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
ucs2_strnlen(const ucs2_char_t * s,size_t maxlength)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
ucs2_strlen(const ucs2_char_t * s)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
ucs2_strsize(const ucs2_char_t * data,unsigned long maxlength)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
ucs2_strncmp(const ucs2_char_t * a,const ucs2_char_t * b,size_t len)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
ucs2_utf8size(const ucs2_char_t * src)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
ucs2_as_utf8(u8 * dest,const ucs2_char_t * src,unsigned long maxlength)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");
117