Patent ID: 7159003
Filing Date: 2007-01-02
Classification: G06F,H03M

Abstract:
1. A method for adding respective digits of two numbers, each digit having a plurality of bits, so that the sum has a redundant sign-digit format, the method comprising: determining an initial threshold; adding with a first adder the bits of each digit to generate a first result; comparing the first result with the initial threshold to determine whether or not the first result has a first carry; adding with a second adder the first result to an input first carry of a previous digit and subtracting with the second adder a value equal to the radix of the digit from the first result if the first result has a first carry in order to generate an intermediate result; comparing the intermediate result with a prescribed value to determine whether or not the intermediate result has a second carry; and adding with a third adder the intermediate result to an input second carry of a previous digit and subtracting with the third adder the value equal to the radix of the digit from the intermediate result if the intermediate result has a second carry.