STEP PSAM Commands STEP
NAME
step, next, stepi - single step through the executing DAP
program
SYNOPSIS
step [ <number> ]
next [ <number> ]
stepi [ <number> ]
DESCRIPTION
The step and next commands execute the next <number> execut-
able FORTRAN-PLUS statements and then return control to
psam. The stepi command executes the next <number> instruc-
tions in an APAL program and then returns control to psam.
If the parameter <number> is omitted its value is assumed to
be 1.
The single stepping behaviour of the step and next commands
only occurs in FORTRAN-PLUS procedures compiled with the
dapf option -g. Where the current procedure is not a
FORTRAN-PLUS procedure compiled with the -g option, step and
next behave in the same way as continue, until such a pro-
cedure (if any) is encountered.
The step and next commands differ only in the way in which
procedure calls are stepped. The step command steps into
called procedures whereas the next command treats them as a
single statement. To be precise, in the step command the
next statement following a statement containing a procedure
call is the first executable statement in the called pro-
cedure; in the next command it is the next executable state-
ment in the calling procedure.
If a program interrupt (a pause, breakpoint or run-time
error) is encountered while single stepping the interrupt is
obeyed and single stepping terminates.
The step command is available in Breakpoint Edit Mode, giv-
ing the user the opportunity to begin single stepping from
the entry point of a FORTRAN-PLUS program.
When single stepping with stepi into a newly called APAL
procedure the output of the backtrack command appears incom-
plete until the stack is set up.
SEE ALSO
backtrack, continue
AMT Release 4.1S Last change: 11th May 1989 1