Motorola MPC860 PowerQUICC User Manual page 963

Byte Mask
Compare
Size
Comparator G
Eq Eq
Byte 0 Lt
Lt
Eq
Eq
Byte 1
Lt
Lt
Size
Eq
Eq
Logic
Byte 2
Lt
Lt
Eq Eq
Byte 3
Lt
Lt
Byte Mask
Comparator H
Eq
Eq
Byte 0 Lt
Lt
Eq
Eq
Byte 1
Lt
Lt
Size
Eq
Eq
Logic
Byte 2
Lt
Lt
Eq Eq
Byte 3
Lt
Lt
Figure 37-3. Load/Store Support General Structure
Each of the two load/store data comparators (G and H) is 32 bits wide and can be
programmed to treat numbers as signed or unsigned. Each data comparator operates as four
independent byte comparators. Each byte comparator has a mask bit and generates two
output signalsÑequal and less than (if the mask bit is not set.) Therefore, each 32-bit
comparator has eight output signals. These signals generate the equal and less-than signals
according to the compare size programmed by the user (byte, half-word, word). All signals
are signiÞcant in byte mode. In half-word mode, only four signals from each 32-bit
comparator are signiÞcant; when operating in word mode, only two signals are signiÞcant.
One of the next four match events is generated by the equal and less-than signalsÑequal,
not equal, greater than, or less than, depending on the compare type programmed.
Therefore, from the two 32-bit comparators, eight match indications are generatedÑ
Gmatch[0Ð3] and Hmatch[0Ð3]. According to the lower bits of the address and the size of
the cycle, only match indications detected on bytes with valid information are validated.
The rest are negated. If the executed cycle has a smaller size than the compare size (a byte
access when the compare size is word or half-word), no match indication is asserted. The
match indication signals generate four load/store data events as shown in Table 37-7.
MOTOROLA
Compare
Type
Compare
Byte
Type
Qualifier
Logic
Logic
Compare
Byte
Type
Qualifier
Logic
Logic
Chapter 37. System Development and Debugging
Data
Cycle Size
Comparator E
Lt Eq
Compare
Type
Type Logic
Generator
G
H
AND-OR Logic
(G&H)
(G|H)
Part VI. Debug and Test
Comparator F
Lt Eq
Type Logic
Events
L-watchpoint 0
L-watchpoint 1
L-breakpoint
37-13