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Logical Group Instructions (Part-VI) - RLC, RRC, RAL, RAR

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RLC:
  • This instruction rotates the contents of accumulator to the left by one bit.
  • It will shift B0 to B1, B1 to B2,............B7 to B0 as well as to carry flag.
  • Only CY flag is modified.
  • It is a one byte instruction.
  • Implied addressing mode is used.
Before execution:


After execution:

Example:
If A = 0101 0111 = 57H and CY = 1
RLC ; Now A = 10101110 = AEH and CY = 0.

RRC:
  • This instruction rotates the contents of accumulator to the right by one bit.
  • It will shift B7 to B6, B6 to B5,............B0 to B7 as well as to carry flag.
  • Only CY flag is modified.
  • It is a one byte instruction.
  • Implied addressing mode is used.
Before execution:


After execution:


Example:
If A = 1001 1010 = 9AH and CY = 1
RLC ; Now A = 0100 1101 = 4DH and CY = 0.

RAL:
  • This instruction rotates the contents of accumulator to the left by one bit along with the carry.
  • It will shift B0 to B1, B1 to B2,............B7 to CY and CY to B0.
  • Only CY flag is modified.
  • It is a one byte instruction.
  • Implied addressing mode is used.
Before execution:


After execution:


Example:
If A = 0101 0111 = 57H and CY = 1
RLC ; Now A = 1010 1111 = AFH and CY = 0.

RAR:
  • This instruction rotates the contents of accumulator to the right by one bit along with the carry.
  • It will shift B7 to B6, B6 to B5,............B0 to CY and CY to B7.
  • Only CY flag is modified.
  • It is a one byte instruction.
  • Implied addressing mode is used.
Before execution:


After execution:


Example:
If A = 1001 1010 = 9AH and CY = 1
RLC ; Now A = 1100 1101 = CDH and CY = 0.
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