HD64F2145 datasheet(93/829 Pages) RENESAS

93 / 829 page

Rev. 2.0, 08/02, page 53 of 788

2.7.1

The register field of the instruction code specifies an 8-, 16-, or 32-bit general register which

contains the operand. R0H to R7H and R0L to R7L can be specified as 8-bit registers. R0 to R7

and E0 to E7 can be specified as 16-bit registers. ER0 to ER7 can be specified as 32-bit registers.

2.7.2

The register field of the instruction code specifies an address register (ERn) which contains the

address of a memory operand. If the address is a program instruction address, the lower 24 bits are

valid and the upper 8 bits are all assumed to be 0 (H'00).

2.7.3

A 16-bit or 32-bit displacement contained in the instruction code is added to an address register

(ERn) specified by the register field of the instruction, and the sum gives the address of a memory

operand. A 16-bit displacement is sign-extended when added.

2.7.4

specifies an address register (ERn) which contains the address of a memory operand. After the

operand is accessed, 1, 2, or 4 is added to the address register contents and the sum is stored in the

address register. The value added 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.

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 16 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.

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