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INSTRUCTION SET S3C8275X/F8275X/C8278X/F8278X/C8274X/F8274X
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.