Instruction Execution Timing
MOTOROLA
ColdFire Core
3-13
3.6.1
TIMING ASSUMPTIONS
For the timing data presented in this section, the following assumptions apply:
1. The operand execution pipeline (OEP) is loaded with the opword and all required extension words
at the beginning of each instruction execution. This implies that the OEP does not wait for the
instruction fetch pipeline (IFP) to supply opwords and/or extension words.
2. The OEP does not experience any sequence-related pipeline stalls. For ColdFire 5200 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 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, i.e., 16 bit
operands aligned on 0-modulo-2 addresses, 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 the following table.
3.6.2
MOVE INSTRUCTION EXECUTION TIMES
the timing for MOVE.L.
Note: 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.
Table 3-9 Misaligned Operand References
ADDRESS[1:0]
SIZE
KBUS
OPERATIONS
ADDITIONAL C(R/W)
X1
Word
Byte, Byte
2(1/0) if read
1(0/1) if write
X1
Long
Byte, Word, Byte
3(2/0) if read
2(0/2) if write
10
Long
Word, Word
2(1/0) if read
1(0/1) if write
F
re
e
sc
a
le
S
e
m
ic
o
n
d
u
c
to
r,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
c
..
.