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/* implementation of the LZO1[XY]-1 compression algorithm
This file is part of the LZO real-time data compression library.
Copyright (C) 1996..2008 Markus Franz Xaver Johannes Oberhumer
All Rights Reserved.
Markus F.X.J. Oberhumer <markus@oberhumer.com>
http://www.oberhumer.com/opensource/lzo/
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.
*/
/***********************************************************************
// compress a block of data.
************************************************************************/
static NOINLINE unsigned
do_compress(const uint8_t* in, unsigned in_len,
uint8_t* out, unsigned* out_len,
void* wrkmem)
{
register const uint8_t* ip;
uint8_t* op;
const uint8_t* const in_end = in + in_len;
const uint8_t* const ip_end = in + in_len - M2_MAX_LEN - 5;
const uint8_t* ii;
const void* *const dict = (const void**) wrkmem;
op = out;
ip = in;
ii = ip;
ip += 4;
for (;;) {
register const uint8_t* m_pos;
unsigned m_off;
unsigned m_len;
unsigned dindex;
D_INDEX1(dindex,ip);
GINDEX(m_pos,m_off,dict,dindex,in);
if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M4_MAX_OFFSET))
goto literal;
#if 1
if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
goto try_match;
D_INDEX2(dindex,ip);
#endif
GINDEX(m_pos,m_off,dict,dindex,in);
if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M4_MAX_OFFSET))
goto literal;
if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
goto try_match;
goto literal;
try_match:
#if 1 && defined(LZO_UNALIGNED_OK_2)
if (* (const lzo_ushortp) m_pos != * (const lzo_ushortp) ip)
#else
if (m_pos[0] != ip[0] || m_pos[1] != ip[1])
#endif
{
} else {
if (m_pos[2] == ip[2]) {
#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] |= (uint8_t)(3);
*op++ = *ii++; *op++ = *ii++; *op++ = *ii++;
goto code_match;
}
if (m_pos[3] == ip[3])
#endif
goto match;
}
else {
/* still need a better way for finding M1 matches */
#if 0
/* a M1 match */
#if 0
if (m_off <= M1_MAX_OFFSET && lit > 0 && lit <= 3)
#else
if (m_off <= M1_MAX_OFFSET && lit == 3)
#endif
{
register unsigned t;
t = lit;
assert(op - 2 > out); op[-2] |= (uint8_t)(t);
do *op++ = *ii++; while (--t > 0);
assert(ii == ip);
m_off -= 1;
*op++ = (uint8_t)(M1_MARKER | ((m_off & 3) << 2));
*op++ = (uint8_t)(m_off >> 2);
ip += 2;
goto match_done;
}
#endif
}
}
/* a literal */
literal:
UPDATE_I(dict, 0, dindex, ip, in);
++ip;
if (ip >= ip_end)
break;
continue;
/* a match */
match:
UPDATE_I(dict, 0, dindex, ip, in);
/* store current literal run */
if (pd(ip, ii) > 0) {
register unsigned t = pd(ip, ii);
if (t <= 3) {
assert(op - 2 > out);
op[-2] |= (uint8_t)(t);
}
else if (t <= 18)
*op++ = (uint8_t)(t - 3);
else {
register unsigned tt = t - 18;
*op++ = 0;
while (tt > 255) {
tt -= 255;
*op++ = 0;
}
assert(tt > 0);
*op++ = (uint8_t)(tt);
}
