OVMS3/OVMS.V3/components/duktape/examples/codepage-conv/duk_codepage_conv.c

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/*
* Convert an 8-bit input string (e.g. ISO-8859-1) into CESU-8.
* Calling code supplies the "code page" as a 256-entry array of
* codepoints for the conversion.
*
* This is useful when input data is in non-UTF-8 format and must
* be converted at runtime, e.g. when compiling non-UTF-8 source
* code. Another alternative is to use e.g. iconv.
*/
#include "duktape.h"
/* Decode an 8-bit string using 'codepage' into Unicode codepoints and
* re-encode into CESU-8. Codepage argument must point to a 256-entry
* table. Only supports BMP (codepoints U+0000 to U+FFFF).
*/
void duk_decode_string_codepage(duk_context *ctx, const char *str, size_t len, unsigned int *codepage) {
unsigned char *tmp;
size_t tmplen, i;
unsigned char *p;
unsigned int cp;
tmplen = 3 * len; /* max expansion is 1 input byte -> 3 output bytes */
if (tmplen / 3 != len) {
/* Temporary buffer length wraps. */
(void) duk_error(ctx, DUK_ERR_RANGE_ERROR, "input string too long");
return;
}
tmp = (unsigned char *) duk_push_fixed_buffer(ctx, tmplen);
for (i = 0, p = tmp; i < len; i++) {
cp = codepage[((unsigned char *) str)[i]] & 0xffffUL;
if (cp < 0x80UL) {
*p++ = (unsigned char) cp;
} else if (cp < 0x800UL) {
*p++ = (unsigned char) (0xc0 + ((cp >> 6) & 0x1f));
*p++ = (unsigned char) (0x80 + (cp & 0x3f));
} else {
/* In CESU-8 all codepoints in [0x0000,0xFFFF] are
* allowed, including surrogates.
*/
*p++ = (unsigned char) (0xe0 + ((cp >> 12) & 0x0f));
*p++ = (unsigned char) (0x80 + ((cp >> 6) & 0x3f));
*p++ = (unsigned char) (0x80 + (cp & 0x3f));
}
}
duk_push_lstring(ctx, (const char *) tmp, (duk_size_t) (p - tmp));
/* [ ... tmp res ] */
duk_remove(ctx, -2);
}