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/* lzo_swd.ch -- sliding window dictionary
This file is part of the LZO real-time data compression library.
Copyright (C) 1996-2015 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/
*/
#if (LZO_UINT_MAX < LZO_0xffffffffL)
# error "LZO_UINT_MAX"
#endif
#if defined(LZO_DEBUG)
# include <stdio.h>
#endif
#if defined(__LZO_CHECKER)
# include <stdlib.h>
#endif
/***********************************************************************
//
************************************************************************/
/* unsigned type for dictionary access - don't waste memory here */
#if (0UL + SWD_N + SWD_F + SWD_F < 65535UL)
typedef lzo_uint16_t swd_uint;
# define SWD_UINT_MAX 0xffffu
#else
typedef lzo_uint32_t swd_uint;
# define SWD_UINT_MAX 0xffffffffu
#endif
#define swd_uintp swd_uint *
#define SWD_UINT(x) ((swd_uint)(x))
#ifndef SWD_HSIZE
# define SWD_HSIZE 16384
#endif
#ifndef SWD_MAX_CHAIN
# define SWD_MAX_CHAIN 2048
#endif
#if !defined(HEAD3)
#if 1
# define HEAD3(b,p) \
((DMUL(0x9f5f,(((((lzo_xint)b[p]<<5)^b[p+1])<<5)^b[p+2]))>>5) & (SWD_HSIZE-1))
#else
# define HEAD3(b,p) \
((DMUL(0x9f5f,(((((lzo_xint)b[p+2]<<5)^b[p+1])<<5)^b[p]))>>5) & (SWD_HSIZE-1))
#endif
#endif
#if !(SWD_NO_HEAD2) && (SWD_THRESHOLD == 1) && !defined(HEAD2)
# if 1 && (LZO_OPT_UNALIGNED16)
# define HEAD2(b,p) UA_GET_NE16((b)+(p))
# else
# define HEAD2(b,p) (b[p] ^ ((unsigned)b[(p)+1]<<8))
# endif
# define NIL2 SWD_UINT_MAX
#endif
#ifndef IF_HEAD2
#define IF_HEAD2(s) /*empty*/
#endif
typedef struct
{
/* public - "built-in" */
lzo_uint swd_n;
lzo_uint swd_f;
lzo_uint swd_threshold;
/* public - configuration */
lzo_uint max_chain;
lzo_uint nice_length;
lzo_bool use_best_off;
lzo_uint lazy_insert;
/* public - output */
lzo_uint m_len;
lzo_uint m_off;
lzo_uint look;
int b_char;
#if defined(SWD_BEST_OFF)
lzo_uint best_off[ SWD_BEST_OFF ];
#endif
/* semi public */
LZO_COMPRESS_T* c;
lzo_uint m_pos;
#if defined(SWD_BEST_OFF)
lzo_uint best_pos[ SWD_BEST_OFF ];
#endif
/* private */
const lzo_bytep dict;
const lzo_bytep dict_end;
lzo_uint dict_len;
/* private */
lzo_uint ip; /* input pointer (lookahead) */
lzo_uint bp; /* buffer pointer */
lzo_uint rp; /* remove pointer */
lzo_uint b_size;
lzo_bytep b_wrap;
lzo_uint node_count;
lzo_uint first_rp;
#if defined(__LZO_CHECKER)
/* malloc arrays of the exact size to detect any overrun */
unsigned char* b;
swd_uint* head3;
swd_uint* succ3;
swd_uint* best3;
swd_uint* llen3;
# ifdef HEAD2
swd_uint* head2;
# endif
#else
unsigned char b [ SWD_N + SWD_F + SWD_F ];
swd_uint head3 [ SWD_HSIZE ];
swd_uint succ3 [ SWD_N + SWD_F ];
swd_uint best3 [ SWD_N + SWD_F ];
swd_uint llen3 [ SWD_HSIZE ];
# ifdef HEAD2
swd_uint head2 [ 65536L ];
# endif
#endif
}
lzo_swd_t;
#define lzo_swd_p lzo_swd_t *
#define s_b(s) s->b
#define s_head3(s) s->head3
#define s_succ3(s) s->succ3
#define s_best3(s) s->best3
#define s_llen3(s) s->llen3
#ifdef HEAD2
#define s_head2(s) s->head2
#endif
#define SIZEOF_LZO_SWD_T (sizeof(lzo_swd_t))
/* Access macro for head3.
