The MPC8xx Core
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor
3-15
Integer processor The core implements the following integer instructions:
• Arithmetic instructions
• Compare instructions
• Trap instructions
• Logical instructions
• Rotate and shift instructions
Move to/from
SPR instructions
Move to/from invalid SPRs in which SPR[0] = 1 invokes the privileged instruction error exception
handler if the processor is in user mode.
Integer arithmetic
instructions
Attempting to use
divw
to perform either 0x80000000
÷
-1 or <anything>
÷
0 sets the contents of
r
D to 0x80000000 and if Rc =1, the contents of CR0 are LT = 1, GT = 0, and EQ = 0. SO is set to
the correct value.
In the
cmpi
,
cmp
,
cmpli
, and
cmpl
instructions, the L bit is applicable for 64-bit implementations.
For the MPC885, if L = 1 the instruction form is invalid. The core ignores this bit and, therefore, the
behavior when L = 1 is identical to the valid form instruction with L = 0.
Integer load/store
with update
instructions
For load with update and store with update instructions where
r
A = 0, the EA is written into
r
0. For
load with update instructions where
r
A =
r
D,
r
A is boundedly undefined.
Integer load/ store
multiple
instructions
For these types of instructions, EA must be a multiple of four. If it is not, the system alignment error
handler is invoked. For an
lmw
instruction (if
r
A is in the range of registers to be loaded), the
instruction completes normally.
r
A is then loaded from the memory location as follows:
r
A <- MEM(EA+(
r
A-
r
D)*4, 4)
Integer load string
instructions
Load string instructions behave like load multiple instructions with respect to invalid format in which
r
A is in the range of registers to be loaded. If
r
A is in the range, it is updated from memory.
Memory
synchronization
instructions
For these instructions, if EA is not a multiple of four, the system alignment error handler is invoked.
Optional
instructions
No optional instructions are supported.
Little-endian byte
ordering
The LSU supports little-endian byte ordering as specified in the UISA. In little-endian mode, trying
to execute an unaligned individual scalar or multiple/string access causes an alignment exception.
Table 3-3. UISA-Level Features (continued)
Functionality
Description
Summary of Contents for PowerQUICC MPC870
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