Datasheet

Section 2 CPU
Rev. 3.00 Mar 21, 2006 page 53 of 788
REJ09B0300-0300
Register Indirect with Pre-Decrement—@–ERn: The value 1, 2, or 4 is subtracted from an
address register (ERn) specified by the register field in the instruction code, and the result
becomes the address of a memory operand. The result is also stored in the address register. The
value subtracted is 1 for byte access, 2 for word access, and 4 for longword access. For word or
longword transfer instructions, the register value should be even.
2.7.5 Absolute Address—@aa:8, @aa:16, @aa:24, or @aa:32
The instruction code contains the absolute address of a memory operand. The absolute address
may be 8 bits long (@aa:8), 16 bits long (@aa:16), 24 bits long (@aa:24), or 32 bits long
(@aa:32). Table 2.12 indicates the accessible absolute address ranges.
To access data, the absolute address should be 8 bits (@aa:8), 16 bits (@aa:16), or 32 bits
(@aa:32) long. For an 8-bit absolute address, the upper 24 bits are all assumed to be 1 (H'FFFF).
For a 16-bit absolute address, the upper 16 bits are a sign extension. For a 32-bit absolute address,
the entire address space is accessed.
A 24-bit absolute address (@aa:24) indicates the address of a program instruction. The upper 8
bits are all assumed to be 0 (H'00).
Table 2.12 Absolute Address Access Ranges
Absolute Address Normal Mode Advanced Mode
8 bits (@aa:8) H'FF00 to H'FFFF H'FFFF00 to H'FFFFFF
16 bits (@aa:16) H'000000 to H'007FFF,
H'FF8000 to H'FFFFFF
Data address
32 bits (@aa:32)
Program instruction
address
24 bits (@aa:24)
H'0000 to H'FFFF
H'000000 to H'FFFFFF
2.7.6 Immediate—#xx:8, #xx:16, or #xx:32
The 8-bit (#xx:8), 16-bit (#xx:16), or 32-bit (#xx:32) immediate data contained in an instruction
code can be used directly as an operand.
The ADDS, SUBS, INC, and DEC instructions implicitly contain immediate data in their
instruction codes. Some bit manipulation instructions contain 3-bit immediate data in the
instruction code, specifying a bit number. The TRAPA instruction contains 2-bit immediate data
in its instruction code, specifying a vector address.