INSTRUCTION SET
S3C80A5B
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); 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 changed during 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 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 register 00H, leaving the value 55H (01010101B). The
MSB of register 00H resets the carry flag to "1" and sets the overflow flag.