gen.subproj/ppc.subproj/strncmp.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /* Copyright (c) 1992, 1997 NeXT Software, Inc.  All rights reserved.
  23  *
  24  *      File:   libc/gen/ppc/strncmp.c
  25  *
  26  *      This file contains machine dependent code for string comparison
  27  *
  28  * HISTORY
  29  *  24-Jan-1997 Umesh Vaishampayan (umeshv@NeXT.com)
  30  *      Ported to PPC.
  31  * 24-Nov-92  Derek B Clegg (dclegg@next.com)
  32  *      Created.
  33  */
  34 #import <string.h>
  35
  36 /* This routine should be optimized. */
  37
  38 /* ANSI sez:
  39  *   The `strncmp' function compares not more than `n' characters (characters
  40  *   that follow a null character are not compared) from the array pointed to
  41  *   by `s1' to the array pointed to by `s2'.
  42  *   The `strncmp' function returns an integer greater than, equal to, or less
  43  *   than zero, according as the possibly null-terminated array pointed to by
  44  *   `s1' is greater than, equal to, or less than the possibly null-terminated
  45  *   array pointed to by `s2'.  [4.11.4.4]
  46  */
  47 int
  48 strncmp(const char *s1, const char *s2, size_t n)
  49 {
  50     for ( ; n > 0; s1++, s2++, --n)
  51         if (*s1 != *s2)
  52             return ((*(unsigned char *)s1 < *(unsigned char *)s2) ? -1 : +1);
  53         else if (*s1 == '\0')
  54             return 0;
  55     return 0;
  56 }