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1
2
CLOCK
BUS
WRITE
CONTROLLER
FOR 1
INSTRUCTION
MOVE A1,(AO)+
CONTROLLER
EXECUTION
MOVE.W A1,(AO)+
TIME
5.7.2.2 TIMING EXAMPLE 2—BRANCH INSTRUCTIONS. Example 2 shows what
happens when a branch instruction is executed for both the taken and not-taken cases.
(see Figures 5-34 and 5-35). The instruction stream is for a simple limit check with the
variable already in a data register.
Instructions
1
2
CLOCK
1 PRE-
BUS
FETCH
CONTROLLER
INSTRUCTION
MOVEQ
CONTROLLER
EXECUTION
MOVEQ
TIME
#7,D1
MOTOROLA
Freescale Semiconductor, Inc.
3
4
5
6
7
1 PRE-
READ
FETCH
FOR 2
EA FETCH
ADDQ
ADDQ.W #1,(AO)
Figure 5-33. Example 1—Instruction Stream
MOVEQ
CMP.L
BLE.B
MOVE.L
3
4
5
6
7
2 PRE-
PRE-
FETCH
FETCH
OFFSET
CMP
TAKEN
CALC
CMP
BLE.B NOT TAKEN
D1,D0
Figure 5-34. Example 2—Branch Taken
MC68340 USER'S MANUAL
For More Information On This Product,
Go to: www.freescale.com
8
9
0
1
2
3
2 PRE-
WRITE
FETCH
FOR 2
ADDQ
EA CALC
TO <EA>
CLR
#7, D1
D1, D0
NEXT
D1, (A0)
8
9
0
1
2
3
PRE-
PRE-
FETCH
FETCH
TAKEN
TAKEN
4
5
8
6
7
3 PRE-
3 PRE-
WRITE
FETCH
FETCH
FOR 3
CLR
<EA>
CLR.W $30(A1)
4
WRITE
FOR 3
NEXT
INST.
5- 95
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