FPGETMASK(3)

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

LIBRARY
libc

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 containing 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 specified 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) rounding mode. The fpgetmask(), fpsetmask(), fpgetsticky(), and fpsetsticky() functions return the (previous) exception mask and exception history bits.

SEE ALSO
sigaction(2)