/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2013 Ed Schouten <ed@FreeBSD.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <errno.h>
#include <uchar.h>
#include "mblocal.h"

typedef struct {
        char16_t        lead_surrogate;
        mbstate_t       c32_mbstate;
} _Char16State;

size_t
c16rtomb_l(char * __restrict s, char16_t c16, mbstate_t * __restrict ps,
    locale_t locale)
{
        _Char16State *cs;
        char32_t c32;

        FIX_LOCALE(locale);
        if (ps == NULL)
                ps = &(XLOCALE_CTYPE(locale)->c16rtomb);
        cs = (_Char16State *)ps;

        /* If s is a null pointer, the value of parameter c16 is ignored. */
        if (s == NULL) {
                c32 = 0;
        } else if (cs->lead_surrogate >= 0xd800 &&
            cs->lead_surrogate <= 0xdbff) {
                /* We should see a trail surrogate now. */
                if (c16 < 0xdc00 || c16 > 0xdfff) {
                        errno = EILSEQ;
                        return ((size_t)-1);
                }
                c32 = 0x10000 + ((cs->lead_surrogate & 0x3ff) << 10 |
                    (c16 & 0x3ff));
        } else if (c16 >= 0xd800 && c16 <= 0xdbff) {
                /* Store lead surrogate for next invocation. */
                cs->lead_surrogate = c16;
                return (0);
        } else {
                /* Regular character. */
                c32 = c16;
        }
        cs->lead_surrogate = 0;

        return (c32rtomb_l(s, c32, &cs->c32_mbstate, locale));
}

size_t
c16rtomb(char * __restrict s, char16_t c16, mbstate_t * __restrict ps)
{

        return (c16rtomb_l(s, c16, ps, __get_locale()));
}