minix/lib/libc/arch/alpha/gen/flt_rounds.c

/* $NetBSD: flt_rounds.c,v 1.9 2011/06/12 05:44:36 matt Exp $ */

/*
 * Copyright (c) 1995 Christopher G. Demetriou
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *          This product includes software developed for the
 *          NetBSD Project.  See http://www.NetBSD.org/ for
 *          information about NetBSD.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>>
 */

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: flt_rounds.c,v 1.9 2011/06/12 05:44:36 matt Exp $");
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <machine/ieeefp.h>
#include <machine/float.h>

/*
 * These come from <float.h> defintion
 */
#define	FLT_ROUND_MAP \
	( (0 << (FP_RZ*2))	/* round to zero */			\
	| (1 << (FP_RN*2))	/* round to nearest */			\
	| (3 << (FP_RM*2))	/* round to negative infinity */	\
	| (2 << (FP_RP*2)))	/* round to positive infinity */

int
__flt_rounds(void)
{
	union {
		double d;
		uint64_t u64;
	} fpcrval;
	uint64_t old;

	__asm("excb; mf_fpcr %0; excb" : "=f" (fpcrval.d));
	old = (fpcrval.u64 >> 58) & 3;

	return (FLT_ROUND_MAP >> (old << 1)) & 3;
}