1  /*
       2   * Copyright (c) 1987 Regents of the University of California.
       3   * All rights reserved.
       4   *
       5   * Redistribution and use in source and binary forms are permitted
       6   * provided that this notice is preserved and that due credit is given
       7   * to the University of California at Berkeley. The name of the University
       8   * may not be used to endorse or promote products derived from this
       9   * software without specific written prior permission. This software
      10   * is provided ``as is'' without express or implied warranty.
      11   */
      12  
      13  /*
      14    
      15  @deftypefn Supplemental int strncasecmp (const char *@var{s1}, const char *@var{s2})
      16  
      17  A case-insensitive @code{strncmp}.
      18  
      19  @end deftypefn
      20  
      21  */
      22  
      23  #if defined(LIBC_SCCS) && !defined(lint)
      24  static char sccsid[] = "@(#)strcasecmp.c	5.5 (Berkeley) 11/24/87";
      25  #endif /* LIBC_SCCS and not lint */
      26  
      27  #include <ansidecl.h>
      28  #include <stddef.h>
      29  
      30  /*
      31   * This array is designed for mapping upper and lower case letter
      32   * together for a case independent comparison.  The mappings are
      33   * based upon ascii character sequences.
      34   */
      35  static const unsigned char charmap[] = {
      36  	'\000', '\001', '\002', '\003', '\004', '\005', '\006', '\007',
      37  	'\010', '\011', '\012', '\013', '\014', '\015', '\016', '\017',
      38  	'\020', '\021', '\022', '\023', '\024', '\025', '\026', '\027',
      39  	'\030', '\031', '\032', '\033', '\034', '\035', '\036', '\037',
      40  	'\040', '\041', '\042', '\043', '\044', '\045', '\046', '\047',
      41  	'\050', '\051', '\052', '\053', '\054', '\055', '\056', '\057',
      42  	'\060', '\061', '\062', '\063', '\064', '\065', '\066', '\067',
      43  	'\070', '\071', '\072', '\073', '\074', '\075', '\076', '\077',
      44  	'\100', '\141', '\142', '\143', '\144', '\145', '\146', '\147',
      45  	'\150', '\151', '\152', '\153', '\154', '\155', '\156', '\157',
      46  	'\160', '\161', '\162', '\163', '\164', '\165', '\166', '\167',
      47  	'\170', '\171', '\172', '\133', '\134', '\135', '\136', '\137',
      48  	'\140', '\141', '\142', '\143', '\144', '\145', '\146', '\147',
      49  	'\150', '\151', '\152', '\153', '\154', '\155', '\156', '\157',
      50  	'\160', '\161', '\162', '\163', '\164', '\165', '\166', '\167',
      51  	'\170', '\171', '\172', '\173', '\174', '\175', '\176', '\177',
      52  	'\200', '\201', '\202', '\203', '\204', '\205', '\206', '\207',
      53  	'\210', '\211', '\212', '\213', '\214', '\215', '\216', '\217',
      54  	'\220', '\221', '\222', '\223', '\224', '\225', '\226', '\227',
      55  	'\230', '\231', '\232', '\233', '\234', '\235', '\236', '\237',
      56  	'\240', '\241', '\242', '\243', '\244', '\245', '\246', '\247',
      57  	'\250', '\251', '\252', '\253', '\254', '\255', '\256', '\257',
      58  	'\260', '\261', '\262', '\263', '\264', '\265', '\266', '\267',
      59  	'\270', '\271', '\272', '\273', '\274', '\275', '\276', '\277',
      60  	'\300', '\341', '\342', '\343', '\344', '\345', '\346', '\347',
      61  	'\350', '\351', '\352', '\353', '\354', '\355', '\356', '\357',
      62  	'\360', '\361', '\362', '\363', '\364', '\365', '\366', '\367',
      63  	'\370', '\371', '\372', '\333', '\334', '\335', '\336', '\337',
      64  	'\340', '\341', '\342', '\343', '\344', '\345', '\346', '\347',
      65  	'\350', '\351', '\352', '\353', '\354', '\355', '\356', '\357',
      66  	'\360', '\361', '\362', '\363', '\364', '\365', '\366', '\367',
      67  	'\370', '\371', '\372', '\373', '\374', '\375', '\376', '\377',
      68  };
      69  
      70  int
      71  strncasecmp(const char *s1, const char *s2, register size_t n)
      72  {
      73      register unsigned char u1, u2;
      74  
      75      for (; n != 0; --n) {
      76  	u1 = (unsigned char) *s1++;
      77  	u2 = (unsigned char) *s2++;
      78  	if (charmap[u1] != charmap[u2]) {
      79  	    return charmap[u1] - charmap[u2];
      80  	}
      81  	if (u1 == '\0') {
      82  	    return 0;
      83  	}
      84      }
      85      return 0;
      86  }