Fig. 2
From: An optimized FM-index library for nucleotide and amino acid search
The 5 AVX2 vectors that comprise a nucleotide BWT window. The milestone counts for A, C, G, and T are stored in vector 0. Vector 1 contains the milestone for the ambiguity symbol ‘X’ and a 24 byte padding section to align the bit vectors to the 32 byte alignment necessary for AVX2 instructions. Vectors 2-4 contain the bits representing the symbols in the window