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ROL
Operation:
Description:
Shifts all bits of memory location M one place to the left. Bit 0 is loaded
from the C status bit. The C bit is loaded from the most significant bit of
M. Rotate operations include the carry bit to allow extension of shift and
rotate operations to multiple bytes. For example, to shift a 24-bit value
one bit to the left, the sequence ASL LOW, ROL MID, ROL HIGH could
be used where LOW, MID and HIGH refer to the low-order, middle and
high-order bytes of the 24-bit value, respectively.
Condition Codes and Boolean Formulas:
S
–
N:
Z:
V:
C:
Addressing Modes, Machine Code, and Execution Times:
Source Form
ROL opr16a
ROL oprx0_xysp
ROL oprx9,xysp
ROL oprx16,xysp
ROL [D ,xysp ]
ROL [ oprx16,xysp ]
MOTOROLA
6-170
Rotate Left Memory
C
X
H
I
N
Z
∆
∆
–
–
–
Set if MSB of result is set; cleared otherwise.
Set if result is $00; cleared otherwise.
N ⊕ C = [N • C] + [N • C] (for N and C after the shift)
Set if (N is set and C is cleared) or (N is cleared and C is set); cleared oth-
erwise (for values of N and C after the shift).
M7
Set if the MSB of M was set before the shift; cleared otherwise.
Address Mode
EXT
IDX
IDX1
IDX2
[D,IDX]
[IDX2]
INSTRUCTION GLOSSARY
b7
b0
– – – – – –
V
C
∆
∆
Object Code
75 hh ll
65 xb
65 xb ff
65 xb ee ff
65 xb
65 xb ee ff
ROL
Cycles
Access Detail
4
rOPw
3
rPw
4
rPOw
5
frPPw
6
fIfrPw
6
fIPrPw
CPU12
REFERENCE MANUAL
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