/* lzo1f_1.c -- implementation of the LZO1F-1 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 "lzo_conf.h"
#include "lzo/lzo1f.h"
/***********************************************************************
//
************************************************************************/
#define M2_MAX_OFFSET 0x0800
#define M3_MAX_OFFSET 0x3fff
#define M3_MARKER 224
#ifndef LZO_HASH
#define LZO_HASH LZO_HASH_LZO_INCREMENTAL_A
#endif
#define D_BITS 14
#define D_INDEX1(d,p) d = DM(DMUL(0x21,DX3(p,5,5,6)) >> 5)
#define D_INDEX2(d,p) d = (d & (D_MASK & 0x7ff)) ^ (D_HIGH | 0x1f)
#include "lzo_dict.h"
/***********************************************************************
// compress a block of data.
************************************************************************/
static __lzo_noinline
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;
lzo_bytep op;
const lzo_bytep const in_end = in + in_len;
const lzo_bytep const ip_end = in + in_len - 9;
const lzo_bytep ii;
lzo_dict_p const dict = (lzo_dict_p) wrkmem;
op = out;
ip = in;
ii = ip;
ip++;
for (;;)
{
const lzo_bytep m_pos;
LZO_DEFINE_UNINITIALIZED_VAR(lzo_uint, m_off, 0);
lzo_uint m_len;
lzo_uint dindex;
lzo_uint lit;
DINDEX1(dindex,ip);
GINDEX(m_pos,m_off,dict,dindex,in);
if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M3_MAX_OFFSET))
goto literal;
#if 1
if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
goto try_match;
DINDEX2(dindex,ip);
#endif
GINDEX(m_pos,m_off,dict,dindex,in);
if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M3_MAX_OFFSET))
goto literal;
if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
goto try_match;
goto literal;
try_match:
#if 0 && (LZO_OPT_UNALIGNED16)
if (UA_GET_NE16(m_pos) != UA_GET_NE16(ip))
#else
if (m_pos[0] != ip[0] || m_pos[1] != ip[1])
#endif
{
}
else
{
if (m_pos[2] == ip[2])
{
m_pos += 3;
#if 0
if (m_off <= M2_MAX_OFFSET)
goto match;
if (lit <= 3)
goto match;
if (lit == 3) /* better compression, but slower */
{
assert(op - 2 > out); op[-2] |= LZO_BYTE(3);
*op++ = *ii++; *op++ = *ii++; *op++ = *ii++;
goto code_match;
}
if (*m_pos == ip[3])
#endif
goto match;
}
}
/* a literal */
literal:
UPDATE_I(dict,0,dindex,ip,in);
if (++ip >= ip_end)
break;
continue;
/* a match */
match:
UPDATE_I(dict,0,dindex,ip,in);
/* store current literal run */
lit = pd(ip,ii);
if (lit > 0)
{
lzo_uint t = lit;
if (t < 4 && op > out)
op[-2] = LZO_BYTE(op[-2] | t);
else if (t <= 31)
*op++ = LZO_BYTE(t);
else
{
lzo_uint tt = t - 31;
*op++ = 0;
while (tt > 255)
{
tt -= 255;
UA_SET1(op, 0);
op++;
}
assert(tt > 0);
*op++ = LZO_BYTE(tt);
}
do *op++ = *ii++; while (--t > 0);
}
assert(ii == ip);
/* code the match */
ip += 3;
if (*m_pos++ != *ip++ || *m_pos++ != *ip++ || *m_pos++ != *ip++ ||
*m_pos++ != *ip++ || *m_pos++ != *ip++ || *m_pos++ != *ip++)
{
--ip;
m_len = pd(ip, ii);
assert(m_len >= 3); assert(m_len <= 8);
if (m_off <= M2_MAX_OFFSET)
{
m_off -= 1;
*op++ = LZO_BYTE(((m_len - 2) << 5) | ((m_off & 7) << 2));
*op++ = LZO_BYTE(m_off >> 3);
}
else if (m_len == 3 && m_off <= 2*M2_MAX_OFFSET && lit > 0)
{
m_off -= 1;
/* m_off -= M2_MAX_OFFSET; */
*op++ = LZO_BYTE(((m_off & 7) << 2));
*op++ = LZO_BYTE(m_off >> 3);
}
else
{
*op++ = LZO_BYTE(M3_MARKER | (m_len - 2));
*op++ = LZO_BYTE((m_off & 63) << 2);
*op++ = LZO_BYTE(m_off >> 6);
}
}
else
{
{
const lzo_bytep end;
end = in_end;
while (ip < end && *m_pos == *ip)
m_pos++, ip++;
m_len = pd(ip, ii);
}
assert(m_len >= 3);
if (m_len <= 33)
*op++ = LZO_BYTE(M3_MARKER | (m_len - 2));
else
{
m_len -= 33;
*op++ = M3_MARKER | 0;
while (m_len > 255)
{
m_len -= 255;
UA_SET1(op, 0);
op++;
}
assert(m_len > 0);
*op++ = LZO_BYTE(m_len);
}
*op++ = LZO_BYTE((m_off & 63) << 2);
*op++ = LZO_BYTE(m_off >> 6);
}
ii = ip;
if (ip >= ip_end)
break;
}
/* store final literal run */
if (pd(in_end,ii) > 0)
{
lzo_uint t = pd(in_end,ii);
if (t < 4 && op > out)
op[-2] = LZO_BYTE(op[-2] | t);
else if (t <= 31)
*op++ = LZO_BYTE(t);
else
{
lzo_uint tt = t - 31;
*op++ = 0;
while (tt > 255)
{
tt -= 255;
UA_SET1(op, 0);
op++;
}
assert(tt > 0);
*op++ = LZO_BYTE(tt);
}
UA_COPYN(op, ii, t);
op += t;
}
*out_len = pd(op, out);
return LZO_E_OK;
}
/***********************************************************************
// public entry point
************************************************************************/
LZO_PUBLIC(int)
lzo1f_1_compress ( const lzo_bytep in , lzo_uint in_len,
lzo_bytep out, lzo_uintp out_len,
lzo_voidp wrkmem )
{
lzo_bytep op = out;
int r = LZO_E_OK;
if (in_len == 0)
*out_len = 0;
else if (in_len <= 10)
{
*op++ = LZO_BYTE(in_len);
do *op++ = *in++; while (--in_len > 0);
*out_len = pd(op, out);
}
else
r = do_compress(in,in_len,out,out_len,wrkmem);
if (r == LZO_E_OK)
{
op = out + *out_len;
op[0] = M3_MARKER | 1;
op[1] = 0;
op[2] = 0;
*out_len += 3;
}
return r;
}
/*
vi:ts=4:et
*/