axd - afnix cross debugger
axd [options] file
[h]
prints the help message
[v]
prints the program version
[i] path
add a directory path to the resolver
[e] mode
force the encoding mode
[f] runini
run initial file
[f] emacs
enable emacs mode
[f] assert
enable assertion checking
[f] noseed
do not seed the random engine
[f] seed
seed the random engine
axd invokes the AFNIX cross debugger. The axd client permits to debug an AFNIX
program by inserting breakpoint at strategic positions in the source code.
During a debugging session, when a breakpoint is reached, the program is
suspended and the debugger prompt is shown. Since the debugger is based on the
AFNIX interpreter, the full power of the AFNIX interpreter is available at the
debugger prompt.
The current version is the 3.7.0 release.
axc, axd, axl,
AFNIX comes with an extensive documentation. The documentation is available
online or in the doc directory in the form of formatted xhtml documents.
axd has been written by (
[email protected]) Amaury Darsch.
This chapter is short introduction to the cross debugger or axd. The debugger is
a special interpreter that is designed to help the developer to trace an
application. The debugger is designed to operate in a stand-alone mode or with
Emacs. If you plan to use the debugger with Emacs, you will have to install a
gud-mode package.
A sample debugger session
The cross debugger or axd is a special interpreter that gives the developer the
opportunity to trace an application and examine the object contents during the
execution. Operations normally available in a debugger are available with axd.
Such operations include breakpoints, stepping, stack tracing, and many others.
Because axd is built on top of the interpreter, all standard operations are
supported by the debugger.
Starting the debugger
The debugger is started with the command axd. Within Emacs, the command Meta-x
axd will do the same. When the debugger is started, an axd prompt is
displayed. At this stage, there is no difference with the standard
interpreter, except that a new nameset called axd is defined with all debugger
commands. The axd:quit or axd:quit commands will terminate the session.
zsh> axd
(axd)axd:quit
Debugger commands
All debugger commands are located in the axd nameset. For example, the command
to set a breakpoint is axd:break. Since typing such command can be annoying,
it is possible to rebind them at your convenience. For example, the form const
b axd:break will define the symbol b as the breakpoint command, but care
should be taken with this approach if your program uses the same symbol.
Debugging session example
The first example that demonstrates the use of axd is located in the directory
exp/ref, that is part of this distribution. The platform information example
EXP0501.als will be used for illustration. A simple session and the original
source code is given below.
zsh> axi EXP0501.als
major version number : 3
minor version number : 2
patch version number : 0
interpreter version : 3.2.0
program name : afnix
operating system name : linux
operating system type : unix
machine size : 64
afnix official uri : http://www.afnix.org
The source code for this example is given below.
# many comments before
println "major version number : " interp:major-version
println "minor version number : " interp:minor-version
println "patch version number : " interp:patch-version
println "interpreter version : " interp:version
println "program name : " interp:program-name
println "operating system name : " interp:os-name
println "operating system type : " interp:os-type
println "machine size : " interp:machine-size
println "afnix official url : " interp:afnix-uri
The debugger is started with the file to debug. The axd:info command can be used
to print some information.
zsh> axd EXP0501.als
(axd) axd:info
debugger version : 3.2.0
os name : linux
os type : unix
initial file : EXP0501.als
form file name : EXP0501.als
form line number : 17
verbose mode : true
max line display : 10
defined breakpoints : 0
(axd)
Along with the version, initial file name and other information, is the form
file name and the form line number that indicates where the debugger is
position. Another way to get this information is with the axd:list command
that display the file at its current break position.
(axd) axd:list
17 println "major version number : " interp:major-version
18 println "minor version number : " interp:minor-version
19 println "patch version number : " interp:patch-version
20 println "interpreter version : " interp:version
21 println "program name : " interp:program-name
22 println "operating system name : " interp:os-name
23 println "operating system type : " interp:os-type
24 println "afnix official uri : " interp:afnix-uri
25
26
(axd)
With this in place it is possible to run the program. The axd:run command will
do the job, but will not give you the opportunity to do something since there
is no breakpoint installed. So, installing a breakpoint is simply achieved by
giving the file name and line number. To make life easier, the axd:break
command takes also 0 or argument. Without argument, a breakpoint is set at the
current position. With one integer argument, a breakpoint is set at the
specified line in the current file. If the verbose mode is active (which is
the default), a message is printed to indicate the breakpoint index.