* head3[key] may be uninitialized if the list is emtpy,
* but then its value will never be used.
*/
#if 1 || defined(__LZO_CHECKER)
# define s_get_head3(s,key) \
((swd_uint)((s_llen3(s)[key] == 0) ? SWD_UINT_MAX : s_head3(s)[key]))
#else
# define s_get_head3(s,key) (s_head3(s)[key])
#endif
/***********************************************************************
//
************************************************************************/
static
void swd_initdict(lzo_swd_p s, const lzo_bytep dict, lzo_uint dict_len)
{
s->dict = s->dict_end = NULL;
s->dict_len = 0;
if (!dict || dict_len == 0)
return;
if (dict_len > s->swd_n)
{
dict += dict_len - s->swd_n;
dict_len = s->swd_n;
}
s->dict = dict;
s->dict_len = dict_len;
s->dict_end = dict + dict_len;
lzo_memcpy(s_b(s), dict, dict_len);
s->ip = dict_len;
}
static
void swd_insertdict(lzo_swd_p s, lzo_uint node, lzo_uint len)
{
lzo_uint key;
s->node_count = s->swd_n - len;
s->first_rp = node;
if (len) do
{
key = HEAD3(s_b(s), node);
s_succ3(s)[node] = s_get_head3(s, key);
s_head3(s)[key] = SWD_UINT(node);
s_best3(s)[node] = SWD_UINT(s->swd_f + 1);
s_llen3(s)[key]++;
assert(s_llen3(s)[key] <= s->swd_n);
#ifdef HEAD2
IF_HEAD2(s)
{
key = HEAD2(s_b(s), node);
s_head2(s)[key] = SWD_UINT(node);
}
#endif
node++;
}
while (--len != 0);
}
/***********************************************************************
//
************************************************************************/
static void swd_exit(lzo_swd_p s);
static
int swd_init(lzo_swd_p s, const lzo_bytep dict, lzo_uint dict_len)
{
#if defined(__LZO_CHECKER)
unsigned r = 1;
s->b = (lzo_bytep) malloc(SWD_N + SWD_F + SWD_F);
s->head3 = (swd_uintp) malloc(sizeof(swd_uint) * SWD_HSIZE);
s->succ3 = (swd_uintp) malloc(sizeof(swd_uint) * (SWD_N + SWD_F));
s->best3 = (swd_uintp) malloc(sizeof(swd_uint) * (SWD_N + SWD_F));
s->llen3 = (swd_uintp) malloc(sizeof(swd_uint) * SWD_HSIZE);
r &= s->b != NULL;
r &= s->head3 != NULL;
r &= s->succ3 != NULL;
r &= s->best3 != NULL;
r &= s->llen3 != NULL;
#ifdef HEAD2
IF_HEAD2(s)
{
s->head2 = (swd_uintp) malloc(sizeof(swd_uint) * 65536L);
r &= s->head2 != NULL;
}
#endif
if (r != 1)
{
swd_exit(s);
return LZO_E_OUT_OF_MEMORY;
}
#endif
s->m_len = 0;
s->m_off = 0;
#if defined(SWD_BEST_OFF)
{
unsigned i;
for (i = 0; i < SWD_BEST_OFF; i++)
s->best_off[i] = s->best_pos[i] = 0;
}
#endif
s->swd_n = SWD_N;
s->swd_f = SWD_F;
s->swd_threshold = SWD_THRESHOLD;
/* defaults */
s->max_chain = SWD_MAX_CHAIN;
s->nice_length = s->swd_f;
s->use_best_off = 0;
s->lazy_insert = 0;
s->b_size = s->swd_n + s->swd_f;
#if 0
if (2 * s->swd_f >= s->swd_n || s->b_size + s->swd_f >= SWD_UINT_MAX)
