lib/ucs2_string.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/ucs2_string.h>
   3 #include <linux/module.h>
   4
   5 /* Return the number of unicode characters in data */
   6 unsigned long
   7 ucs2_strnlen(const ucs2_char_t *s, size_t maxlength)
   8 {
   9         unsigned long length = 0;
  10
  11         while (*s++ != 0 && length < maxlength)
  12                 length++;
  13         return length;
  14 }
  15 EXPORT_SYMBOL(ucs2_strnlen);
  16
  17 unsigned long
  18 ucs2_strlen(const ucs2_char_t *s)
  19 {
  20         return ucs2_strnlen(s, ~0UL);
  21 }
  22 EXPORT_SYMBOL(ucs2_strlen);
  23
  24 /*
  25  * Return the number of bytes is the length of this string
  26  * Note: this is NOT the same as the number of unicode characters
  27  */
  28 unsigned long
  29 ucs2_strsize(const ucs2_char_t *data, unsigned long maxlength)
  30 {
  31         return ucs2_strnlen(data, maxlength/sizeof(ucs2_char_t)) * sizeof(ucs2_char_t);
  32 }
  33 EXPORT_SYMBOL(ucs2_strsize);
  34
  35 int
  36 ucs2_strncmp(const ucs2_char_t *a, const ucs2_char_t *b, size_t len)
  37 {
  38         while (1) {
  39                 if (len == 0)
  40                         return 0;
  41                 if (*a < *b)
  42                         return -1;
  43                 if (*a > *b)
  44                         return 1;
  45                 if (*a == 0) /* implies *b == 0 */
  46                         return 0;
  47                 a++;
  48                 b++;
  49                 len--;
  50         }
  51 }
  52 EXPORT_SYMBOL(ucs2_strncmp);
  53
  54 unsigned long
  55 ucs2_utf8size(const ucs2_char_t *src)
  56 {
  57         unsigned long i;
  58         unsigned long j = 0;
  59
  60         for (i = 0; src[i]; i++) {
  61                 u16 c = src[i];
  62
  63                 if (c >= 0x800)
  64                         j += 3;
  65                 else if (c >= 0x80)
  66                         j += 2;
  67                 else
  68                         j += 1;
  69         }
  70
  71         return j;
  72 }
  73 EXPORT_SYMBOL(ucs2_utf8size);
  74
  75 /*
  76  * copy at most maxlength bytes of whole utf8 characters to dest from the
  77  * ucs2 string src.
  78  *
  79  * The return value is the number of characters copied, not including the
  80  * final NUL character.
  81  */
  82 unsigned long
  83 ucs2_as_utf8(u8 *dest, const ucs2_char_t *src, unsigned long maxlength)
  84 {
  85         unsigned int i;
  86         unsigned long j = 0;
  87         unsigned long limit = ucs2_strnlen(src, maxlength);
  88
  89         for (i = 0; maxlength && i < limit; i++) {
  90                 u16 c = src[i];
  91
  92                 if (c >= 0x800) {
  93                         if (maxlength < 3)
  94                                 break;
  95                         maxlength -= 3;
  96                         dest[j++] = 0xe0 | (c & 0xf000) >> 12;
  97                         dest[j++] = 0x80 | (c & 0x0fc0) >> 6;
  98                         dest[j++] = 0x80 | (c & 0x003f);
  99                 } else if (c >= 0x80) {
 100                         if (maxlength < 2)
 101                                 break;
 102                         maxlength -= 2;
 103                         dest[j++] = 0xc0 | (c & 0x7c0) >> 6;
 104                         dest[j++] = 0x80 | (c & 0x03f);
 105                 } else {
 106                         maxlength -= 1;
 107                         dest[j++] = c & 0x7f;
 108                 }
 109         }
 110         if (maxlength)
 111                 dest[j] = '\0';
 112         return j;
 113 }
 114 EXPORT_SYMBOL(ucs2_as_utf8);
 115
 116 MODULE_LICENSE("GPL v2");