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/*
* big5enc.c - multibyte encoding of Big5
*/
#ifndef ENUM_CHARSETS
#include "charset.h"
#include "internal.h"
/*
* Big5 has no associated data, so `charset' may be ignored.
*/
static void read_big5(charset_spec const *charset, long int input_chr,
charset_state *state,
void (*emit)(void *ctx, long int output), void *emitctx)
{
UNUSEDARG(charset);
/*
* For reading Big5, state->s0 simply contains the single
* stored lead byte when we are half way through a double-byte
* character, or 0 if we aren't.
*/
if (state->s0 == 0) {
if (input_chr >= 0xA1 && input_chr <= 0xFE) {
/*
* Lead byte. Just store it.
*/
state->s0 = input_chr;
} else {
/*
* Anything else we pass straight through unchanged.
*/
emit(emitctx, input_chr);
}
} else {
/*
* We have a stored lead byte. We expect a valid followup
* byte.
*/
if ((input_chr >= 0x40 && input_chr <= 0x7E) ||
(input_chr >= 0xA1 && input_chr <= 0xFE)) {
emit(emitctx, big5_to_unicode(state->s0 - 0xA1, input_chr - 0x40));
} else {
emit(emitctx, ERROR);
}
state->s0 = 0;
}
}
/*
* Big5 is a stateless multi-byte encoding (in the sense that just
* after any character has been completed, the state is always the
* same); hence when writing it, there is no need to use the
* charset_state.
*/
static int write_big5(charset_spec const *charset, long int input_chr,
charset_state *state,
void (*emit)(void *ctx, long int output), void *emitctx)
{
UNUSEDARG(charset);
UNUSEDARG(state);
if (input_chr == -1)
return TRUE; /* stateless; no cleanup required */
if (input_chr < 0x80) {
emit(emitctx, input_chr);
return TRUE;
} else {
int r, c;
if (unicode_to_big5(input_chr, &r, &c)) {
emit(emitctx, r + 0xA1);
emit(emitctx, c + 0x40);
return TRUE;
} else {
return FALSE;
}
}
}
const charset_spec charset_CS_BIG5 = {
CS_BIG5, read_big5, write_big5, NULL
};
#else /* ENUM_CHARSETS */
ENUM_CHARSET(CS_BIG5)
#endif /* ENUM_CHARSETS */
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