1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
|
/* 68k FPU control word definitions.
Copyright (C) 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#ifndef _FPU_CONTROL_H
#define _FPU_CONTROL_H
/*
* Motorola floating point control register bits.
*
* 31-16 -> reserved (read as 0, ignored on write)
* 15 -> enable trap for BSUN exception
* 14 -> enable trap for SNAN exception
* 13 -> enable trap for OPERR exception
* 12 -> enable trap for OVFL exception
* 11 -> enable trap for UNFL exception
* 10 -> enable trap for DZ exception
* 9 -> enable trap for INEX2 exception
* 8 -> enable trap for INEX1 exception
* 7-6 -> Precision Control
* 5-4 -> Rounding Control
* 3-0 -> zero (read as 0, write as 0)
*
*
* Precision Control:
* 00 - round to extended precision
* 01 - round to single precision
* 10 - round to double precision
* 11 - undefined
*
* Rounding Control:
* 00 - rounding to nearest (RN)
* 01 - rounding toward zero (RZ)
* 10 - rounding (down)toward minus infinity (RM)
* 11 - rounding (up) toward plus infinity (RP)
*
* The hardware default is 0x0000. I choose 0x5400.
*/
#include <features.h>
/* masking of interrupts */
#define _FPU_MASK_BSUN 0x8000
#define _FPU_MASK_SNAN 0x4000
#define _FPU_MASK_OPERR 0x2000
#define _FPU_MASK_OVFL 0x1000
#define _FPU_MASK_UNFL 0x0800
#define _FPU_MASK_DZ 0x0400
#define _FPU_MASK_INEX1 0x0200
#define _FPU_MASK_INEX2 0x0100
/* precision control */
#define _FPU_EXTENDED 0x00 /* RECOMMENDED */
#define _FPU_DOUBLE 0x80
#define _FPU_SINGLE 0x40 /* DO NOT USE */
/* rounding control */
#define _FPU_RC_NEAREST 0x00 /* RECOMMENDED */
#define _FPU_RC_ZERO 0x10
#define _FPU_RC_DOWN 0x20
#define _FPU_RC_UP 0x30
#define _FPU_RESERVED 0xFFFF000F /* Reserved bits in fpucr */
/* Now two recommended fpucr */
/* The fdlibm code requires no interrupts for exceptions. Don't
change the rounding mode, it would break long double I/O! */
#define _FPU_DEFAULT 0x00000000
/* IEEE: same as above, but exceptions. We must make it non-zero so
that __setfpucw works. This bit will be ignored. */
#define _FPU_IEEE 0x00000001
/* Type of the control word. */
typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__SI__)));
/* Macros for accessing the hardware control word. */
#define _FPU_GETCW(cw) __asm__ ("fmove%.l %!, %0" : "=dm" (cw))
#define _FPU_SETCW(cw) __asm__ volatile ("fmove%.l %0, %!" : : "dm" (cw))
/* Default control word set at startup. */
extern fpu_control_t __fpu_control;
__BEGIN_DECLS
/* Called at startup. It can be used to manipulate fpu control register. */
extern void __setfpucw __P ((fpu_control_t));
__END_DECLS
#endif /* _M68K_FPU_CONTROL_H */
|
