23-16
MPC561/MPC563 Reference Manual
MOTOROLA
Watchpoints and Breakpoints Support
result of the assertion of MSR[RI] when operating in the masked mode), the first instruction
will not cause an instruction breakpoint if the ignore first match (IFM) bit in the instruction
support control register (ICTRL) is set (used for “continue”).
When the IFM bit is clear, every matched instruction can cause an instruction breakpoint
(used for “go from x”). This bit is set by the software and cleared by the hardware after the
first instruction breakpoint match is ignored. Load/store breakpoints and all counter
generated breakpoints (instruction and load/store) are not affected by this mode.
23.2.1.6 Generating Six Compare Types
Using the four compare types mentioned above (equal, not equal, greater than, less than) it
is possible to generate also two more compare types: greater than or equal and less than or
equal.
Generating the greater than or equal compare type can be done by using the greater
than compare type and programming the comparator to the needed value minus 1.
Generating the less than or equal compare type can be done by using the less than
compare type and programming the comparator to the needed value plus 1.
This method does not work for the following boundary cases:
Less than or equal of the largest unsigned number (1111...1)
Greater than or equal of the smallest unsigned number (0000...0)
Less than or equal of the maximum positive number when in signed mode (0111...1)
Greater than or equal of the maximum negative number when in signed mode
(1000...)
These boundary cases need no special support because they all mean ‘a(chǎn)lways true’ and can
be programmed using the ignore option of the load/store watchpoint programming (refer to
23.2.2
Instruction Support
There are four instruction address comparators A,B,C, and D. Each is 30 bits long,
generating two output signals: equal and less than. These signals are used to generate one
of the following four events: equal, not equal, greater than, less than.
The instruction watchpoints and breakpoint are generated using these events and according
to user programming. Note that using the OR option enables “out of range” detect.