include/linux/nls.h

   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  11  * wchar_t values is now outdated.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 */
  40 enum utf16_endian {
  41         UTF16_HOST_ENDIAN,
  42         UTF16_LITTLE_ENDIAN,
  43         UTF16_BIG_ENDIAN
  44 };
  45
  46 /* nls.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, wchar_t *pwcs);
  56 extern int utf16s_to_utf8s(const wchar_t *pwcs, int len,
  57                 enum utf16_endian endian, u8 *s, int maxlen);
  58
  59 static inline unsigned char nls_tolower(struct nls_table *t, unsigned char c)
  60 {
  61         unsigned char nc = t->charset2lower[c];
  62
  63         return nc ? nc : c;
  64 }
  65
  66 static inline unsigned char nls_toupper(struct nls_table *t, unsigned char c)
  67 {
  68         unsigned char nc = t->charset2upper[c];
  69
  70         return nc ? nc : c;
  71 }
  72
  73 static inline int nls_strnicmp(struct nls_table *t, const unsigned char *s1,
  74                 const unsigned char *s2, int len)
  75 {
  76         while (len--) {
  77                 if (nls_tolower(t, *s1++) != nls_tolower(t, *s2++))
  78                         return 1;
  79         }
  80
  81         return 0;
  82 }
  83
  84 /*
  85  * nls_nullsize - return length of null character for codepage
  86  * @codepage - codepage for which to return length of NULL terminator
  87  *
  88  * Since we can't guarantee that the null terminator will be a particular
  89  * length, we have to check against the codepage. If there's a problem
  90  * determining it, assume a single-byte NULL terminator.
  91  */
  92 static inline int
  93 nls_nullsize(const struct nls_table *codepage)
  94 {
  95         int charlen;
  96         char tmp[NLS_MAX_CHARSET_SIZE];
  97
  98         charlen = codepage->uni2char(0, tmp, NLS_MAX_CHARSET_SIZE);
  99
 100         return charlen > 0 ? charlen : 1;
 101 }
 102
 103 #define MODULE_ALIAS_NLS(name)  MODULE_ALIAS("nls_" __stringify(name))
 104
 105 #endif /* _LINUX_NLS_H */
 106