ROTATE THEN OPERATE ON SELECTED BITS FACILITY AND INSTRUCTIONS THEREFORE

摘要

In a method of operating a computer, a rotate-then-operate instruction having a T bit is fetched and executed wherein a first operand in a first register is rotated byan amount and a Boolean operation is performed on a selected portion of the rotated first operand and a second operand in of a second register. If the T bit is '0' the selected portion of the result of the Boolean operation is inserted into corresponding bits of a second operand of a second register. If the T bit is '1', in addition to the inserted bits,the bits other than the selected portion of the rotated first operand are saved in the second register.