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212 lines
7.2 KiB
C
212 lines
7.2 KiB
C
/*
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* Copyright (c) 2000-2008 Marc Alexander Lehmann <schmorp@schmorp.de>
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*
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* Redistribution and use in source and binary forms, with or without modifica-
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* tion, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
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* CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
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* CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
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* ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Alternatively, the contents of this file may be used under the terms of
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* the GNU General Public License ("GPL") version 2 or any later version,
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* in which case the provisions of the GPL are applicable instead of
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* the above. If you wish to allow the use of your version of this file
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* only under the terms of the GPL and not to allow others to use your
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* version of this file under the BSD license, indicate your decision
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* by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL. If you do not delete the
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* provisions above, a recipient may use your version of this file under
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* either the BSD or the GPL.
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*/
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#ifndef LZF_H
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#define LZF_H
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/***********************************************************************
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**
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** lzf -- an extremely fast/free compression/decompression-method
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** http://liblzf.plan9.de/
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**
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** This algorithm is believed to be patent-free.
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**
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***********************************************************************/
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#define LZF_VERSION 0x0105 /* 1.5, API version */
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/*
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* Compress in_len bytes stored at the memory block starting at
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* in_data and write the result to out_data, up to a maximum length
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* of out_len bytes.
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*
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* If the output buffer is not large enough or any error occurs return 0,
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* otherwise return the number of bytes used, which might be considerably
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* more than in_len (but less than 104% of the original size), so it
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* makes sense to always use out_len == in_len - 1), to ensure _some_
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* compression, and store the data uncompressed otherwise (with a flag, of
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* course.
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*
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* lzf_compress might use different algorithms on different systems and
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* even different runs, thus might result in different compressed strings
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* depending on the phase of the moon or similar factors. However, all
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* these strings are architecture-independent and will result in the
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* original data when decompressed using lzf_decompress.
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*
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* The buffers must not be overlapping.
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*
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* If the option LZF_STATE_ARG is enabled, an extra argument must be
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* supplied which is not reflected in this header file. Refer to lzfP.h
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* and lzf_c.c.
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*
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*/
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unsigned int
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lzf_compress (const void *const in_data, unsigned int in_len,
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void *out_data, unsigned int out_len);
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/*
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* Decompress data compressed with some version of the lzf_compress
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* function and stored at location in_data and length in_len. The result
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* will be stored at out_data up to a maximum of out_len characters.
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*
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* If the output buffer is not large enough to hold the decompressed
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* data, a 0 is returned and errno is set to E2BIG. Otherwise the number
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* of decompressed bytes (i.e. the original length of the data) is
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* returned.
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*
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* If an error in the compressed data is detected, a zero is returned and
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* errno is set to EINVAL.
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*
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* This function is very fast, about as fast as a copying loop.
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*/
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unsigned int
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lzf_decompress (const void *const in_data, unsigned int in_len,
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void *out_data, unsigned int out_len);
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/*
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* Size of hashtable is (1 << HLOG) * sizeof (char *)
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* decompression is independent of the hash table size
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* the difference between 15 and 14 is very small
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* for small blocks (and 14 is usually a bit faster).
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* For a low-memory/faster configuration, use HLOG == 13;
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* For best compression, use 15 or 16 (or more, up to 23).
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*/
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#ifndef HLOG
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# define HLOG 16
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#endif
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/*
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* Sacrifice very little compression quality in favour of compression speed.
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* This gives almost the same compression as the default code, and is
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* (very roughly) 15% faster. This is the preferred mode of operation.
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*/
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#ifndef VERY_FAST
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# define VERY_FAST 1
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#endif
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/*
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* Sacrifice some more compression quality in favour of compression speed.
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* (roughly 1-2% worse compression for large blocks and
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* 9-10% for small, redundant, blocks and >>20% better speed in both cases)
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* In short: when in need for speed, enable this for binary data,
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* possibly disable this for text data.
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*/
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#ifndef ULTRA_FAST
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# define ULTRA_FAST 0
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#endif
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/*
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* Unconditionally aligning does not cost very much, so do it if unsure
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*/
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#ifndef STRICT_ALIGN
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# define STRICT_ALIGN !(defined(__i386) || defined (__amd64))
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#endif
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/*
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* You may choose to pre-set the hash table (might be faster on some
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* modern cpus and large (>>64k) blocks, and also makes compression
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* deterministic/repeatable when the configuration otherwise is the same).
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*/
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#ifndef INIT_HTAB
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# define INIT_HTAB 1
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#endif
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/*
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* Avoid assigning values to errno variable? for some embedding purposes
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* (linux kernel for example), this is necessary. NOTE: this breaks
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* the documentation in lzf.h.
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*/
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#ifndef AVOID_ERRNO
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# define AVOID_ERRNO 0
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#endif
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/*
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* Wether to pass the LZF_STATE variable as argument, or allocate it
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* on the stack. For small-stack environments, define this to 1.
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* NOTE: this breaks the prototype in lzf.h.
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*/
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#ifndef LZF_STATE_ARG
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# define LZF_STATE_ARG 0
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#endif
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/*
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* Wether to add extra checks for input validity in lzf_decompress
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* and return EINVAL if the input stream has been corrupted. This
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* only shields against overflowing the input buffer and will not
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* detect most corrupted streams.
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* This check is not normally noticeable on modern hardware
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* (<1% slowdown), but might slow down older cpus considerably.
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*/
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#ifndef CHECK_INPUT
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# define CHECK_INPUT 1
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#endif
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/*****************************************************************************/
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/* nothing should be changed below */
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typedef unsigned char u8;
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typedef const u8 *LZF_STATE[1 << (HLOG)];
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#if !STRICT_ALIGN
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/* for unaligned accesses we need a 16 bit datatype. */
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# include <limits.h>
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# if USHRT_MAX == 65535
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typedef unsigned short u16;
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# elif UINT_MAX == 65535
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typedef unsigned int u16;
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# else
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# undef STRICT_ALIGN
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# define STRICT_ALIGN 1
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# endif
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#endif
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#if ULTRA_FAST
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# if defined(VERY_FAST)
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# undef VERY_FAST
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# endif
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#endif
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#if INIT_HTAB
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# ifdef __cplusplus
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# include <cstring>
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# else
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# include <string.h>
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# endif
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#endif
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#endif
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