libiberty/strncasecmp.c

   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 }