nx_alu_divider_r4.nx

nx_alu_divider_r4.nx -- the divider's QUANTITATIVE exceed: a RADIX-4 divider that resolves 2 quotient bits per iteration, so W/2 subtract-stages instead of the radix-2 restoring divider's W -- ~half the sequential latency depth. This is the QUANT half of the full exceed (the QUAL half = exhaustive 100% verification, nx_alu_divider_exhaustive_test). A full S-class exceed needs BOTH: radix-4 must be FASTER (fewer stages, measured) AND still 100%-correct (exhaustively verified) -- faster AND more capable. Algorithm (radix-4 restoring, MSB-first, width even): precompute b, 2b, 3b; rem=0, quo=0; for s in 0..W/2-1: rem4 = (rem<<2) | next-2-bits(a) q in {0,1,2,3} = count of {rem4>=b, rem4>=2b, rem4>=3b} (rem4<4b => q<=3) rem = rem4 - q*b ; quo = (quo<<2) | q Reuses nx_alu_divider's div_const/div_op2/div_mux gate-builders. Research: radix-4 SRT/restoring division -- Parhami, Computer Arithmetic; Hennessy & Patterson. [CANON] license_tier: ORIGINAL