1/*-
2 * SPDX-License-Identifier: BSD-4-Clause
3 *
4 * Copyright (c) 2003 Peter Wemm.
5 * Copyright (c) 1990 Andrew Moore, Talke Studio
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37#ifndef _X86_X86_IEEEFP_H_
38#define _X86_X86_IEEEFP_H_
39
40/* Deprecated historical FPU control interface */
41
42/*
43 * IEEE floating point type, constant and function definitions.
44 * XXX: {FP,SSE}*FLD and {FP,SSE}*OFF are undocumented pollution.
45 */
46
47/*
48 * Rounding modes.
49 */
50typedef enum {
51 FP_RN=0, /* round to nearest */
52 FP_RM, /* round down towards minus infinity */
53 FP_RP, /* round up towards plus infinity */
54 FP_RZ /* truncate */
55} fp_rnd_t;
56
57/*
58 * Precision (i.e., rounding precision) modes.
59 */
60typedef enum {
61 FP_PS=0, /* 24 bit (single-precision) */
62 FP_PRS, /* reserved */
63 FP_PD, /* 53 bit (double-precision) */
64 FP_PE /* 64 bit (extended-precision) */
65} fp_prec_t;
66
67#define fp_except_t int
68
69/*
70 * Exception bit masks.
71 */
72#define FP_X_INV 0x01 /* invalid operation */
73#define FP_X_DNML 0x02 /* denormal */
74#define FP_X_DZ 0x04 /* zero divide */
75#define FP_X_OFL 0x08 /* overflow */
76#define FP_X_UFL 0x10 /* underflow */
77#define FP_X_IMP 0x20 /* (im)precision */
78#define FP_X_STK 0x40 /* stack fault */
79
80/*
81 * FPU control word bit-field masks.
82 */
83#define FP_MSKS_FLD 0x3f /* exception masks field */
84#define FP_PRC_FLD 0x300 /* precision control field */
85#define FP_RND_FLD 0xc00 /* rounding control field */
86
87/*
88 * FPU status word bit-field masks.
89 */
90#define FP_STKY_FLD 0x3f /* sticky flags field */
91
92/*
93 * FPU control word bit-field offsets (shift counts).
94 */
95#define FP_MSKS_OFF 0 /* exception masks offset */
96#define FP_PRC_OFF 8 /* precision control offset */
97#define FP_RND_OFF 10 /* rounding control offset */
98
99/*
100 * FPU status word bit-field offsets (shift counts).
101 */
102#define FP_STKY_OFF 0 /* sticky flags offset */
103
104#define __fldcw(addr) __asm __volatile("fldcw %0" : : "m" (*(addr)))
105#define __fldenv(addr) __asm __volatile("fldenv %0" : : "m" (*(addr)))
106#define __fnclex() __asm __volatile("fnclex")
107#define __fnstcw(addr) __asm __volatile("fnstcw %0" : "=m" (*(addr)))
108#define __fnstenv(addr) __asm __volatile("fnstenv %0" : "=m" (*(addr)))
109#define __fnstsw(addr) __asm __volatile("fnstsw %0" : "=m" (*(addr)))
110#define __ldmxcsr(addr) __asm __volatile("ldmxcsr %0" : : "m" (*(addr)))
111#define __stmxcsr(addr) __asm __volatile("stmxcsr %0" : "=m" (*(addr)))
112
113/*
114 * Load the control word. Be careful not to trap if there is a currently
115 * unmasked exception (ones that will become freshly unmasked are not a
116 * problem). This case must be handled by a save/restore of the
117 * environment or even of the full x87 state. Accessing the environment
118 * is very inefficient, so only do it when necessary.
119 */
120static __inline void
121__fnldcw(unsigned short _cw, unsigned short _newcw)
122{
123 struct {
124 unsigned _cw;
125 unsigned _other[6];
126 } _env;
127 unsigned short _sw;
128
129 if ((_cw & FP_MSKS_FLD) != FP_MSKS_FLD) {
130 __fnstsw(&_sw);
131 if (((_sw & ~_cw) & FP_STKY_FLD) != 0) {
132 __fnstenv(&_env);
133 _env._cw = _newcw;
134 __fldenv(&_env);
135 return;
136 }
137 }
138 __fldcw(&_newcw);
139}
140
141#endif/* _X86_X86_IEEEFP_H_ */