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297 lines
6.9 KiB
C
297 lines
6.9 KiB
C
/* implementation of the LZO1[XY]-1 compression algorithm
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This file is part of the LZO real-time data compression library.
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Copyright (C) 1996..2008 Markus Franz Xaver Johannes Oberhumer
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All Rights Reserved.
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Markus F.X.J. Oberhumer <markus@oberhumer.com>
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http://www.oberhumer.com/opensource/lzo/
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The LZO library is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of
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the License, or (at your option) any later version.
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The LZO library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with the LZO library; see the file COPYING.
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If not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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/***********************************************************************
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// compress a block of data.
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************************************************************************/
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static NOINLINE unsigned
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do_compress(const uint8_t* in, unsigned in_len,
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uint8_t* out, unsigned* out_len,
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void* wrkmem)
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{
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register const uint8_t* ip;
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uint8_t* op;
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const uint8_t* const in_end = in + in_len;
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const uint8_t* const ip_end = in + in_len - M2_MAX_LEN - 5;
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const uint8_t* ii;
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const void* *const dict = (const void**) wrkmem;
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op = out;
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ip = in;
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ii = ip;
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ip += 4;
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for (;;) {
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register const uint8_t* m_pos;
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unsigned m_off;
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unsigned m_len;
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unsigned dindex;
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D_INDEX1(dindex,ip);
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GINDEX(m_pos,m_off,dict,dindex,in);
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if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M4_MAX_OFFSET))
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goto literal;
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#if 1
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if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
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goto try_match;
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D_INDEX2(dindex,ip);
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#endif
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GINDEX(m_pos,m_off,dict,dindex,in);
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if (LZO_CHECK_MPOS_NON_DET(m_pos,m_off,in,ip,M4_MAX_OFFSET))
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goto literal;
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if (m_off <= M2_MAX_OFFSET || m_pos[3] == ip[3])
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goto try_match;
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goto literal;
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try_match:
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#if 1 && defined(LZO_UNALIGNED_OK_2)
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if (* (const lzo_ushortp) m_pos != * (const lzo_ushortp) ip)
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#else
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if (m_pos[0] != ip[0] || m_pos[1] != ip[1])
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#endif
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{
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} else {
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if (m_pos[2] == ip[2]) {
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#if 0
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if (m_off <= M2_MAX_OFFSET)
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goto match;
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if (lit <= 3)
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goto match;
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if (lit == 3) { /* better compression, but slower */
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assert(op - 2 > out); op[-2] |= (uint8_t)(3);
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*op++ = *ii++; *op++ = *ii++; *op++ = *ii++;
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goto code_match;
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}
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if (m_pos[3] == ip[3])
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#endif
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goto match;
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}
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else {
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/* still need a better way for finding M1 matches */
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#if 0
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/* a M1 match */
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#if 0
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if (m_off <= M1_MAX_OFFSET && lit > 0 && lit <= 3)
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#else
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if (m_off <= M1_MAX_OFFSET && lit == 3)
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#endif
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{
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register unsigned t;
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t = lit;
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assert(op - 2 > out); op[-2] |= (uint8_t)(t);
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do *op++ = *ii++; while (--t > 0);
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assert(ii == ip);
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m_off -= 1;
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*op++ = (uint8_t)(M1_MARKER | ((m_off & 3) << 2));
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*op++ = (uint8_t)(m_off >> 2);
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ip += 2;
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goto match_done;
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}
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#endif
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}
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}
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/* a literal */
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literal:
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UPDATE_I(dict, 0, dindex, ip, in);
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++ip;
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if (ip >= ip_end)
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break;
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continue;
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/* a match */
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match:
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UPDATE_I(dict, 0, dindex, ip, in);
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/* store current literal run */
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if (pd(ip, ii) > 0) {
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register unsigned t = pd(ip, ii);
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if (t <= 3) {
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assert(op - 2 > out);
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op[-2] |= (uint8_t)(t);
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}
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else if (t <= 18)
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*op++ = (uint8_t)(t - 3);
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else {
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register unsigned tt = t - 18;
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*op++ = 0;
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while (tt > 255) {
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tt -= 255;
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*op++ = 0;
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}
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assert(tt > 0);
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*op++ = (uint8_t)(tt);
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}
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do *op++ = *ii++; while (--t > 0);
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}
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/* code the match */
