H8SLASH3003 datasheet(58/715 Pages) RENESAS

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2.6.4 Basic Instruction Formats

The H8/300H instructions consist of 2-byte (1-word) units. An instruction consists of an operation

field (OP field), a register field (r field), an effective address extension (EA field), and a condition

field (cc).

Operation Field: Indicates the function of the instruction, the addressing mode, and the operation

to be carried out on the operand. The operation field always includes the first 4 bits of the

instruction. Some instructions have two operation fields.

by 3 bits or 4 bits. Some instructions have two register fields. Some have no register field.

Effective Address Extension: Eight, 16, or 32 bits specifying immediate data, an absolute

address, or a displacement. A 24-bit address or displacement is treated as 32-bit data in which the

first 8 bits are 0 (H'00).

Condition Field: Specifies the branching condition of Bcc instructions.

Figure 2-9 shows examples of instruction formats.

Figure 2-9 Instruction Formats

NOP, RTS, etc.

EA (disp)

Operation field only

ADD.B Rn, Rm, etc.

Operation field and register fields

MOV.B @(d:16, Rn), Rm

Operation field, register fields, and effective address extension

BRA d:8

Operation field, effective address extension, and condition field

EA (disp)

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