/* Raise given exceptions. Copyright (C) 2001-2017 Free Software Foundation, Inc. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see <http://www.gnu.org/licenses/>. */ #include <fenv.h> #include <math.h> int feraiseexcept (int excepts) { /* Raise exceptions represented by EXPECTS. But we must raise only one signal at a time. It is important that if the overflow/underflow exception and the inexact exception are given at the same time, the overflow/underflow exception follows the inexact exception. */ /* First: invalid exception. */ if ((FE_INVALID & excepts) != 0) { /* One example of an invalid operation is 0.0 / 0.0. */ float f = 0.0; __asm__ __volatile__ ("divss %0, %0 " : : "x" (f)); (void) &f; } /* Next: division by zero. */ if ((FE_DIVBYZERO & excepts) != 0) { float f = 1.0; float g = 0.0; __asm__ __volatile__ ("divss %1, %0" : : "x" (f), "x" (g)); (void) &f; } /* Next: overflow. */ if ((FE_OVERFLOW & excepts) != 0) { /* XXX: Is it ok to only set the x87 FPU? */ /* There is no way to raise only the overflow flag. Do it the hard way. */ fenv_t temp; /* Bah, we have to clear selected exceptions. Since there is no `fldsw' instruction we have to do it the hard way. */ __asm__ __volatile__ ("fnstenv %0" : "=m" (*&temp)); /* Set the relevant bits. */ temp.__status_word |= FE_OVERFLOW; /* Put the new data in effect. */ __asm__ __volatile__ ("fldenv %0" : : "m" (*&temp)); /* And raise the exception. */ __asm__ __volatile__ ("fwait"); } /* Next: underflow. */ if ((FE_UNDERFLOW & excepts) != 0) { /* XXX: Is it ok to only set the x87 FPU? */ /* There is no way to raise only the underflow flag. Do it the hard way. */ fenv_t temp; /* Bah, we have to clear selected exceptions. Since there is no `fldsw' instruction we have to do it the hard way. */ __asm__ __volatile__ ("fnstenv %0" : "=m" (*&temp)); /* Set the relevant bits. */ temp.__status_word |= FE_UNDERFLOW; /* Put the new data in effect. */ __asm__ __volatile__ ("fldenv %0" : : "m" (*&temp)); /* And raise the exception. */ __asm__ __volatile__ ("fwait"); } /* Last: inexact. */ if ((FE_INEXACT & excepts) != 0) { /* XXX: Is it ok to only set the x87 FPU? */ /* There is no way to raise only the inexact flag. Do it the hard way. */ fenv_t temp; /* Bah, we have to clear selected exceptions. Since there is no `fldsw' instruction we have to do it the hard way. */ __asm__ __volatile__ ("fnstenv %0" : "=m" (*&temp)); /* Set the relevant bits. */ temp.__status_word |= FE_INEXACT; /* Put the new data in effect. */ __asm__ __volatile__ ("fldenv %0" : : "m" (*&temp)); /* And raise the exception. */ __asm__ __volatile__ ("fwait"); } /* Success. */ return 0; }