Word Data Array Example - NEC uPD98502 User Manual

Network controller
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However, when making half-word accesses into a data array consisting of word data, access to the more-
significant half word requires the address corresponding to the less significant half word (and vice versa). Such code
is not endian-independent. A super-group access (for example, accessing two half words simultaneously as a word
from a half-word data array) causes the same problem. Such problems also arise when a half-word access is made
into a 32-bit register, whereas a word access into a 32-bit register creates no problem.
Big-Endian
M S H W
W 1
I
J
K
L
W 0
A
B
C
D
A
B
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D
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L
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CHAPTER 3 SYSTEM CONTROLLER
Figure 3-3. Word Data Array Example
L S H W
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Data extraction using sequential halfword access
A
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D
E
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Data extraction using sequential halfword access
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Preliminary User's Manual S15543EJ1V0UM
W o r d
M S H W
Data Array
W 1
I
J
W 0
A
B
E
F
A
B
Order Retained
M
N
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J
A
B
Order Lost
I
J
Little-Endian
L S H W
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M
N
O
C
D
E
F
G
G
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C
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K
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C
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M
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H
H
P

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