return LZO_E_ERROR;
#else
LZO_COMPILE_TIME_ASSERT(!(0ul + 2 * SWD_F >= SWD_N))
LZO_COMPILE_TIME_ASSERT(!(0ul + SWD_N + SWD_F + SWD_F >= SWD_UINT_MAX))
#endif
s->b_wrap = s_b(s) + s->b_size;
s->node_count = s->swd_n;
lzo_memset(s_llen3(s), 0, (lzo_uint)sizeof(s_llen3(s)[0]) * (lzo_uint)SWD_HSIZE);
#ifdef HEAD2
IF_HEAD2(s)
{
#if 1
lzo_memset(s_head2(s), 0xff, (lzo_uint)sizeof(s_head2(s)[0]) * 65536L);
assert(s_head2(s)[0] == NIL2);
#else
lzo_xint i;
for (i = 0; i < 65536L; i++)
s_head2(s)[i] = NIL2;
#endif
}
#endif
s->ip = 0;
swd_initdict(s, dict, dict_len);
s->bp = s->ip;
s->first_rp = s->ip;
assert(s->ip + s->swd_f <= s->b_size);
#if 1
s->look = (lzo_uint)(s->c->in_end - s->c->ip);
if (s->look > 0)
{
if (s->look > s->swd_f)
s->look = s->swd_f;
lzo_memcpy(&s_b(s)[s->ip], s->c->ip, s->look);
s->c->ip += s->look;
s->ip += s->look;
}
#else
s->look = 0;
while (s->look < s->swd_f)
{
int c;
if ((c = getbyte(*(s->c))) < 0)
break;
s_b(s)[s->ip] = LZO_BYTE(c);
s->ip++;
s->look++;
}
#endif
if (s->ip == s->b_size)
s->ip = 0;
if (s->look >= 2 && s->dict_len > 0)
swd_insertdict(s, 0, s->dict_len);
s->rp = s->first_rp;
if (s->rp >= s->node_count)
s->rp -= s->node_count;
else
s->rp += s->b_size - s->node_count;
#if 1 || defined(__LZO_CHECKER)
/* initialize memory for the first few HEAD3 (if s->ip is not far
* enough ahead to do this job for us). The value doesn't matter. */
if (s->look < 3)
{
lzo_bytep p = &s_b(s)[s->bp + s->look];
p[0] = p[1] = p[2] = 0;
}
#endif
return LZO_E_OK;
}
static
void swd_exit(lzo_swd_p s)
{
#if defined(__LZO_CHECKER)
/* free in reverse order of allocations */
#ifdef HEAD2
free(s->head2);
s->head2 = NULL;
#endif
free(s->llen3);
s->llen3 = NULL;
free(s->best3);
s->best3 = NULL;
free(s->succ3);
s->succ3 = NULL;
free(s->head3);
s->head3 = NULL;
free(s->b);
s->b = NULL;
#else
LZO_UNUSED(s);
#endif
}
#define swd_pos2off(s,pos) \
(s->bp > (pos) ? s->bp - (pos) : s->b_size - ((pos) - s->bp))
/***********************************************************************
//
************************************************************************/
static __lzo_inline
void swd_getbyte(lzo_swd_p s)
{
int c;
if ((c = getbyte(*(s->c))) < 0)
{
if (s->look > 0)
--s->look;
#if 1 || defined(__LZO_CHECKER)
/* initialize memory - value doesn't matter */
s_b(s)[s->ip] = 0;
if (s->ip < s->swd_f)
s->b_wrap[s->ip] = 0;
#endif
}
else
{
s_b(s)[s->ip] = LZO_BYTE(c);
if (s->ip < s->swd_f)
s->b_wrap[s->ip] = LZO_BYTE(c);
}
if (++s->ip == s->b_size)
s->ip = 0;
if (++s->bp == s->b_size)
s->bp = 0;
if (++s->rp == s->b_size)
s->rp = 0;
}
/***********************************************************************
