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

   1 /* $NetBSD: flt_rounds.c,v 1.7 2005/06/12 05:21:25 lukem 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: flt_rounds.c,v 1.7 2005/06/12 05:21:25 lukem Exp $");
  40 #endif /* LIBC_SCCS and not lint */
  41
  42 #include <sys/types.h>
  43 #include <machine/float.h>
  44
  45 static const int map[] = {
  46         0,      /* round to zero */
  47         3,      /* round to negative infinity */
  48         1,      /* round to nearest */
  49         2       /* round to positive infinity */
  50 };
  51
  52 int
  53 __flt_rounds()
  54 {
  55         double fpcrval;
  56         u_int64_t old;
  57
  58         __asm("trapb");
  59         __asm("mf_fpcr %0" : "=f" (fpcrval));
  60         __asm("trapb");
  61         old = *(u_int64_t *)(void *)&fpcrval;
  62
  63         return map[(old >> 58) & 0x3];
  64 }