Datasheet

Section 2 CPU
Rev.5.00 Nov. 02, 2005 Page 36 of 418
REJ09B0028-0500
• 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 lower 24 bits of the result is 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, or 4 for longword access. For the word or longword access, the register value
should be even.
Absolute Address—@aa:8, @aa:16, @aa:24
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)
For an 8-bit absolute address, the upper 16 bits are all assumed to be 1 (H'FFFF). For a 16-bit
absolute address the upper 8 bits are a sign extension. A 24-bit absolute address can access the
entire address space.
The access ranges of absolute addresses for the group of this LSI are those shown in table 2.11,
because the upper 8 bits are ignored.
Table 2.11 Absolute Address Access Ranges
Absolute Address Access Range
8 bits (@aa:8) H'FF00 to H'FFFF
16 bits (@aa:16) H'0000 to H'FFFF
24 bits (@aa:24) H'0000 to H'FFFF
Immediate—#xx:8, #xx:16, or #xx:32
The instruction contains 8-bit (#xx:8), 16-bit (#xx:16), or 32-bit (#xx:32) immediate data as an
operand.
The ADDS, SUBS, INC, and DEC instructions contain immediate data implicitly. 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.
Program-Counter Relative—@(d:8, PC) or @(d:16, PC)
This mode is used in the BSR instruction. An 8-bit or 16-bit displacement contained in the
instruction is sign-extended and added to the 24-bit PC contents to generate a branch address. The
PC value to which the displacement is added is the address of the first byte of the next instruction,