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D.2
Assembler (fsm911)
The following two items require caution when using little endian areas during
programming in FR-series Assembler:
• Sections
• Data Access
Sections
Little endian areas are allocated primarily for data exchange data with little endian type CPUs.
Therefore, define little endian areas as data sections that store no initial value.
If a little endian area is specified as data section storing a code or initial stack value, the result
of an access by the MB91F109 cannot be guaranteed.
[Example]
/* Correct definition of endian area as a section*/
Little_Word:
Little_Half:
Little_Byte:
Data Access
When accessing data in a little endian area, the data value can be coded independently of the
endian area. However, specify a size matching the size of the data when accessing the data of
the little endian area.
[Example]
.SECTION Little_Area, DATA, ALIGN=4
.RES.W 1
.RES.H 1
.RES.B 1
LDI
#0x01020304, r0
LDI
#Little_Word, r1
LDI
#0x0102, r2
LDI
#Little_Half, r3
LDI
#0x01, r4
LDI
#Little_Byte, r5
APPENDIX D Notes on Using Little Endian Areas
399
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