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authorKarl Berry <karl@freefriends.org>2006-01-17 21:41:51 +0000
committerKarl Berry <karl@freefriends.org>2006-01-17 21:41:51 +0000
commit487ca4806cc046076293cf6cc5fbba0db282bac7 (patch)
tree847b412ab5158dd7bdd7ed7e5a4cc3fbca94be32 /Build/source/texk/kpathsea/strstr.c
parenta3d3111bfe26b8e5f5bc6049dfb2a4ca2edc7881 (diff)
texk 1
git-svn-id: svn://tug.org/texlive/trunk@1485 c570f23f-e606-0410-a88d-b1316a301751
Diffstat (limited to 'Build/source/texk/kpathsea/strstr.c')
-rw-r--r--Build/source/texk/kpathsea/strstr.c125
1 files changed, 125 insertions, 0 deletions
diff --git a/Build/source/texk/kpathsea/strstr.c b/Build/source/texk/kpathsea/strstr.c
new file mode 100644
index 00000000000..5080a9e1e63
--- /dev/null
+++ b/Build/source/texk/kpathsea/strstr.c
@@ -0,0 +1,125 @@
+/* strstr.c - search for a substring in string.
+
+ Copyright (C) 1994, 95 Free Software Foundation, Inc.
+ This file was part of the GNU C Library. Modified by kb@mail.tug.org.
+
+ This 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.
+
+ This 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 this library; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 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 !defined (__STDC__) || !__STDC__
+/* This is a separate conditional since some stdc systems
+ reject `defined (const)'. */
+#ifndef const
+#define const
+#endif
+#endif
+
+typedef unsigned chartype;
+
+char *
+strstr (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 = *needle;
+ if (b != '\0')
+ {
+ haystack--; /* possible ANSI violation */
+ do
+ {
+ c = *++haystack;
+ if (c == '\0')
+ goto ret0;
+ }
+ while (c != b);
+
+ c = *++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 (a == b)
+ break;
+ a = *++haystack;
+ if (a == '\0')
+ goto ret0;
+shloop: }
+ while (a != b);
+
+jin: a = *++haystack;
+ if (a == '\0')
+ goto ret0;
+
+ if (a != c)
+ goto shloop;
+
+ rhaystack = haystack-- + 1;
+ rneedle = needle;
+ a = *rneedle;
+
+ if (*rhaystack == a)
+ do
+ {
+ if (a == '\0')
+ goto foundneedle;
+ ++rhaystack;
+ a = *++needle;
+ if (*rhaystack != a)
+ break;
+ if (a == '\0')
+ goto foundneedle;
+ ++rhaystack;
+ a = *++needle;
+ }
+ while (*rhaystack == a);
+
+ needle = rneedle; /* took the register-poor aproach */
+
+ if (a == '\0')
+ break;
+ }
+ }
+foundneedle:
+ return (char*) haystack;
+ret0:
+ return 0;
+}