X-Git-Url: http://git.ozlabs.org/?a=blobdiff_plain;f=lib%2Fstrstr.c;fp=lib%2Fstrstr.c;h=fbe7cfb121c593f1d6426e014bca01f3d76d1716;hb=f4ebbd9f7ea23e3f0fcbe098754580c220894628;hp=0000000000000000000000000000000000000000;hpb=f42aaadb5c8c5f7f15e5159cbc251e64e1a4ac8f;p=yaboot.git

diff --git a/lib/strstr.c b/lib/strstr.c
new file mode 100644
index 0000000..fbe7cfb
--- /dev/null
+++ b/lib/strstr.c
@@ -0,0 +1,119 @@
+/* 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	*/
+
+#include <string.h>
+
+typedef unsigned chartype;
+
+#undef strstr
+
+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 approach */
+
+	  if (a == '\0')
+	    break;
+        }
+    }
+foundneedle:
+  return (char*) haystack;
+ret0:
+  return 0;
+}