H8S2245 datasheet(94/818 Pages) RENESAS

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Section 2 CPU

Rev.3.00 Mar. 26, 2007 Page 52 of 772

REJ09B0355-0300

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'FFFFFF). For a 16-bit absolute address the upper 16 bits are a sign extension. A 32-bit absolute

address can access the entire address space.

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 indicates the accessible absolute address ranges.

Table 2.12

Absolute Address Access Ranges

Absolute Address

Normal Mode

Advanced Mode

Data address

8 bits (@aa:8)

H'FF00 to H'FFFF

H'FFFF00 to H'FFFFFF

16 bits (@aa:16)

H'0000 to H'FFFF

H'000000 to H'007FFF,

H'FF8000 to H'FFFFFF

32 bits (@aa:32)

H'000000 to H'FFFFFF

Program instruction

address

24 bits (@aa:24)

(6) 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.

(7) Program-Counter Relative—@(d:8, PC) or @(d:16, PC)

This mode is used in the Bcc and BSR instructions. 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.

Only the lower 24 bits of this branch address are valid; the upper 8 bits are all assumed to be 0

(H'00). The PC value to which the displacement is added is the address of the first byte of the next

instruction, so the possible branching range is –126 to +128 bytes (–63 to +64 words) or –32766 to

+32768 bytes (–16383 to +16384 words) from the branch instruction. The resulting value should

be an even number.

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