calculate data transfer bits

gistfile1.coffee

  # Convert bit rate from and to another rate
  #
  # amount:   data being converted
  # unitFrom: `from` unit. bps|kbps|mbps|gbps
  # unitTo:   `to` unit. bps|kbps|mbps|gbps
  #
  # uses double bitwise not `~~` as `Math.floor`
  # uses `+` as type coercion to `int`
  Util.bitCalculate = (amount, unitFrom, unitTo, maxDecimals=2) ->
    base = 1000

    switch unitFrom
      when 'bps'
        switch unitTo
          when 'kbps'
            result = amount / Math.pow base, 1
          when 'mbps'
            result = amount / Math.pow base, 2
          when 'gbps'
            result = amount / Math.pow base, 3
          else
            result = amount

      when 'kbps'
        switch unitTo
          when 'bps'
            result = amount * Math.pow base, 1
          when 'mbps'
            result = amount / Math.pow base, 1
          when 'gbps'
            result = amount / Math.pow base, 3
          else
            result = amount

      when 'mbps'
        switch unitTo
          when 'bps'
            result = amount * Math.pow base, 2
          when 'kbps'
            result = amount * Math.pow base, 1
          when 'gbps'
            result = amount / Math.pow base, 1
          else
            result = amount

      when 'gpbs'
        switch unitTo
          when 'bps'
            result = ~~(amount * Math.pow(base, 3))
          when 'kbps'
            result = ~~(amount * Math.pow(base, 2))
          when 'mbps'
            result = amount * Math.pow base, 1
          else
            result = amount

    regex = new RegExp "\\d+\\.?\\d{#{maxDecimals}}"
    "#{+String(result).match regex}#{_.capitalize(unitTo)}"