linux/include/linux/nls.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_NLS_H
#define _LINUX_NLS_H

#include <linux/init.h>

/* Unicode has changed over the years.  Unicode code points no longer
 * fit into 16 bits; as of Unicode 5 valid code points range from 0
 * to 0x10ffff (17 planes, where each plane holds 65536 code points).
 *
 * The original decision to represent Unicode characters as 16-bit
 * wchar_t values is now outdated.  But plane 0 still includes the
 * most commonly used characters, so we will retain it.  The newer
 * 32-bit unicode_t type can be used when it is necessary to
 * represent the full Unicode character set.
 */

/* Plane-0 Unicode character */
wchar_t;
#define MAX_WCHAR_T …

/* Arbitrary Unicode character */
unicode_t;

struct nls_table { … };

/* this value hold the maximum octet of charset */
#define NLS_MAX_CHARSET_SIZE …

/* Byte order for UTF-16 strings */
enum utf16_endian { … };

/* nls_base.c */
extern int __register_nls(struct nls_table *, struct module *);
extern int unregister_nls(struct nls_table *);
extern struct nls_table *load_nls(const char *charset);
extern void unload_nls(struct nls_table *);
extern struct nls_table *load_nls_default(void);
#define register_nls(nls) …

extern int utf8_to_utf32(const u8 *s, int len, unicode_t *pu);
extern int utf32_to_utf8(unicode_t u, u8 *s, int maxlen);
extern int utf8s_to_utf16s(const u8 *s, int len,
		enum utf16_endian endian, wchar_t *pwcs, int maxlen);
extern int utf16s_to_utf8s(const wchar_t *pwcs, int len,
		enum utf16_endian endian, u8 *s, int maxlen);

static inline unsigned char nls_tolower(struct nls_table *t, unsigned char c)
{ … }

static inline unsigned char nls_toupper(struct nls_table *t, unsigned char c)
{ … }

static inline int nls_strnicmp(struct nls_table *t, const unsigned char *s1,
		const unsigned char *s2, int len)
{ … }

/*
 * nls_nullsize - return length of null character for codepage
 * @codepage - codepage for which to return length of NULL terminator
 *
 * Since we can't guarantee that the null terminator will be a particular
 * length, we have to check against the codepage. If there's a problem
 * determining it, assume a single-byte NULL terminator.
 */
static inline int
nls_nullsize(const struct nls_table *codepage)
{ … }

#define MODULE_ALIAS_NLS(name) …

#endif /* _LINUX_NLS_H */