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assert(ii == ip);
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ip += 3;
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if (m_pos[3] != *ip++ || m_pos[4] != *ip++ || m_pos[5] != *ip++
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|| m_pos[6] != *ip++ || m_pos[7] != *ip++ || m_pos[8] != *ip++
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#ifdef LZO1Y
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|| m_pos[ 9] != *ip++ || m_pos[10] != *ip++ || m_pos[11] != *ip++
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|| m_pos[12] != *ip++ || m_pos[13] != *ip++ || m_pos[14] != *ip++
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#endif
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) {
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--ip;
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m_len = pd(ip, ii);
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assert(m_len >= 3);
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assert(m_len <= M2_MAX_LEN);
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if (m_off <= M2_MAX_OFFSET) {
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m_off -= 1;
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#if defined(LZO1X)
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*op++ = (uint8_t)(((m_len - 1) << 5) | ((m_off & 7) << 2));
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*op++ = (uint8_t)(m_off >> 3);
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#elif defined(LZO1Y)
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*op++ = (uint8_t)(((m_len + 1) << 4) | ((m_off & 3) << 2));
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*op++ = (uint8_t)(m_off >> 2);
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#endif
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}
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else if (m_off <= M3_MAX_OFFSET) {
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m_off -= 1;
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*op++ = (uint8_t)(M3_MARKER | (m_len - 2));
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goto m3_m4_offset;
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} else {
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#if defined(LZO1X)
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m_off -= 0x4000;
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assert(m_off > 0);
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assert(m_off <= 0x7fff);
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*op++ = (uint8_t)(M4_MARKER | ((m_off & 0x4000) >> 11) | (m_len - 2));
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goto m3_m4_offset;
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#elif defined(LZO1Y)
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goto m4_match;
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#endif
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}
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}
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else {
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{
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const uint8_t* end = in_end;
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const uint8_t* m = m_pos + M2_MAX_LEN + 1;
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while (ip < end && *m == *ip)
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m++, ip++;
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m_len = pd(ip, ii);
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}
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assert(m_len > M2_MAX_LEN);
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if (m_off <= M3_MAX_OFFSET) {
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m_off -= 1;
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if (m_len <= 33)
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*op++ = (uint8_t)(M3_MARKER | (m_len - 2));
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else {
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m_len -= 33;
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*op++ = M3_MARKER | 0;
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goto m3_m4_len;
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}
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} else {
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#if defined(LZO1Y)
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m4_match:
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#endif
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m_off -= 0x4000;
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assert(m_off > 0);
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assert(m_off <= 0x7fff);
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if (m_len <= M4_MAX_LEN)
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*op++ = (uint8_t)(M4_MARKER | ((m_off & 0x4000) >> 11) | (m_len - 2));
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else {
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m_len -= M4_MAX_LEN;
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*op++ = (uint8_t)(M4_MARKER | ((m_off & 0x4000) >> 11));
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m3_m4_len:
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while (m_len > 255) {
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m_len -= 255;
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*op++ = 0;
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}
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assert(m_len > 0);
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*op++ = (uint8_t)(m_len);
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}
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}
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m3_m4_offset:
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*op++ = (uint8_t)((m_off & 63) << 2);
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*op++ = (uint8_t)(m_off >> 6);
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}
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#if 0
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match_done:
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#endif
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ii = ip;
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if (ip >= ip_end)
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break;
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}
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*out_len = pd(op, out);
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return pd(in_end, ii);
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}
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/***********************************************************************
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// public entry point
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************************************************************************/
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int DO_COMPRESS(const uint8_t* in, unsigned in_len,
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uint8_t* out, unsigned* out_len,
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void* wrkmem)
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{
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uint8_t* op = out;
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unsigned t;
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if (in_len <= M2_MAX_LEN + 5)
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t = in_len;
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else {
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t = do_compress(in,in_len,op,out_len,wrkmem);
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op += *out_len;
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}
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if (t > 0) {
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const uint8_t* ii = in + in_len - t;
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if (op == out && t <= 238)
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*op++ = (uint8_t)(17 + t);
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else if (t <= 3)
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op[-2] |= (uint8_t)(t);
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else if (t <= 18)
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*op++ = (uint8_t)(t - 3);
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else {
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unsigned tt = t - 18;
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*op++ = 0;
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while (tt > 255) {
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tt -= 255;
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*op++ = 0;
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}
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assert(tt > 0);
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*op++ = (uint8_t)(tt);
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}
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do *op++ = *ii++; while (--t > 0);
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}
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*op++ = M4_MARKER | 1;
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*op++ = 0;
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*op++ = 0;
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*out_len = pd(op, out);
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return 0; /*LZO_E_OK*/
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}
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