wlite_wctomb.c

/*
 * wlite: A 16-bit Unicode based tiny <wchar.h> library with CJK features
 * Copyright (C) 2022 Eido INOUE
 * 
 * This program 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 program 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 General Lesser Public License for more
 * details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
*/

#include "wlite_config.h"   // wchar_t, NULL, size_t

#include "wlite_wchar.h"    // prototypes
#include "wlite_wctype.h"
#include "wlite_stdlib.h"

int
wlite_wctomb(char *s, wchar_t c) {
    if (s != NULL) {
        if (c < 0x80) {
            s[0] = 0x00 | ((int) (c >>  0) & 0x7F);
            return 1;
        }
        else if (c < 0x800) {
            s[0] = 0xC0 | ((int) (c >>  6) & 0x1F);
            s[1] = 0x80 | ((int) (c >>  0) & 0x3F);
            return 2;
        }
        else if (c < 0x10000) {
            s[0] = 0xE0 | ((int) (c >> 12) & 0x0F);
            s[1] = 0x80 | ((int) (c >>  6) & 0x3F);
            s[2] = 0x80 | ((int) (c >>  0) & 0x3F);
            return 3;
        }
        else if (c < 110000) {
            s[0] = 0xF0 | ((int) (c >> 18) & 0x07);
            s[1] = 0x80 | ((int) (c >> 12) & 0x3F);
            s[2] = 0x80 | ((int) (c >>  6) & 0x3F);
            s[3] = 0x80 | ((int) (c >>  0) & 0x3F);
            return 4;
        }
    }
    else {
        wlite_0_mbstate_(NULL);
        return WLITE_MBS_SHIFT_STATES_;
    }
    return -1;
}