lib/libc/arch/alpha/gen/fpsetround.c

   1 /* $NetBSD: fpsetround.c,v 1.10 2005/12/24 23:10:08 perry Exp $ */
   2
   3 /*
   4  * Copyright (c) 1995 Christopher G. Demetriou
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *          This product includes software developed for the
  18  *          NetBSD Project.  See http://www.NetBSD.org/ for
  19  *          information about NetBSD.
  20  * 4. The name of the author may not be used to endorse or promote products
  21  *    derived from this software without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  24  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  25  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  26  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  27  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  28  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  29  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  30  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  31  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  32  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  33  *
  34  * <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>>
  35  */
  36
  37 #include <sys/cdefs.h>
  38 #if defined(LIBC_SCCS) && !defined(lint)
  39 __RCSID("$NetBSD: fpsetround.c,v 1.10 2005/12/24 23:10:08 perry Exp $");
  40 #endif /* LIBC_SCCS and not lint */
  41
  42 #include "namespace.h"
  43
  44 #include <sys/types.h>
  45 #include <ieeefp.h>
  46
  47 #ifdef __weak_alias
  48 __weak_alias(fpsetround,_fpsetround)
  49 #endif
  50
  51 fp_rnd
  52 fpsetround(rnd_dir)
  53         fp_rnd rnd_dir;
  54 {
  55         double fpcrval;
  56         u_int64_t old, new;
  57
  58         __asm("excb");
  59         __asm("mf_fpcr %0" : "=f" (fpcrval));
  60         old = *(u_int64_t *)(void *)&fpcrval;
  61
  62         new = old & ~(long)0x0c00000000000000;
  63         new = (long)rnd_dir << 58;
  64         *(u_int64_t *)(void *)&fpcrval = new;
  65
  66         __asm("mt_fpcr %0" : : "f" (fpcrval));
  67         __asm("excb");
  68
  69         return ((old >> 58) & 0x3);
  70 }