pascal/pdx/pdx.1

.\" Copyright (c) 1983, 1990, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" %sccs.include.redist.roff%
.\"
.\"	@(#)pdx.1	8.1 (Berkeley) 06/06/93
.\"
.Dd
.Dt PDX 1
.Os BSD 4.2
.Sh NAME
.Nm pdx
.Nd pascal debugger
.Sh SYNOPSIS
.Nm pdx
.Op Fl r
.Op Ar objfile
.Sh DESCRIPTION
.Nm Pdx
is a tool for source level debugging and execution of
Pascal programs.
The
.Ar objfile
is an object file produced by the Pascal translator
.Xr pi 1 .
If no
.Ar objfile
is specified,
.Nm pdx
looks
for a file named ``obj'' in the current directory.
The object file contains a symbol table which includes the name of the
all the source files translated by
.Xr pi 1
to create it.
These files are available for perusal while using the debugger.
.Pp
If the file
.Dq Pa .pdxinit
exists in the current directory, then the
debugger commands in it are executed.
.Pp
.Bl -tag -width flag r
.It Fl r
The
.Fl r
option causes the
.Ar objfile
to be executed immediately;
if it terminates successfully
.Nm pdx
exits.
Otherwise it reports the reason for termination
and offers the user the option of entering the debugger
or simply letting
.Xr px
continue with a traceback.
If
.Fl r
is not specified,
.Nm pdx
just prompts and waits for a command.
.El
.Pp
The commands are:
.Pp
.Bl -tag -width flag -compact
.It Xo
.Ic run
.Op Ar args
.Op Ic \&< Ar filename
.Op Ic \&> Ar filename
.Xc
Start executing
.Ar objfile  ,
passing
.Ar args
as command line arguments;
.Ic \&<
or
.Ic \&>
can be used to redirect input or output in the usual manner.
.Pp
.It Xo
.Ic trace
.Op Ic in Ar procedure/function
.Op Ic if Ar condition
.Xc
.It Xo
.Ic trace
.Ar source-line-number
.Op Ic if Ar condition
.Xc
.It Xo
.Ic trace
.Ar procedure/function
.Op Ic in Ar procedure/function
.Op Ic if Ar condition
.Xc
.It Xo
.Ic trace
.Ar expression Ic at Ar source-line-number
.Op Ic if Ar condition
.Xc
.It Xo
.Ic trace
.Ar variable
.Op Ic in Ar procedure/function
.Op Ic if Ar condition
.Xc
Have tracing information printed when the program is executed.
A number is associated with the command that is used
to turn the tracing off (see the
.Ic delete
command).
.Pp
The first argument describes what is to be traced.
If it is a
.Ar source-line-number  ,
then the line is printed
immediately prior to being executed.
Source line numbers in a file other than the current one
must be preceded by the name of the file and a colon, e.g.
``mumble.p:17''.
.Pp
If the argument is a procedure or function name then
every time it is called, information is printed telling
what routine called it, from what source line it was called,
and what parameters were passed to it.
In addition, its return is noted, and if it's a function
then the value it is returning is also printed.
.Pp
If the argument is an
.Ar expression
with an
.Ic at
clause
then the value of the expression is printed whenever the
identified source line is reached.
.Pp
If the argument is a variable then the name and value of the variable
is printed whenever it changes.
Execution is substantially slower during this form of tracing.
.Pp
If no argument is specified then all source lines are printed
before they are executed.
Execution is substantially slower during this form of tracing.
.Pp
The clause
.Dq Ic in Ar procedure/function
restricts tracing information
to be printed only while executing inside the given procedure
or function.
.Pp
.Ar Condition
is a Pascal boolean expression and is
evaluated prior to printing the tracing information;
if it is false then the information is not printed.
.Pp
There is no restriction on the amount of information
that can be traced.
.Pp
.ne 10
.It Ic stop if Ar condition
.It Xo
.Ic stop at Ar source-line-number
.Op Ic if Ar condition
.Xc
.It Xo
.Ic stop in Ar procedure/function
.Op Ic if Ar condition
.Xc
.It Xo
.Ic stop Ar variable
.Op Ic if Ar condition
.Xc
Stop execution when the given line is reached, procedure or function
called, variable changed, or condition true.
.Pp
.It Ic delete Ar command-number
The trace or stop corresponding to the given number is removed.
The numbers associated with traces and stops are printed by
the
.Ic status
command.
.Pp
.It Ic status Op Ic \&> Ar filename
Print out
the currently active
.Ic trace
and
.Ic stop
commands.
.Pp
.It Ic cont
Continue execution from where it stopped.
This can only be
done when the program was stopped by an interrupt
or through use of the
.Ic stop
command.
.Pp
.It Ic step
Execute one source line.
.Pp
.It Ic next
Execute up to the next source line.
The difference between this and
.Ic step
is that
if the line contains a call to a procedure or function
the
.Ic step
command will stop at the beginning of that
block, while the
.Ic next
command will not.
.Pp
.It Xo
.Ic print Ar expression
.Op Ic \&, Ar expression ...
.Xc
Print out the values of the Pascal expressions.
