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fpsetround.c revision 1.4 
      1 /*	$NetBSD: fpsetround.c,v 1.4 2004/04/02 22:55:19 matt Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1999 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Dan Winship.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the NetBSD
     21  *	Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 #include <sys/cdefs.h>
     40 
     41 #include "namespace.h"
     42 
     43 #include <sys/types.h>
     44 #include <ieeefp.h>
     45 #include <powerpc/fpu.h>
     46 
     47 #ifdef __weak_alias
     48 __weak_alias(fpsetround,_fpsetround)
     49 #endif
     50 
     51 #define	ROUNDBITS	FPSCR_RN
     52 
     53 fp_rnd
     54 fpsetround(fp_rnd rnd_dir)
     55 {
     56 	u_int64_t fpscr;
     57 	fp_rnd old;
     58 
     59 	__asm__ __volatile("mffs %0" : "=f"(fpscr));
     60 	old = ((fp_rnd)fpscr & ROUNDBITS);
     61 	fpscr = (fpscr & ~ROUNDBITS) | (rnd_dir & ROUNDBITS);
     62 	__asm__ __volatile("mtfsf 0xff,%0" :: "f"(fpscr));
     63 	return (old);
     64 }
     65