MPC555
/
MPC556
BURST BUFFER
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
4-5
Figure 4-2 Example of Compressed Code
Each instruction is divided to four bytes, marked X1, X2, X3 and X4. For each such
byte a separate (Huffman coding) vocabulary is generated, marked Tx1, Tx2, Tx3 and
Tx4. Once compressed, each instruction yields four symbols (corresponding to the X1,
X2, X3, and X4 input bytes). Therefore, in order to compress a given code, four vocab-
ularies are required. This partitionong produced a better comression ratio.
Figure 4-3 Instruction Coding
4
1
Original Code
4
SAVED
0
4
8
8
c
10
14
18
Compressed
0
3
2
1
0
4
8
8
c
10
14
18
0
2
3
0
23 24
vocabulary1
31
15
8
7
Tx1
X1
16
X2
X3
X4
vocabulary2
vocabulary3
vocabulary4
Tx2
Tx3
Tx4
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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