SAF-C164SM Infineon Technologies, SAF-C164SM Datasheet - Page 61

• Manufacturer Part Number: SAF-C164SM
• Description: 16-Bit CMOS Microcontroller
• Manufacturer: Infineon Technologies

Sequential Instruction Processing
Each single instruction must pass through each of the four pipeline stages regardless of
whether or not all possible stage operations are actually performed. Because passing
through one pipeline stage takes at least one machine cycle, any isolated instruction
takes at least four machine cycles to be completed. Pipelining, however, allows parallel
(simultaneous) processing of up to four instructions. Thus, most of the instructions seem
to be processed in one machine cycle as soon as the pipeline has been filled once after
reset (see
Instruction pipelining increases the average instruction throughput considered over a
certain period of time. In the following, any execution time specification for an instruction
always refers to the average execution time due to pipelined parallel instruction
processing.
Figure 4-2
Standard Branch Instruction Processing
Instruction pipelining helps to speed up sequential program processing. If a branch is
taken, the instruction which has already been fetched is most likely not the instruction
which must be decoded next. Thus, at least one additional machine cycle is normally
required to fetch the branch target instruction. This extra machine cycle is provided by
means of an injected instruction (see
Figure 4-3
User’s Manual
FETCH
DECODE
EXECUTE
WRITEBACK
FETCH
DECODE
EXECUTE
WRITEBACK
Figure
Sequential Instruction Pipelining
Standard Branch Instruction Pipelining
Time
Time
4-2).
1 Machine Cycle
1 Machine Cycle
BRANCH
...
...
I
I
1
n
BRANCH
I
n+2
...
I
I
I
2
1
n
Injection
Figure
BRANCH
4-4
(
I
I
TARGET
INJECT
I
I
I
I
4-3).
3
2
1
n
)
BRANCH
I
(
TARGET+1
I
I
TARGET
INJECT
Central Processing Unit (CPU)
I
I
I
I
4
3
2
1
)
I
I
(
TARGET+2
TARGET+1
I
I
TARGET
INJECT
I
I
I
I
5
4
3
2
C164CM/C164SM
)
I
I
I
TARGET+3
TARGET+2
TARGET+1
I
TARGET
Derivatives
MCT04327
MCT04328
V1.0, 2002-02
I
I
I
I
6
5
4
3