usr/src/lib/libc/port/gen/strcasecmp.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*      Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T     */
  28 /*        All Rights Reserved   */
  29
  30 /*
  31  * Portions of this source code were derived from Berkeley 4.3 BSD
  32  * under license from the Regents of the University of California.
  33  */
  34
  35 #pragma ident   "%Z%%M% %I%     %E% SMI"
  36
  37 #include "lint.h"
  38 #include <sys/types.h>
  39 #include <strings.h>
  40
  41 /*
  42  * This array is designed for mapping upper and lower case letter
  43  * together for a case independent comparison.  The mappings are
  44  * based upon ascii character sequences.
  45  */
  46
  47 extern const char strcase_charmap[];
  48
  49 int
  50 strcasecmp(const char *s1, const char *s2)
  51 {
  52         const unsigned char     *cm = (const unsigned char *)strcase_charmap;
  53         const unsigned char     *us1 = (const unsigned char *)s1;
  54         const unsigned char     *us2 = (const unsigned char *)s2;
  55
  56         while (cm[*us1] == cm[*us2++])
  57                 if (*us1++ == '\0')
  58                         return (0);
  59         return (cm[*us1] - cm[*(us2 - 1)]);
  60 }