Move Instruction Execution Times; Misaligned Operand References - Motorola ColdFire MCF5281 User Manual

Instruction Execution Timing
2. The OEP does not experience any sequence-related pipeline stalls. For V2 ColdFire
processors, the most common example of this type of stall involves consecutive
store operations, excluding the MOVEM instruction. For all STORE operations
(except MOVEM), certain hardware resources within the processor are marked as
"busy" for two processor clock cycles after the final DSOC cycle of the store
instruction. If a subsequent STORE instruction is encountered within this 2-cycle
window, it will be stalled until the resource again becomes available. Thus, the
maximum pipeline stall involving consecutive STORE operations is 2 cycles. The
MOVEM instruction uses a different set of resources and this stall does not apply.
3. The OEP completes all memory accesses without any stall conditions caused by the
memory itself. Thus, the timing details provided in this section assume that an
infinite zero-wait state memory is attached to the processor core.
4. All operand data accesses are aligned on the same byte boundary as the operand
size: that is, 16 bit operands aligned on 0-modulo-2 addresses and 32 bit operands
aligned on 0-modulo-4 addresses.
If the operand alignment fails these guidelines, it is misaligned. The processor core
decomposes the misaligned operand reference into a series of aligned accesses as shown in
Table 2-10.
2.8.2

MOVE Instruction Execution Times

The execution times for the MOVE.{B,W} instructions are shown in Table 2-11, while
Table 2-12 provides the timing for MOVE.L.
For all tables in this section, the execution time of any instruction using the PC-relative
effective addressing modes is the same for the comparable An-relative mode.
The nomenclature "xxx.wl" refers to both forms of absolute addressing, xxx.w and xxx.l.
2-22
Table 2-10. Misaligned Operand References
Address[1:0] Size
X1 Word
X1 Long
10 Long
MCF5282 User's Manual
Kbus Additional
Operations C(R/W)
Byte, Byte 2(1/0) if read
1(0/1) if write
Byte, Word, Byte 3(2/0) if read
2(0/2) if write
Word, Word 2(1/0) if read
1(0/1) if write
MOTOROLA