(axd) axd:break 19
setting breakpoint 0 in file EXP0501.als at line 19
(axd)axd:run
major version number : 3
minor version number : 2
breakpoint 0 in file EXP0501.als at line 19
(axd)
The axd:run command starts the program and immediately stops at the breakpoint.
Note that the debugger prints a message to indicate the cause of such break.
After this, stepping is achieved with the axd:next command. Resuming the
execution is done with the axd:continue command. The axd:exit or axd:quit
command terminates the session.
(axd)axd:next
patch version number : 3
(axd)axd:next
interpreter version : 3-2-0
(axd)axd:continue
program name : axd
operating system name : linux
operating system type : unix
afnix official uri : http://www.afnix.org
(axd)axd:quit
This chapter describes in detail the usage of the cross debugger or axc. The
debugger is a special application that is built on top of the interpreter. For
this reason, the debugger provides the full execution environment with special
commands bound into a dedicated nameset.
Invocation and termination
The axd debugger is started by typing the command axd. Once started, the
debugger reads the commands from the terminal. Since the debugger is built on
top of the interpreter, any command is in fact a special form that is executed
by the interpreter. The natural way to invoke the debugger is to pass the
primary file to debug with eventually some arguments.
zsh> axd PROGRAM [arguments]
When the debugger is started, a prompt '(axd)' indicates that the session is
running. The debugger session is terminated with the commands axd:exit or
axd:quit.
zsh> axd PROGRAM
(axd) axd:quit
zsh>
Debugger options
The available options can be seen with the h option and the current version with
the v option. This mode of operations is similar to the one found with the
interpreter.
zsh> axd [h]
usage: axd [options] [file] [arguments]
[h] print this help message
[v] print version information
[i] path add a path to the resolver
[e mode] force the encoding mode
[f runini] run initial file
[f emacs] enable emacs mode
[f assert] enable assertion checks
[f nopath] do not set initial path
Running the program
When a program is run within the debugger, a primary file must be used to
indicate where to start the program. The file name can be given either as an
axd command argument or with the axd:load command. The first available form in
the primary file is used as the program starting point.
Loading the program
The axd:load command loads the primary file and mark the first available form as
the starting form for the program execution. The command takes a file name as
its first argument. The resolver rule apply for the file name resolution.
If the string name has the .als extension, the string is considered to be the
file name.
If the string name has the .axc extension or no extension, the string is used
to search a file that has a .als extension or that belongs to a
librarian.
Note that these operations are also dependent on the i option that adds a path
or a librarian to the search-path.
Starting the program
The axd:run command starts the program at the first available form in the
primary file. The program is executed until a breakpoint or any other halting
condition is reached. Generally, when the program execution is suspended, an
entry into the debugger is done and the prompt is shown at the command line.
(axd)axd:run
The axd:run is the primary command to execute before the program can be
debugged. Eventually, a file name can be used as the primary file to execute.
(axd)axd:run "test.als"
Setting program arguments
Since the debugger is built on top of the interpreter, it is possible to set
directly the argument vector. The argument vector is bound to the interpreter
with the qualified name interp:argv. The standard vector can be used to
manipulate the argument vector.
(axd)interp:argv:reset
(axd)interp:argv:append "hello"
In this example, the interpreter argument vector is reset and then a single
argument string is added to the vector. If one wants to see the interpreter
argument vector, a simple procedure can be used as shown below.
const argc (interp:argv:length)
loop (trans i 0) (< i argc) (i:++) {
trans arg (interp:argv:get i)
println "argv[" i "] = " arg
}
Breakpoints operations
Breakpoints are set with the axd:break command. If a breakpoint is reached
during the program execution, the program is suspended and the debugger
session is resumed with a command prompt. At the command prompt, the full
interpreter is available. It permits to examine symbols.
Breakpoint command
The axd:break command sets a breakpoint in a file at a specified line number. If
the file is not specified, the primary file is used instead. If the line
number is not specified, the first available form in the current file is used.
