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5fbef188 RM |
1 | /* FPU control word bits. i387 version. |
2 | Copyright (C) 1993, 1995, 1996 Free Software Foundation, Inc. | |
d2f5be2a UD |
3 | This file is part of the GNU C Library. |
4 | Contributed by Olaf Flebbe. | |
5 | ||
6 | The GNU C Library is free software; you can redistribute it and/or | |
7 | modify it under the terms of the GNU Library General Public License as | |
8 | published by the Free Software Foundation; either version 2 of the | |
9 | License, or (at your option) any later version. | |
10 | ||
11 | The GNU C Library is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | Library General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Library General Public | |
17 | License along with the GNU C Library; see the file COPYING.LIB. If | |
18 | not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
19 | Boston, MA 02111-1307, USA. */ | |
20 | ||
21 | #ifndef _FPU_CONTROL_H | |
a5113b14 | 22 | #define _FPU_CONTROL_H 1 |
d2f5be2a UD |
23 | |
24 | /* Here is the dirty part. Settup up your 387 through the control word | |
42d2676e | 25 | * (cw) register. |
d2f5be2a UD |
26 | * |
27 | * 15-13 12 11-10 9-8 7-6 5 4 3 2 1 0 | |
28 | * | reserved | IC | RC | PC | reserved | PM | UM | OM | ZM | DM | IM | |
29 | * | |
30 | * IM: Invalid operation mask | |
31 | * DM: Denormalized operand mask | |
32 | * ZM: Zero-divide mask | |
33 | * OM: Overflow mask | |
34 | * UM: Underflow mask | |
35 | * PM: Precision (inexact result) mask | |
42d2676e | 36 | * |
d2f5be2a UD |
37 | * Mask bit is 1 means no interrupt. |
38 | * | |
39 | * PC: Precision control | |
40 | * 11 - round to extended precision | |
41 | * 10 - round to double precision | |
42 | * 00 - round to single precision | |
43 | * | |
44 | * RC: Rounding control | |
45 | * 00 - rounding to nearest | |
46 | * 01 - rounding down (toward - infinity) | |
47 | * 10 - rounding up (toward + infinity) | |
48 | * 11 - rounding toward zero | |
49 | * | |
50 | * IC: Infinity control | |
51 | * That is for 8087 and 80287 only. | |
52 | * | |
53 | * The hardware default is 0x037f. I choose 0x1372. | |
54 | */ | |
55 | ||
56 | #include <features.h> | |
57 | ||
58 | /* masking of interrupts */ | |
42d2676e | 59 | #define _FPU_MASK_IM 0x01 |
d2f5be2a UD |
60 | #define _FPU_MASK_DM 0x02 |
61 | #define _FPU_MASK_ZM 0x04 | |
62 | #define _FPU_MASK_OM 0x08 | |
63 | #define _FPU_MASK_UM 0x10 | |
64 | #define _FPU_MASK_PM 0x20 | |
65 | ||
66 | /* precision control */ | |
dd0e4e0c RM |
67 | #define _FPU_EXTENDED 0x300 |
68 | #define _FPU_DOUBLE 0x200 /* fdlibm requires double precision */ | |
d2f5be2a UD |
69 | #define _FPU_SINGLE 0x0 /* DO NOT USE */ |
70 | ||
71 | /* rounding control */ | |
72 | #define _FPU_RC_NEAREST 0x0 /* RECOMMENDED */ | |
73 | #define _FPU_RC_DOWN 0x400 | |
74 | #define _FPU_RC_UP 0x800 | |
75 | #define _FPU_RC_ZERO 0xC00 | |
76 | ||
77 | #define _FPU_RESERVED 0xF0C0 /* Reserved bits in cw */ | |
78 | ||
79 | ||
dd0e4e0c RM |
80 | /* The fdlibm code requires strict IEEE double precision arithmetic, |
81 | and no interrupts for exceptions, rounding to nearest. */ | |
d2f5be2a | 82 | |
a5113b14 | 83 | #define _FPU_DEFAULT 0x137f |
d2f5be2a UD |
84 | |
85 | /* IEEE: same as above, but exceptions */ | |
a5113b14 | 86 | #define _FPU_IEEE 0x137f |
d2f5be2a | 87 | |
2a072de4 RM |
88 | /* Type of the control word. */ |
89 | typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__HI__))); | |
90 | ||
91 | /* Macros for accessing the hardware control word. */ | |
dcf0671d UD |
92 | #define _FPU_GETCW(cw) __asm__ ("fnstcw %0" : "=m" (*&cw)) |
93 | #define _FPU_SETCW(cw) __asm__ ("fldcw %0" : : "m" (*&cw)) | |
2a072de4 RM |
94 | |
95 | /* Default control word set at startup. */ | |
96 | extern fpu_control_t __fpu_control; | |
d2f5be2a UD |
97 | |
98 | __BEGIN_DECLS | |
99 | ||
2a072de4 RM |
100 | /* Called at startup. It can be used to manipulate fpu control register. */ |
101 | extern void __setfpucw __P ((fpu_control_t)); | |
d2f5be2a UD |
102 | |
103 | __END_DECLS | |
104 | ||
105 | #endif /* fpu_control.h */ |