INSTRUCTION SET
S3C80A5B
6-62
OR
—
Logical OR
OR
dst,src
Operation:
dst
←
dst OR src
The source operand is logically ORed with the destination operand and the result is stored in the
destination. The contents of the source are unaffected. The OR operation results in a "1" being
stored whenever either of the corresponding bits in the two operands is a "1"; otherwise a "0" is
stored.
Flags:
C:
Unaffected.
Z:
Set if the result is "0"; cleared otherwise.
S:
Set if the result bit 7 is set; cleared otherwise.
V:
Always cleared to "0".
D:
Unaffected.
H:
Unaffected.
Format:
Bytes
Cycles
Opcode
(Hex)
Addr Mode
dst src
opc
dst | src
2
4
42
r
r
6
43
r
lr
opc
src
dst
3
6
44
R
R
6
45
R
IR
opc
dst
src
3
6
46
R
IM
Examples:
Given: R0 = 15H, R1 = 2AH, R2 = 01H, register 00H = 08H, register 01H = 37H, and
register 08H = 8AH:
OR
R0,R1
→
R0 = 3FH, R1 = 2AH
OR
R0,@R2
→
R0 = 37H, R2 = 01H, register 01H = 37H
OR
00H,01H
→
Register 00H = 3FH, register 01H = 37H
OR
01H,@00H
→
Register 00H = 08H, register 01H = 0BFH
OR
00H,#02H
→
Register 00H = 0AH
In the first example, if working register R0 contains the value 15H and register R1 the value 2AH, the
statement "OR R0,R1" logical-ORs the R0 and R1 register contents and stores the result (3FH) in
destination register R0.
The other examples show the use of the logical OR instruction with the various addressing modes
and formats.