455 lines
9.4 KiB
Plaintext
455 lines
9.4 KiB
Plaintext
/* lzo1x_d.ch -- implementation of the LZO1X decompression algorithm
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This file is part of the LZO real-time data compression library.
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Copyright (C) 1996-2002 Markus Franz Xaver Johannes Oberhumer
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All Rights Reserved.
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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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59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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Markus F.X.J. Oberhumer
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<markus@oberhumer.com>
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*/
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#include "lzo1_d.ch"
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#undef __COPY4
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#define __COPY4(dst,src) * (lzo_uint32p)(dst) = * (const lzo_uint32p)(src)
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#undef COPY4
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#if defined(LZO_UNALIGNED_OK_4)
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# define COPY4(dst,src) __COPY4(dst,src)
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#elif defined(LZO_ALIGNED_OK_4)
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# define COPY4(dst,src) __COPY4((lzo_ptr_t)(dst),(lzo_ptr_t)(src))
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#endif
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/***********************************************************************
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// decompress a block of data.
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************************************************************************/
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#if defined(DO_DECOMPRESS)
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LZO_PUBLIC(int)
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DO_DECOMPRESS ( const lzo_byte *in , lzo_uint in_len,
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lzo_byte *out, lzo_uintp out_len,
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lzo_voidp wrkmem )
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#endif
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{
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register lzo_byte *op;
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register const lzo_byte *ip;
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register lzo_uint t;
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#if defined(COPY_DICT)
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lzo_uint m_off;
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const lzo_byte *dict_end;
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#else
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register const lzo_byte *m_pos;
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#endif
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const lzo_byte * const ip_end = in + in_len;
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#if defined(HAVE_ANY_OP)
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lzo_byte * const op_end = out + *out_len;
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#endif
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#if defined(LZO1Z)
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lzo_uint last_m_off = 0;
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#endif
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LZO_UNUSED(wrkmem);
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#if defined(__LZO_QUERY_DECOMPRESS)
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if (__LZO_IS_DECOMPRESS_QUERY(in,in_len,out,out_len,wrkmem))
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return __LZO_QUERY_DECOMPRESS(in,in_len,out,out_len,wrkmem,0,0);
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#endif
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#if defined(COPY_DICT)
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if (dict)
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{
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if (dict_len > M4_MAX_OFFSET)
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{
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dict += dict_len - M4_MAX_OFFSET;
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dict_len = M4_MAX_OFFSET;
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}
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dict_end = dict + dict_len;
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}
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else
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{
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dict_len = 0;
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dict_end = NULL;
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}
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#endif /* COPY_DICT */
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*out_len = 0;
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op = out;
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ip = in;
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if (*ip > 17)
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{
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t = *ip++ - 17;
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if (t < 4)
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goto match_next;
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assert(t > 0); NEED_OP(t); NEED_IP(t+1);
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do *op++ = *ip++; while (--t > 0);
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goto first_literal_run;
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}
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while (TEST_IP && TEST_OP)
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{
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t = *ip++;
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if (t >= 16)
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goto match;
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/* a literal run */
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if (t == 0)
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{
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NEED_IP(1);
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while (*ip == 0)
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{
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t += 255;
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ip++;
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NEED_IP(1);
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}
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t += 15 + *ip++;
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}
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/* copy literals */
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assert(t > 0); NEED_OP(t+3); NEED_IP(t+4);
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#if defined(LZO_UNALIGNED_OK_4) || defined(LZO_ALIGNED_OK_4)
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#if !defined(LZO_UNALIGNED_OK_4)
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if (PTR_ALIGNED2_4(op,ip))
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{
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#endif
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COPY4(op,ip);
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op += 4; ip += 4;
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if (--t > 0)
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{
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if (t >= 4)
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{
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do {
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COPY4(op,ip);
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op += 4; ip += 4; t -= 4;
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} while (t >= 4);
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if (t > 0) do *op++ = *ip++; while (--t > 0);
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}
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else
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do *op++ = *ip++; while (--t > 0);
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}
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#if !defined(LZO_UNALIGNED_OK_4)
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}
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else
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#endif
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#endif
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#if !defined(LZO_UNALIGNED_OK_4)
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{
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*op++ = *ip++; *op++ = *ip++; *op++ = *ip++;
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do *op++ = *ip++; while (--t > 0);
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}
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#endif
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first_literal_run:
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t = *ip++;
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if (t >= 16)
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goto match;
