/* lzo1.c -- implementation of the LZO1 algorithm
This file is part of the LZO real-time data compression library.
Copyright (C) 1996-2014 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
<markus@oberhumer.com>
http://www.oberhumer.com/opensource/lzo/
*/
#include "lzo_conf.h"
#include "lzo/lzo1.h"
/***********************************************************************
// 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;
}
/*
vi:ts=4:et
*/