do *op++ = *ii++; while (--t > 0);
}
/* code the match */
assert(ii == ip);
ip += 3;
if (m_pos[3] != *ip++ || m_pos[4] != *ip++ || m_pos[5] != *ip++
|| m_pos[6] != *ip++ || m_pos[7] != *ip++ || m_pos[8] != *ip++
#ifdef LZO1Y
|| m_pos[ 9] != *ip++ || m_pos[10] != *ip++ || m_pos[11] != *ip++
|| m_pos[12] != *ip++ || m_pos[13] != *ip++ || m_pos[14] != *ip++
#endif
) {
--ip;
m_len = pd(ip, ii);
assert(m_len >= 3);
assert(m_len <= M2_MAX_LEN);
if (m_off <= M2_MAX_OFFSET) {
m_off -= 1;
#if defined(LZO1X)
*op++ = (uint8_t)(((m_len - 1) << 5) | ((m_off & 7) << 2));
*op++ = (uint8_t)(m_off >> 3);
#elif defined(LZO1Y)
*op++ = (uint8_t)(((m_len + 1) << 4) | ((m_off & 3) << 2));
*op++ = (uint8_t)(m_off >> 2);
#endif
}
else if (m_off <= M3_MAX_OFFSET) {
m_off -= 1;
*op++ = (uint8_t)(M3_MARKER | (m_len - 2));
goto m3_m4_offset;
} else {
#if defined(LZO1X)
m_off -= 0x4000;
assert(m_off > 0);
assert(m_off <= 0x7fff);
*op++ = (uint8_t)(M4_MARKER | ((m_off & 0x4000) >> 11) | (m_len - 2));
goto m3_m4_offset;
#elif defined(LZO1Y)
goto m4_match;
#endif
}
}
else {
{
const uint8_t* end = in_end;
const uint8_t* m = m_pos + M2_MAX_LEN + 1;
while (ip < end && *m == *ip)
m++, ip++;
m_len = pd(ip, ii);
}
assert(m_len > M2_MAX_LEN);
if (m_off <= M3_MAX_OFFSET) {
m_off -= 1;
if (m_len <= 33)
*op++ = (uint8_t)(M3_MARKER | (m_len - 2));
else {
m_len -= 33;
*op++ = M3_MARKER | 0;
goto m3_m4_len;
}
} else {
#if defined(LZO1Y)
m4_match:
#endif
m_off -= 0x4000;
assert(m_off > 0);
assert(m_off <= 0x7fff);
if (m_len <= M4_MAX_LEN)
*op++ = (uint8_t)(M4_MARKER | ((m_off & 0x4000) >> 11) | (m_len - 2));
else {
m_len -= M4_MAX_LEN;
*op++ = (uint8_t)(M4_MARKER | ((m_off & 0x4000) >> 11));
m3_m4_len:
while (m_len > 255) {
m_len -= 255;
*op++ = 0;
}
assert(m_len > 0);
*op++ = (uint8_t)(m_len);
}
}
m3_m4_offset:
*op++ = (uint8_t)((m_off & 63) << 2);
*op++ = (uint8_t)(m_off >> 6);
}
#if 0
match_done:
#endif
ii = ip;
if (ip >= ip_end)
break;
}
*out_len = pd(op, out);
return pd(in_end, ii);
}
/***********************************************************************
// public entry point
************************************************************************/
int DO_COMPRESS(const uint8_t* in, unsigned in_len,
uint8_t* out, unsigned* out_len,
void* wrkmem)
{
uint8_t* op = out;
unsigned t;
if (in_len <= M2_MAX_LEN + 5)
t = in_len;
else {
t = do_compress(in,in_len,op,out_len,wrkmem);
op += *out_len;
}
if (t > 0) {
const uint8_t* ii = in + in_len - t;
if (op == out && t <= 238)
*op++ = (uint8_t)(17 + t);
else if (t <= 3)
op[-2] |= (uint8_t)(t);
else if (t <= 18)
*op++ = (uint8_t)(t - 3);
else {
unsigned tt = t - 18;
*op++ = 0;
while (tt > 255) {
tt -= 255;
*op++ = 0;
}
assert(tt > 0);
*op++ = (uint8_t)(tt);
}
do *op++ = *ii++; while (--t > 0);
}
*op++ = M4_MARKER | 1;
*op++ = 0;
*op++ = 0;
*out_len = pd(op, out);
return 0; /*LZO_E_OK*/
}
|
