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

   1 /* $NetBSD: flt_rounds.c,v 1.10 2014/08/03 19:14:24 wiz 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 1.10 2014/08/03 19:14:24 wiz Exp $");
  40 #endif /* LIBC_SCCS and not lint */
  41
  42 #include <sys/types.h>
  43 #include <machine/ieeefp.h>
  44 #include <machine/float.h>
  45
  46 /*
  47  * These come from <float.h> definition
  48  */
  49 #define FLT_ROUND_MAP \
  50         ( (0 << (FP_RZ*2))      /* round to zero */                     \
  51         | (1 << (FP_RN*2))      /* round to nearest */                  \
  52         | (3 << (FP_RM*2))      /* round to negative infinity */        \
  53         | (2 << (FP_RP*2)))     /* round to positive infinity */
  54
  55 int
  56 __flt_rounds(void)
  57 {
  58         union {
  59                 double d;
  60                 uint64_t u64;
  61         } fpcrval;
  62         uint64_t old;
  63
  64         __asm("excb; mf_fpcr %0; excb" : "=f" (fpcrval.d));
  65         old = (fpcrval.u64 >> 58) & 3;
  66
  67         return (FLT_ROUND_MAP >> (old << 1)) & 3;
  68 }