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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /sysdeps/generic/memmem.c
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+/* Copyright (C) 1991, 1992, 1993, 1994 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.  */
+
+#include <ansidecl.h>
+#include <stddef.h>
+#include <string.h>
+
+
+/* Return the first occurrence of NEEDLE in HAYSTACK.  */
+PTR
+DEFUN(memmem, (haystack, haystack_len,
+	       needle, needle_len),
+      CONST PTRCONST haystack AND CONST size_t haystack_len AND
+      CONST PTRCONST needle AND CONST size_t needle_len)
+{
+  register CONST char *begin;
+  register CONST char *CONST last_possible
+    = (CONST char *) haystack + haystack_len - needle_len;
+
+  if (needle_len == 0)
+    return (PTR) &((CONST char *) haystack)[needle_len - 1];
+
+  for (begin = (CONST char *) haystack; begin <= last_possible; ++begin)
+    if (begin[0] == ((CONST char *) needle)[0] &&
+	!memcmp ((CONST PTR) &begin[1],
+		 (CONST PTR) ((CONST char *) needle + 1),
+		 needle_len - 1))
+      return (PTR) begin;
+
+  return NULL;
+}