xref: /onnv-gate/usr/src/lib/libc/i386/fp/fpsetround.c (revision 6812:febeba71273d)
10Sstevel@tonic-gate /*
20Sstevel@tonic-gate  * CDDL HEADER START
30Sstevel@tonic-gate  *
40Sstevel@tonic-gate  * The contents of this file are subject to the terms of the
5*6812Sraf  * Common Development and Distribution License (the "License").
6*6812Sraf  * You may not use this file except in compliance with the License.
70Sstevel@tonic-gate  *
80Sstevel@tonic-gate  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
90Sstevel@tonic-gate  * or http://www.opensolaris.org/os/licensing.
100Sstevel@tonic-gate  * See the License for the specific language governing permissions
110Sstevel@tonic-gate  * and limitations under the License.
120Sstevel@tonic-gate  *
130Sstevel@tonic-gate  * When distributing Covered Code, include this CDDL HEADER in each
140Sstevel@tonic-gate  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
150Sstevel@tonic-gate  * If applicable, add the following below this CDDL HEADER, with the
160Sstevel@tonic-gate  * fields enclosed by brackets "[]" replaced with your own identifying
170Sstevel@tonic-gate  * information: Portions Copyright [yyyy] [name of copyright owner]
180Sstevel@tonic-gate  *
190Sstevel@tonic-gate  * CDDL HEADER END
200Sstevel@tonic-gate  */
21*6812Sraf 
22*6812Sraf /*
23*6812Sraf  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24*6812Sraf  * Use is subject to license terms.
25*6812Sraf  */
26*6812Sraf 
270Sstevel@tonic-gate /*	Copyright (c) 1990, 1991 UNIX System Laboratories, Inc.	*/
280Sstevel@tonic-gate /*	Copyright (c) 1988 AT&T	*/
290Sstevel@tonic-gate /*	  All Rights Reserved  	*/
300Sstevel@tonic-gate 
310Sstevel@tonic-gate #pragma ident	"%Z%%M%	%I%	%E% SMI"
320Sstevel@tonic-gate 
33*6812Sraf #pragma weak _fpsetround = fpsetround
340Sstevel@tonic-gate 
35*6812Sraf #include "lint.h"
360Sstevel@tonic-gate #include <ieeefp.h>
370Sstevel@tonic-gate #include "fp.h"
380Sstevel@tonic-gate 
390Sstevel@tonic-gate extern int	_sse_hw;
400Sstevel@tonic-gate extern void	_getmxcsr(int *), _putmxcsr(int);
410Sstevel@tonic-gate 
420Sstevel@tonic-gate fp_rnd
fpsetround(fp_rnd newrnd)430Sstevel@tonic-gate fpsetround(fp_rnd newrnd)
440Sstevel@tonic-gate {
450Sstevel@tonic-gate 	struct _cw87 cw;
460Sstevel@tonic-gate 	fp_rnd oldrnd;
470Sstevel@tonic-gate 	int	mxcsr;
480Sstevel@tonic-gate 	extern int __flt_rounds;  /* ANSI value for rounding */
490Sstevel@tonic-gate 
500Sstevel@tonic-gate 	newrnd &= 0x3;	/* mask off all ubt last 2 bits */
510Sstevel@tonic-gate 	switch (newrnd) {	/* set ANSI rounding mode */
520Sstevel@tonic-gate 	case FP_RN:	__flt_rounds = 1;
530Sstevel@tonic-gate 			break;
540Sstevel@tonic-gate 	case FP_RM:	__flt_rounds = 3;
550Sstevel@tonic-gate 			break;
560Sstevel@tonic-gate 	case FP_RP:	__flt_rounds = 2;
570Sstevel@tonic-gate 			break;
580Sstevel@tonic-gate 	case FP_RZ:	__flt_rounds = 0;
590Sstevel@tonic-gate 			break;
600Sstevel@tonic-gate 	};
610Sstevel@tonic-gate 	_getcw(&cw);
620Sstevel@tonic-gate 	oldrnd = (fp_rnd)cw.rnd;
630Sstevel@tonic-gate 	cw.rnd = newrnd;
640Sstevel@tonic-gate 	_putcw(cw);
650Sstevel@tonic-gate 	if (_sse_hw) {
660Sstevel@tonic-gate 		_getmxcsr(&mxcsr);
670Sstevel@tonic-gate 		mxcsr = (mxcsr & ~0x6000) | ((int)newrnd << 13);
680Sstevel@tonic-gate 		_putmxcsr(mxcsr);
690Sstevel@tonic-gate 	}
700Sstevel@tonic-gate 	return (oldrnd);
710Sstevel@tonic-gate }
72