MPC555CME Freescale Semiconductor, MPC555CME Datasheet - Page 188

• Manufacturer Part Number: MPC555CME
• Description: KIT EVALUATION FOR MPC555
• Manufacturer: Freescale Semiconductor
• Type: Microcontrollerr

Specifications of MPC555CME

• Contents: Module Board, Installation Guide, Power Supply, Cable, Software and more
• Processor To Be Evaluated: MPC555
• Data Bus Width: 32 bit
• Interface Type: RS-232
• For Use With/related Products: MPC555
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

MPC555
USER’S MANUAL
compression purposes. The resulting uncompressed elf code (with compression
hooks) will load and run like any other elf code.
The software compression tool compresses the elf code (x.elf) and produces a com-
pressed elf code (x.elf.sqz). The system sees the compressed elf code as regular elf
formatted code for purposes of loading into hardware (when programming the flash).
However, the decompression module must now be used to run the compressed elf
code.
Figure 4-11
Once generated, this code can be loaded into flash or SRAM (internal or external) .
The compression tool replaces regular PowerPC instructions by their “compressed”
representation which contain fewer data bits. The compressed data bit representation
is contained in the vocabulary. The vocabulary is structured into a binary bounded
Huffman code tree. This method has the result of the first instructions being repre-
sented by fewer bits. Further instructions require more bits for unique decoding.
Therefore, the instructions that occur most in code should be represented earlier in the
vocabulary structure. This would produce the most condensed code. A statistical study
was made of typical application code. The existing vocabulary is fixed for Phase A
Compiler/
Linker
/
MPC556
illustrates the several steps for generating compressed executable code.
Figure 4-11 Code Compression Process (Phase A)
Program
Executable
Non-compressed
Vocabulary
x.elf (with hooks)
Rev. 15 October 2000
BURST BUFFER
Compressor
Tool
Program
Executable
Compressed
x.elf.sqz
MOTOROLA
4-12