sim/erc32/float.c

   1 /* This file is part of SIS (SPARC instruction simulator)
   2
   3    Copyright (C) 1995-2020 Free Software Foundation, Inc.
   4    Contributed by Jiri Gaisler, European Space Agency
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  18
  19 /* This file implements the interface between the host and the simulated
  20    FPU.  IEEE trap handling is done as follows:
  21      1. In the host, all IEEE traps are masked
  22      2. After each simulated FPU instruction, check if any exception
  23         occured by reading the exception bits from the host FPU status
  24         register (get_accex()).
  25      3. Propagate any exceptions to the simulated FSR.
  26      4. Clear host exception bits.
  27  */
  28
  29 #include "config.h"
  30 #include "sis.h"
  31 #include <fenv.h>
  32
  33 /* This routine should return the accrued exceptions */
  34 int
  35 get_accex()
  36 {
  37     int fexc, accx;
  38
  39     fexc = fetestexcept (FE_ALL_EXCEPT);
  40     accx = 0;
  41     if (fexc & FE_INEXACT)
  42         accx |= 1;
  43     if (fexc & FE_DIVBYZERO)
  44         accx |= 2;
  45     if (fexc & FE_UNDERFLOW)
  46         accx |= 4;
  47     if (fexc & FE_OVERFLOW)
  48         accx |= 8;
  49     if (fexc & FE_INVALID)
  50         accx |= 0x10;
  51     return accx;
  52 }
  53
  54 /* How to clear the accrued exceptions */
  55 void
  56 clear_accex()
  57 {
  58     feclearexcept (FE_ALL_EXCEPT);
  59 }
  60
  61 /* How to map SPARC FSR onto the host */
  62 void
  63 set_fsr(fsr)
  64 uint32 fsr;
  65 {
  66     int fround;
  67
  68     fsr >>= 30;
  69     switch (fsr) {
  70         case 0:
  71             fround = FE_TONEAREST;
  72             break;
  73         case 1:
  74             fround = FE_TOWARDZERO;
  75             break;
  76         case 2:
  77             fround = FE_UPWARD;
  78             break;
  79         case 3:
  80             fround = FE_DOWNWARD;
  81             break;
  82      }
  83      fesetround (fround);
  84 }