Implementation of Fully Pipelined Signed BCD Multiplier

Abstract

Decimal multiplication is one of the most frequently used operations in financial, scientific, commercial and internet-based applications. For having an efficient implementation, a fully pipelined decimal multiplier designed with Carry Save Addition and coded into a reduced group of BCD-4221. This design is based on multiplier operands recoded in Signed-Digit radix-10, a simplified partial products generator, and decimal adders. First to reduce the additional corrections that are present in BCD addition are avoided by -converting the 8421 to 4221 code which does not results in the codes A-F. 1 to 5 multiples of multiplicand are generated using various codes such as 5221, 5421 are used for the generation of the multiplicand multiple generator outputs which contains the 1 to 5 multiples of the multiplicand and one of the value is selected form output available from radix 10 signed recoding algorithm so that the required partial product is generated, partial product for 6 to 9 multiples are generated by using the multiplexer and the XOR gate. Once all the partial products are generated then these are reduced using carry save adder by dividing all the partial products into 4 bits each. Finally two outputs are generated sum and the carry. These two products generated are added using the binary coded decimal adder, before the addition is done the sum and the carry are in the 4221 format these are needed to be converted into 8421 code. The unsigned binary coded multiplier is extended to the signed binary coded multiplier.