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CHAPTER 3 MEMORY SPACE, CPU AND CONTROL UNIT
3.4
Data Structure
The following data structures are used in the FR series:
• Bit ordering: Little endian
• Byte ordering: Big endian
I Bit ordering
FR uses little-endian bit ordering.
Figure 3.4-1 "Bit configuration of data items according to bit ordering" shows the bit
configuration of data items according to the specified bit ordering.
Figure 3.4-1 Bit configuration of data Items according to bit ordering
Bit
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
MSB
I Byte ordering
FR uses big-endian byte ordering.
Figure 3.4-2 "Byte configuration according to byte ordering" shows the byte configuration of data
items according to byte ordering.
Memory
b i t
7
1 0 1 0 1 0 1 0
Address n
Address (n + 1)
1 1 0 0 1 1 0 0
Address (n + 2)
1 1 1 1 1 1 1 1
Address (n + 3)
0 0 0 1 0 0 0 1
44
Figure 3.4-2 Byte configuration according to byte ordering
0
M S B
b i t 3 1
2 3
1 0 1 0 1 0 1 0 1 1 0 0 1 1 0 0 1 1 1 1 1 1 1 1 0 0 0 1 0 0 0 1
9
8
7
6
5
4
3
2
L S B
1 5
7
1
0
LSB
0
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