xref: /kernel/linux/linux-5.10/lib/ucs2_string.c (revision 8c2ecf20) 
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 */
6unsigned long
7ucs2_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}
15EXPORT_SYMBOL(ucs2_strnlen);
16
17unsigned long
18ucs2_strlen(const ucs2_char_t *s)
19{
20        return ucs2_strnlen(s, ~0UL);
21}
22EXPORT_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 */
28unsigned long
29ucs2_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}
33EXPORT_SYMBOL(ucs2_strsize);
34
35int
36ucs2_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}
52EXPORT_SYMBOL(ucs2_strncmp);
53
54unsigned long
55ucs2_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}
73EXPORT_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 */
82unsigned long
83ucs2_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}
114EXPORT_SYMBOL(ucs2_as_utf8);
115
116MODULE_LICENSE("GPL v2");
117