contrib/tcpdump/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         0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
  25         0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
  26         0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
  27         0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
  28         0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
  29         0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
  30         0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
  31         0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
  32         0x40, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
  33         0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
  34         0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
  35         0x78, 0x79, 0x7a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
  36         0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
  37         0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
  38         0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
  39         0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
  40         0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
  41         0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
  42         0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
  43         0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
  44         0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
  45         0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
  46         0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
  47         0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
  48         0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
  49         0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
  50         0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
  51         0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
  52         0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
  53         0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
  54         0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
  55         0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff,
  56 };
  57
  58 int
  59 ascii_strcasecmp(const char *s1, const char *s2)
  60 {
  61         register const unsigned char *cm = charmap,
  62                         *us1 = (const unsigned char *)s1,
  63                         *us2 = (const unsigned char *)s2;
  64
  65         while (cm[*us1] == cm[*us2++])
  66                 if (*us1++ == '\0')
  67                         return(0);
  68         return(cm[*us1] - cm[*--us2]);
  69 }
  70
  71 int
  72 ascii_strncasecmp(const char *s1, const char *s2, register size_t n)
  73 {
  74         register const unsigned char *cm = charmap,
  75                         *us1 = (const unsigned char *)s1,
  76                         *us2 = (const unsigned char *)s2;
  77
  78         for (;;) {
  79                 if (n == 0) {
  80                         /*
  81                          * We've run out of characters that we should
  82                          * compare, and they've all been equal; return
  83                          * 0, to indicate that the prefixes are the
  84                          * same.
  85                          */
  86                         return(0);
  87                 }
  88                 if (cm[*us1] != cm[*us2++]) {
  89                         /*
  90                          * We've found a mismatch.
  91                          */
  92                         break;
  93                 }
  94                 if (*us1++ == '\0') {
  95                         /*
  96                          * We've run out of characters *to* compare,
  97                          * and they've all been equal; return 0, to
  98                          * indicate that the strings are the same.
  99                          */
 100                         return(0);
 101                 }
 102                 n--;
 103         }
 104         return(cm[*us1] - cm[*--us2]);
 105 }