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nls.h
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1 #ifndef _LINUX_NLS_H
2 #define _LINUX_NLS_H
3 
4 #include <linux/init.h>
5 
6 /* Unicode has changed over the years. Unicode code points no longer
7  * fit into 16 bits; as of Unicode 5 valid code points range from 0
8  * to 0x10ffff (17 planes, where each plane holds 65536 code points).
9  *
10  * The original decision to represent Unicode characters as 16-bit
11  * wchar_t values is now outdated. But plane 0 still includes the
12  * most commonly used characters, so we will retain it. The newer
13  * 32-bit unicode_t type can be used when it is necessary to
14  * represent the full Unicode character set.
15  */
16 
17 /* Plane-0 Unicode character */
18 typedef u16 wchar_t;
19 #define MAX_WCHAR_T 0xffff
20 
21 /* Arbitrary Unicode character */
22 typedef u32 unicode_t;
23 
24 struct nls_table {
25  const char *charset;
26  const char *alias;
27  int (*uni2char) (wchar_t uni, unsigned char *out, int boundlen);
28  int (*char2uni) (const unsigned char *rawstring, int boundlen,
29  wchar_t *uni);
30  const unsigned char *charset2lower;
31  const unsigned char *charset2upper;
32  struct module *owner;
33  struct nls_table *next;
34 };
35 
36 /* this value hold the maximum octet of charset */
37 #define NLS_MAX_CHARSET_SIZE 6 /* for UTF-8 */
38 
39 /* Byte order for UTF-16 strings */
44 };
45 
46 /* nls_base.c */
47 extern int register_nls(struct nls_table *);
48 extern int unregister_nls(struct nls_table *);
49 extern struct nls_table *load_nls(char *);
50 extern void unload_nls(struct nls_table *);
51 extern struct nls_table *load_nls_default(void);
52 
53 extern int utf8_to_utf32(const u8 *s, int len, unicode_t *pu);
54 extern int utf32_to_utf8(unicode_t u, u8 *s, int maxlen);
55 extern int utf8s_to_utf16s(const u8 *s, int len,
56  enum utf16_endian endian, wchar_t *pwcs, int maxlen);
57 extern int utf16s_to_utf8s(const wchar_t *pwcs, int len,
58  enum utf16_endian endian, u8 *s, int maxlen);
59 
60 static inline unsigned char nls_tolower(struct nls_table *t, unsigned char c)
61 {
62  unsigned char nc = t->charset2lower[c];
63 
64  return nc ? nc : c;
65 }
66 
67 static inline unsigned char nls_toupper(struct nls_table *t, unsigned char c)
68 {
69  unsigned char nc = t->charset2upper[c];
70 
71  return nc ? nc : c;
72 }
73 
74 static inline int nls_strnicmp(struct nls_table *t, const unsigned char *s1,
75  const unsigned char *s2, int len)
76 {
77  while (len--) {
78  if (nls_tolower(t, *s1++) != nls_tolower(t, *s2++))
79  return 1;
80  }
81 
82  return 0;
83 }
84 
85 /*
86  * nls_nullsize - return length of null character for codepage
87  * @codepage - codepage for which to return length of NULL terminator
88  *
89  * Since we can't guarantee that the null terminator will be a particular
90  * length, we have to check against the codepage. If there's a problem
91  * determining it, assume a single-byte NULL terminator.
92  */
93 static inline int
94 nls_nullsize(const struct nls_table *codepage)
95 {
96  int charlen;
98 
99  charlen = codepage->uni2char(0, tmp, NLS_MAX_CHARSET_SIZE);
100 
101  return charlen > 0 ? charlen : 1;
102 }
103 
104 #define MODULE_ALIAS_NLS(name) MODULE_ALIAS("nls_" __stringify(name))
105 
106 #endif /* _LINUX_NLS_H */
107