User`s guide

Chapter 7: Debugging Machine Language Code

Consider a single-precision ﬂoating point array named array. You can

examine the six consecutive elements, beginning with the ﬁfth element, by

entering:

(dbx) &array[4] / 6f

7fffc748: 0.2500000 0.2000000 0.1666667 0.1428571

7fffc758: 0.1250000 0.1111111

Setting Machine-Level Breakpoints

dbx allows you to set breakpoints while debugging machine code just as you

can while debugging source code. You set breakpoints at the machine code

level using the stopi command.

The conditional and unconditional versions of the stopi commands work in

the same way as the stop command described in “Setting Breakpoints” on

page 59, with these exceptions:

• The stopi command checks its breakpoint conditions on a machine-

instruction level instead of a source-code level.

• The stopi at command requires an address rather than a line number.

Each breakpoint is assigned a number when you create it. Use this number

to reference the breakpoint in the various commands provided for

manipulating breakpoints (for example, disable, enable, and delete, all

described in “Managing Breakpoints, Traces, and Conditional Commands”

on page 70).

Syntax of the

stopi

Command

The syntax of the stopi command is:

stopi at Sets an unconditional breakpoint at the current instruction.

stopi at address

Sets an unconditional breakpoint at the speciﬁed address.

stopi in procedure

Sets an unconditional breakpoint to stop execution upon

entering the speciﬁed procedure.