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[/] [openrisc/] [trunk/] [gnu-src/] [gdb-7.1/] [gdb/] [gnulib/] [memmem.c] - Blame information for rev 227

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1 227 jeremybenn
/* Copyright (C) 1991,92,93,94,96,97,98,2000,2004,2007,2008,2009,2010
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Free Software Foundation, Inc.
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   This file is part of the GNU C Library.
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   This program is free software; you can redistribute it and/or modify
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   it under the terms of the GNU General Public License as published by
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   the Free Software Foundation; either version 3, or (at your option)
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   any later version.
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   This program 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 along
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   with this program; if not, write to the Free Software Foundation,
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   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
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/* This particular implementation was written by Eric Blake, 2008.  */
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#ifndef _LIBC
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# include <config.h>
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#endif
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/* Specification of memmem.  */
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#include <string.h>
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#ifndef _LIBC
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# define __builtin_expect(expr, val)   (expr)
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#endif
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#define RETURN_TYPE void *
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#define AVAILABLE(h, h_l, j, n_l) ((j) <= (h_l) - (n_l))
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#include "str-two-way.h"
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/* Return the first occurrence of NEEDLE in HAYSTACK.  Return HAYSTACK
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   if NEEDLE_LEN is 0, otherwise NULL if NEEDLE is not found in
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   HAYSTACK.  */
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void *
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memmem (const void *haystack_start, size_t haystack_len,
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        const void *needle_start, size_t needle_len)
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{
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  /* Abstract memory is considered to be an array of 'unsigned char' values,
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     not an array of 'char' values.  See ISO C 99 section 6.2.6.1.  */
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  const unsigned char *haystack = (const unsigned char *) haystack_start;
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  const unsigned char *needle = (const unsigned char *) needle_start;
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  if (needle_len == 0)
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    /* The first occurrence of the empty string is deemed to occur at
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       the beginning of the string.  */
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    return (void *) haystack;
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  /* Sanity check, otherwise the loop might search through the whole
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     memory.  */
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  if (__builtin_expect (haystack_len < needle_len, 0))
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    return NULL;
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  /* Use optimizations in memchr when possible, to reduce the search
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     size of haystack using a linear algorithm with a smaller
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     coefficient.  However, avoid memchr for long needles, since we
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     can often achieve sublinear performance.  */
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  if (needle_len < LONG_NEEDLE_THRESHOLD)
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    {
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      haystack = memchr (haystack, *needle, haystack_len);
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      if (!haystack || __builtin_expect (needle_len == 1, 0))
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        return (void *) haystack;
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      haystack_len -= haystack - (const unsigned char *) haystack_start;
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      if (haystack_len < needle_len)
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        return NULL;
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      return two_way_short_needle (haystack, haystack_len, needle, needle_len);
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    }
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  else
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    return two_way_long_needle (haystack, haystack_len, needle, needle_len);
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}
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#undef LONG_NEEDLE_THRESHOLD

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