aboutsummaryrefslogtreecommitdiff
path: root/string/strcasestr.c
diff options
context:
space:
mode:
Diffstat (limited to 'string/strcasestr.c')
-rw-r--r--string/strcasestr.c142
1 files changed, 142 insertions, 0 deletions
diff --git a/string/strcasestr.c b/string/strcasestr.c
new file mode 100644
index 0000000..1dde43c
--- /dev/null
+++ b/string/strcasestr.c
@@ -0,0 +1,142 @@
+/* Return the offset of one string within another.
+ Copyright (C) 1994, 1996-2000, 2004 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+/*
+ * My personal strstr() implementation that beats most other algorithms.
+ * Until someone tells me otherwise, I assume that this is the
+ * fastest implementation of strstr() in C.
+ * I deliberately chose not to comment it. You should have at least
+ * as much fun trying to understand it, as I had to write it :-).
+ *
+ * Stephen R. van den Berg, berg@pool.informatik.rwth-aachen.de */
+
+#if HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <ctype.h>
+
+#if defined _LIBC || defined HAVE_STRING_H
+# include <string.h>
+#endif
+
+#ifdef _LIBC
+# include <locale/localeinfo.h>
+# define TOLOWER(c) __tolower_l ((unsigned char) c, loc)
+#else
+# define TOLOWER(c) _tolower (c)
+#endif
+
+typedef unsigned chartype;
+
+#undef strcasestr
+#undef __strcasestr
+
+char *
+__strcasestr (phaystack, pneedle)
+ const char *phaystack;
+ const char *pneedle;
+{
+ register const unsigned char *haystack, *needle;
+ register chartype b, c;
+#ifdef _LIBC
+ __locale_t loc = _NL_CURRENT_LOCALE;
+#endif
+
+ haystack = (const unsigned char *) phaystack;
+ needle = (const unsigned char *) pneedle;
+
+ b = TOLOWER (*needle);
+ if (b != '\0')
+ {
+ haystack--; /* possible ANSI violation */
+ do
+ {
+ c = *++haystack;
+ if (c == '\0')
+ goto ret0;
+ }
+ while (TOLOWER (c) != (int) b);
+
+ c = TOLOWER (*++needle);
+ if (c == '\0')
+ goto foundneedle;
+ ++needle;
+ goto jin;
+
+ for (;;)
+ {
+ register chartype a;
+ register const unsigned char *rhaystack, *rneedle;
+
+ do
+ {
+ a = *++haystack;
+ if (a == '\0')
+ goto ret0;
+ if (TOLOWER (a) == (int) b)
+ break;
+ a = *++haystack;
+ if (a == '\0')
+ goto ret0;
+shloop:
+ ;
+ }
+ while (TOLOWER (a) != (int) b);
+
+jin: a = *++haystack;
+ if (a == '\0')
+ goto ret0;
+
+ if (TOLOWER (a) != (int) c)
+ goto shloop;
+
+ rhaystack = haystack-- + 1;
+ rneedle = needle;
+ a = TOLOWER (*rneedle);
+
+ if (TOLOWER (*rhaystack) == (int) a)
+ do
+ {
+ if (a == '\0')
+ goto foundneedle;
+ ++rhaystack;
+ a = TOLOWER (*++needle);
+ if (TOLOWER (*rhaystack) != (int) a)
+ break;
+ if (a == '\0')
+ goto foundneedle;
+ ++rhaystack;
+ a = TOLOWER (*++needle);
+ }
+ while (TOLOWER (*rhaystack) == (int) a);
+
+ needle = rneedle; /* took the register-poor approach */
+
+ if (a == '\0')
+ break;
+ }
+ }
+foundneedle:
+ return (char*) haystack;
+ret0:
+ return 0;
+}
+
+weak_alias (__strcasestr, strcasestr)