FPGETROUND(3C-SVR4) RISC/os Reference Manual  FPGETROUND(3C-SVR4)



NAME
     fpgetround, fpsetround, fpgetmask, fpsetmask, fpgetsticky,
          fpsetsticky - IEEE floating-point environment control

SYNOPSIS
     #include <ieeefp.h>

     fp_rnd fpgetround (void);

     fp_rnd fpsetround (fp_rnd rnd_dir);

     fp_except fpgetmask (void);

     fp_except fpsetmask (fp_except mask);

     fp_except fpgetsticky (void);

     fp_except fpsetsticky (fp_except sticky);

DESCRIPTION
     There are five floating-point exceptions: divide-by-zero,
     overflow, underflow, imprecise (inexact) result, and invalid
     operation.  When a floating-point exception occurs, the
     corresponding sticky bit is set (1), and if the mask bit is
     enabled (1), the trap takes place.  These routines let the
     user change the behavior on occurrence of any of these
     exceptions, as well as change the rounding mode for
     floating-point operations.

          FP_X_INV  /* invalid operation exception */
          FP_X_OFL  /* overflow exception */
          FP_X_UFL  /* underflow exception */
          FP_X_DZ        /* divide-by-zero exception */
          FP_X_IMP  /* imprecise (loss of precision) */
          FP_RN     /* round to nearest representative number */
          FP_RP     /* round to plus infinity */
          FP_RM     /* round to minus infinity */
          FP_RZ     /* round to zero (truncate) */

     fpgetround returns the current rounding mode.

     fpsetround sets the rounding mode and returns the previous
     rounding mode.

     fpgetmask returns the current exception masks.

     fpsetmask sets the exception masks and returns the previous
     setting.

     fpgetsticky returns the current exception sticky flags.





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FPGETROUND(3C-SVR4) RISC/os Reference Manual  FPGETROUND(3C-SVR4)



     fpsetsticky sets (clears) the exception sticky flags and
     returns the previous setting.

     The default environment is rounding mode set to nearest
     (FP_RN) and all traps disabled.

     Individual bits may be examined using the constants defined
     in ieeefp.h.

SEE ALSO
     isnan(3C).

NOTES
     fpsetsticky modifies all sticky flags.  fpsetmask changes
     all mask bits.  fpsetmask clears the sticky bit correspond-
     ing to any exception being enabled.

     C requires truncation (round to zero) for floating point to
     integral conversions.  The current rounding mode has no
     effect on these conversions.

     One must clear the sticky bit to recover from the trap and
     to proceed.  If the sticky bit is not cleared before the
     next trap occurs, a wrong exception type may be signaled.































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