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568035b7 | 1 | /* Copyright (C) 1995-2013 Free Software Foundation, Inc. |
33a934a3 | 2 | This file is part of the GNU C Library. |
30de3b18 | 3 | |
33a934a3 | 4 | The GNU C Library is free software; you can redistribute it and/or |
41bdb6e2 AJ |
5 | modify it under the terms of the GNU Lesser General Public |
6 | License as published by the Free Software Foundation; either | |
7 | version 2.1 of the License, or (at your option) any later version. | |
30de3b18 | 8 | |
33a934a3 UD |
9 | The GNU C Library is distributed in the hope that it will be useful, |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 12 | Lesser General Public License for more details. |
30de3b18 | 13 | |
41bdb6e2 | 14 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 PE |
15 | License along with the GNU C Library; if not, see |
16 | <http://www.gnu.org/licenses/>. */ | |
30de3b18 RM |
17 | |
18 | /* | |
19 | * The original strstr() file contains the following comment: | |
20 | * | |
21 | * My personal strstr() implementation that beats most other algorithms. | |
22 | * Until someone tells me otherwise, I assume that this is the | |
23 | * fastest implementation of strstr() in C. | |
24 | * I deliberately chose not to comment it. You should have at least | |
25 | * as much fun trying to understand it, as I had to write it :-). | |
26 | * | |
27 | * Stephen R. van den Berg, berg@pool.informatik.rwth-aachen.de */ | |
28 | ||
29 | #include <wchar.h> | |
30 | ||
31 | wchar_t * | |
32 | wcsstr (haystack, needle) | |
33 | const wchar_t *haystack; | |
34 | const wchar_t *needle; | |
35 | { | |
2e09a79a | 36 | wchar_t b, c; |
30de3b18 RM |
37 | |
38 | if ((b = *needle) != L'\0') | |
39 | { | |
40 | haystack--; /* possible ANSI violation */ | |
41 | do | |
42 | if ((c = *++haystack) == L'\0') | |
43 | goto ret0; | |
44 | while (c != b); | |
45 | ||
46 | if (!(c = *++needle)) | |
47 | goto foundneedle; | |
48 | ++needle; | |
49 | goto jin; | |
50 | ||
51 | for (;;) | |
52 | { | |
2e09a79a JM |
53 | wchar_t a; |
54 | const wchar_t *rhaystack, *rneedle; | |
30de3b18 RM |
55 | |
56 | do | |
57 | { | |
58 | if (!(a = *++haystack)) | |
59 | goto ret0; | |
60 | if (a == b) | |
61 | break; | |
62 | if ((a = *++haystack) == L'\0') | |
63 | goto ret0; | |
64 | shloop: ; | |
65 | } | |
66 | while (a != b); | |
67 | ||
68 | jin: if (!(a = *++haystack)) | |
69 | goto ret0; | |
70 | ||
71 | if (a != c) | |
72 | goto shloop; | |
73 | ||
74 | if (*(rhaystack = haystack-- + 1) == (a = *(rneedle = needle))) | |
75 | do | |
76 | { | |
77 | if (a == L'\0') | |
78 | goto foundneedle; | |
79 | if (*++rhaystack != (a = *++needle)) | |
80 | break; | |
81 | if (a == L'\0') | |
82 | goto foundneedle; | |
83 | } | |
84 | while (*++rhaystack == (a = *++needle)); | |
85 | ||
86 | needle = rneedle; /* took the register-poor approach */ | |
87 | ||
88 | if (a == L'\0') | |
89 | break; | |
90 | } | |
91 | } | |
92 | foundneedle: | |
93 | return (wchar_t*) haystack; | |
94 | ret0: | |
95 | return NULL; | |
96 | } | |
7799b7b3 UD |
97 | /* This alias is for backward compatibility with drafts of the ISO C |
98 | standard. Unfortunately the Unix(TM) standard requires this name. */ | |
99 | weak_alias (wcsstr, wcswcs) |