Table of Contents
Advertisement
Calculation of Effective Address: Table 1-12 shows how the H8/300 calculates effective
addresses in each addressing mode.
Arithmetic, logic, and shift instructions use register direct addressing (1). The ADD.B,
ADDX, SUBX, CMP.B, AND, OR, and XOR instructions can also use immediate addressing
(6).
The MOV instruction uses all the addressing modes except program-counter relative (7) and
memory indirect (8).
Bit manipulation instructions use register direct (1), register indirect (2), or absolute (5)
addressing to identify a byte operand and 3-bit immediate addressing to identify a bit within
the byte. The BSET, BCLR, BNOT, and BTST instructions can also use register direct
addressing (1) to identify the bit.
Effective Address Calculation
Table 1-12 explains how the effective address is calculated in each addressing mode.
Table 1-12, Effective Address Calculation (1)
Addressing mode,
No.
instruction format
1
Register direct Rn.
15
8 7
OP
15
8 7
2
Register indirect @Rn
15
7 6
OP
15
7 6
OP
4 3
0
reg m
reg n
0
4 3
0
reg
4 3
0
reg
Effective address
calculation
None
15
16-bit register contents
15
16-bit register contents
29
Effective
address
3
0
reg m
Operand are contained in
registers m and n
0
15
0
15
Operand is at address
indicated by register
Operand is at address
indicated by register
3
0
reg n
0
0
Advertisement
Table of Contents
