Computer Hardware User's Guide

Rotate Right ROR
13-207 Assembly Language Instructions
Syntax ROR dst
Operation dst right-rotated one bit through carry bit → dst
Operands dst register (R n , 0 ≤ n ≤ 27)
Opcode
31 24 23 16 8 7 015
000 10 0
1 10
dst
11 11 11 1 1 1 11 11 11 111
Description The contents of the dst operand are right rotated one bit and loaded into the
dst register. The LSB is rotated into the carry (C) bit and also transferred into
the MSB.
Rotate right:
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 ROR R7
Before Instruction After Instruction
R7 00 0000 0421 R7 00 8000 0210
LUF 0 LUF 0
LV 0 LV 0
UF 0 UF 0
N 0 N 1
Z 0 Z 0
V 0 V 0
C 0 C 1
Mode Bit