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