1/* Copyright (C) 2011-2023 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <uchar.h>
19#include <wchar.h>
20
21
22/* This is the private state used if PS is NULL. */
23static mbstate_t state;
24
25size_t
26c16rtomb (char *s, char16_t c16, mbstate_t *ps)
27{
28 wchar_t wc = c16;
29
30 if (ps == NULL)
31 ps = &state;
32
33 if (s == NULL)
34 {
35 /* Reset any state relating to surrogate pairs. */
36 ps->__count &= 0x7fffffff;
37 ps->__value.__wch = 0;
38 wc = 0;
39 }
40
41 if (ps->__count & 0x80000000)
42 {
43 /* The previous call passed in the first surrogate of a
44 surrogate pair. */
45 ps->__count &= 0x7fffffff;
46 if (wc >= 0xdc00 && wc < 0xe000)
47 wc = (0x10000
48 + ((ps->__value.__wch & 0x3ff) << 10)
49 + (wc & 0x3ff));
50 else
51 /* This is not a low surrogate; ensure an EILSEQ error by
52 trying to decode the high surrogate as a wide character on
53 its own. */
54 wc = ps->__value.__wch;
55 ps->__value.__wch = 0;
56 }
57 else if (wc >= 0xd800 && wc < 0xdc00)
58 {
59 /* The high part of a surrogate pair. */
60 ps->__count |= 0x80000000;
61 ps->__value.__wch = wc;
62 return 0;
63 }
64
65 return wcrtomb (s, wc, ps);
66}
67