OBITS) == (MIN_MATCH - THRESHOLD));
op[-2] &= OMASK;
assert((op[-2] >> OBITS) == 0);
/* copy 1 literal */
*op++ = *ii;
LZO_STATS(lzo_stats->r1_matches++);
r1 = ip; /* set new R1 pointer */
}
else if (t < R0MIN)
{
/* inline the copying of a short run */
#if (LBITS < 8)
if (t < (1 << (8-LBITS)) && ii - im >= MIN_MATCH_LONG)
{
/* Code a very short literal run into the
* previous long match length byte.
*/
LZO_STATS(lzo_stats->lit_runs_after_long_match++);
LZO_STATS(lzo_stats->lit_run_after_long_match[t]++);
assert(ii - im <= MAX_MATCH_LONG);
assert((op[-1] >> LBITS) == 0);
op[-1] |= t << LBITS;
MEMCPY_DS(op, ii, t);
}
else
#endif
{
LZO_STATS(lzo_stats->lit_runs++);
LZO_STATS(lzo_stats->lit_run[t]++);
*op++ = LZO_BYTE(t);
MEMCPY_DS(op, ii, t);
r1 = ip; /* set new R1 pointer */
}
}
else if (t < R0FAST)
{
/* inline the copying of a short R0 run */
LZO_STATS(lzo_stats->r0short_runs++);
*op++ = 0; *op++ = LZO_BYTE(t - R0MIN);
MEMCPY_DS(op, ii, t);
r1 = ip; /* set new R1 pointer */
}
else
op = store_run(op,ii,t);
}
#if (LBITS < 8)
im = ip;
#endif
/* 2) 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
{
/* we've found a short match */
lzo_uint m_len;
/* 2a) compute match parameters */
assert(ip-m_pos == (int)m_off);
--ip; /* ran one too far, point back to non-match */
m_len = ip - ii;
assert(m_len >= MIN_MATCH_SHORT);
assert(m_len <= MAX_MATCH_SHORT);
assert(m_off >= MIN_OFFSET);
assert(m_off <= MAX_OFFSET);
assert(ii-m_off == m_pos_sav);
assert(lzo_memcmp(m_pos_sav,ii,m_len) == 0);
m_off -= MIN_OFFSET;
/* 2b) code a short match */
/* 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);
#if defined(LZO_COLLECT_STATS)
lzo_stats->short_matches++;
lzo_stats->short_match[m_len]++;
if (m_off < OSIZE)
lzo_stats->short_match_offset_osize[m_len]++;
if (m_off < 256)
lzo_stats->short_match_offset_256[m_len]++;
if (m_off < 1024)
lzo_stats->short_match_offset_1024[m_len]++;
#endif
/* 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_byte *end;
lzo_uint m_len;
assert(ip <= in_end);
assert(ii == ip - MIN_MATCH_LONG);
#if defined(__LZO_CHECKER)
if (in_end - ip <= (MAX_MATCH_LONG - MIN_MATCH_LONG))
#else
if (in_end <= ip + (MAX_MATCH_LONG - MIN_MATCH_LONG))
#endif
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);
/* 2a) compute match parameters */
m_len = (ip - ii);
assert(m_len >= MIN_MATCH_LONG);
assert(m_len <= MAX_MATCH_LONG);
assert(m_off >= MIN_OFFSET);
assert(m_off <= MAX_OFFSET);
assert(ii-m_off == m_pos_sav);
assert(lzo_memcmp(m_pos_sav,ii,m_len) == 0);
assert(ip-m_pos == (int)m_off);
m_off -= MIN_OFFSET;
/* 2b) code the long match */
/* 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);
#if defined(LZO_COLLECT_STATS)
lzo_stats->long_matches++;
lzo_stats->long_match[m_len]++;
#endif
/* 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 the next literal run */
assert(ii == ip);
}
} while (ip < ip_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 = op - out;
return 0; /* compression went ok */
}
/***********************************************************************
// LZO1A compress public entry point.
************************************************************************/
LZO_PUBLIC(int)
lzo1a_compress ( const lzo_byte *in , lzo_uint in_len,
lzo_byte *out, lzo_uintp out_len,
lzo_voidp wrkmem )
{
int r = LZO_E_OK;
#if defined(__LZO_QUERY_COMPRESS)
if (__LZO_IS_COMPRESS_QUERY(in,in_len,out,out_len,wrkmem))
return __LZO_QUERY_COMPRESS(in,in_len,out,out_len,wrkmem,D_SIZE,lzo_sizeof(lzo_dict_t));
#endif
#if defined(LZO_COLLECT_STATS)
memset(lzo_stats,0,sizeof(*lzo_stats));
lzo_stats->rbits = RBITS;
lzo_stats->clevel = CLEVEL;
lzo_stats->dbits = DBITS;
lzo_stats->lbits = LBITS;
lzo_stats->min_match_short = MIN_MATCH_SHORT;
lzo_stats->max_match_short = MAX_MATCH_SHORT;
lzo_stats->min_match_long = MIN_MATCH_LONG;
lzo_stats->max_match_long = MAX_MATCH_LONG;
lzo_stats->min_offset = MIN_OFFSET;
lzo_stats->max_offset = MAX_OFFSET;
lzo_stats->r0min = R0MIN;
lzo_stats->r0fast = R0FAST;
lzo_stats->r0max = R0MAX;
lzo_stats->in_len = in_len;
#endif
/* 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 = store_run(out,in,in_len) - out;
#endif
}
else
r = do_compress(in,in_len,out,out_len,wrkmem);
#if defined(LZO_COLLECT_STATS)
lzo_stats->short_matches -= lzo_stats->r1_matches;
lzo_stats->short_match[MIN_MATCH] -= lzo_stats->r1_matches;
lzo_stats->out_len = *out_len;
#endif
return r;
}
/*
vi:ts=4:et
*/