MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
A-1
Appendix A
MPC562/MPC564 Compression Features
The MPC562/MPC564 contains a number of code compression features not found in the
MPC561/MPC563 that function from the burst buffer controller module (BBC) module of the device.
The BBC’s instruction code decompressor unit (ICDU) is responsible for on-line (previously compressed)
instruction code decompression in the decompression on mode. The ICDU contains a 2-Kbyte RAM
(DECRAM) that is used for decompressor vocabulary table storage when compression is enabled or as
general-purpose memory on the U-bus when compression is disabled.
NOTE
The code compression features of the MPC562/MPC564 are different than
the code compression of the MPC556.
A.1
ICDU Key Features
The following are instruction code decompression unit key features:
•
Instruction code on-line decompression is based on an “instruction class” algorithm.
•
There is no need for address translation between compressed and non-compressed address spaces
— ICDU provides the “next instruction address” to the RCPU.
•
In most cases, instruction decompression takes one clock.
•
Code decompression is pipelined:
— No performance penalty during sequential program flow execution
— Minimal performance penalty due to change of program flow execution
•
Two operation modes are available: decompression on and decompression off. Switches between
compressed and non-compressed user application software is possible.
•
Adaptive vocabularies scheme is supported; each user application can have its own optimum
vocabularies.
A.2
Class-Based Compression Model Main Principles
The operational model used by the MPC562/MPC564 is explained in the sections below.
A.2.1
Compression Model Features
•
Implemented for MPC56x architecture
•
Up to 50% instruction code size reduction
•
No need for address translation tables
Summary of Contents for MPC561
Page 84: ...MPC561 MPC563 Reference Manual Rev 1 2 lxxxiv Freescale Semiconductor...
Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...