master
1/* 68k FPU control word definitions.
2 Copyright (C) 1996-2025 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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#ifndef _FPU_CONTROL_H
20#define _FPU_CONTROL_H
21
22/*
23 * Motorola floating point control register bits.
24 *
25 * 31-16 -> reserved (read as 0, ignored on write)
26 * 15 -> enable trap for BSUN exception
27 * 14 -> enable trap for SNAN exception
28 * 13 -> enable trap for OPERR exception
29 * 12 -> enable trap for OVFL exception
30 * 11 -> enable trap for UNFL exception
31 * 10 -> enable trap for DZ exception
32 * 9 -> enable trap for INEX2 exception (INEX on Coldfire)
33 * 8 -> enable trap for INEX1 exception (IDE on Coldfire)
34 * 7-6 -> Precision Control (only bit 6 is used on Coldfire)
35 * 5-4 -> Rounding Control
36 * 3-0 -> zero (read as 0, write as 0)
37 *
38 *
39 * Precision Control:
40 * 00 - round to extended precision
41 * 01 - round to single precision
42 * 10 - round to double precision
43 * 11 - undefined
44 *
45 * Rounding Control:
46 * 00 - rounding to nearest (RN)
47 * 01 - rounding toward zero (RZ)
48 * 10 - rounding (down)toward minus infinity (RM)
49 * 11 - rounding (up) toward plus infinity (RP)
50 *
51 * The hardware default is 0x0000. I choose 0x5400.
52 */
53
54#include <features.h>
55
56#if defined (__mcoldfire__) && !defined (__mcffpu__)
57
58# define _FPU_RESERVED 0xffffffff
59# define _FPU_DEFAULT 0x00000000
60# define _FPU_GETCW(cw) ((cw) = 0)
61# define _FPU_SETCW(cw) ((void) (cw))
62
63#else
64
65/* masking of interrupts */
66# define _FPU_MASK_BSUN 0x8000
67# define _FPU_MASK_SNAN 0x4000
68# define _FPU_MASK_OPERR 0x2000
69# define _FPU_MASK_OVFL 0x1000
70# define _FPU_MASK_UNFL 0x0800
71# define _FPU_MASK_DZ 0x0400
72# define _FPU_MASK_INEX1 0x0200
73# define _FPU_MASK_INEX2 0x0100
74
75/* precision control */
76# ifdef __mcoldfire__
77# define _FPU_DOUBLE 0x00
78# else
79# define _FPU_EXTENDED 0x00 /* RECOMMENDED */
80# define _FPU_DOUBLE 0x80
81# endif
82# define _FPU_SINGLE 0x40 /* DO NOT USE */
83
84/* rounding control */
85# define _FPU_RC_NEAREST 0x00 /* RECOMMENDED */
86# define _FPU_RC_ZERO 0x10
87# define _FPU_RC_DOWN 0x20
88# define _FPU_RC_UP 0x30
89
90# ifdef __mcoldfire__
91# define _FPU_RESERVED 0xFFFF800F
92# else
93# define _FPU_RESERVED 0xFFFF000F /* Reserved bits in fpucr */
94# endif
95
96
97/* Now two recommended fpucr */
98
99/* The fdlibm code requires no interrupts for exceptions. Don't
100 change the rounding mode, it would break long double I/O! */
101# define _FPU_DEFAULT 0x00000000
102
103/* IEEE: same as above, but exceptions. We must make it non-zero so
104 that __setfpucw works. This bit will be ignored. */
105# define _FPU_IEEE 0x00000001
106
107/* Macros for accessing the hardware control word. */
108# define _FPU_GETCW(cw) __asm__ ("fmove%.l %!, %0" : "=dm" (cw))
109# define _FPU_SETCW(cw) __asm__ volatile ("fmove%.l %0, %!" : : "dm" (cw))
110#endif
111
112/* Type of the control word. */
113typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__SI__)));
114
115/* Default control word set at startup. */
116extern fpu_control_t __fpu_control;
117
118#endif /* _M68K_FPU_CONTROL_H */