XL Fortran Enterprise Edition for AIX : User's Guide - IBM

Another method is to use the ieee_set_halting_mode subroutine in the
ieee_exceptions module. This portable, elemental subroutine allows you to set the
halting (trapping) status for any FPSCR exception flags. For example:
USE, INTRINSIC :: ieee_exceptions
TYPE(IEEE_STATUS_TYPE) SAVED_FPSCR
CALL ieee_get_status(SAVED_FPSCR)
! Saves the current value of the
! fpscr register
CALL ieee_set_halting_mode(IEEE_DIVIDE_BY_ZERO, .TRUE.) ! Enabled trapping
! ... ! of divide-by-zero.
CALL IEEE_SET_STATUS(SAVED_FPSCR)
! Restore fpscr register
xlf_fp_util Procedures
The xlf_fp_util procedures allow you to query and control the floating-point status
and control register (fpscr) of the processor directly. These procedures are more
efficient than the fpsets and fpgets subroutines because they are mapped into
inlined machine instructions that manipulate the floating-point status and control
register directly.
The intrinsic module, xlf_fp_util, contains the interfaces and data type definitions
for these procedures and the definitions for the named constants that are needed
by the procedures. This module enables type checking of these procedures at
compile time rather than link time. The following files are supplied for the
xlf_fp_util module:
File names File type Locations
xlf_fp_util.mod
module symbol file
(32–bit)
module symbol file
(64–bit)
/usr/lpp/xlf/include_d7
/usr/lpp/xlf/include
/usr/lpp/xlf/include
To use the procedures, you must add a USE XLF_FP_UTIL statement to your
source file. For more information, see USE, in the XL Fortran Enterprise Edition for
AIX Language Reference.
When compiling with the -U option, you must code the names of these procedures
in all lowercase.
For a list of the xlf_fp_util procedures, see the Service and Utility Procedures section
in the XL Fortran Enterprise Edition for AIX Language Reference.
fpgets and fpsets Subroutines
The fpsets and fpgets subroutines provide a way to manipulate or query the
floating-point status and control register. Instead of calling the operating system
routines directly, you pass information back and forth in fpstat, an array of
logicals. The following table shows the most commonly used array elements that
deal with exceptions:
Table 19. Exception Bits to Use with fpsets and fpgets
Array Element to
Set to Enable
Array Element to
Check if Exception
Occurred
Exception Indicated When .TRUE.
n/a fpstat(fpfx) Floating-point exception summary
300 XL Fortran Enterprise Edition for AIX : User’s Guide