118
Chapter 3
CPU System Functions
Preliminary User’s Manual U17566EE1V2UM00
(1)
Wrap-around of data space
If an operand address calculation exceeds 32 bits, only the lower 32 bits of the
result are considered. Therefore, the addresses 0000 0000
H
and FFFF FFFF
H
are contiguous addresses. This results in a wrap-around of the data space:
Figure 3-5
Wrap-around of data space
(2)
Wrap-around of program space
If an instruction address calculation exceeds 26 bits, only the lower 26 bits of
the result are considered. Therefore, the addresses 0000 0000
H
and
03FF FFFF
H
are contiguous addresses. This results in a wrap-around of the
program space:
Figure 3-6
Wrap-around of program space
Caution
No instruction can be fetched from the 4 KB area of 03FF F000
H
to
03FF FFFF
H
because this area is defined as peripheral I/O area. Therefore, do
not execute any branch to this area.
FFFF FFFEH
FFFF FFFFH
0000 0000H
0000 0001H
D
a
t
a
s
p
a
ce
D
a
t
a
s
p
a
ce
(-)
direction
(+)
direction
03FF FFFEH
03FF FFFFH
0000 0000H
0000 0001H
Progr
a
m
s
p
a
ce
Progr
a
m
s
p
a
ce
(-)
direction
(+)
direction
electronic components distributor