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,
ROR
ROTATE RIGHT
ROR
Operation:
(temp)-
COUNT
do
while
(temp)
"*
0
Flags Affected:
(CF) -
low-order
bit
of
(EA)
, (EA) - (EA) I 2
high-order
bit
of
(EA) - (CF)
(temp)
-
(temp)-1
if
COU NT = 1
then
if
high-order
bit
of
(EA)
"*
next-
to-high-order
bit
of
(EA)
then
(OF)-1
else
(OF) - 0
else
(OF)
undefined
Description:
ROR
destination,
count
ROR (Rotate Right) operates similar to ROL
except that the bits in the destination byte or
word are rotated right instead of left.
Encoding:
11101
00
v w 1 mod
001
rIm 1
if
v = 0
then
COUNT = 1
else
COUNT
= (CL)
CF,.OF
ROR
Operand
Clocks*
Transfers
Bytes
register, 1 2
- 2
register,
CL
8+
4/bit
- 2
memory, 1
15(23)
+
EA
2
2-4
memory,
CL
20(28)
+
EA
+
41
bit 2
2-4
ROR
Coding
Example
ROR
AL, 1
ROR
BX,
CL
ROR
PORT_STATUS, 1
ROR
CMD_WORD, CL
*b(w): where b denotes the number of
clock cycles for byte operands and
w denotes the number of
clock cycles for word operands.
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