pTAL Reference Manual (H06.08+)

Built-In Routines

HP pTAL Reference Manual—523746-006

15-5

$ATOMIC_ADD

$ATOMIC_ADD atomically adds two INT values.

var input,output

sINT:variable

is the variable that $ATOMIC_ADD increments.

value input

sINT:value

is the value $ATOMIC_ADD adds to var.

$ATOMIC_ADD performs the following operation:

var := var + value

The read, add, and store operations are performed without interruption, as if the three

operations were one.

The following table shows examples of $ATOMIC_ADD:

Sets condition code Yes (according the final value of var )

Sets $CARRY Yes, if traps are disabled

Sets $OVERFLOW Yes, if traps are disabled; otherwise, traps on overflow

Example 15-3. $ATOMIC_ADD Routine

INT var;

INT value;

$ATOMIC_ADD (var, value);

var value result

%H1234 %HAAAA %HBCDE

%H1234 %H5555 %H6789

%H6789 %HAAAA %H1233

%H6789 %H5555 %HBCDE

$ATOMIC_ADD ( ) ;

VST607.vsd

var

value