H8SSLASH2224 datasheet(177/1071 Pages) RENESAS

177 / 1071 page

Section 2 CPU

Rev. 5.00 Aug 08, 2006 page 91 of 982

REJ09B0054-0500

2.7.1

The register field of the instruction specifies an 8-, 16-, or 32-bit general register containing 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 the operand on memory. 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 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

Decrement—@-ERn

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 transfer instruction, or 4 for

longword transfer instruction. For the 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 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 transfer instruction, or 4 for longword transfer

instruction. For the 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.

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