Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help 
FPGETROUND(3)		 BSD Library Functions Manual		 FPGETROUND(3)

NAME
     fpgetround, fpsetround, fpsetprec,	fpgetprec, fpgetmask, fpsetmask,
     fpgetsticky, fpresetsticky	-- IEEE	floating point interface

SYNOPSIS
     #include <ieeefp.h>

     typedef enum {
	     FP_RN,	     /*	round to nearest */
	     FP_RM,	     /*	round down to minus infinity */
	     FP_RP,	     /*	round up to plus infinity */
	     FP_RZ	     /*	truncate */
     } fp_rnd_t;

     fp_rnd_t
     fpgetround(void);

     fp_rnd_t
     fpsetround(fp_rnd_t direction);

     typedef enum {
	     FP_PS,	     /*	24 bit (single-precision) */
	     FP_PRS,	     /*	reserved */
	     FP_PD,	     /*	53 bit (double-precision) */
	     FP_PE	     /*	64 bit (extended-precision) */
     } fp_prec_t;

     fp_prec_t
     fpgetprec(void);

     fp_prec_t
     fpsetprec(fp_prec_t precision);

     #define fp_except_t     int
     #define FP_X_INV	     0x01    /*	invalid	operation */
     #define FP_X_DNML	     0x02    /*	denormal */
     #define FP_X_DZ	     0x04    /*	zero divide */
     #define FP_X_OFL	     0x08    /*	overflow */
     #define FP_X_UFL	     0x10    /*	underflow */
     #define FP_X_IMP	     0x20    /*	(im)precision */
     #define FP_X_STK	     0x40    /*	stack fault */

     fp_except_t
     fpgetmask(void);

     fp_except_t
     fpsetmask(fp_except_t mask);

     fp_except_t
     fpgetsticky(void);

     fp_except_t
     fpresetsticky(fp_except_t sticky);

DESCRIPTION
     The routines described herein are deprecated.  New	code should use	the
     functionality provided by fenv(3).

     When a floating point exception is	detected, the exception	sticky flag is
     set and the exception mask	is tested.  If the mask	is set,	then a trap
     occurs.  These routines allow both	setting	the floating point exception
     masks, and	resetting the exception	sticky flags after an exception	is de-
     tected.  In addition, they	allow setting the floating point rounding mode
     and precision.

     The fpgetround() function returns the current floating point rounding
     mode.

     The fpsetround() function sets the	floating point rounding	mode and re-
     turns the previous	mode.

     The fpgetprec() function returns the current floating point precision.

     The fpsetprec() function sets the floating	point precision	and returns
     the previous precision.

     The fpgetmask() function returns the current floating point exception
     masks.

     The fpsetmask() function sets the floating	point exception	masks and re-
     turns the previous	masks.

     The fpgetsticky() function	returns	the current floating point sticky
     flags.

     The fpresetsticky() function clears the floating point sticky flags and
     returns the previous flags.

     Sample code which prevents	a trap on divide-by-zero:

	   fpsetmask(~FP_X_DZ);
	   a = 1.0;
	   b = 0;
	   c = a / b;
	   fpresetsticky(FP_X_DZ);
	   fpsetmask(FP_X_DZ);

IMPLEMENTATION NOTES
     The fpgetprec() and fpsetprec() functions provide functionality unavail-
     able on many platforms.  At present, they are implemented only on the
     i386 and amd64 platforms.

SEE ALSO
     fenv(3), isnan(3)

CAVEATS
     After a floating point exception and before a mask	is set,	the sticky
     flags must	be reset.  If another exception	occurs before the sticky flags
     are reset,	then a wrong exception type may	be signaled.

HISTORY
     These routines are	based on SysV/386 routines of the same name.

BSD				August 23, 1993				   BSD
NAME | SYNOPSIS | DESCRIPTION | IMPLEMENTATION NOTES | SEE ALSO | CAVEATS | HISTORY

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=fpsetprec&sektion=3&manpath=FreeBSD+6.0-RELEASE+and+Ports>

home | help