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+/* lzo1b_9x.c -- implementation of the LZO1B-999 compression algorithm
+
+ This file is part of the LZO real-time data compression library.
+
+ Copyright (C) 2008 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 2007 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 2006 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 2005 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 2004 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 2003 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 2002 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 2001 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 2000 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 1999 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 1998 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 1997 Markus Franz Xaver Johannes Oberhumer
+ Copyright (C) 1996 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 "config1b.h"
+
+
+/***********************************************************************
+//
+************************************************************************/
+
+#define N 0xffffL /* size of ring buffer */
+#define THRESHOLD 2 /* lower limit for match length */
+#define F 2048 /* upper limit for match length */
+
+
+#define LZO1B
+#define LZO_COMPRESS_T lzo1b_999_t
+#define lzo_swd_t lzo1b_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_m++;
+ }
+ return op;
+}
+
+
+/***********************************************************************
+// this is a public function, but there is no prototype in a header file
+************************************************************************/
+
+LZO_EXTERN(int)
+lzo1b_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)
+lzo1b_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(LZO1B_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;
+
+ 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 match */
+ if (lit == 1 && c->r1_m_len == M2_MIN_LEN)
+ lazy_match_min_gain = -1;
+ 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 match */
+ if (c->r1_m_len == M2_MIN_LEN)
+ 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);
+ 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);
+ }
+ 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
+ {
+ 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);
+ }
+
+ 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)
+lzo1b_999_compress ( const lzo_bytep in , lzo_uint in_len,
+ lzo_bytep out, lzo_uintp out_len,
+ lzo_voidp wrkmem )
+{
+ return lzo1b_999_compress_callback(in,in_len,out,out_len,wrkmem,
+ (lzo_callback_p) 0, 0);
+}
+
+
+/*
+vi:ts=4:et
+*/
+
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