rol,   ror,

rol, ( Rd --)

Rotate Left trough Carry

Shifts all bits in Rd one place to the left. The C Flag is shifted into bit 0 of Rd. Bit 7 is shifted into the C Flag. This operation, combined with LSL, effectively multiplies multi-byte signed and unsigned values by two.

ror, ( Rd --)

Rotate Right through Carry.

Shifts all bits in Rd one place to the right. The C Flag is shifted into bit 7 of Rd. Bit 0 is shifted into the C Flag. This operation, combined with ASR, effectively divides multi-byte signed values by two. Combined with LSR it effectively divides multi-byte unsigned values by two. The Carry Flag can be used to round the result.