xref: /freebsd/lib/libc/arm/gen/flt_rounds.c (revision 4543ef516683042d46f3bd3bb8a4f3f746e00499)
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 <fenv.h>
30 #include <float.h>
31 
32 #ifndef __ARM_PCS_VFP
33 #include "softfloat-for-gcc.h"
34 #include "milieu.h"
35 #include "softfloat.h"
36 #endif
37 
38 int
39 __flt_rounds(void)
40 {
41 	int mode;
42 
43 #ifndef __ARM_PCS_VFP
44 	/*
45 	 * Translate our rounding modes to the unnamed
46 	 * manifest constants required by C99 et. al.
47 	 */
48 	mode = __softfloat_float_rounding_mode;
49 #else /* __ARM_PCS_VFP */
50 	/*
51 	 * Read the floating-point status and control register
52 	 */
53 	__asm __volatile("vmrs %0, fpscr" : "=&r"(mode));
54 	mode &= _ROUND_MASK;
55 #endif /* __ARM_PCS_VFP */
56 
57 	switch (mode) {
58 	case FE_TOWARDZERO:
59 		return (0);
60 	case FE_TONEAREST:
61 		return (1);
62 	case FE_UPWARD:
63 		return (2);
64 	case FE_DOWNWARD:
65 		return (3);
66 	}
67 	return (-1);
68 }
69