IEEE_HANDLER

Intel® Fortran Compiler Classic and Intel® Fortran Compiler Developer Guide and Reference

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ID 767251

Date 6/24/2024

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IEEE_HANDLER

Portability Function: Establishes a handler for IEEE exceptions.

Module

USE IFPORT

result = IEEE_HANDLER (action, exception, handler)

action	(Input) Character(). One of the following literal IEEE actions: 'GET', 'SET', or 'CLEAR'. For more details on these actions, see IEEE_FLAGS.
exception	(Input) Character(). One of the following literal IEEE exception flags: 'inexact', 'underflow', 'overflow', 'division', 'invalid', 'all' (which equals the previous five flags), or 'common' (which equals 'invalid', 'overflow', 'underflow', and 'division'). The flags 'all' or 'common' should only be used for actions SET or CLEAR.
handler	(Input) The address of an external signal-handling routine.

Results

The result type is INTEGER(4) on IA-32 architecture; INTEGER(8) on Intel® 64 architecture. The result is 0 if successful; otherwise, 1.

IEEE_HANDLER calls a signal-handling routine to establish a handler for IEEE exceptions. It also enables an FPU trap corresponding to the required exception.

The state of the FPU is not defined in the handler routine. When the FPU trap occurs, the program invokes the handler routine. After the handler routine is executed, the program terminates.

The handler routine gets the exception code in the SIGINFO argument. SIGNO is the number of the system signal. The meaning of the SIGINFO constants appear in the following table (defined in the IFPORT module):

FPE$INVALID	Invalid operation
FPE$ZERODIVIDE	Divide-by-zero
FPE$OVERFLOW	Numeric overflow
FPE$UNDERFLOW	Numeric underflow
FPE$INEXACT	Inexact result (precision)

'GET' actions return the location of the current handler routine for exception cast to an INTEGER.

Example

The following example creates a handler routine and sets it to trap divide-by-zero:

PROGRAM TEST_IEEE
 REAL :: X, Y, Z
 CALL FPE_SETUP
 X = 0.
 Y = 1.
 Z = Y / X
END PROGRAM
SUBROUTINE FPE_SETUP
USE IFPORT
IMPLICIT NONE
 INTERFACE
   SUBROUTINE FPE_HANDLER(SIGNO, SIGINFO)
     INTEGER(4), INTENT(IN) :: SIGNO, SIGINFO
   END SUBROUTINE
 END INTERFACE
 INTEGER IR
 IR = IEEE_HANDLER('set','division',FPE_HANDLER)
END SUBROUTINE FPE_SETUP
SUBROUTINE FPE_HANDLER(SIG, CODE)
 USE IFPORT
 IMPLICIT NONE
 INTEGER SIG, CODE
 IF(CODE.EQ.FPE$ZERODIVIDE) PRINT *,'Occurred divide by zero.'
 CALL ABORT
END SUBROUTINE FPE_HANDLER

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IEEE_HANDLER

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