ppc/gen/strncmp.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /* Copyright (c) 1992, 1997 NeXT Software, Inc.  All rights reserved.
  26  *
  27  *      File:   libc/gen/ppc/strncmp.c
  28  *
  29  *      This file contains machine dependent code for string comparison
  30  *
  31  * HISTORY
  32  *  24-Jan-1997 Umesh Vaishampayan (umeshv@NeXT.com)
  33  *      Ported to PPC.
  34  * 24-Nov-92  Derek B Clegg (dclegg@next.com)
  35  *      Created.
  36  */
  37 #import <string.h>
  38
  39 /* This routine should be optimized. */
  40
  41 /* ANSI sez:
  42  *   The `strncmp' function compares not more than `n' characters (characters
  43  *   that follow a null character are not compared) from the array pointed to
  44  *   by `s1' to the array pointed to by `s2'.
  45  *   The `strncmp' function returns an integer greater than, equal to, or less
  46  *   than zero, according as the possibly null-terminated array pointed to by
  47  *   `s1' is greater than, equal to, or less than the possibly null-terminated
  48  *   array pointed to by `s2'.  [4.11.4.4]
  49  */
  50 int
  51 strncmp(const char *s1, const char *s2, size_t n)
  52 {
  53     for ( ; n > 0; s1++, s2++, --n)
  54         if (*s1 != *s2)
  55             return ((*(unsigned char *)s1 < *(unsigned char *)s2) ? -1 : +1);
  56         else if (*s1 == '\0')
  57             return 0;
  58     return 0;
  59 }