23-18
MPC561/MPC563 Reference Manual
MOTOROLA
Watchpoints and Breakpoints Support
Modes”). Each comparator generates two output signals: equal and less than. These signals
are used to generate one of the following four events (one from each comparator): equal,
not equal, greater than, less than.
There are two load/store data comparators (comparators G,H) each is 32 bits wide and can
be programmed to treat numbers either as signed values or as unsigned values. Each data
comparator operates as four independent byte comparators. Each byte comparator has a
mask bit and generates two output signals: equal and less than, if the mask bit is not set.
Therefore, each 32 bit comparator has eight output signals.
These signals are used to generate the “equal and less than” signals according to the
compare size programmed (byte, half-word, word). When operating in byte mode all
signals are significant, when operating in half-word mode only four signals from each 32
bit comparator are significant. When operating in word mode only two signals from each
32 bit comparator are significant.
From the new “equal and less than” signals and according to the compare type programmed
one of the following four match events are generated: equal, not equal, greater than, less
than. Therefore, from the two 32-bit comparators eight match indications are generated:
Gmatch[0:3], Hmatch[0:3].
According to the lower bits of the address and the size of the cycle, only match indications
that were detected on bytes that have valid information are validated, the rest are negated.
Note that if the cycle executed has a smaller size than the compare size (e.g., a byte access
when the compare size is word or half-word) no match indication will be asserted.
Using the match indication signals four load/store data events are generated in the
following way.
The four load/store data events together with the match events of the load/store address
comparators and the instruction watchpoints are used to generate the load/store watchpoints
and breakpoint according to the programming.
Table 23-7. Load/Store Data Events
Event Name
Event Function 1
1 ‘&’ denotes a logical AND, ‘|’ denotes a logical OR
G
(Gmatch0 | Gmatch1 | Gmatch2 | Gmatch3)
H
(Hmatch0 | Hmatch1 | Hmatch2 | Hmatch3)
(G&H)
((Gmatch0 & Hmatch0) | (Gmatch1 & Hmatch1) | (Gmatch2 & Hmatch2) | (Gmatch3 & Hmatch3))
(G | H)
((Gmatch0 | Hmatch0) | (Gmatch1 | Hmatch1) | (Gmatch2 | Hmatch2) | (Gmatch3 | Hmatch3))