MPC562/MPC564 Compression Features
MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
A-13
— The ICDU:
– Converts the COF address to a word-aligned physical address to access the memory
– Fetches the compressed instruction code from the memory, decompresses it and delivers
non-compressed instruction code, together with the bit-aligned next instruction address, to
the RCPU.
Figure A-12. Code Decompression Process
A.2.13
Compression Environment Initialization
In order to commence the execution of the compressed code, the DECRAM and the class information (in
the DCCR registers) must be programmed. The data to be programmed is supplied by the compressor tool
and the vocabulary generator. There are two initialization scenarios:
1. Wake up in decompression off mode — If the chip wakes up with decompression disabled, the
initialization routine can be executed at any time before entering decompression on mode. After
the compression environment is initialized, the operational mode would be changed to
decompression on.
2. Wake up in decompression on mode — If the chip wakes up in decompression on mode, it has to
process compressed instructions without the vocabularies and class parameters. Thus, all
instructions executed until the end of the initialization routine should be compressed in the global
bypass format. DECRAM loading is an essential part of this intialization routine. After DECRAM
loading, efficient compressed code may be used.
Compressed
Memory
Instructions
De
Vocabulary
compressor
MPC500
Embedded
CPU
Bit-Aligned COF
Noncompressed
Instruction Code
Address
COF Word Aligned
Physical Address
Compressed
Instruction
Compressed Space
“Next Instruction”
Address
Code
Classes (DCCR)
Registers
ICDU
Summary of Contents for MPC561
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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...
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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...