Variables declared in an outer block but having
the same identifier as one in the current block may be
referenced as
.Dq Ar block-name \&. variable
.Pp
.It Ic whatis Ar identifier
Print the declaration of the given identifier.
.Pp
.It Ic which Ar identifier
Print the full qualification of the given identifer, i.e.
the outer blocks that the identifier is associated with.
.Pp
.It Ic assign Ar variable Ar expression
Assign the value of the expression to the variable.
.Pp
.It Ic call Ar procedure Ns (parameters)
Execute the object code associated with the named procedure or function.
.Pp
.It Ic help
Print out a synopsis of
.Nm pdx
commands.
.Pp
.It Ic gripe
Invokes a mail program to send a message to the person in charge of
.Nm pdx  .
.Pp
.It Ic where
Print out
a list of the active procedures and functions and the respective source
line where they are called.
.Pp
.It Ic source Ar filename
Read
.Nm pdx
commands from the given
.Ar filename  .
Especially useful when the
.Ar filename
has been created by redirecting
a
.Ic status
command from an earlier debugging session.
.Pp
.It Ic dump Op Ic \&> Ar filename
Print the names and values of all active
data.
.Pp
.It Xo
.Ic list
.Oo Ar source-line-number
.Op \&, Ar source-line-number Oc
.Xc
.It Ic list Ar procedure/function
List the lines in the current source file from the first line number to
the second inclusive.
As in the editor
``$'' can be used to refer to the last line.
If no lines are specified, the entire file is listed.
If the name of a procedure or function is given
lines
.Ar n-k
to
.Ar n+k
are listed where
.Ar n
is the first statement
in the procedure or function and
.Ar k
is small.
.Pp
.It Ic file Op Ar filename
Change the current source file name to
.Ar filename  .
If none is specified then the current source file name is printed.
.Pp
.It Ic edit Op Ar filename
.It Ic edit Ar procedure Ns / Ns Ar function-name
Invoke an editor on
.Ar filename
or the current source file if none
is specified.
If a
.Ar procedure
or
.Ar function
name is specified,
the editor is invoked on the file that contains it.
Which editor is invoked by default depends on the installation.
The default can be overridden by setting the environment variable
.Ev EDITOR
to the name of the desired editor.
.Pp
.It Ic pi
Recompile the program and read in the new symbol table information.
.Pp
.It Ic sh Ar command-line
Pass the command line to the shell for execution.
The SHELL environment variable determines which shell is used.
.Pp
.It Ic alias Ar new-command-name Ar old-command-name
This command makes
.Nm pdx
respond to
.Ar new-command-name
the way it used to respond to
.Ar old-command-name  .
.Pp
.It Ic quit
Exit
.Nm pdx  .
.El
.Pp
The following commands deal with the program at the
.Ar px
instruction
level rather than source level.
They are not intended for general use.
.Pp
.Bl -tag -width Fl -compact
.It Xo
.Ic tracei
.Op Ar address
.Op Ic if Ar cond
.Xc
.It Xo
.Ic tracei
.Op Ar variable
.Op Ic at Ar address
.Op Ic if Ar cond
.Xc
.It Xo
.Ic stopi
.Op Ar address
.Op Ic if Ar cond
.Xc
.It Xo
.Ic stopi
.Op Ic at
.Op Ar address
.Op Ic if Ar cond
.Xc
Turn on tracing or set a stop using a
.Ic px
machine
instruction addresses.
.Pp
.It Xo
.Ic xi Ar address
.Op Ic \&, Ar address
.Xc
Print the instructions starting at the first
.Ar address  .
Instructions up to
the second
.Ar address
are printed.
.Pp
.It Xo
.Ic xd Ar address
.Op Ic \&, Ar address
.Xc
Print in octal the specified data location(s).
.El
.Sh ENVIRONMENT
.Bl -tag -width Ar
.It Ev EDITOR
The
.Ic edit
function uses the
.Ev EDITOR
environment variable to see what editor to use.
.It Ev SHELL
The function
.Ic sh
checks the
.Ev SHELL
variable to see which shell to
execute.
.El
.Sh FILES
.Bl -tag -width .pdxinit -compact
.It Pa obj
Pascal object file
.It Pa .pdxinit
.Nm Pdx
initialization file
.El
.Sh SEE ALSO
.Xr pi 1 ,
.Xr px 1
.Rs
.%T "An Introduction to Pdx"
.Re
.Sh HISTORY
.Nm Pdx
appeared in
.Bx 4.2 .
.Sh BUGS
.Nm Pdx
does not understand sets,
and provides no information about files.
.Pp
The
.Ic whatis
command doesn't quite work for variant records.
.Pp
Bad things will happen if a procedure invoked with
the
.Ic call
command does a non-local goto.
.Pp
The commands
.Ic step
and
.Ic next
should be able to take a
.Ar count
that specifies how many lines to execute.
.Pp
There should be commands
.Ic stepi
and
.Ic nexti
that correspond
to
.Ic step
and
.Ic next
but work at the instruction level.
.Pp
There should be a way to get an address associated with
a line number, procedure or function, and variable.
.Pp
Most of the command names are too long.
.Pp
The alias facility is quite weak.
.Pp
A
.Xr csh 1 Ns \-like
history capability would improve the situation.