Breakpoint Debugger Commands — MAME Documentation 0.287 documentation

# Breakpoint Debugger Commands

bpset

  sets a breakpoint at <address>

bpclear

  clears a specific breakpoint or all breakpoints

bpdisable

  disables a specific breakpoint or all breakpoints

bpenable

  enables a specific breakpoint or all breakpoints

bplist

  lists breakpoints

Breakpoints halt execution and activate the debugger before a CPU executes an instruction at a particular address.

## bpset

bp[set] <address>[:<CPU>][,<condition>[,<action>]]

Sets a new execution breakpoint at the specified <address>. The <address> may optionally be followed by a colon and a tag or debugger CPU number to set a breakpoint for a specific CPU. If no CPU is specified, the breakpoint will be set for the CPU currently visible in the debugger.

The optional <condition> parameter lets you specify an expression that will be evaluated each time the breakpoint address is hit. If the result of the expression is true (non-zero), the breakpoint will halt execution; otherwise, execution will continue with no notification. The optional <action> parameter provides a command to be executed whenever the breakpoint is hit and the <condition> is true. Note that you may need to surround the action with braces `{ }` to ensure commas and semicolons within the command are not interpreted in the context of the `bpset` command itself.

Each breakpoint that is set is assigned a numeric index which can be used to refer to it in other breakpoint commands. Breakpoint indices are unique throughout a session.

Examples:

`bp 1234`

  Set a breakpoint for the visible CPU that will halt execution whenever the PC is equal to 1234.

`bp 23456,a0 == 0 && a1 == 0`

  Set a breakpoint for the visible CPU that will halt execution whenever the PC is equal to 23456 and the expression `a0 == 0 && a1 == 0` is true.

`bp 3456:audiocpu,1,{ printf "A0=%08X\n",a0 ; g }`

  Set a breakpoint for the CPU with the absolute tag path `:audiocpu` that will halt execution whenever the PC is equal to 3456. When this happens, print A0=<a0val> to the debugger console and resume execution.

`bp 45678:2,a0==100,{ a0 = ff ; g }`

  Set a breakpoint on the third CPU in the system (zero-based index) that will halt execution whenever the PC is equal to 45678 and the expression `a0 == 100` is true. When that happens, set a0 to ff and resume execution.

`temp0 = 0 ; bp 567890,++temp0 >= 10`

  Set a breakpoint for the visible CPU that will halt execution whenever the PC is equal to 567890 and the expression `++temp0 >= 10` is true. This effectively breaks only after the breakpoint has been hit sixteen times.

Back to Breakpoint Debugger Commands

## bpclear

bpclear [<bpnum>[,…]]

Clear breakpoints. If <bpnum> is specified, the breakpoints referred to will be cleared. If <bpnum> is not specified, all breakpoints will be cleared.

Examples:

`bpclear 3`

  Clear the breakpoint with index 3.

`bpclear`

  Clear all breakpoints.

Back to Breakpoint Debugger Commands

## bpdisable

bpdisable [<bpnum>[,…]]

Disable breakpoints. If <bpnum> is specified, the breakpoints referred to will be disabled. If <bpnum> is not specified, all breakpoints will be disabled.

Note that disabling a breakpoint does not delete it, it just temporarily marks the breakpoint as inactive. Disabled breakpoints will not cause execution to halt, their associated condition expressions will not be evaluated, and their associated commands will not be executed.

Examples:

`bpdisable 3`

  Disable the breakpoint with index 3.

`bpdisable`

  Disable all breakpoints.

Back to Breakpoint Debugger Commands

## bpenable

bpenable [<bpnum>[,…]]

Enable breakpoints. If <bpnum> is specified, the breakpoint referred to will be enabled. If <bpnum> is not specified, all breakpoints will be enabled.

Examples:

`bpenable 3`

  Enable the breakpoint with index 3.

`bpenable`

  Enable all breakpoints.

Back to Breakpoint Debugger Commands

## bplist

bplist [<CPU>]

List current breakpoints, along with their indices and any associated conditions or actions. If no <CPU> is specified, breakpoints for all CPUs in the system will be listed; if a <CPU> is specified, only breakpoints for that CPU will be listed. The <CPU> can be specified by tag or by debugger CPU number (see Specifying devices and address spaces for details).

Examples:

`bplist`

  List all breakpoints.

`bplist .`

  List all breakpoints for the visible CPU.

`bplist maincpu`

  List all breakpoints for the CPU with the absolute tag path `:maincpu`.

Back to Breakpoint Debugger Commands