docs: def blockmix_salsa8(BY, Yi, r):
      """Blockmix; Used by SMix"""
  
      start = (2 * r - 1) * 16
      X = BY[start:start+16]                             # BlockMix - 1
      tmp = [0]*16
  
      for i in xrange(2 * r):                            # BlockMix - 2
          #blockxor(BY, i * 16, X, 0, 16)                # BlockMix - 3(inner)
          salsa20_8(X, tmp, BY, i * 16, BY, Yi + i*16)   # BlockMix - 3(outer)
          #array_overwrite(X, 0, BY, Yi + (i * 16), 16)  # BlockMix - 4
  
      for i in xrange(r):                                # BlockMix - 6
          BY[i * 16:(i * 16)+(16)] = BY[Yi + (i * 2) * 16:(Yi + (i * 2) * 16)+(16)]
          BY[(i + r) * 16:((i + r) * 16)+(16)] = BY[Yi + (i*2 + 1) * 16:(Yi + (i*2 + 1) * 16)+(16)]