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/*
* 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 */
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