Nice Bytes

nicebytes.rb

# encoding: utf-8
module NiceBytes
  K = 2.0**10
  M = 2.0**20
  G = 2.0**30
  T = 2.0**40
  def nice_bytes( bytes, max_digits=3 )
    value, suffix, precision = case bytes
      when 0...K
        [ bytes, 'B', 0 ]
      else
        value, suffix = case bytes
          when K...M then [ bytes / K, 'kiB' ]
          when M...G then [ bytes / M, 'MiB' ]
          when G...T then [ bytes / G, 'GiB' ]
          else            [ bytes / T, 'TiB' ]
        end
        used_digits = case value
          when   0...10   then 1
          when  10...100  then 2
          when 100...1000 then 3
          else 4
        end
        leftover_digits = max_digits - used_digits
        [ value, suffix, leftover_digits > 0 ? leftover_digits : 0 ]
    end
    "%.#{precision}f#{suffix}" % value
  end
  module_function :nice_bytes  # Allow NiceBytes.nice_bytes outside of Sinatra
end