1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22/*
23 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27/*
28 *	Copyright (c) 1990, 1991 UNIX System Laboratories, Inc.
29 *	Copyright (c) 1988 AT&T
30 *	  All Rights Reserved
31 */
32
33#pragma ident	"%Z%%M%	%I%	%E% SMI"
34
35/*
36 * Establish the default settings for the floating-point state for a C language
37 * program:
38 *	rounding mode		-- round to nearest default by OS,
39 *	exceptions enabled	-- all masked
40 *	sticky bits		-- all clear by default by OS.
41 *      precision control       -- double extended
42 * Set _fp_hw according to what floating-point hardware is available.
43 * Set _sse_hw according to what SSE hardware is available.
44 * Set __flt_rounds according to the rounding mode.
45 */
46
47#pragma weak _fpstart = __fpstart
48
49#include	"lint.h"
50#include	<sys/types.h>
51#include	<sys/sysi86.h>	/* for SI86FPHW/SI86FPSTART definitions */
52#include	<sys/fp.h>	/* for FPU_CW_INIT and SSE_MXCSR_INIT */
53
54extern int	__fltrounds();
55
56int	_fp_hw;			/* default: bss: 0 == no hardware */
57int	_sse_hw;		/* default: bss: 0 == no sse */
58int	__flt_rounds;		/* ANSI rounding mode */
59
60void
61__fpstart()
62{
63	/*
64	 * query OS for HW status and ensure the x87 and (optional)
65	 * SSE control words are (will be) set correctly.
66	 */
67	if ((_sse_hw = sysi86(SI86FPSTART,
68	    &_fp_hw, FPU_CW_INIT, SSE_MXCSR_INIT)) == -1) {
69		extern void _putcw();
70
71		/*
72		 * (fallback to old syscall on old kernels)
73		 */
74		_sse_hw = 0;
75		(void) sysi86(SI86FPHW, &_fp_hw);
76		_putcw(0x133f);
77	}
78
79	/*
80	 * At this point the x87 fp environment that has been (or more
81	 * hopefully, will be) established by the kernel is:
82	 *
83	 * affine infinity	0x1000
84	 * round to nearest	0x0000
85	 * 64-bit doubles	0x0300
86	 * precision, underflow, overflow, zero-divide, denorm, invalid masked
87	 *			0x003f
88	 *
89	 * which conforms to the 4th edition i386 ABI definition.
90	 *
91	 * Additionally, if we have SSE hardware, we've also masked all
92	 * the same traps, and have round to nearest.
93	 */
94
95	__flt_rounds = 1;	/* ANSI way of saying round-to-nearest */
96}
97