Renesas H8/300 Series Programming Manual page 41

16-bit general registers are indicated by a 3-bit r
by a 4-bit r , r , or r
s d
@–Rn addressing modes are always 16-bit registers. Data registers are 8-bit or 16-bit registers
depending on the size of the operand. For 8-bit registers, the lower three bits of r
give the register number. The most significant bit is "1" if the lower byte of the register is
used, or "0" if the upper byte is used. Registers are thus indicated as follows:
16-Bit register
r , r , or r
s d n
Register
0 0 0
0 0 1
:
1 1 1
Bit Data Access: Bit data are accessed as the n-th bit of a byte operand in a general register or
memory. The bit number is given by 3-bit immediate data, or by a value in a general register.
When a bit number is specified in a general register, only the lower three bits of the register are
significant. Two examples are shown below.
BSET R1L, R2H
R1L
R2H
value. Address registers used in the @Rn, @(disp:16, Rn), @Rn+, and
n
R0
R1
:
R7
don't care
0 1 1 0 0 1 0 1
Bit 3 is set to "1"
, r , or r value. 8-bit registers are indicated
s d n
8-Bit registers
r , r , or r Register
s d n
0 0 0 0
0 0 0 1
:
0 1 1 1
1 0 0 0
1 0 0 1
:
1 1 1 1
0 1 1
Bit number = 3
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R0H
R1H
:
R7H
R0L
R1L
:
R7L
, r , or r
s d n