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#if defined(COPY_DICT)
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#if defined(LZO1Z)
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m_off = (1 + M2_MAX_OFFSET) + (t << 6) + (*ip++ >> 2);
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last_m_off = m_off;
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#else
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m_off = (1 + M2_MAX_OFFSET) + (t >> 2) + (*ip++ << 2);
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#endif
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NEED_OP(3);
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t = 3; COPY_DICT(t,m_off)
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#else /* !COPY_DICT */
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#if defined(LZO1Z)
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t = (1 + M2_MAX_OFFSET) + (t << 6) + (*ip++ >> 2);
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m_pos = op - t;
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last_m_off = t;
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#else
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m_pos = op - (1 + M2_MAX_OFFSET);
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m_pos -= t >> 2;
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m_pos -= *ip++ << 2;
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#endif
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TEST_LOOKBEHIND(m_pos,out); NEED_OP(3);
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*op++ = *m_pos++; *op++ = *m_pos++; *op++ = *m_pos;
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#endif /* COPY_DICT */
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goto match_done;
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/* handle matches */
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while (TEST_IP && TEST_OP)
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{
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match:
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if (t >= 64) /* a M2 match */
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{
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#if defined(COPY_DICT)
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#if defined(LZO1X)
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m_off = 1 + ((t >> 2) & 7) + (*ip++ << 3);
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t = (t >> 5) - 1;
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#elif defined(LZO1Y)
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m_off = 1 + ((t >> 2) & 3) + (*ip++ << 2);
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t = (t >> 4) - 3;
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#elif defined(LZO1Z)
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m_off = t & 0x1f;
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if (m_off >= 0x1c)
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m_off = last_m_off;
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else
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{
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m_off = 1 + (m_off << 6) + (*ip++ >> 2);
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last_m_off = m_off;
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}
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t = (t >> 5) - 1;
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#endif
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#else /* !COPY_DICT */
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#if defined(LZO1X)
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m_pos = op - 1;
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m_pos -= (t >> 2) & 7;
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m_pos -= *ip++ << 3;
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t = (t >> 5) - 1;
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#elif defined(LZO1Y)
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m_pos = op - 1;
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m_pos -= (t >> 2) & 3;
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m_pos -= *ip++ << 2;
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t = (t >> 4) - 3;
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#elif defined(LZO1Z)
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{
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lzo_uint off = t & 0x1f;
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m_pos = op;
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if (off >= 0x1c)
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{
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assert(last_m_off > 0);
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m_pos -= last_m_off;
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}
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else
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{
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off = 1 + (off << 6) + (*ip++ >> 2);
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m_pos -= off;
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last_m_off = off;
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}
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}
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t = (t >> 5) - 1;
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#endif
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TEST_LOOKBEHIND(m_pos,out); assert(t > 0); NEED_OP(t+3-1);
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goto copy_match;
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#endif /* COPY_DICT */
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}
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else if (t >= 32) /* a M3 match */
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{
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t &= 31;
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if (t == 0)
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{
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NEED_IP(1);
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while (*ip == 0)
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{
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t += 255;
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ip++;
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NEED_IP(1);
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}
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t += 31 + *ip++;
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}
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#if defined(COPY_DICT)
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#if defined(LZO1Z)
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m_off = 1 + (ip[0] << 6) + (ip[1] >> 2);
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last_m_off = m_off;
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#else
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m_off = 1 + (ip[0] >> 2) + (ip[1] << 6);
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#endif
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#else /* !COPY_DICT */
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#if defined(LZO1Z)
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{
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lzo_uint off = 1 + (ip[0] << 6) + (ip[1] >> 2);
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m_pos = op - off;
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last_m_off = off;
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}
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#elif defined(LZO_UNALIGNED_OK_2) && (LZO_BYTE_ORDER == LZO_LITTLE_ENDIAN)
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m_pos = op - 1;
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m_pos -= (* (const lzo_ushortp) ip) >> 2;
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#else
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m_pos = op - 1;
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m_pos -= (ip[0] >> 2) + (ip[1] << 6);
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#endif
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#endif /* COPY_DICT */
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ip += 2;
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}
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else if (t >= 16) /* a M4 match */
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{
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#if defined(COPY_DICT)
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m_off = (t & 8) << 11;
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#else /* !COPY_DICT */
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m_pos = op;
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m_pos -= (t & 8) << 11;
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#endif /* COPY_DICT */
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t &= 7;
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if (t == 0)
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{
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NEED_IP(1);
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while (*ip == 0)
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{
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t += 255;
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ip++;
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NEED_IP(1);
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}
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t += 7 + *ip++;
