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Diffstat (limited to 'REORG.TODO/string/memmem.c')
-rw-r--r-- | REORG.TODO/string/memmem.c | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/REORG.TODO/string/memmem.c b/REORG.TODO/string/memmem.c new file mode 100644 index 0000000000..54fca4966d --- /dev/null +++ b/REORG.TODO/string/memmem.c @@ -0,0 +1,81 @@ +/* Copyright (C) 1991-2017 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +/* This particular implementation was written by Eric Blake, 2008. */ + +#ifndef _LIBC +# include <config.h> +#endif + +/* Specification of memmem. */ +#include <string.h> + +#ifndef _LIBC +# define __builtin_expect(expr, val) (expr) +# define __memmem memmem +#endif + +#define RETURN_TYPE void * +#define AVAILABLE(h, h_l, j, n_l) ((j) <= (h_l) - (n_l)) +#include "str-two-way.h" + +#undef memmem + +/* Return the first occurrence of NEEDLE in HAYSTACK. Return HAYSTACK + if NEEDLE_LEN is 0, otherwise NULL if NEEDLE is not found in + HAYSTACK. */ +void * +__memmem (const void *haystack_start, size_t haystack_len, + const void *needle_start, size_t needle_len) +{ + /* Abstract memory is considered to be an array of 'unsigned char' values, + not an array of 'char' values. See ISO C 99 section 6.2.6.1. */ + const unsigned char *haystack = (const unsigned char *) haystack_start; + const unsigned char *needle = (const unsigned char *) needle_start; + + if (needle_len == 0) + /* The first occurrence of the empty string is deemed to occur at + the beginning of the string. */ + return (void *) haystack; + + /* Sanity check, otherwise the loop might search through the whole + memory. */ + if (__glibc_unlikely (haystack_len < needle_len)) + return NULL; + + /* Use optimizations in memchr when possible, to reduce the search + size of haystack using a linear algorithm with a smaller + coefficient. However, avoid memchr for long needles, since we + can often achieve sublinear performance. */ + if (needle_len < LONG_NEEDLE_THRESHOLD) + { + haystack = memchr (haystack, *needle, haystack_len); + if (!haystack || __builtin_expect (needle_len == 1, 0)) + return (void *) haystack; + haystack_len -= haystack - (const unsigned char *) haystack_start; + if (haystack_len < needle_len) + return NULL; + return two_way_short_needle (haystack, haystack_len, needle, needle_len); + } + else + return two_way_long_needle (haystack, haystack_len, needle, needle_len); +} +libc_hidden_def (__memmem) +weak_alias (__memmem, memmem) +libc_hidden_weak (memmem) + +#undef LONG_NEEDLE_THRESHOLD |