Debug in Depth
ARM DDI 0210C
Copyright © 2001, 2004 ARM Limited. All rights reserved.
B-57
B.18
Coupling breakpoints and watchpoints
You can couple watchpoint units 1 and 0 together using the
CHAIN
and
RANGE
inputs. Using
CHAIN
enables Watchpoint 0 to be triggered only if Watchpoint 1 has
previously matched. The use of
RANGE
enables simple range checking to be
performed by combining the outputs of both watchpoints.
B.18.1
Breakpoint and watchpoint coupling example
Let:
Av[31:0]
be the value in the address value register
Am[31:0]
be the value in the address mask register
A[31:0]
be the address bus from the ARM7TDMI core
Dv[31:0]
be the value in the data value register
Dm[31:0]
be the value in the data mask register
D[31:0]
be the data bus from the ARM7TDMI core
Cv[8:0]
be the value in the control value register
Cm[7:0]
be the value in the control mask register
C[9:0]
be the combined control bus from the ARM7TDMI core, other
watchpoint registers and the
EXTERN
signal.
CHAINOUT signal
The
CHAINOUT
signal is derived as follows:
WHEN (({Av[31:0],Cv[4:0]} XNOR {A[31:0],C[4:0]}) OR {Am[31:0],Cm[4:0]} == 0xFFFFFFFFF)
CHAINOUT = ((({Dv[31:0],Cv[7:5]} XNOR {D[31:0],C[7:5]}) OR {Dm[31:0],Cm[7:5]}) == 0x7FFFFFFFF)
The
CHAINOUT
output of watchpoint register 1 provides the
CHAIN
input to
Watchpoint 0. This
CHAIN
input enables you to specify complicated configurations of
breakpoints and watchpoints.
Note
There is no
CHAIN
input to Watchpoint 1 and no
CHAIN
output from Watchpoint 0.
Consider, for example, the request by a debugger to breakpoint on the instruction at
location YYY when running process XXX in a multi-process system. If the current
process ID is stored in memory, you can implement the above function with a
watchpoint and breakpoint chained together. The watchpoint address points to a known
memory location containing the current process ID. The watchpoint data points to the
required process ID. The
ENABLE
bit is cleared.
Содержание ARM7TDMI
Страница 6: ...Contents vi Copyright 2001 2004 ARM Limited All rights reserved ARM DDI 0210C ...
Страница 10: ...List of Tables x Copyright 2001 2004 ARM Limited All rights reserved ARM DDI 0210C ...
Страница 14: ...List of Figures xiv Copyright 2001 2004 ARM Limited All rights reserved ARM DDI 0210C ...
Страница 46: ...Introduction 1 26 Copyright 2001 2004 ARM Limited All rights reserved ARM DDI 0210C ...
Страница 120: ...Coprocessor Interface 4 18 Copyright 2001 2004 ARM Limited All rights reserved ARM DDI 0210C ...
Страница 142: ...Debug Interface 5 22 Copyright 2001 2004 ARM Limited All rights reserved ARM DDI 0210C ...
Страница 276: ...Differences Between Rev 3a and Rev 4 C 6 Copyright 2001 2004 ARM Limited All rights reserved ARM DDI 0210C ...
Страница 282: ...Glossary Glossary 6 Copyright 2001 2004 ARM Limited All rights reserved ARM DDI 0210C ...