elinks/src/intl/charsets.h

#ifndef EL__INTL_CHARSETS_H
#define EL__INTL_CHARSETS_H

typedef uint32_t unicode_val_T;

/* U+FFFD REPLACEMENT CHARACTER.  Used when no Unicode mapping is
 * known for a byte in a codepage, or when invalid UTF-8 is received
 * from a terminal.  After generating the character, ELinks then
 * treats it like any other Unicode character.  The user can also type
 * this character directly, and it can occur in documents.  */
#define UCS_REPLACEMENT_CHARACTER ((unicode_val_T) 0xFFFD)

/* A special value that fits in unicode_val_T but is outside the range
 * of Unicode characters.  utf8_to_unicode and cp_to_unicode return
 * this if the input is too short.  This is also used as a placeholder
 * for the second cell of a double-cell character.  */
#define UCS_NO_CHAR ((unicode_val_T) 0xFFFFFFFD)

/*   replacement character. See u2cp(). */
#define NBSP_CHAR ((unsigned char) 1)
#define NBSP_CHAR_STRING "\001"

struct conv_table {
	int t;
	union {
		unsigned char *str;
		struct conv_table *tbl;
	} u;
};

enum convert_string_mode {
	CSM_DEFAULT, /* Convert any char. */
	CSM_QUERY, /* Special handling of '&' and '=' chars. */
	CSM_FORM, /* Special handling of '&' and '=' chars in forms. */
	CSM_NONE, /* Convert nothing. */
};

struct conv_table *get_translation_table(int, int);
unsigned char *get_entity_string(const unsigned char *str, const int strlen, int encoding);

/* The convert_string() name is also used by Samba (version 3.0.3), which
 * provides libnss_wins.so.2, which is called somewhere inside
 * _nss_wins_gethostbyname_r(). This name clash causes the elinks hostname
 * lookup thread to crash so we need to rename the symbol. */
/* Reported by Derek Poon and filed as bug 453 */
#undef convert_string
#define convert_string convert_string_elinks

/* This routine converts a string from one charset to another according to the
 * passed @convert_table, potentially also decoding SGML (HTML) entities along
 * the way (according to @mode). It either returns dynamically allocated
 * converted string of length @length, or if the @callback is non-NULL it calls
 * it each few bytes instead and always returns NULL (@length is undefined).
 * Note that it's ok not to care and pass NULL as @length. */
unsigned char *convert_string(struct conv_table *convert_table,
			      unsigned char *chars, int charslen, int cp,
			      enum convert_string_mode mode, int *length,
			      void (*callback)(void *data, unsigned char *buf, int buflen),
			      void *callback_data);

int get_cp_index(unsigned char *);
unsigned char *get_cp_name(int);
unsigned char *get_cp_mime_name(int);
int is_cp_utf8(int);
void free_conv_table(void);
#ifdef CONFIG_UTF8
inline unsigned char *encode_utf8(unicode_val_T);
inline unsigned char *utf8_prevchar(unsigned char *, int, unsigned char *);
inline int utf8charlen(const unsigned char *);
int utf8_char2cells(unsigned char *, unsigned char *);
int utf8_ptr2cells(unsigned char *, unsigned char *);
int utf8_ptr2chars(unsigned char *, unsigned char *);
int utf8_cells2bytes(unsigned char *, int, unsigned char *);
/* How utf8_step_forward and utf8_step_backward count steps.  */
enum utf8_step {
	/* Each step is one character, even if it is a combining or
	 * double-width character.  */
	utf8_step_characters,

	/* Each step is one cell.  If the specified number of steps
	 * would end in the middle of a double-width character, do not
	 * include the character.  */
	utf8_step_cells_fewer,

	/* Each step is one cell.  If the specified number of steps
	 * would end in the middle of a double-width character,
	 * include the whole character.  */
	utf8_step_cells_more
};
unsigned char *utf8_step_forward(unsigned char *, unsigned char *,
				 int, enum utf8_step, int *);
unsigned char *utf8_step_backward(unsigned char *, unsigned char *,
				  int, enum utf8_step, int *);
inline int unicode_to_cell(unicode_val_T);
unicode_val_T unicode_fold_label_case(unicode_val_T);
inline int strlen_utf8(unsigned char **);
inline unicode_val_T utf8_to_unicode(unsigned char **, unsigned char *);
unicode_val_T cp_to_unicode(int, unsigned char **, unsigned char *);
#endif /* CONFIG_UTF8 */

unicode_val_T cp2u(int, unsigned char);
unsigned char *cp2utf8(int, int);

unsigned char *u2cp_(unicode_val_T, int, int no_nbsp_hack);
#define u2cp(u, to) u2cp_(u, to, 0)
#define u2cp_no_nbsp(u, to) u2cp_(u, to, 1)

void init_charsets_lookup(void);
void free_charsets_lookup(void);

/* UTF-16 encodes each Unicode character U+0000...U+FFFF as a single
 * 16-bit code unit, and each character U+10000...U+10FFFF as a pair
 * of two code units: a high surrogate followed by a low surrogate.
 * The range U+D800...U+DFFF is reserved for these surrogates.  */
#define is_utf16_surrogate(u)           (((u) & 0xFFFFF800) == 0xD800)
#define is_utf16_high_surrogate(u)      (((u) & 0xFFFFFC00) == 0xD800)
#define is_utf16_low_surrogate(u)       (((u) & 0xFFFFFC00) == 0xDC00)
#define join_utf16_surrogates(high,low) (0x10000 + (((high) - 0xD800L) << 10) + ((low) - 0xDC00))
#define needs_utf16_surrogates(u)       ((uint32_t) ((u) - 0x10000) < 0x100000)
#define get_utf16_high_surrogate(u)     (0xD800 + (((u) - 0x10000) >> 10))
#define get_utf16_low_surrogate(u)      (0xDC00 + ((u) & 0x3FF))

#endif