/* * internal.h - internal header stuff for the charset library. */#ifndef charset_internal_h#define charset_internal_h/* This invariably comes in handy */#define lenof(x) ( sizeof((x)) / sizeof(*(x)) )/* This is an invalid Unicode value used to indicate an error. */#define ERROR 0xFFFFL		       /* Unicode value representing error */typedef struct charset_spec charset_spec;typedef struct sbcs_data sbcs_data;struct charset_spec {    int charset;		       /* numeric identifier */    /*     * A function to read the character set and output Unicode     * characters. The `emit' function expects to get Unicode chars     * passed to it; it should be sent ERROR for any encoding error     * on the input.     */    void (*read)(charset_spec const *charset, long int input_chr,		 charset_state *state,		 void (*emit)(void *ctx, long int output), void *emitctx);    /*     * A function to read Unicode characters and output in this     * character set. The `emit' function expects to get byte     * values passed to it; it should be sent ERROR for any     * non-representable characters on the input.     */    void (*write)(charset_spec const *charset, long int input_chr,		  charset_state *state,		  void (*emit)(void *ctx, long int output), void *emitctx);    void const *data;};/* * This is the format of `data' used by the SBCS read and write * functions; so it's the format used in all SBCS definitions. */struct sbcs_data {    /*     * This is a simple mapping table converting each SBCS position     * to a Unicode code point. Some positions may contain ERROR,     * indicating that that byte value is not defined in the SBCS     * in question and its occurrence in input is an error.     */    unsigned long sbcs2ucs[256];    /*     * This lookup table is used to convert Unicode back to the     * SBCS. It consists of the valid byte values in the SBCS,     * sorted in order of their Unicode translation. So given a     * Unicode value U, you can do a binary search on this table     * using the above table as a lookup: when testing the Xth     * position in this table, you branch according to whether     * sbcs2ucs[ucs2sbcs[X]] is less than, greater than, or equal     * to U.     *      * Note that since there may be fewer than 256 valid byte     * values in a particular SBCS, we must supply the length of     * this table as well as the contents.     */    unsigned char ucs2sbcs[256];    int nvalid;};/* * Prototypes for internal library functions. */charset_spec const *charset_find_spec(int charset);void read_sbcs(charset_spec const *charset, long int input_chr,	       charset_state *state,	       void (*emit)(void *ctx, long int output), void *emitctx);void write_sbcs(charset_spec const *charset, long int input_chr,		charset_state *state,		void (*emit)(void *ctx, long int output), void *emitctx);/* * Placate compiler warning about unused parameters, of which we * expect to have some in this library. */#define UNUSEDARG(x) ( (x) = (x) )#endif /* charset_internal_h */