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+/* lzo1x_c.ch -- implementation of the LZO1[XY]-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/
+ */
+
+
+
+/***********************************************************************
+// compress a block of data.
+************************************************************************/
+
+static __lzo_noinline lzo_uint
+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 - M2_MAX_LEN - 5;
+ const lzo_bytep ii;
+ lzo_dict_p const dict = (lzo_dict_p) wrkmem;
+
+ op = out;
+ ip = in;
+ ii = ip;
+
+ ip += 4;
+ for (;;)
+ {
+ register const lzo_bytep m_pos;
+ lzo_uint m_off;
+ lzo_uint m_len;
+ lzo_uint dindex;
+
+ DINDEX1(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;
+ DINDEX2(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 __lzo_likely(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] |= LZO_BYTE(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 lzo_uint t;
+
+ t = lit;
+ assert(op - 2 > out); op[-2] |= LZO_BYTE(t);
+ do *op++ = *ii++; while (--t > 0);
+ assert(ii == ip);
+ m_off -= 1;
+ *op++ = LZO_BYTE(M1_MARKER | ((m_off & 3) << 2));
+ *op++ = LZO_BYTE(m_off >> 2);
+ ip += 2;
+ goto match_done;
+ }
+#endif
+ }
+ }
+
+
+ /* a literal */
+literal:
+ UPDATE_I(dict,0,dindex,ip,in);
+ ++ip;
+ if __lzo_unlikely(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 lzo_uint t = pd(ip,ii);
+
+ if (t <= 3)
+ {
+ assert(op - 2 > out);
+ op[-2] |= LZO_BYTE(t);
+ }
+ else if (t <= 18)
+ *op++ = LZO_BYTE(t - 3);
+ else
+ {
+ register lzo_uint tt = t - 18;
+
+ *op++ = 0;
+ while (tt > 255)
+ {
+ tt -= 255;
+ *op++ = 0;
+ }
+ assert(tt > 0);
+ *op++ = LZO_BYTE(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++ = LZO_BYTE(((m_len - 1) << 5) | ((m_off & 7) << 2));
+ *op++ = LZO_BYTE(m_off >> 3);
+#elif defined(LZO1Y)
+ *op++ = LZO_BYTE(((m_len + 1) << 4) | ((m_off & 3) << 2));
+ *op++ = LZO_BYTE(m_off >> 2);
+#endif
+ }
+ else if (m_off <= M3_MAX_OFFSET)
+ {
+ m_off -= 1;
+ *op++ = LZO_BYTE(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++ = LZO_BYTE(M4_MARKER |
+ ((m_off & 0x4000) >> 11) | (m_len - 2));
+ goto m3_m4_offset;
+ }
+#elif defined(LZO1Y)
+ goto m4_match;
+#endif
+ }
+ else
+ {
+ {
+ const lzo_bytep end = in_end;
+ const lzo_bytep 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++ = LZO_BYTE(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++ = LZO_BYTE(M4_MARKER |
+ ((m_off & 0x4000) >> 11) | (m_len - 2));
+ else
+ {
+ m_len -= M4_MAX_LEN;
+ *op++ = LZO_BYTE(M4_MARKER | ((m_off & 0x4000) >> 11));
+m3_m4_len:
+ while (m_len > 255)
+ {
+ m_len -= 255;
+ *op++ = 0;
+ }
+ assert(m_len > 0);
+ *op++ = LZO_BYTE(m_len);
+ }
+ }
+
+m3_m4_offset:
+ *op++ = LZO_BYTE((m_off & 63) << 2);
+ *op++ = LZO_BYTE(m_off >> 6);
+ }
+
+#if 0
+match_done:
+#endif
+ ii = ip;
+ if __lzo_unlikely(ip >= ip_end)
+ break;
+ }
+
+ *out_len = pd(op, out);
+ return pd(in_end,ii);
+}
+
+
+/***********************************************************************
+// public entry point
+************************************************************************/
+
+LZO_PUBLIC(int)
+DO_COMPRESS ( const lzo_bytep in , lzo_uint in_len,
+ lzo_bytep out, lzo_uintp out_len,
+ lzo_voidp wrkmem )
+{
+ lzo_bytep op = out;
+ lzo_uint t;
+
+ if __lzo_unlikely(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 lzo_bytep ii = in + in_len - t;
+
+ if (op == out && t <= 238)
+ *op++ = LZO_BYTE(17 + t);
+ else if (t <= 3)
+ op[-2] |= LZO_BYTE(t);
+ else if (t <= 18)
+ *op++ = LZO_BYTE(t - 3);
+ else
+ {
+ lzo_uint tt = t - 18;
+
+ *op++ = 0;
+ while (tt > 255)
+ {
+ tt -= 255;
+ *op++ = 0;
+ }
+ assert(tt > 0);
+ *op++ = LZO_BYTE(tt);
+ }
+ do *op++ = *ii++; while (--t > 0);
+ }
+
+ *op++ = M4_MARKER | 1;
+ *op++ = 0;
+ *op++ = 0;
+
+ *out_len = pd(op, out);
+ return LZO_E_OK;
+}
+
+
+/*
+vi:ts=4:et
+*/
+
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