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path: root/arch/all/iconv/src/conv/utf8_to_wchar.c
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/* ****************************************************************************
 * conv/utf8_to_wchar.c -- UTF-8 to `wchar_t`.
 *
 * Copyright (C) 2017 Thomas "Cakeisalie5" Touhey <thomas@touhey.fr>
 *
 * This file is part of the 'all/iconv' module in libcarrot, an experimental
 * modular libc project.
 *
 * This file is free software: you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation, either version 3 of the License, or (at your option)
 * any later version.
 *
 * This file is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Lesser Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this file. If not, see <http://www.gnu.org/licenses/>.
 * ************************************************************************* */
#include "../iconv.h"
#define set_utf8_cookie(c_count, c_ini) { \
	count = (c_count); \
	val   = (c_ini); }

/**
 *	__iconv_utf8_to_wchar:
 *	Convert one UTF-8 sequence to a wchar_t.
 *
 *	@arg	step		the step data.
 *	@return				the error code (0 if ok).
 */

int __iconv_utf8_to_wchar(struct __iconv_step *step)
{
	int byte = *step->in;
	wchar_t *out; wchar_t val;
	int outleft;

	/* Initialize the output. */
	if (step->next) {
		/* Next step input buffer. */
		step->next->in = (void*)&val;
		step->next->inleft = sizeof(wchar_t);
		outleft = sizeof(wchar_t);
		out = &val;

		/* Next step output buffer. */
		step->next->out     = step->out;
		step->next->outleft = step->outleft;
	} else {
		out = (wchar_t*)step->out;
		outleft = step->outleft;
	}

	/* Check if too big. */
	if (outleft < (int)sizeof(wchar_t))
		return (I_E2BIG);

	/* Check if it's special. */
	if (byte & 0x80) {
		unsigned char *in = (void*)step->in;
		int count;

		if (~byte & 0x40) {
			/* error: not a starting byte! */
			return (I_EILSEQ);
		}

		/* Make the cookie. */
		if (~byte & 0x20)
			set_utf8_cookie(1, byte & 0x1F)
		else if (~byte & 0x10)
			set_utf8_cookie(2, byte & 0x0F)
		else if (~byte & 0x08)
			set_utf8_cookie(3, byte & 0x07)
		else if (~byte & 0x04)
			set_utf8_cookie(4, byte & 0x03)
		else if (~byte & 0x02)
			set_utf8_cookie(5, byte & 0x01)
		else {
			/* error: not a valid starting byte */
			return (I_EILSEQ);
		}

		/* Get the data. */
		if (step->inleft - 1 < count)
			return (I_EINVAL);

		step->in     += count;
		step->inleft -= count;
		while (--count) {
			int byte = *++in;
			if (~byte & 0x80 || byte & 0x40) {
				/* not a valid continuation byte! */
				return (I_EILSEQ);
			}

			val = (val << 6) | (byte & 0x3F);
		}
	} else val = byte;

	/* Put into the final thing. */
	*out = val;

	/* Call next step, end otherwise. */
	if (step->next)
		return ((*step->next_func)(step->next));
	return (0);
}