Intel XENIX 286 Programmers Guide (86) - Tenox.tc

XENIX Programming adb: Program Debugger
Breakpoints are typically set to stop program execution at a specific place in the
program, such as the beginning of a function, so that the contents of registers and
memory can be examined. For example, the command
main:br
sets a breakpoint at the start of the function main. The breakpoint is taken just as
control enters the function and before the function's stack frame is created.
A breakpoint with a count is typically used within a function that is called several times
during execution of a program, or within the instructions that correspond to a for or
while statement. Such a breakpoint allows the program to cont inue to execute until the
given function or instructions have been executed the specified number of times. For
example, the command
light,S:br
sets a breakpoint at the fifth invocation of the function light. The breakpoint does not
stop the program until function light has been called five times.
Note that no more than 16 breakpoints at a time are allowed.
Displaying Breakpoints
The command $b displays the location and count of each currently defined breakpoint.
Breakpoints are listed by address, along with any count and/or command associated with
them.
Continuing Execution
You can continue the execution of a program after it has been stopped by a breakpoint
by using the :co command. The command has the form
[ address 1 [,count] :co [signal]
where address is the address of the instruction at which you wish to continue execution,
count is the number of breakpoints you wish to ignore, and signal is the number of the
signal to send to the program (see signal in "System Functions" in the XENIX 286 C
Library Guide).
If no address is given, the program starts at the next instruction after the breakpoint. If
count is given, adb ignores the first count breakpoints.
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