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[glibc.git] / sysdeps / m68k / fpu_control.h
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1 /* 68k FPU control word definitions.
2 Copyright (C) 1996 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Library General Public License as
7 published by the Free Software Foundation; either version 2 of the
8 License, or (at your option) any later version.
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 Library General Public License for more details.
15 You should have received a copy of the GNU Library General Public
16 License along with the GNU C Library; see the file COPYING.LIB. If
17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
18 Cambridge, MA 02139, USA. */
20 #ifndef _FPU_CONTROL_H
21 #define _FPU_CONTROL_H
24 * Motorola floating point control register bits.
26 * 31-16 -> reserved (read as 0, ignored on write)
27 * 15 -> enable trap for BSUN exception
28 * 14 -> enable trap for SNAN exception
29 * 13 -> enable trap for OPERR exception
30 * 12 -> enable trap for OVFL exception
31 * 11 -> enable trap for UNFL exception
32 * 10 -> enable trap for DZ exception
33 * 9 -> enable trap for INEX2 exception
34 * 8 -> enable trap for INEX1 exception
35 * 7-6 -> Precision Control
36 * 5-4 -> Rounding Control
37 * 3-0 -> zero (read as 0, write as 0)
40 * Precision Control:
41 * 00 - round to extended precision
42 * 01 - round to single precision
43 * 10 - round to double precision
44 * 11 - undefined
46 * Rounding Control:
47 * 00 - rounding to nearest (RN)
48 * 01 - rounding toward zero (RZ)
49 * 10 - rounding (down)toward minus infinity (RM)
50 * 11 - rounding (up) toward plus infinity (RP)
52 * The hardware default is 0x0000. I choose 0x5400.
55 #include <features.h>
57 /* masking of interrupts */
58 #define _FPU_MASK_BSUN 0x8000
59 #define _FPU_MASK_SNAN 0x4000
60 #define _FPU_MASK_OPERR 0x2000
61 #define _FPU_MASK_OVFL 0x1000
62 #define _FPU_MASK_UNFL 0x0800
63 #define _FPU_MASK_DZ 0x0400
64 #define _FPU_MASK_INEX1 0x0200
65 #define _FPU_MASK_INEX2 0x0100
67 /* precision control */
68 #define _FPU_EXTENDED 0x00 /* RECOMMENDED */
69 #define _FPU_DOUBLE 0x80
70 #define _FPU_SINGLE 0x40 /* DO NOT USE */
72 /* rounding control */
73 #define _FPU_RC_NEAREST 0x00 /* RECOMMENDED */
74 #define _FPU_RC_ZERO 0x10
75 #define _FPU_RC_DOWN 0x20
76 #define _FPU_RC_UP 0x30
78 #define _FPU_RESERVED 0xFFFF000F /* Reserved bits in fpucr */
81 /* Now two recommended fpucr */
83 /* The fdlibm code requires no interrupts for exceptions. Don't
84 change the rounding mode, it would break long double I/O! */
85 #define _FPU_DEFAULT 0x00000000
87 /* IEEE: same as above, but exceptions. We must make it non-zero so
88 that __setfpucw works. This bit will be ignored. */
89 #define _FPU_IEEE 0x00000001
91 /* Type of the control word. */
92 typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__SI__)));
94 /* Macros for accessing the hardware control word. */
95 #define _FPU_GETCW(cw) __asm__ ("fmove%.l %!, %0" : "=dm" (cw))
96 #define _FPU_SETCW(cw) __asm__ volatile ("fmove%.l %0, %!" : : "dm" (cw))
98 /* Default control word set at startup. */
99 extern fpu_control_t __fpu_control;
101 __BEGIN_DECLS
103 /* Called at startup. It can be used to manipulate fpu control register. */
104 extern void __setfpucw __P ((fpu_control_t));
106 __END_DECLS
108 #endif /* _M68K_FPU_CONTROL_H */