// remove node from lists
************************************************************************/
static __lzo_inline
void swd_remove_node(lzo_swd_p s, lzo_uint node)
{
if (s->node_count == 0)
{
lzo_uint key;
#ifdef LZO_DEBUG
if (s->first_rp != LZO_UINT_MAX)
{
if (node != s->first_rp)
printf("Remove %5ld: %5ld %5ld %5ld %5ld %6ld %6ld\n",
(long)node, (long)s->rp, (long)s->ip, (long)s->bp,
(long)s->first_rp, (long)(s->ip - node),
(long)(s->ip - s->bp));
assert(node == s->first_rp);
s->first_rp = LZO_UINT_MAX;
}
#endif
key = HEAD3(s_b(s), node);
assert(s_llen3(s)[key] > 0);
--s_llen3(s)[key];
#ifdef HEAD2
IF_HEAD2(s)
{
key = HEAD2(s_b(s), node);
assert(s_head2(s)[key] != NIL2);
if ((lzo_uint) s_head2(s)[key] == node)
s_head2(s)[key] = NIL2;
}
#endif
}
else
--s->node_count;
}
/***********************************************************************
//
************************************************************************/
static
void swd_accept(lzo_swd_p s, lzo_uint n)
{
assert(n <= s->look);
if (n) do
{
lzo_uint key;
swd_remove_node(s, s->rp);
/* add bp into HEAD3 */
key = HEAD3(s_b(s), s->bp);
s_succ3(s)[s->bp] = s_get_head3(s, key);
s_head3(s)[key] = SWD_UINT(s->bp);
s_best3(s)[s->bp] = SWD_UINT(s->swd_f + 1);
s_llen3(s)[key]++;
assert(s_llen3(s)[key] <= s->swd_n);
#ifdef HEAD2
/* add bp into HEAD2 */
IF_HEAD2(s)
{
key = HEAD2(s_b(s), s->bp);
s_head2(s)[key] = SWD_UINT(s->bp);
}
#endif
swd_getbyte(s);
}
while (--n != 0);
}
/***********************************************************************
//
************************************************************************/
static
void swd_search(lzo_swd_p s, lzo_uint node, lzo_uint cnt)
{
const lzo_bytep p1;
const lzo_bytep p2;
const lzo_bytep px;
lzo_uint m_len = s->m_len;
const lzo_bytep b = s_b(s);
const lzo_bytep bp = s_b(s) + s->bp;
const lzo_bytep bx = s_b(s) + s->bp + s->look;
unsigned char scan_end1;
assert(s->m_len > 0);
scan_end1 = bp[m_len - 1];
for (; cnt-- > 0; node = s_succ3(s)[node])
{
p1 = bp;
p2 = b + node;
px = bx;
assert(m_len < s->look);
if (
#if 1
p2[m_len - 1] == scan_end1 &&
p2[m_len] == p1[m_len] &&
#endif
p2[0] == p1[0] &&
p2[1] == p1[1])
{
lzo_uint i;
assert(lzo_memcmp(bp, &b[node], 3) == 0);
#if 0 && (LZO_OPT_UNALIGNED32)
p1 += 3;
p2 += 3;
while (p1 + 4 <= px && UA_GET_NE32(p1) == UA_GET_NE32(p2))
p1 += 4, p2 += 4;
while (p1 < px && *p1 == *p2)
p1 += 1, p2 += 1;
#else
p1 += 2;
p2 += 2;
do {}
while (++p1 < px && *p1 == *++p2);
#endif
i = pd(p1, bp);
#ifdef LZO_DEBUG
if (lzo_memcmp(bp, &b[node], i) != 0)
printf("%5ld %5ld %5ld %02x/%02x %02x/%02x\n",
(long)s->bp, (long) node, (long) i,
