Bit wise calculations

[AmitKumarDas]

• multiplication by shifts & adds

  - n * 3 = (n*2) + (n*1) = (n << 1) + (n)

• multiplications

  12 * 2 = 12 << 1
  12 * 4 = 12 << 2
  12 * 8 = 12 << 3
  12 * 16 = 12 << 4
  12 * 32 = 12 << 5
  12 * 64 = 12 << 6
  12 * 128 = 12 << 7
  12 * 256 = 12 << 8

• divisions

  12 / 2 = 12 >> 1
  12 / 4 = 12 >> 2
  12 / 8 = 12 >> 3
  12 / 16 = 12 >> 4
  12 / 32 = 12 >> 5
  12 / 64 = 12 >> 6
  12 / 128 = 12 >> 7
  12 / 256 = 12 >> 8

• tips

  chunk length = 1024 * 1024 = 2^10 * 2^10 = 2^20
  chunk shift = 20