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flt_rounds.c revision 1.2 
      1  1.2  thorpej /*	$NetBSD: flt_rounds.c,v 1.2 1997/07/18 00:30:30 thorpej Exp $	*/
      2  1.1      cgd 
      3  1.1      cgd /*
      4  1.1      cgd  * Copyright (c) 1995 Christopher G. Demetriou
      5  1.1      cgd  * All rights reserved.
      6  1.1      cgd  *
      7  1.1      cgd  * Redistribution and use in source and binary forms, with or without
      8  1.1      cgd  * modification, are permitted provided that the following conditions
      9  1.1      cgd  * are met:
     10  1.1      cgd  * 1. Redistributions of source code must retain the above copyright
     11  1.1      cgd  *    notice, this list of conditions and the following disclaimer.
     12  1.1      cgd  * 2. Redistributions in binary form must reproduce the above copyright
     13  1.1      cgd  *    notice, this list of conditions and the following disclaimer in the
     14  1.1      cgd  *    documentation and/or other materials provided with the distribution.
     15  1.1      cgd  * 3. All advertising materials mentioning features or use of this software
     16  1.1      cgd  *    must display the following acknowledgement:
     17  1.1      cgd  *      This product includes software developed by Christopher G. Demetriou
     18  1.1      cgd  *	for the NetBSD Project.
     19  1.1      cgd  * 4. The name of the author may not be used to endorse or promote products
     20  1.1      cgd  *    derived from this software without specific prior written permission
     21  1.1      cgd  *
     22  1.1      cgd  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     23  1.1      cgd  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     24  1.1      cgd  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     25  1.1      cgd  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     26  1.1      cgd  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     27  1.1      cgd  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     28  1.1      cgd  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     29  1.1      cgd  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     30  1.1      cgd  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     31  1.1      cgd  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     32  1.1      cgd  */
     33  1.1      cgd 
     34  1.1      cgd #include <sys/types.h>
     35  1.2  thorpej #include <machine/float.h>
     36  1.1      cgd 
     37  1.1      cgd static const int map[] = {
     38  1.1      cgd 	0,	/* round to zero */
     39  1.1      cgd 	3,	/* round to negative infinity */
     40  1.1      cgd 	1,	/* round to nearest */
     41  1.1      cgd 	2	/* round to positive infinity */
     42  1.1      cgd };
     43  1.1      cgd 
     44  1.1      cgd int
     45  1.1      cgd __flt_rounds()
     46  1.1      cgd {
     47  1.1      cgd 	double fpcrval;
     48  1.1      cgd 	u_int64_t old;
     49  1.1      cgd 
     50  1.1      cgd 	__asm__("trapb");
     51  1.1      cgd 	__asm__("mf_fpcr %0" : "=f" (fpcrval));
     52  1.1      cgd 	__asm__("trapb");
     53  1.1      cgd 	old = *(u_int64_t *)&fpcrval;
     54  1.1      cgd 
     55  1.1      cgd 	return map[(old >> 58) & 0x3];
     56  1.1      cgd }
     57