Computer Hardware User's Guide

ROL Rotate Left
13-204
Syntax ROL dst
Operation dst left-rotated 1 bit → dst
Operands dst register (R n , 0 ≤ n ≤ 27)
Opcode
31 24 23 16 8 7 015
000 1 0 1
0 10
dst
11 0000000000000001
Description The contents of the dst operand are left rotated one bit and loaded into the dst
register. This is a circular rotation, with the MSB simultaneously transferred
into the carry (C) bit and the LSB.
Rotate left:
C dst
Cycles 1
Status Bits These condition flags are modified only if the destination register is R7–R0.
LUF Unaffected
LV Unaffected
UF 0
N MSB of the output
Z 1 if a 0 output is generated; 0 otherwise
V 0
C Set to the value of the bit rotated out of the high-order bit; unaffected
if
dst is not R7 – R0
OVM Operation is not affected by OVM bit value.
Example ROL R3
Before Instruction After Instruction
R3 00 8002 5CD4 R3 00 0004 B9A9
LUF 0 LUF 0
LV 0 LV 0
UF 0 UF 0
N 0 N 0
Z 0 Z 0
V 0 V 0
C 0 C 1
Mode Bit