/* lzo1c_9x.c -- implementation of the LZO1C-999 compression 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 "config1c.h"
/***********************************************************************
//
************************************************************************/
#define SWD_N 16383 /* size of ring buffer */
#define SWD_THRESHOLD 2 /* lower limit for match length */
#define SWD_F 2048 /* upper limit for match length */
#define LZO1C 1
#define LZO_COMPRESS_T lzo1c_999_t
#define lzo_swd_t lzo1c_999_swd_t
#include "lzo_mchw.ch"
/***********************************************************************
//
************************************************************************/
static lzo_bytep
code_match ( LZO_COMPRESS_T *c, lzo_bytep op, lzo_uint m_len, lzo_uint m_off )
{
if (m_len <= M2_MAX_LEN && m_off <= M2_MAX_OFFSET)
{
assert(m_len >= M2_MIN_LEN);
assert(m_off >= M2_MIN_OFFSET);
m_off -= M2_MIN_OFFSET;
/* code match len + low offset bits */
*op++ = LZO_BYTE(((m_len - (M2_MIN_LEN - 2)) << M2O_BITS) |
(m_off & M2O_MASK));
/* code high offset bits */
*op++ = LZO_BYTE(m_off >> M2O_BITS);
c->m2_m++;
}
else
{
assert(m_len >= M3_MIN_LEN);
assert(m_off <= M3_MAX_OFFSET);
m_off -= M3_MIN_OFFSET - M3_EOF_OFFSET;
/* code match len */
if (m_len <= M3_MAX_LEN)
*op++ = LZO_BYTE(M3_MARKER | (m_len - (M3_MIN_LEN - 1)));
else
{
assert(m_len >= M4_MIN_LEN);
/* code M4 match len flag */
*op++ = M4_MARKER;
/* code match len */
m_len -= M4_MIN_LEN - 1;
while (m_len > 255)
{
m_len -= 255;
*op++ = 0;
}
assert(m_len > 0);
*op++ = LZO_BYTE(m_len);
}
/* code low offset bits */
*op++ = LZO_BYTE(m_off & M3O_MASK);
/* code high offset bits */
*op++ = LZO_BYTE(m_off >> M3O_BITS);
c->r1_m_len = 0;
c->m3 = op;
c->m3_m++;
}
return op;
}
/***********************************************************************
// this is a public function, but there is no prototype in a header file
************************************************************************/
LZO_EXTERN(int)
lzo1c_999_compress_callback ( const lzo_bytep in , lzo_uint in_len,
lzo_bytep out, lzo_uintp out_len,
lzo_voidp wrkmem,
lzo_callback_p cb,
lzo_uint max_chain );
LZO_PUBLIC(int)
lzo1c_999_compress_callback ( const lzo_bytep in , lzo_uint in_len,
lzo_bytep out, lzo_uintp out_len,
lzo_voidp wrkmem,
lzo_callback_p cb,
lzo_uint max_chain )
{
lzo_bytep op;
const lzo_bytep ii;
lzo_uint lit;
lzo_uint m_len, m_off;
LZO_COMPRESS_T cc;
LZO_COMPRESS_T * const c = &cc;
lzo_swd_p const swd = (lzo_swd_p) wrkmem;
int r;
/* sanity check */
LZO_COMPILE_TIME_ASSERT(LZO1C_999_MEM_COMPRESS >= SIZEOF_LZO_SWD_T)
c->init = 0;
c->ip = c->in = in;
c->in_end = in + in_len;
c->cb = cb;
c->r1_r = c->m3_r = c->m2_m = c->m3_m = 0;
op = out;
ii = c->ip; /* point to start of literal run */
lit = 0;
c->r1_m_len = 0;
c->m3 = out + 1; /* pointer after last m3/m4 match */
r = init_match(c,swd,NULL,0,0);
if (r != 0)
return r;
if (max_chain > 0)
swd->max_chain = max_chain;
r = find_match(c,swd,0,0);
if (r != 0)
return r;
while (c->look > 0)
{
int lazy_match_min_gain = -1;
lzo_uint ahead = 0;
m_len = c->m_len;
m_off = c->m_off;
#if 0
printf("%5ld: %5d len:%3d off:%5d\n", (c->ip-c->look)-in, c->look,
m_len, m_off);
#endif
assert(c->ip - c->look >= in);
if (lit == 0)
ii = c->ip - c->look;
assert(ii + lit == c->ip - c->look);
assert(swd->b_char == *(c->ip - c->look));
if ((m_len < M2_MIN_LEN) ||
(m_len < M3_MIN_LEN && m_off > M2_MAX_OFFSET))
{
m_len = 0;
}
else
{
assert(c->ip - c->look - m_off >= in);
assert(c->ip - c->look - m_off + m_len < c->ip);
