ADAPTO: full-adder based reconfigurable architecture for bit level operations

Low cost microprocessors and DSPs are optimized to perform general arithmetic and logic operations on native wordlength. On the other hand, the efficiency decreases when they process shorter data (more clock cycles per operation are required). Recently different solutions have been proposed to overcome this problem. Among those, the one based on a main processor with a Reconfigurable Unit (RU) used as coprocessor (to speed up fine grained operations) is the most common. Typically those coprocessors, similar to FPGA, are composed by Look-Up Tables (LUTs) and pass transistors interconnects. In this way, due to the great number of reconfiguration bits, it is impossible to obtain together a run-time reconfiguration and an efficient implementation, avoiding idle hardware resources. This paper proposes a new dynamic reconfigurable architecture that can be embedded in microprocessors or low cost DSPs to accelerate the execution of the above mentioned operations. The goal of ADAPTO (Adder-based Dynamic Architecture for Processing Tailored Operators) is to reduce the hardware complexity and the reconfiguration time, with respect to typical LUT based Reconfigurable array. ADAPTO supports both hardware reconfiguration and instruction execution in the same processor clock cycle. This goal has been obtained by using a new reconfigurable unit based on full adders, instead LUTs, and simplifying the network interconnect.