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/*
* Copyright (c) 2000-2012 Marc Alexander Lehmann <schmorp@schmorp.de>
*
* Redistribution and use in source and binary forms, with or without modifica-
* tion, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
* CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
* CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
* ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Alternatively, the contents of this file may be used under the terms of
* the GNU General Public License ("GPL") version 2 or any later version,
* in which case the provisions of the GPL are applicable instead of
* the above. If you wish to allow the use of your version of this file
* only under the terms of the GPL and not to allow others to use your
* version of this file under the BSD license, indicate your decision
* by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL. If you do not delete the
* provisions above, a recipient may use your version of this file under
* either the BSD or the GPL.
*/
#include "lzfP.h"
#define HASH(p) (p[0] << 6) ^ (p[1] << 3) ^ p[2]
#if __GNUC__ >= 3
# define expect(expr,value) __builtin_expect ((expr),(value))
# define inline inline
#else
# define expect(expr,value) (expr)
# define inline static
#endif
#define expect_false(expr) expect ((expr) != 0, 0)
#define expect_true(expr) expect ((expr) != 0, 1)
/*
* compressed format
*
* 000LLLLL <L+1> ; literal, L+1=1..33 octets
* LLLooooo oooooooo ; backref L+1=1..7 octets, o+1=1..4096 offset
* 111ooooo LLLLLLLL oooooooo ; backref L+8 octets, o+1=1..4096 offset
*
*/
unsigned int
lzf_compress_best (const void *const in_data, unsigned int in_len,
void *out_data, unsigned int out_len
#if LZF_STATE_ARG
, LZF_STATE_BEST state
#endif
)
{
const u8 *ip = (const u8 *)in_data;
u8 *op = (u8 *)out_data;
const u8 *in_end = ip + in_len;
u8 *out_end = op + out_len;
#if !LZF_STATE_ARG
LZF_STATE_BEST state;
#endif
#define STATE state[0]
int lit;
if (!in_len || !out_len)
return 0;
lit = 0; op++; /* start run */
lit++; *op++ = *ip++;
while (ip < in_end - 2)
{
int best_l = 0;
const u8 *best_p;
int e = (in_end - ip < LZF_MAX_REF ? in_end - ip : LZF_MAX_REF) - 1;
unsigned int res = ((unsigned long)ip) & (LZF_MAX_OFF - 1);
u16 hash = HASH (ip);
u16 diff;
const u8 *b = ip < (u8 *)in_data + LZF_MAX_OFF ? in_data : ip - LZF_MAX_OFF;
const u8 *p = STATE.first [hash];
STATE.prev [res] = ip - p; /* update ptr to previous hash match */
STATE.first [hash] = ip; /* first hash match is here */
if (p < ip)
while (p >= b)
{
if (p[2] == ip[2]) /* first two bytes almost always match */
if (p[best_l] == ip[best_l]) /* new match must be longer than the old one to qualify */
if (p[1] == ip[1] && p[0] == ip[0]) /* just to be sure */
{
int l = 3;
while (p[l] == ip[l] && l < e)
++l;
if (l >= best_l)
{
best_p = p;
best_l = l;
}
}
diff = STATE.prev [((unsigned long)p) & (LZF_MAX_OFF - 1)];
p = diff ? p - diff : 0;
}
if (best_l)
{
int len = best_l;
int off = ip - best_p - 1;
if (expect_false (op + 3 + 1 >= out_end)) /* first a faster conservative test */
if (op - !lit + 3 + 1 >= out_end) /* second the exact but rare test */
return 0;
op [- lit - 1] = lit - 1; /* stop run */
op -= !lit; /* undo run if length is zero */
len -= 2; /* len is now #octets - 1 */
ip++;
if (len < 7)
{
*op++ = (off >> 8) + (len << 5);
}
else
{
*op++ = (off >> 8) + ( 7 << 5);
*op++ = len - 7;
}
*op++ = off;
lit = 0; op++; /* start run */
ip += len + 1;
if (expect_false (ip >= in_end - 2))
break;
ip -= len + 1;
//printf (" fill %p for %d\n", ip, len);//D
do
{
u16 hash = HASH (ip);
res = ((unsigned long)ip) & (LZF_MAX_OFF - 1);
p = STATE.first [hash];
STATE.prev [res] = ip - p; /* update ptr to previous hash match */
STATE.first [hash] = ip; /* first hash match is here */
ip++;
}
while (len--);
}
else
{
/* one more literal byte we must copy */
if (expect_false (op >= out_end))
return 0;
lit++; *op++ = *ip++;
if (expect_false (lit == LZF_MAX_LIT))
{
op [- lit - 1] = lit - 1; /* stop run */
lit = 0; op++; /* start run */
}
}
}
if (op + 3 > out_end) /* at most 3 bytes can be missing here */
return 0;
while (ip < in_end)
{
lit++; *op++ = *ip++;
if (expect_false (lit == LZF_MAX_LIT))
{
op [- lit - 1] = lit - 1; /* stop run */
lit = 0; op++; /* start run */
}
}
op [- lit - 1] = lit - 1; /* end run */
op -= !lit; /* undo run if length is zero */
return op - (u8 *)out_data;
#undef STATE
}
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