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-rw-r--r--wcsmbs/wcsstr.c97
1 files changed, 97 insertions, 0 deletions
diff --git a/wcsmbs/wcsstr.c b/wcsmbs/wcsstr.c
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+/* Copyright (C) 1995, 1996 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., 675 Mass Ave,
+Cambridge, MA 02139, USA. */
+
+/*
+ * The original strstr() file contains the following comment:
+ *
+ * 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 */
+
+#include <wchar.h>
+
+wchar_t *
+wcsstr (haystack, needle)
+ const wchar_t *haystack;
+ const wchar_t *needle;
+{
+ register wchar_t b, c;
+
+ if ((b = *needle) != L'\0')
+ {
+ haystack--; /* possible ANSI violation */
+ do
+ if ((c = *++haystack) == L'\0')
+ goto ret0;
+ while (c != b);
+
+ if (!(c = *++needle))
+ goto foundneedle;
+ ++needle;
+ goto jin;
+
+ for (;;)
+ {
+ register wchar_t a;
+ register const wchar_t *rhaystack, *rneedle;
+
+ do
+ {
+ if (!(a = *++haystack))
+ goto ret0;
+ if (a == b)
+ break;
+ if ((a = *++haystack) == L'\0')
+ goto ret0;
+shloop: ;
+ }
+ while (a != b);
+
+jin: if (!(a = *++haystack))
+ goto ret0;
+
+ if (a != c)
+ goto shloop;
+
+ if (*(rhaystack = haystack-- + 1) == (a = *(rneedle = needle)))
+ do
+ {
+ if (a == L'\0')
+ goto foundneedle;
+ if (*++rhaystack != (a = *++needle))
+ break;
+ if (a == L'\0')
+ goto foundneedle;
+ }
+ while (*++rhaystack == (a = *++needle));
+
+ needle = rneedle; /* took the register-poor approach */
+
+ if (a == L'\0')
+ break;
+ }
+ }
+foundneedle:
+ return (wchar_t*) haystack;
+ret0:
+ return NULL;
+}