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APPENDIX D Notes on Using Little Endian Areas
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 endi an 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 sto ring a code or in itial stack v alue, the result
of an access by the MB91F109 cannot be guaranteed.
[Example]
/* Correct definition of endian area as a section*/
.SECTION Little_Area, DATA, ALIGN=4
Little_Word:
.RES.W 1
Little_Half:
.RES.H 1
Little_Byte:
.RES.B 1
Data Access
When accessing data in a little endian area, the data value can be coded independentl y of the
endian area. However, specify a size matching the size of the data when accessing the data of
the little endian area.
[Example]
LDI #0x01020304, r0
LDI #Little_Word, r1
LDI #0x0102, r2
LDI #Little_Half, r3
LDI #0x01, r4
LDI #Little_Byte, r5