fpsetmask(3) - NetBSD Manual Pages

FPGETMASK(3)            NetBSD Library Functions Manual           FPGETMASK(3)


NAME

     fpgetmask, fpgetround, fpgetsticky, fpsetmask, fpsetround, fpsetsticky --
     IEEE FP mode control


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <ieeefp.h>

     fp_except
     fpgetmask(void);

     fp_rnd
     fpgetround(void);

     fp_except
     fpgetsticky(void);

     fp_except
     fpsetmask(fp_except mask);

     fp_rnd
     fpsetround(fp_rnd rnd_dir);

     fp_except
     fpsetsticky(fp_except sticky);


DESCRIPTION

     A rounding mode is one of FP_RZ, FP_RM, FP_RN, or FP_RP, for rounding
     towards zero, rounding (Minus infinity) down, rounding to nearest, and
     rounding (Plus infinity) up.  The default mode is FP_RN.

     An fp_except value is a bitmask specifying an exception type and contain-
     ing any of the values listed below.

           FP_X_INV      Invalid Operation
           FP_X_DZ       Division by zero
           FP_X_OFL      Overflow
           FP_X_UFL      Underflow
           FP_X_IMP      Imprecision (inexact)
           FP_X_IOV      Integer Overflow

     The fpsetmask() function will set the current exception mask, i.e., it
     will cause future operations with the specified result status to raise
     the SIGFPE exception.  The fpgetmask() function will return the current
     exception mask.

     The fpsetround() function will cause future operations to use the speci-
     fied dynamic rounding mode.  The fpgetround() function will return the
     current rounding mode.

     Note:   On some architectures, instructions can optionally specify static
             rounding modes and exception enables that will supersede the
             specified dynamic mode.  On other architectures, these features
             may not be fully supported.

     A ``sticky'' status word may be maintained in which a bit is set every
     time an exceptional floating point condition is encountered, whether or
     not a SIGFPE is generated.  The fpsetsticky() function will set or clear
     the specified exception history bits.  The fpgetsticky() function will
     return the exception history bits.


RETURN VALUES

     The fpgetround() and fpsetround() functions return the (previous) round-
     ing mode.  The fpgetmask(), fpsetmask(), fpgetsticky(), and fpsetsticky()
     functions return the (previous) exception mask and exception history
     bits.


SEE ALSO

     sigaction(2)

NetBSD 5.1                       April 4, 2004                      NetBSD 5.1