GNU Linux-libre 5.19-rc6-gnu
[releases.git] / 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");