  float    a     4*{1, 64, 128} = 0 / 0.3
        step 0: 
          block 0: [0:0,  0:63,   0:127] = 0 / 0
        step 1: 
          block 0: [0:0,  0:63,   0:127] = 0.1 / 0.1
        step 2: 
          block 0: [0:0,  0:63,   0:127] = 0.2 / 0.2
        step 3: 
          block 0: [0:0,  0:63,   0:127] = 0.3 / 0.3
