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INSTRUCTION SET S3C84E5/C84E9/P84E9
6-72
RLC — Rotate Left through Carry
RLC dst
Operation: dst (0) ← C
C ← dst (7)
dst (n + 1) ← dst (n), n = 0–6
The contents of the destination operand with the carry flag are rotated left one bit position. The initial
value of bit 7 replaces the carry flag (C), and the initial value of the carry flag replaces bit zero.
7 0
C
Flags: C: Set if the bit rotated from the most significant bit position (bit 7) was "1".
Z: Set if the result is "0"; cleared otherwise.
S: Set if the result bit 7 is set; cleared otherwise.
V: Set if arithmetic overflow occurred, that is, if the sign of the destination is changed during
the rotation; cleared otherwise.
D: Unaffected.
H: Unaffected.
Format:
Bytes Cycles Opcode
(Hex)
Addr Mode
dst
opc dst 2 4 10 R
4 11 IR
Examples: Given: Register 00H = 0AAH, register 01H = 02H, and register 02H = 17H, C = "0":
RLC 00H → Register 00H = 54H, C = "1"
RLC @01H → Register 01H = 02H, register 02H = 2EH, C = "0"
In the first example, if the general register 00H has the value 0AAH (10101010B), the statement
"RLC 00H" rotates 0AAH one bit position to the left. The initial value of bit 7 sets the carry flag and
the initial value of the C flag replaces bit zero of the register 00H, leaving the value 55H (01010101B).
The MSB of the register 00H resets the carry flag to "1" and sets the overflow flag.