Scripting: The Debugger Shell, Getting Started…

(this is the first in an occasional series around the scripting in eclipse and codewarrior. post a comment – let me know what you think!)

writing code should be fun, and debugging it is just a necessity because i rarely get it right the first time. eclipse with its gui is a great thing, and so is a command line interface. luckily the codewarrior eclipse engineers have added that kind of tool for the codewarrior debugger: the debugger shell as command line debugger using the tcl scripting language. this gives me a powerful way to deal with the embedded target board: from basic access to memory, to stepping and controlling the execution up to programming the flash memory.

the debugger shell is available from the window > show view menu:

show view: debugger shell

a good command to use is help . this lists the built-in commands:

help command

it has an auto-completion feature as well: start typing a command and then press tab : this will show all matching commands with the syntax:

quick help

most commands have as well a short version: so i can type help or just h . that saves me some writing time. additionally i can use the cursor keys to go up and down my command history.

if i default launch configuration, i simply use the debug command:

%>debug
launching {1}: 0% complete 
: 0% complete 
: 7% complete 
launching application: 7% complete 
creating debug session: 7% complete 
launching executable: 7% complete 
preparing executable: 7% complete 
loading symbolic information: 7% complete 
finished loading symbolic information: 7% complete 
preparing executable: 7% complete 
thread break: stopped, 0x0, 0x0, cpu68k, test_uiwidgets.elf (state, tid, pid, cpu, target) 
thread set: stopped, 0x0, 0x0, cpu68k, test_uiwidgets.elf (state, tid, pid, cpu, target) 
downloading 14468 bytes...: 7% complete 
download using 3rd party component...: 7% complete 
download using 3rd party component...: 100% complete 
thread break: stopped, 0x0, 0x0, cpu68k, test_uiwidgets.elf (state, tid, pid, cpu, target)

but how to know which one is the default launch configuration? there is the launch command which tells this:

%>launch
 *>0 - test_uiwidgets_mcf51jm128_internal_flash_pne u-multilink [codewarrior download] 
   1 - twr-lcd jm128 bootloader pne [codewarrior download] 
   2 - attach fslbot mcf52259_internal_flash [codewarrior attach] 
   3 - tower mcf52259 hotsync [codewarrior attach]

the line item with the star (*) denotes my current default launch configuration. knowing the list of launches, i can use any index to debug a project:

%>debug 1

or i can use the name:

%>debug "twr-lcd jm128 bootloader pne"

terminating or killing the debug session is simple using the kill command:

%>kill
thread exit: stopped, 0x0, 0x0, cpu68k, twr-lcdbootloader.elf (state, tid, pid, cpu, target)

stepping is easy: step asm or stepi steps an assembly instruction:

%>step asm
%>stepi

there are as well stepping instruction to step over , step into or step out of a function:

%>step into
%>step over
%>step out

to set a breakpoint, i use the bp command. using bp without argument will list my breakpoints as well.

%>bp main
  id  instance       address   type  enabled?  process  description 
  #5        #1  m:0x00002f86  -auto  enabled        $0  processorexpert.c, line 53, main [twr-lcdbootloader.elf]

to resume the application, i use the command go :

%>go

if it does not hit a breakpoint, i use stop to halt the target:

%>stop

to inspect my variables, i use the var command:

%>var filestatus
$00         
%>var bl_flasherased
$01

and to inspect the memory, i use the mem command:

%>mem 0x00800874 16
    800874  $0000177a $00002f84 $00002f98 $00002c8a   z... ./.. ./.. .,..  
    800884  $00000000 $00002c9c $00000000 $65000c03   .... .,.. .... ...e  
    800894  $4a004d00 $31003200 $3800001e $45ff0000   .m.j .2.1 ...8 ...e  
    8008a4  $0200eb3c $904d5344 $4f53352e $30000220   <... dsm. .5so  ..0

ok, that’s enough for now. this allows me to do all the basic debugging.

next time i’m going to explore how i can script a debug session. i want to automate things. the goal is to use scripts for unit tests using the debugger shell.

happy shell debugging