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-rw-r--r--sysdeps/generic/strcasestr.c129
1 files changed, 129 insertions, 0 deletions
diff --git a/sysdeps/generic/strcasestr.c b/sysdeps/generic/strcasestr.c
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+/* Return the offset of one string within another.
+ Copyright (C) 1994, 1996, 1997 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 Library General Public License as
+ published by the Free Software Foundation; either version 2 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
+ Library General Public License for more details.
+
+ You should have received a copy of the GNU Library General Public
+ License along with the GNU C Library; see the file COPYING.LIB. 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
+
+typedef unsigned chartype;
+
+#undef strstr
+
+char *
+__strcasestr (phaystack, pneedle)
+ const char *phaystack;
+ const char *pneedle;
+{
+ register const unsigned char *haystack, *needle;
+ register chartype b, c;
+
+ 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) != 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) == b)
+ break;
+ a = *++haystack;
+ if (a == '\0')
+ goto ret0;
+shloop: }
+ while (tolower (a) != b);
+
+jin: a = *++haystack;
+ if (a == '\0')
+ goto ret0;
+
+ if (tolower (a) != c)
+ goto shloop;
+
+ rhaystack = haystack-- + 1;
+ rneedle = needle;
+ a = tolower (*rneedle);
+
+ if (tolower (*rhaystack) == a)
+ do
+ {
+ if (a == '\0')
+ goto foundneedle;
+ ++rhaystack;
+ a = tolower (*++needle);
+ if (tolower (*rhaystack) != a)
+ break;
+ if (a == '\0')
+ goto foundneedle;
+ ++rhaystack;
+ a = tolower (*++needle);
+ }
+ while (tolower (*rhaystack) == a);
+
+ needle = rneedle; /* took the register-poor approach */
+
+ if (a == '\0')
+ break;
+ }
+ }
+foundneedle:
+ return (char*) haystack;
+ret0:
+ return 0;
+}
+
+weak_alias (__strcasestr, strcasestr)