Efficient structure for computing mixed-radix projections from residue number systems

Claim 1

Apparatus for converting input data signals represented in a redundant residue number system having N moduli, to output mixed-radix projection data signals from which error detection and correction information can be derived, comprising: a set of N-1 arrays, S i , where i-1 through N-1, each array S i comprising an MRC structure of size N=i+1, except for S 1 which comprises an MRC structure of size N but without the N-1 th stage, the output thereof being provided after stage N-2; each said array S i having at array positions for which i>j a ROMij, and having at all other array positions therein a latch, wherein said ROMij performs the operation r=[((p-1)mj.sup.-1)]((p-q)m.sub.j.sup.-1)modulo m.sub.i where m j -1 is an integer such that (m j -1 ×m j ) modulo m j =1, r is the output, p is the higher order input and q is the other input of said ROMij, on the input data signals thereto, and wherein the ROMij which occupies column x, stage y of S z is determined by i=x+z-1 and j=y+z-1; wherein the inputs to said S 1 array are k 1 through k N and the outputs thereof are N mixed radix digits, S 1 (1) through S 1 (N); and wherein the inputs to all other S i arrays are the N-i+1 p-inputs of Stage i-1 of S 1 , and the outputs thereof are mixed radix digits S i (i) through S i (N) whereby the mixed-radix representation of each of the N projections of the input residue number are available for subsequent identification of erroneous residue digits.