The Tcpdump Group git mirrors - tcpdump/blob - ascii_strcasecmp.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 #include "ascii_strcasecmp.h"
  14
  15 /*
  16  * This array maps upper-case ASCII letters to their lower-case
  17  * equivalents; all other byte values are mapped to themselves,
  18  * so this is locale-independent and intended to be locale-independent,
  19  * to avoid issues with, for example, "i" and "I" not being lower-case
  20  * and upper-case versions of the same letter in Turkish, where
  21  * there are separate "i with dot" and "i without dot" letters.
  22  */
  23 static const unsigned char charmap[] = {
  24         '\000', '\001', '\002', '\003', '\004', '\005', '\006', '\007',
  25         '\010', '\011', '\012', '\013', '\014', '\015', '\016', '\017',
  26         '\020', '\021', '\022', '\023', '\024', '\025', '\026', '\027',
  27         '\030', '\031', '\032', '\033', '\034', '\035', '\036', '\037',
  28         '\040', '\041', '\042', '\043', '\044', '\045', '\046', '\047',
  29         '\050', '\051', '\052', '\053', '\054', '\055', '\056', '\057',
  30         '\060', '\061', '\062', '\063', '\064', '\065', '\066', '\067',
  31         '\070', '\071', '\072', '\073', '\074', '\075', '\076', '\077',
  32         '\100', '\141', '\142', '\143', '\144', '\145', '\146', '\147',
  33         '\150', '\151', '\152', '\153', '\154', '\155', '\156', '\157',
  34         '\160', '\161', '\162', '\163', '\164', '\165', '\166', '\167',
  35         '\170', '\171', '\172', '\133', '\134', '\135', '\136', '\137',
  36         '\140', '\141', '\142', '\143', '\144', '\145', '\146', '\147',
  37         '\150', '\151', '\152', '\153', '\154', '\155', '\156', '\157',
  38         '\160', '\161', '\162', '\163', '\164', '\165', '\166', '\167',
  39         '\170', '\171', '\172', '\173', '\174', '\175', '\176', '\177',
  40         '\200', '\201', '\202', '\203', '\204', '\205', '\206', '\207',
  41         '\210', '\211', '\212', '\213', '\214', '\215', '\216', '\217',
  42         '\220', '\221', '\222', '\223', '\224', '\225', '\226', '\227',
  43         '\230', '\231', '\232', '\233', '\234', '\235', '\236', '\237',
  44         '\240', '\241', '\242', '\243', '\244', '\245', '\246', '\247',
  45         '\250', '\251', '\252', '\253', '\254', '\255', '\256', '\257',
  46         '\260', '\261', '\262', '\263', '\264', '\265', '\266', '\267',
  47         '\270', '\271', '\272', '\273', '\274', '\275', '\276', '\277',
  48         '\300', '\301', '\302', '\303', '\304', '\305', '\306', '\307',
  49         '\310', '\311', '\312', '\313', '\314', '\315', '\316', '\317',
  50         '\320', '\321', '\322', '\323', '\324', '\325', '\326', '\327',
  51         '\330', '\331', '\332', '\333', '\334', '\335', '\336', '\337',
  52         '\340', '\341', '\342', '\343', '\344', '\345', '\346', '\347',
  53         '\350', '\351', '\352', '\353', '\354', '\355', '\356', '\357',
  54         '\360', '\361', '\362', '\363', '\364', '\365', '\366', '\367',
  55         '\370', '\371', '\372', '\373', '\374', '\375', '\376', '\377',
  56 };
  57
  58 int
  59 ascii_strcasecmp(s1, s2)
  60         const char *s1, *s2;
  61 {
  62         register const unsigned char *cm = charmap,
  63                         *us1 = (const unsigned char *)s1,
  64                         *us2 = (const unsigned char *)s2;
  65
  66         while (cm[*us1] == cm[*us2++])
  67                 if (*us1++ == '\0')
  68                         return(0);
  69         return(cm[*us1] - cm[*--us2]);
  70 }
  71
  72 int
  73 ascii_strncasecmp(s1, s2, n)
  74         const char *s1, *s2;
  75         register size_t n;
  76 {
  77         register const unsigned char *cm = charmap,
  78                         *us1 = (const unsigned char *)s1,
  79                         *us2 = (const unsigned char *)s2;
  80
  81         for (;;) {
  82                 if (n == 0) {
  83                         /*
  84                          * We've run out of characters that we should
  85                          * compare, and they've all been equal; return
  86                          * 0, to indicate that the prefixes are the
  87                          * same.
  88                          */
  89                         return(0);
  90                 }
  91                 if (cm[*us1] != cm[*us2++]) {
  92                         /*
  93                          * We've found a mismatch.
  94                          */
  95                         break;
  96                 }
  97                 if (*us1++ == '\0') {
  98                         /*
  99                          * We've run out of characters *to* compare,
 100                          * and they've all been equal; return 0, to
 101                          * indicate that the strings are the same.
 102                          */
 103                         return(0);
 104                 }
 105                 n--;
 106         }
 107         return(cm[*us1] - cm[*--us2]);
 108 }