bp[0], bp[1], b[node], b[node + 1]);
#endif
assert(lzo_memcmp(bp, &b[node], i) == 0);
#if defined(SWD_BEST_OFF)
if (i < SWD_BEST_OFF)
{
if (s->best_pos[i] == 0)
s->best_pos[i] = node + 1;
}
#endif
if (i > m_len)
{
s->m_len = m_len = i;
s->m_pos = node;
if (m_len == s->look)
return;
if (m_len >= s->nice_length)
return;
if (m_len > (lzo_uint) s_best3(s)[node])
return;
scan_end1 = bp[m_len - 1];
}
}
}
}
/***********************************************************************
//
************************************************************************/
#ifdef HEAD2
static
lzo_bool swd_search2(lzo_swd_p s)
{
lzo_uint key;
assert(s->look >= 2);
assert(s->m_len > 0);
key = s_head2(s)[ HEAD2(s_b(s), s->bp) ];
if (key == NIL2)
return 0;
#ifdef LZO_DEBUG
if (lzo_memcmp(&s_b(s)[s->bp], &s_b(s)[key], 2) != 0)
printf("%5ld %5ld %02x/%02x %02x/%02x\n", (long)s->bp, (long)key,
s_b(s)[s->bp], s_b(s)[s->bp + 1], s_b(s)[key], s_b(s)[key + 1]);
#endif
assert(lzo_memcmp(&s_b(s)[s->bp], &s_b(s)[key], 2) == 0);
#if defined(SWD_BEST_OFF)
if (s->best_pos[2] == 0)
s->best_pos[2] = key + 1;
#endif
if (s->m_len < 2)
{
s->m_len = 2;
s->m_pos = key;
}
return 1;
}
#endif
/***********************************************************************
//
************************************************************************/
static
void swd_findbest(lzo_swd_p s)
{
lzo_uint key;
lzo_uint cnt, node;
lzo_uint len;
assert(s->m_len > 0);
/* get current head, add bp into HEAD3 */
key = HEAD3(s_b(s), s->bp);
node = s_succ3(s)[s->bp] = s_get_head3(s, key);
cnt = s_llen3(s)[key]++;
assert(s_llen3(s)[key] <= s->swd_n + s->swd_f);
if (cnt > s->max_chain && s->max_chain > 0)
cnt = s->max_chain;
s_head3(s)[key] = SWD_UINT(s->bp);
s->b_char = s_b(s)[s->bp];
len = s->m_len;
if (s->m_len >= s->look)
{
if (s->look == 0)
s->b_char = -1;
s->m_off = 0;
s_best3(s)[s->bp] = SWD_UINT(s->swd_f + 1);
}
else
{
#if defined(HEAD2)
if (swd_search2(s) && s->look >= 3)
swd_search(s, node, cnt);
#else
if (s->look >= 3)
swd_search(s, node, cnt);
#endif
if (s->m_len > len)
s->m_off = swd_pos2off(s, s->m_pos);
s_best3(s)[s->bp] = SWD_UINT(s->m_len);
#if defined(SWD_BEST_OFF)
if (s->use_best_off)
{
unsigned i;
for (i = 2; i < SWD_BEST_OFF; i++)
if (s->best_pos[i] > 0)
s->best_off[i] = swd_pos2off(s, s->best_pos[i] - 1);
else
s->best_off[i] = 0;
}
#endif
}
swd_remove_node(s, s->rp);
#ifdef HEAD2
/* add bp into HEAD2 */
IF_HEAD2(s)
{
key = HEAD2(s_b(s), s->bp);
s_head2(s)[key] = SWD_UINT(s->bp);
}
#endif
}
#undef HEAD3
#undef HEAD2
#undef IF_HEAD2
#undef s_get_head3
/* vim:set ts=4 sw=4 et: */
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