pTAL Reference Manual (G06.24+, H06.09+, J06.03+)

$OPTIONAL (j > 2, j) ); ! Pass j if j > 2
END;
You can use $OPTIONAL when one procedure provides a front-end interface for another procedure
that does the actual work, as Example 292 (page 335) shows.
Example 292 $OPTIONAL Routine for a Front-End Interface
PROC p1 (i, j) EXTENSIBLE;
INT .i;
INT .j;
BEGIN
! Lots of code
END;
PROC p2 (p, q) EXTENSIBLE;
INT .p;
INT .q;
BEGIN
! Lots of code
CALL p1 ($OPTIONAL ($PARAM (p), p ),
$OPTIONAL ($PARAM (q), q ));
! Lots of code
END;
$OVERFLOW
$OVERFLOW returns a value indicating whether an overflow occurred during certain arithmetic
operations.
NopTAL privileged procedure
NoCan be executed only by privileged procedures
NoSets condition code
NoSets $CARRY
NoSets $OVERFLOW
$OVERFLOW indicates whether an overflow occurred. You can test $OVERFLOW only if overflow
traps are disabled and only following an assignment statement in which the final operator executed
on the right side of the assignment is one $FIX of a REAL or REAL(64) value of the following operators
or built-in routines:
• Negate (unary -), +, -, *, /,’/’
• $DBL of an INT, FIXED, REAL, or REAL(64) value
• $FLTR of a REAL(64) value
• $FIX of a REAL or REAL(64) value
• $FIXD
• $FIXI
• $FIXL
• $FIXR of a REAL or REAL(64) value
Nonatomic Operations 335