(axd) axd:break "demo.als" 12
Setting breakpoint 0 in file demo.als at line 12
In this example, a breakpoint is set in the file demo.als at the line number 12.
The file name does not have to be the primary file. If another file name is
specified, the file is loaded, instrumented and the breakpoint is set.
Viewing breakpoints
The axd:break-info command reports some information about the current breakpoint
setting.
(axd) axd:break "demo.als" 12
(axd) axd:break "test.als" 18
(axd) axd:break-info
Breakpoint 0 in file demo.als at line 12
Breakpoint 1 in file test.als at line 18
Resuming execution
The axd:continue command resumes the program execution after a breakpoint. The
program execution continues until another breaking condition is reached or the
program terminates.
(axd) axd:run
Breakpoint 0 in file demo.als at line 12
(axd) axd:continue
In this example, the program is run and stopped at breakpoint 0. The
axd:continue command resumes the program execution.
This appendix is a reference of the cross debugger or axd. The cross debugger is
started with the axd command. All control commands are bound to the axd
nameset.
break
The axd:breakbreak command sets a breakpoint. Without argument a breakpoint is
set in the current file at the current line. With a line number, the
breakpoint is set in the current file. With two arguments, the first one is
used as the file name and the second one is used as the line number.
Syntax
axd:break axd:break "line" axd:break
"file" "line"
(axd) axd:break "demo.als" 12
(axd) axd:break 25
The first example sets a breakpoint in the file demo.als at line 12. The second
example sets a breakpoint in the current file at line 25. Without argument,
the command sets the breakpoint at the current line. The current line can be
seen with the axd:info command.
break-info
The axd:break-info control command reports some information about the current
breakpoints.
Syntax
axd:break-info
(axd) axd:break "demo.als" 12
(axd) axd:break "test.als" 18
(axd) axd:break-info
Breakpoint 0 in file demo.als at line 12
Breakpoint 1 in file test.als at line 18
In this example, two breakpoints are set. One in file demo.als at line 12 and
one in file test.als at line 18. The axd:break-info command reports the
current breakpoint settings.
continue
The axd:continue control command resumes the program execution after a
breakpoint. The program execution continues until a breakpoint or another
terminating condition is reached.
Syntax
axd:continue
(axd) axd:run
Breakpoint 0 in file demo.als at line 12
(axd) axd:continue
In this example, the program is run and stopped at breakpoint 0. The
axd:continue command resumes the program execution.
exit
The axd:exit command terminates a debugger session. This command is similar to
the axd:quit command.
Syntax
axd:exit
(axd) axd:exit
info
The axd:info command reports some debugger information. Such information
includes the debugger version, the operating system, the primary input file,
the primary input file source and more.
Syntax
axd:info
(axd) axd:info
debugger version : ..
os name : linux
os type : unix
initial file : 0501
form file name : 0501.als
form line number : 17
verbose mode : true
max line display : 10
defined breakpoints : 0
list
The axd:list command display the form listing starting at the current session
line number. The current form line number can also be seen with the axd:info
command. The number of line is a debugger parameter. The first line to display
can also be set as the first parameter. A file name can also be set.
Syntax
axd:list axd:list "line" axd:list
"file" "line"
(axd) axd:list
(axd) axd:list 20
(axd) axd:list "file.als" 20
The first example shows the listing at the current debugger line. The second
example starts the listing at line 20. The third example starts at line 20
with file file.als.
load
The axd:load command sets the initial or default file to be used with the
axd:run control command.
Syntax
axd:load "file"
(axd) axd:load "demo.als"
In this example, the file demo.als is set as the primary file. Using the
axd:info command will report at which line, the first available form has been
found.
next
The axd:next command executes the next line in the source file. The axd:next
command does not take argument.
Syntax
axd:next
(axd) axd:next
quit
The axd:quit command terminates a debugger session. This command is similar to
the axd:exit command.
Syntax
axd:quit
(axd) axd:quit
run
The axd:run command executes the default file in the slave interpreter. Without
argument, the initial or default file is executed. The axd:load command can be
used to set the initial file. With one argument, the file name argument is
used as the initial file.
Syntax
axd:run axd:run "file"
(axd) axd:run
(axd) axd:run "demo.als"
The first example runs the initial file. The second example sets the initial
file as demo.als and run it.