xref: /illumos-gate/usr/src/lib/libc/i386/fp/fpsetround.c (revision 1da57d55)
17c478bd9Sstevel@tonic-gate /*
27c478bd9Sstevel@tonic-gate  * CDDL HEADER START
37c478bd9Sstevel@tonic-gate  *
47c478bd9Sstevel@tonic-gate  * The contents of this file are subject to the terms of the
5*7257d1b4Sraf  * Common Development and Distribution License (the "License").
6*7257d1b4Sraf  * You may not use this file except in compliance with the License.
77c478bd9Sstevel@tonic-gate  *
87c478bd9Sstevel@tonic-gate  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
97c478bd9Sstevel@tonic-gate  * or http://www.opensolaris.org/os/licensing.
107c478bd9Sstevel@tonic-gate  * See the License for the specific language governing permissions
117c478bd9Sstevel@tonic-gate  * and limitations under the License.
127c478bd9Sstevel@tonic-gate  *
137c478bd9Sstevel@tonic-gate  * When distributing Covered Code, include this CDDL HEADER in each
147c478bd9Sstevel@tonic-gate  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
157c478bd9Sstevel@tonic-gate  * If applicable, add the following below this CDDL HEADER, with the
167c478bd9Sstevel@tonic-gate  * fields enclosed by brackets "[]" replaced with your own identifying
177c478bd9Sstevel@tonic-gate  * information: Portions Copyright [yyyy] [name of copyright owner]
187c478bd9Sstevel@tonic-gate  *
197c478bd9Sstevel@tonic-gate  * CDDL HEADER END
207c478bd9Sstevel@tonic-gate  */
217c478bd9Sstevel@tonic-gate 
227c478bd9Sstevel@tonic-gate /*
23*7257d1b4Sraf  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
247c478bd9Sstevel@tonic-gate  * Use is subject to license terms.
257c478bd9Sstevel@tonic-gate  */
267c478bd9Sstevel@tonic-gate 
27*7257d1b4Sraf /*	Copyright (c) 1990, 1991 UNIX System Laboratories, Inc.	*/
28*7257d1b4Sraf /*	Copyright (c) 1988 AT&T	*/
29*7257d1b4Sraf /*	  All Rights Reserved  	*/
30*7257d1b4Sraf 
31*7257d1b4Sraf #pragma weak _fpsetround = fpsetround
327c478bd9Sstevel@tonic-gate 
33*7257d1b4Sraf #include "lint.h"
347c478bd9Sstevel@tonic-gate #include <ieeefp.h>
357c478bd9Sstevel@tonic-gate #include "fp.h"
367c478bd9Sstevel@tonic-gate 
377c478bd9Sstevel@tonic-gate extern int	_sse_hw;
387c478bd9Sstevel@tonic-gate extern void	_getmxcsr(int *), _putmxcsr(int);
397c478bd9Sstevel@tonic-gate 
407c478bd9Sstevel@tonic-gate fp_rnd
fpsetround(fp_rnd newrnd)417c478bd9Sstevel@tonic-gate fpsetround(fp_rnd newrnd)
427c478bd9Sstevel@tonic-gate {
437c478bd9Sstevel@tonic-gate 	struct _cw87 cw;
447c478bd9Sstevel@tonic-gate 	fp_rnd oldrnd;
457c478bd9Sstevel@tonic-gate 	int	mxcsr;
467c478bd9Sstevel@tonic-gate 	extern int __flt_rounds;  /* ANSI value for rounding */
477c478bd9Sstevel@tonic-gate 
487c478bd9Sstevel@tonic-gate 	newrnd &= 0x3;	/* mask off all ubt last 2 bits */
497c478bd9Sstevel@tonic-gate 	switch (newrnd) {	/* set ANSI rounding mode */
507c478bd9Sstevel@tonic-gate 	case FP_RN:	__flt_rounds = 1;
517c478bd9Sstevel@tonic-gate 			break;
527c478bd9Sstevel@tonic-gate 	case FP_RM:	__flt_rounds = 3;
537c478bd9Sstevel@tonic-gate 			break;
547c478bd9Sstevel@tonic-gate 	case FP_RP:	__flt_rounds = 2;
557c478bd9Sstevel@tonic-gate 			break;
567c478bd9Sstevel@tonic-gate 	case FP_RZ:	__flt_rounds = 0;
577c478bd9Sstevel@tonic-gate 			break;
587c478bd9Sstevel@tonic-gate 	};
597c478bd9Sstevel@tonic-gate 	_getcw(&cw);
607c478bd9Sstevel@tonic-gate 	oldrnd = (fp_rnd)cw.rnd;
617c478bd9Sstevel@tonic-gate 	cw.rnd = newrnd;
627c478bd9Sstevel@tonic-gate 	_putcw(cw);
637c478bd9Sstevel@tonic-gate 	if (_sse_hw) {
647c478bd9Sstevel@tonic-gate 		_getmxcsr(&mxcsr);
657c478bd9Sstevel@tonic-gate 		mxcsr = (mxcsr & ~0x6000) | ((int)newrnd << 13);
667c478bd9Sstevel@tonic-gate 		_putmxcsr(mxcsr);
677c478bd9Sstevel@tonic-gate 	}
687c478bd9Sstevel@tonic-gate 	return (oldrnd);
697c478bd9Sstevel@tonic-gate }
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