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}
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#if defined(COPY_DICT)
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#if defined(LZO1Z)
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m_off += (ip[0] << 6) + (ip[1] >> 2);
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#else
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m_off += (ip[0] >> 2) + (ip[1] << 6);
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#endif
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ip += 2;
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if (m_off == 0)
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goto eof_found;
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m_off += 0x4000;
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#if defined(LZO1Z)
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last_m_off = m_off;
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#endif
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#else /* !COPY_DICT */
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#if defined(LZO1Z)
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m_pos -= (ip[0] << 6) + (ip[1] >> 2);
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#elif defined(LZO_UNALIGNED_OK_2) && (LZO_BYTE_ORDER == LZO_LITTLE_ENDIAN)
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m_pos -= (* (const lzo_ushortp) ip) >> 2;
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#else
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m_pos -= (ip[0] >> 2) + (ip[1] << 6);
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#endif
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ip += 2;
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if (m_pos == op)
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goto eof_found;
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m_pos -= 0x4000;
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#if defined(LZO1Z)
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last_m_off = op - m_pos;
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#endif
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#endif /* COPY_DICT */
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}
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else /* a M1 match */
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{
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#if defined(COPY_DICT)
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#if defined(LZO1Z)
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m_off = 1 + (t << 6) + (*ip++ >> 2);
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last_m_off = m_off;
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#else
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m_off = 1 + (t >> 2) + (*ip++ << 2);
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#endif
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NEED_OP(2);
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t = 2; COPY_DICT(t,m_off)
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#else /* !COPY_DICT */
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#if defined(LZO1Z)
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t = 1 + (t << 6) + (*ip++ >> 2);
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m_pos = op - t;
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last_m_off = t;
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#else
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m_pos = op - 1;
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m_pos -= t >> 2;
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m_pos -= *ip++ << 2;
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#endif
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TEST_LOOKBEHIND(m_pos,out); NEED_OP(2);
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*op++ = *m_pos++; *op++ = *m_pos;
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#endif /* COPY_DICT */
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goto match_done;
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}
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/* copy match */
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#if defined(COPY_DICT)
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NEED_OP(t+3-1);
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t += 3-1; COPY_DICT(t,m_off)
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#else /* !COPY_DICT */
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TEST_LOOKBEHIND(m_pos,out); assert(t > 0); NEED_OP(t+3-1);
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#if defined(LZO_UNALIGNED_OK_4) || defined(LZO_ALIGNED_OK_4)
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#if !defined(LZO_UNALIGNED_OK_4)
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if (t >= 2 * 4 - (3 - 1) && PTR_ALIGNED2_4(op,m_pos))
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{
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assert((op - m_pos) >= 4); /* both pointers are aligned */
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#else
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if (t >= 2 * 4 - (3 - 1) && (op - m_pos) >= 4)
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{
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#endif
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COPY4(op,m_pos);
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op += 4; m_pos += 4; t -= 4 - (3 - 1);
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do {
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COPY4(op,m_pos);
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op += 4; m_pos += 4; t -= 4;
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} while (t >= 4);
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if (t > 0) do *op++ = *m_pos++; while (--t > 0);
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}
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else
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#endif
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{
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copy_match:
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*op++ = *m_pos++; *op++ = *m_pos++;
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do *op++ = *m_pos++; while (--t > 0);
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}
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#endif /* COPY_DICT */
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match_done:
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#if defined(LZO1Z)
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t = ip[-1] & 3;
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#else
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t = ip[-2] & 3;
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#endif
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if (t == 0)
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break;
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/* copy literals */
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match_next:
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assert(t > 0); NEED_OP(t); NEED_IP(t+1);
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do *op++ = *ip++; while (--t > 0);
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t = *ip++;
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}
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}
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#if defined(HAVE_TEST_IP) || defined(HAVE_TEST_OP)
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/* no EOF code was found */
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*out_len = op - out;
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return LZO_E_EOF_NOT_FOUND;
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#endif
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eof_found:
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assert(t == 1);
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*out_len = op - out;
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return (ip == ip_end ? LZO_E_OK :
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(ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN));
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#if defined(HAVE_NEED_IP)
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input_overrun:
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*out_len = op - out;
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return LZO_E_INPUT_OVERRUN;
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#endif
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#if defined(HAVE_NEED_OP)
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output_overrun:
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*out_len = op - out;
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return LZO_E_OUTPUT_OVERRUN;
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#endif
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#if defined(LZO_TEST_DECOMPRESS_OVERRUN_LOOKBEHIND)
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lookbehind_overrun:
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*out_len = op - out;
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return LZO_E_LOOKBEHIND_OVERRUN;
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#endif
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}
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/*
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vi:ts=4:et
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*/
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