xref: /freebsd/lib/libc/arm/gen/flt_rounds.c (revision 911f0260390e18cf85f3dbf2c719b593efdc1e3c)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2012 Ian Lepore <freebsd@damnhippie.dyndns.org>
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31 
32 #include <fenv.h>
33 #include <float.h>
34 
35 #ifndef __ARM_PCS_VFP
36 #include "softfloat-for-gcc.h"
37 #include "milieu.h"
38 #include "softfloat.h"
39 #endif
40 
41 int
42 __flt_rounds(void)
43 {
44 	int mode;
45 
46 #ifndef __ARM_PCS_VFP
47 	/*
48 	 * Translate our rounding modes to the unnamed
49 	 * manifest constants required by C99 et. al.
50 	 */
51 	mode = __softfloat_float_rounding_mode;
52 #else /* __ARM_PCS_VFP */
53 	/*
54 	 * Read the floating-point status and control register
55 	 */
56 	__asm __volatile("vmrs %0, fpscr" : "=&r"(mode));
57 	mode &= _ROUND_MASK;
58 #endif /* __ARM_PCS_VFP */
59 
60 	switch (mode) {
61 	case FE_TOWARDZERO:
62 		return (0);
63 	case FE_TONEAREST:
64 		return (1);
65 	case FE_UPWARD:
66 		return (2);
67 	case FE_DOWNWARD:
68 		return (3);
69 	}
70 	return (-1);
71 }
72