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+/* lzo1f_1.c -- implementation of the LZO1F-1 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 "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 )
+{
+ register 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 (;;)
+ {
+ register const lzo_bytep m_pos;
+ lzo_uint m_off;
+ 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 && 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])
+ {
+ 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)
+ {
+ register lzo_uint t = lit;
+
+ if (t < 4 && op > out)
+ op[-2] |= LZO_BYTE(t);
+ else if (t <= 31)
+ *op++ = LZO_BYTE(t);
+ else
+ {
+ register lzo_uint tt = t - 31;
+
+ *op++ = 0;
+ while (tt > 255)
+ {
+ tt -= 255;
+ *op++ = 0;
+ }
+ 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;
+ *op++ = 0;
+ }
+ 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)
+ {
+ register lzo_uint t = pd(in_end,ii);
+
+ if (t < 4 && op > out)
+ op[-2] |= LZO_BYTE(t);
+ else if (t <= 31)
+ *op++ = LZO_BYTE(t);
+ else
+ {
+ register lzo_uint tt = t - 31;
+
+ *op++ = 0;
+ while (tt > 255)
+ {
+ tt -= 255;
+ *op++ = 0;
+ }
+ assert(tt > 0);
+ *op++ = LZO_BYTE(tt);
+ }
+ do *op++ = *ii++; while (--t > 0);
+ }
+
+ *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++ = M3_MARKER | 1;
+ *op++ = 0;
+ *op++ = 0;
+ *out_len += 3;
+ }
+
+ return r;
+}
+
+
+/*
+vi:ts=4:et
+*/
+
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