xref: /freebsd/lib/libc/arm/gen/flt_rounds.c (revision 57718be8fa0bd5edc11ab9a72e68cc71982939a6)
1 /*-
2  * Copyright (c) 2012 Ian Lepore <freebsd@damnhippie.dyndns.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 <fenv.h>
31 #include <float.h>
32 
33 #ifndef __ARM_PCS_VFP
34 #include "softfloat-for-gcc.h"
35 #include "milieu.h"
36 #include "softfloat.h"
37 #endif
38 
39 int
40 __flt_rounds(void)
41 {
42 	int mode;
43 
44 #ifndef __ARM_PCS_VFP
45 	/*
46 	 * Translate our rounding modes to the unnamed
47 	 * manifest constants required by C99 et. al.
48 	 */
49 	mode = __softfloat_float_rounding_mode;
50 #else /* __ARM_PCS_VFP */
51 	/*
52 	 * Read the floating-point status and control register
53 	 */
54 	__asm __volatile("vmrs %0, fpscr" : "=&r"(mode));
55 	mode &= _ROUND_MASK;
56 #endif /* __ARM_PCS_VFP */
57 
58 	switch (mode) {
59 	case FE_TOWARDZERO:
60 		return (0);
61 	case FE_TONEAREST:
62 		return (1);
63 	case FE_UPWARD:
64 		return (2);
65 	case FE_DOWNWARD:
66 		return (3);
67 	}
68 	return (-1);
69 }
70