The high-performance AVR Arithmetic Logic Unit (ALU) operates in direct connection with all 32 general purpose working registers. Within a single clock cycle, arithmetic operations between general purpose registers or between a register and an immediate are executed. The ALU operations are divided into three main categories: arithmetic, logical, and bit-functions. Some implementations of the architecture also provide a powerful multiplier supporting both signed/unsigned multiplication and fractional format.
8-Bit AVR Arithmetic Logic Unit