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glibc  2.9
Functions
fraiseexcpt.c File Reference
#include <fenv.h>
#include <float.h>
#include <math.h>

Go to the source code of this file.

Functions

int feraiseexcept (int excepts)

Function Documentation

int feraiseexcept ( int  excepts)

Definition at line 29 of file fraiseexcpt.c.

{
  /* Raise exceptions represented by EXCEPTS.  But we must raise only one
     signal at a time.  It is important that if the overflow/underflow
     exception and the divide by zero exception are given at the same
     time, the overflow/underflow exception follows the divide by zero
     exception.  */

  /* We do these bits in assembly to be certain GCC doesn't optimize
     away something important, and so we can force delayed traps to
     occur. */

  /* We use "fldd 0(%%sr0,%%sp),%0" to flush the delayed exception */
       
  /* First: Invalid exception.  */
  if (excepts & FE_INVALID)
    {
      /* One example of a invalid operation is 0 * Infinity.  */
      double d = HUGE_VAL;
      __asm__ __volatile__ (
              "      fcpy,dbl %%fr0,%%fr22\n"
              "      fmpy,dbl %0,%%fr22,%0\n"
              "      fldd 0(%%sr0,%%sp),%0"
              : "+f" (d) : : "%fr22" );
    }

  /* Second: Division by zero.  */
  if (excepts & FE_DIVBYZERO)
    {
      double d = 1.0;
      __asm__ __volatile__ (
              "      fcpy,dbl %%fr0,%%fr22\n"
              "      fdiv,dbl %0,%%fr22,%0\n"
              "      fldd 0(%%sr0,%%sp),%0"
              : "+f" (d) : : "%fr22" );
    }

  /* Third: Overflow.  */
  if (excepts & FE_OVERFLOW)
    {
      double d = DBL_MAX;
      __asm__ __volatile__ (
              "      fadd,dbl %0,%0,%0\n"
              "      fldd 0(%%sr0,%%sp),%0"
              : "+f" (d) );
    }

  /* Fourth: Underflow.  */
  if (excepts & FE_UNDERFLOW)
    {
      double d = DBL_MIN;
      double e = 3.0;
      __asm__ __volatile__ (
              "      fdiv,dbl %0,%1,%0\n"
              "      fldd 0(%%sr0,%%sp),%0"
              : "+f" (d) : "f" (e) );
    }

  /* Fifth: Inexact */
  if (excepts & FE_INEXACT)
    {
      double d = M_PI;
      double e = 69.69;
      __asm__ __volatile__ (
              "      fdiv,dbl %0,%1,%%fr22\n"
              "      fcnvfxt,dbl,sgl %%fr22,%%fr22L\n"
              "      fldd 0(%%sr0,%%sp),%%fr22"
              : : "f" (d), "f" (e) : "%fr22" );
    }

  /* Success.  */
  return 0;
}

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