1/* Copyright (C) 2011-2021 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <uchar.h>
20#include <wchar.h>
21
22
23/* This is the private state used if PS is NULL. */
24static mbstate_t state;
25
26size_t
27c16rtomb (char *s, char16_t c16, mbstate_t *ps)
28{
29 wchar_t wc = c16;
30
31 if (ps == NULL)
32 ps = &state;
33
34 if (s == NULL)
35 {
36 /* Reset any state relating to surrogate pairs. */
37 ps->__count &= 0x7fffffff;
38 ps->__value.__wch = 0;
39 wc = 0;
40 }
41
42 if (ps->__count & 0x80000000)
43 {
44 /* The previous call passed in the first surrogate of a
45 surrogate pair. */
46 ps->__count &= 0x7fffffff;
47 if (wc >= 0xdc00 && wc < 0xe000)
48 wc = (0x10000
49 + ((ps->__value.__wch & 0x3ff) << 10)
50 + (wc & 0x3ff));
51 else
52 /* This is not a low surrogate; ensure an EILSEQ error by
53 trying to decode the high surrogate as a wide character on
54 its own. */
55 wc = ps->__value.__wch;
56 ps->__value.__wch = 0;
57 }
58 else if (wc >= 0xd800 && wc < 0xdc00)
59 {
60 /* The high part of a surrogate pair. */
61 ps->__count |= 0x80000000;
62 ps->__value.__wch = wc;
63 return 0;
64 }
65
66 return wcrtomb (s, wc, ps);
67}
68