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1/* FPU control word bits. Alpha-mapped-to-Intel version.
2 Copyright (C) 1996-2019 Free Software Foundation, Inc.
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 Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the 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 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library. If not, see
18 <http://www.gnu.org/licenses/>. */
19
20#ifndef _ALPHA_FPU_CONTROL_H
21#define _ALPHA_FPU_CONTROL_H
22
23/*
24 * Since many programs seem to hardcode the values passed to __setfpucw()
25 * (rather than using the manifest constants) we emulate the x87 interface
26 * here (at least where this makes sense).
27 *
28 * 15-13 12 11-10 9-8 7-6 5 4 3 2 1 0
29 * | reserved | IC | RC | PC | reserved | PM | UM | OM | ZM | DM | IM
30 *
31 * IM: Invalid operation mask
32 * DM: Denormalized operand mask
33 * ZM: Zero-divide mask
34 * OM: Overflow mask
35 * UM: Underflow mask
36 * PM: Precision (inexact result) mask
37 *
38 * Mask bit is 1 means no interrupt.
39 *
40 * PC: Precision control
41 * 11 - round to extended precision
42 * 10 - round to double precision
43 * 00 - round to single precision
44 *
45 * RC: Rounding control
46 * 00 - rounding to nearest
47 * 01 - rounding down (toward - infinity)
48 * 10 - rounding up (toward + infinity)
49 * 11 - rounding toward zero
50 *
51 * IC: Infinity control
52 * That is for 8087 and 80287 only.
53 *
54 * The hardware default is 0x037f. I choose 0x1372.
55 */
56
57#include <features.h>
58
59/* masking of interrupts */
60#define _FPU_MASK_IM 0x01
61#define _FPU_MASK_DM 0x02
62#define _FPU_MASK_ZM 0x04
63#define _FPU_MASK_OM 0x08
64#define _FPU_MASK_UM 0x10
65#define _FPU_MASK_PM 0x20
66
67/* precision control -- without effect on Alpha */
68#define _FPU_EXTENDED 0x300 /* RECOMMENDED */
69#define _FPU_DOUBLE 0x200
70#define _FPU_SINGLE 0x0 /* DO NOT USE */
71
72/*
73 * rounding control---notice that on the Alpha this affects only
74 * instructions with the dynamic rounding mode qualifier (/d).
75 */
76#define _FPU_RC_NEAREST 0x000 /* RECOMMENDED */
77#define _FPU_RC_DOWN 0x400
78#define _FPU_RC_UP 0x800
79#define _FPU_RC_ZERO 0xC00
80
81#define _FPU_RESERVED 0xF0C0 /* Reserved bits in cw */
82
83
84/* Now two recommended cw */
85
86/* Linux default:
87 - extended precision
88 - rounding to positive infinity. There is no /p instruction
89 qualifier. By setting the dynamic rounding mode to +infinity,
90 one can use /d to get round to +infinity with no extra overhead
91 (so long as the default isn't changed, of course...)
92 - no exceptions enabled. */
93
94#define _FPU_DEFAULT 0x137f
95
96/* IEEE: same as above. */
97#define _FPU_IEEE 0x137f
98
99/* Type of the control word. */
100typedef unsigned int fpu_control_t;
101
102/* Default control word set at startup. */
103extern fpu_control_t __fpu_control;
104
105#endif /* _ALPHA_FPU_CONTROL */
106

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