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<title>Breakpoints commands of µCsim</title>
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<h2>Commands of µCsim to manage breakpoints</h2>
Two kind of breakpoint can be used: fetch and event
breakpoint. <B>Fetch</b> breakpoints are classical breakpoints. They
can be placed at any instruction in the code memory. Breakpoint will
be hit if CPU fetches instruction code from the memory location
specified by the breakpoint. Only fetching of first byte of the
instruction hits the breakpoint. If the execution reaches a breakpoint
it stops <i>before</i> the instruction at location specified by the
breakpoint would be executed.
<p><b>Event</b> breakpoints are special onces. They cause stop of
execution if event specified by the breakpoint occures. Event can be a
read or a write operation on any address space location. Event
breakpoint stops execution <i>after</i> specified event occured.
<p>Every breakpoint can be <b>fix</b> (permanent) or <b>dynamic</b>
(temporary). Dynamic breakpoints are automatically removed when they
reached. Some commands place dynamic fetch breakpoints into the code,
for example <a href="#g"><b>go</b></a> or <a
href="#n"><b>next</b></a>.
<p>A <b>hit number</b> can be associated to any breakpoint. This hit
number specifies how many times the breakpoint must be hit before it
causes the execution to stop. This hit number is 1 by default.
<hr>
<a name="break"><h3>break <i>addr [hit]</i>
<br>break <i>memory_type r|w addr [hit]</i></h3></a>
<a name="tbreak"><h3>tbreak<i> addr [hit]</i>
<br>tbreak <i>memory_type r|w addr [hit]</i></h3></a>
Set fetch or event breakpoint. The command specifies if the breakpoint
will be fix (<b>break</b>) or dynamic (temporary)
(<b>tbreak</b>).
<p>Fetch or event breakpoint can be defined. First form defines fetch
while second form defines event breakpoint.
<dl><dt>Fetch breakpoint
<dd>First parameter specifies address where the breakpoint must be
placed to. It should be address of an instruction.
<br>Second parameter is optional and it specifies the hit number. It is
1 by default.
<dt>Event breakpoint
<dd>First parameter specifies class name of memory where we are going
to watch for en event. Class names of memories can be checked by <a
href="cmd_general.html#info_memory">info memory</a> command.
<br>Second parameter specifies the event. It can be <b>r</b> to
specify <b>read</b> operation or <b>w</b> which means <b>write</b>
operation.
<br>Remaining parameters are address of watched memory location and an
optional hit number (1 by default).
</dl>
<pre>
$ <font color="#118811">s51 remoansi.hex</font>
ucsim 0.2.24, Copyright (C) 1997 Daniel Drotos, Talker Bt.
ucsim comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
This is free software, and you are welcome to redistribute it
under certain conditions; type `show c' for details.
58659 bytes read from remoansi.hex
> <font color="#118811">dc 0 0x10</font>
000000 02 01 60 LJMP 0160
* 000003 02 00 3c LJMP 003c
* 000006 ff MOV R7,A
* 000007 ff MOV R7,A
* 000008 ff MOV R7,A
* 000009 ff MOV R7,A
* 00000a ff MOV R7,A
* 00000b 02 3b e0 LJMP 3be0
* 00000e ff MOV R7,A
* 00000f ff MOV R7,A
* 000010 ff MOV R7,A
> <font color="#118811">break 0x160</font>
Breakpoint 1 at 0x000160: CLR P1.0
> <font color="#118811">tbreak 8 2</font>
Breakpoint 2 at 0x000008: MOV R7,A
> <font color="#118811">g</font>
Simulation started, PC=0x000000
Stop at 000160: (4) Breakpoint
F 000160
> </pre>
<hr>
<a name="clear"><h3>clear <i>[addr...]</i></h3></a>
Delete fetch breakpoint. Parameter specifies address of breakpoint. If
there is no breakpoint specified at given address this command prints
out a warning message.
<p>If parameter is not given then breakpoint at current PC will be
deleted if it exists. If more than one address is specified then all
breakpoints at specified addresses will be deleted.
<pre>
> <font color="#118811">i b</font>
Num Type Disp Hit Cnt Address What
1 fetch keep 1 1 0x000160 CLR P1.0
2 fetch del 1 1 0x000180 LJMP 022a
1 event keep 1 1 0x000006 wi
> <font color="#118811">clear 160</font>
No breakpoint at 0000a0
> <font color="#118811">clear 0x160</font>
> <font color="#118811">i b</font>
Num Type Disp Hit Cnt Address What
2 fetch del 1 1 0x000180 LJMP 022a
1 event keep 1 1 0x000006 wi
> </pre>
<hr>
<a name="delete"><h3>delete <i>[number...]</i></h3></a>
Delete breakpoint(s) by its number.
<p>If parameter is not used then all breakpoints are deleted.
<hr>
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