libm/metag/fraiseexcpt.c

   1 /* Raise given exceptions.
   2    Copyright (C) 2013 Imagination Technologies Ltd.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If
  17    not, see <http://www.gnu.org/licenses/>.  */
  18
  19 #include <fenv.h>
  20 #include <math.h>
  21
  22 libm_hidden_proto(feraiseexcept)
  23
  24 int
  25 feraiseexcept (int excepts)
  26 {
  27   /* Raise exceptions represented by EXPECTS.  But we must raise only
  28      one signal at a time.  It is important that if the overflow/underflow
  29      exception and the inexact exception are given at the same time,
  30      the overflow/underflow exception follows the inexact exception.  */
  31
  32   /* First: invalid exception.  */
  33   if ((FE_INVALID & excepts) != 0)
  34     {
  35       /* Reciprocal square root of a negative number is invalid. */
  36       __asm__ volatile(
  37                    "F MOV FX.0,#0xc000 ! -2\n"
  38                    "F RSQ FX.1,FX.0\n"
  39                    );
  40     }
  41
  42   /* Next: division by zero.  */
  43   if ((FE_DIVBYZERO & excepts) != 0)
  44     {
  45       __asm__ volatile(
  46                    "F MOV FX.0,#0\n"
  47                    "F RCP FX.1,FX.0\n"
  48                    );
  49     }
  50
  51   /* Next: overflow.  */
  52   if ((FE_OVERFLOW & excepts) != 0)
  53     {
  54       /* Adding a large number in single precision can cause overflow. */
  55       __asm__ volatile(
  56                    "  MOVT D0.0,#0x7f7f\n"
  57                    "  ADD  D0.0,D0.0,#0xffff\n"
  58                    "F MOV  FX.0,D0.0\n"
  59                    "F ADD  FX.1,FX.0,FX.0\n"
  60                    );
  61     }
  62
  63   /* Next: underflow.  */
  64   if ((FE_UNDERFLOW & excepts) != 0)
  65     {
  66       /* Multiplying a small value by 0.5 will cause an underflow. */
  67       __asm__ volatile(
  68                    "  MOV  D0.0,#1\n"
  69                    "F MOV  FX.0,D0.0\n"
  70                    "  MOVT D0.0,#0x3f00\n"
  71                    "F MOV  FX.1,D0.0\n"
  72                    "F MUL  FX.2,FX.1,FX.0\n"
  73                    );
  74     }
  75
  76   /* Last: inexact.  */
  77   if ((FE_INEXACT & excepts) != 0)
  78     {
  79       /* Converting a small single precision value to half precision
  80          can cause an inexact exception. */
  81       __asm__ volatile(
  82                    "  MOV  D0.0,#0x0001\n"
  83                    "F MOV  FX.0,D0.0\n"
  84                    "F FTOH FX.1,FX.0\n"
  85                    );
  86     }
  87
  88   /* Success.  */
  89   return 0;
  90 }
  91 libm_hidden_def(feraiseexcept)