ROR              Rotate Right                        Flags: O D I T S Z A P C
*               *
ROR destination,count

                      
                                
      Destination          CF   
                             

ROR shifts the word or byte at the destination to the right by the
number of bit positions specified in the second operand, COUNT. As
bits are transferred out the right (low-order) end of the destination,
they re-enter on the left (high-order) end. The Carry Flag is updated
to match the last bit shifted out of the right end.

If COUNT is not equal to 1, the Overflow flag is undefined. If COUNT
is equal to 1, the Overflow Flag is set to the XOR of the top 2 bits
of the result.

                                                                          
Operands                  Clocks   Transfers  Bytes   Example
                        byte(word)
register, 1                 2          -        2     ROR BL,1
register, CL            8 + 4/bit      -        2     ROR AX,CL
memory, 1              15(23) + EA     2       2-4    ROR WORD,1
memory, CL           20(28)+EA+4/bit   2       2-4    ROR BYTE,CL
                                                                          

Notes:         COUNT is normally taken as the value in CL. If,
however, you wish to rotate by only one position,
replace the second operand, CL, with the value 1, as
shown in the first example above.

The 80286 and 80386 microprocessors limit the COUNT
value to 31.  If the COUNT is greater than 31, these
microprocessors use COUNT MOD 32 to produce a new
COUNT between 0 and 31.  This upper bound exists to
limit the amount of time an interrupt response will
be delayed waiting for the instruction to complete.

Multiple RORs that use 1 as the COUNT may be faster
and require less memory than a single ROR that uses
CL for COUNT.

The overflow flag is undefined when the rotate count
is greater than 1.

See also: RCR
See also: ROL
See also: RCL
See also: SAR
See also: SAL
See also: SHL
See also: SHR
See also: EA
See also: Flags

ROR Rotate Right