assert(lzo_memcmp(c->ip - c->look, c->ip - c->look - m_off,
m_len) == 0);
if (lit > 0)
{
/* we have a current literal run: do not try a lazy match,
if the literal could be coded into a r1 or m3 match */
if (lit == 1 && c->r1_m_len == M2_MIN_LEN)
lazy_match_min_gain = -1;
else if (lit == 3 && op == c->m3)
lazy_match_min_gain = -1;
else if (lit < 3 && op == c->m3)
lazy_match_min_gain = 0;
else
lazy_match_min_gain = 1;
#if (M2_MIN_LEN == 2)
if (m_len == 2)
{
/* don't code a match of len 2 if we have to
code a literal run. Code a literal instead. */
m_len = 0;
}
#endif
#if (M2_MIN_LEN == M3_MIN_LEN)
if (m_len == M2_MIN_LEN && m_off > M2_MAX_OFFSET)
{
/* don't code a M3 match of len 3 if we have to
code a literal run. Code a literal instead. */
m_len = 0;
}
#endif
}
else
{
/* no current literal run: only try a lazy match,
if the literal could be coded into a r1 or m3 match */
if (c->r1_m_len == M2_MIN_LEN || op == c->m3)
lazy_match_min_gain = 0;
else
lazy_match_min_gain = -1;
}
}
/* try a lazy match */
if (m_len == 0)
lazy_match_min_gain = -1;
if (lazy_match_min_gain >= 0 && c->look > m_len)
{
assert(m_len > 0);
r = find_match(c,swd,1,0);
assert(r == 0); LZO_UNUSED(r);
assert(c->look > 0);
if (m_len <= M2_MAX_LEN && m_off <= M2_MAX_OFFSET &&
c->m_off > M2_MAX_OFFSET)
lazy_match_min_gain += 1;
if (c->m_len >= m_len + lazy_match_min_gain)
{
c->lazy++;
#if !defined(NDEBUG)
m_len = c->m_len;
m_off = c->m_off;
assert(lzo_memcmp(c->ip - c->look, c->ip - c->look - m_off,
m_len) == 0);
#endif
lit++;
assert(ii + lit == c->ip - c->look);
continue;
}
else
{
ahead = 1;
assert(ii + lit + 1 == c->ip - c->look);
}
assert(m_len > 0);
}
assert(ii + lit + ahead == c->ip - c->look);
if (m_len == 0)
{
/* a literal */
lit++;
r = find_match(c,swd,1,0);
assert(r == 0); LZO_UNUSED(r);
}
else
{
/* 1 - store run */
if (lit > 0)
{
/* code current literal run */
if (lit == 1 && c->r1_m_len == M2_MIN_LEN)
{
/* Code a context sensitive R1 match. */
assert((op[-2] >> M2O_BITS) == (M2_MARKER >> M2O_BITS));
op[-2] &= M2O_MASK;
assert((op[-2] >> M2O_BITS) == 0);
/* copy 1 literal */
*op++ = *ii++;
assert(ii + ahead == c->ip - c->look);
c->r1_r++;
}
else if (lit < 4 && op == c->m3)
{
assert((c->m3[-2] >> M3O_BITS) == 0);
c->m3[-2] = LZO_BYTE(c->m3[-2] | (lit << M3O_BITS));
MEMCPY_DS(op, ii, lit);
assert(ii + ahead == c->ip - c->look);
c->m3_r++;
}
else
{
op = STORE_RUN(op,ii,lit);
}
if (lit < R0FAST)
c->r1_m_len = m_len;
else
c->r1_m_len = 0;
lit = 0;
}
else
c->r1_m_len = 0;
/* 2 - code match */
op = code_match(c,op,m_len,m_off);
r = find_match(c,swd,m_len,1+ahead);
assert(r == 0); LZO_UNUSED(r);
}
c->codesize = pd(op, out);
}
/* store final run */
if (lit > 0)
op = STORE_RUN(op,ii,lit);
#if defined(LZO_EOF_CODE)
*op++ = M3_MARKER | 1;
*op++ = 0;
*op++ = 0;
#endif
c->codesize = pd(op, out);
assert(c->textsize == in_len);
*out_len = pd(op, out);
if (c->cb && c->cb->nprogress)
(*c->cb->nprogress)(c->cb, c->textsize, c->codesize, 0);
#if 0
printf("%ld %ld -> %ld: %ld %ld %ld %ld %ld\n",
(long) c->textsize, (long)in_len, (long) c->codesize,
c->r1_r, c->m3_r, c->m2_m, c->m3_m, c->lazy);
#endif
return LZO_E_OK;
}
/***********************************************************************
//
************************************************************************/
LZO_PUBLIC(int)
lzo1c_999_compress ( const lzo_bytep in , lzo_uint in_len,
lzo_bytep out, lzo_uintp out_len,
lzo_voidp wrkmem )
{
return lzo1c_999_compress_callback(in,in_len,out,out_len,wrkmem,
(lzo_callback_p) 0, 0);
}
/*
vi:ts=4:et
*/