xref: /freebsd/lib/libc/locale/mbrtoc16.c (revision 40a8ac8f62b535d30349faf28cf47106b7041b83)
1 /*-
2  * Copyright (c) 2013 Ed Schouten <ed@FreeBSD.org>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  */
26 
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29 
30 #include <uchar.h>
31 #include "xlocale_private.h"
32 
33 typedef struct {
34 	char16_t	trail_surrogate;
35 	mbstate_t	c32_mbstate;
36 } _Char16State;
37 
38 size_t
39 mbrtoc16_l(char16_t * __restrict pc16, const char * __restrict s, size_t n,
40     mbstate_t * __restrict ps, locale_t locale)
41 {
42 	_Char16State *cs;
43 	char32_t c32;
44 	ssize_t len;
45 
46 	FIX_LOCALE(locale);
47 	if (ps == NULL)
48 		ps = &locale->mbrtoc16;
49 	cs = (_Char16State *)ps;
50 
51 	/*
52 	 * Call straight into mbrtoc32_l() if we don't need to return a
53 	 * character value. According to the spec, if s is a null
54 	 * pointer, the value of parameter pc16 is also ignored.
55 	 */
56 	if (pc16 == NULL || s == NULL) {
57 		cs->trail_surrogate = 0;
58 		return (mbrtoc32_l(NULL, s, n, &cs->c32_mbstate, locale));
59 	}
60 
61 	/* Return the trail surrogate from the previous invocation. */
62 	if (cs->trail_surrogate >= 0xdc00 && cs->trail_surrogate <= 0xdfff) {
63 		*pc16 = cs->trail_surrogate;
64 		cs->trail_surrogate = 0;
65 		return ((size_t)-3);
66 	}
67 
68 	len = mbrtoc32_l(&c32, s, n, &cs->c32_mbstate, locale);
69 	if (len >= 0) {
70 		if (c32 < 0x10000) {
71 			/* Fits in one UTF-16 character. */
72 			*pc16 = c32;
73 		} else {
74 			/* Split up in a surrogate pair. */
75 			c32 -= 0x10000;
76 			*pc16 = 0xd800 | (c32 >> 10);
77 			cs->trail_surrogate = 0xdc00 | (c32 & 0x3ff);
78 		}
79 	}
80 	return (len);
81 }
82 
83 size_t
84 mbrtoc16(char16_t * __restrict pc16, const char * __restrict s, size_t n,
85     mbstate_t * __restrict ps)
86 {
87 
88 	return (mbrtoc16_l(pc16, s, n, ps, __get_locale()));
89 }
90