linux/include/linux/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  11 * wchar_t values is now outdated.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 */
  18typedef u16 wchar_t;
  19#define MAX_WCHAR_T     0xffff
  20
  21/* Arbitrary Unicode character */
  22typedef u32 unicode_t;
  23
  24struct 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 */
  40enum utf16_endian {
  41        UTF16_HOST_ENDIAN,
  42        UTF16_LITTLE_ENDIAN,
  43        UTF16_BIG_ENDIAN
  44};
  45
  46/* nls_base.c */
  47extern int register_nls(struct nls_table *);
  48extern int unregister_nls(struct nls_table *);
  49extern struct nls_table *load_nls(char *);
  50extern void unload_nls(struct nls_table *);
  51extern struct nls_table *load_nls_default(void);
  52
  53extern int utf8_to_utf32(const u8 *s, int len, unicode_t *pu);
  54extern int utf32_to_utf8(unicode_t u, u8 *s, int maxlen);
  55extern int utf8s_to_utf16s(const u8 *s, int len,
  56                enum utf16_endian endian, wchar_t *pwcs, int maxlen);
  57extern int utf16s_to_utf8s(const wchar_t *pwcs, int len,
  58                enum utf16_endian endian, u8 *s, int maxlen);
  59
  60static 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
  67static 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
  74static 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 */
  93static inline int
  94nls_nullsize(const struct nls_table *codepage)
  95{
  96        int charlen;
  97        char tmp[NLS_MAX_CHARSET_SIZE];
  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
 108
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