Fast constant weight codeword to index converter
Jon T. Butler, Tsutomu Sasao · 2011
Constant weight codewords, in which the number of 1's is constant, are essential to combinatorial computing. For example, it is often useful to generate all subsets of a set with a fixed number of elements. In this paper, we show an efficient circuit that converts a constant weight codeword into a unique index of that codeword. This circuit is a necessary part of a circuit that uses constant weight codewords to transmit data on and off chip. Our circuit is based on the combinatorial number system in which the digits are binomial coefficients (rn). Experimental results show the efficiency of our design.