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

   1 /* $NetBSD: fpsetround.c,v 1.12 2012/03/21 20:07:52 he 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 1.12 2012/03/21 20:07:52 he 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(fp_rnd rnd_dir)
  53 {
  54         union {
  55                 double d;
  56                 uint64_t u64;
  57         } fpcrval;
  58         fp_rnd old;
  59
  60         __asm("excb; mf_fpcr %0; excb" : "=f" (fpcrval.d));
  61         old = (fp_rnd)(fpcrval.u64 >> 58) & 0x3;
  62
  63         rnd_dir ^= old;
  64
  65         fpcrval.u64 ^= (long)rnd_dir << 58;
  66
  67         __asm("excb; mt_fpcr %0; excb" : : "f" (fpcrval.d));
  68
  69         return old;
  70 }