CODE GENERATING SYSTEM FOR CARRY SAVE ADDER

摘要

PURPOSE:To ensure a suitable application of a carry save adder to a multiplier circuit of multiple generating system by obtaining a full sum of a 2-bit code part which is adjacent to data parts of the sum and the carry respectively to transmit the code and combining this code and the prescribed value to produce a correct code. CONSTITUTION:The multiplicand data of a multiplicand register 1 and the least significant data of the multiplier register 2 are supplied to a multiple generating circuit 3-1 to produce a multiple of 8 faces. In the same way, the multiplicand data of the register 1 and the next digit data of the register 2 are supplied to a multiple generating circuit 3-2 to obtain a multiple of 8 faces. The multiple produced from the circuit 3-1 is added to a tree group 4-1 of a carry save adder CSA to deliver a sum 7 of 2 faces and a carry 8. At the same time, these sum 7 and carry 8 obtained with low-order digits are matched with a sum 9 and a carry 10 obtained with high-order digits and added together by a CSA5 and a CSA6 respectively.