10.5.2 CLA Pipeline Alignment
The majority of the CLA instructions do not require any special pipeline considerations. This section lists the few
operations that do require special consideration.
•
Write Followed by Read
In both the C28x pipeline and the CLA pipeline, the read operation occurs before the write. This means that
if a read operation immediately follows a write, then the read will complete first as shown in
. In
most cases this does not cause a problem since the contents of one memory location does not depend on
the state of another. For accesses to peripherals where a write to one location can affect the value in another
location, the code must wait for the write to complete before issuing the read as shown in
This behavior is different for the C28x CPU. For the C28x CPU, any write followed by read to the same
location is protected by what is called write-followed-by-read protection. This protection automatically stalls
the pipeline so that the write will complete before the read. In addition, some peripheral frames are protected
such that a C28x CPU write to one location within the frame will always complete before a read to the frame.
The CLA does not have this protection mechanism. Instead the code must wait to perform the read.
Table 10-1. Write Followed by Read - Read Occurs First
Instruction
F1
F2
D1
D2
R1
R2
E
W
I1 MMOV16 @Reg1, MR3
I1
I2 MMOV16 MR2, @Reg2
I2
I1
I2
I1
I2
I1
I2
I1
I2
I1
I2
I1
I2
I1
Table 10-2. Write Followed by Read - Write Occurs First
Instruction
F1
F2
D1
D2
R1
R2
E
W
I1 MMOV16 @Reg1, MR3
I1
I2
I2
I1
I3
I3
I2
I1
I4
I4
I3
I2
I1
I5 MMOV16 MR2, @Reg2
I5
I4
I3
I2
I1
I5
I4
I3
I2
I1
I5
I4
I3
I2
I1
I5
I4
I3
I2
I1
I5
I4
I3
I5
I4
I5
Control Law Accelerator (CLA)
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
TMS320x2806x Microcontrollers
583
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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