65 lines
2.1 KiB
Haskell
65 lines
2.1 KiB
Haskell
{- data size display
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-
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- Copyright 2011 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module DataUnits (roughSize) where
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{- And now a rant:
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-
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- In the beginning, we had powers of two, and they were good.
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-
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- Disk drive manufacturers noticed that some powers of two were
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- sorta close to some powers of ten, and that rounding down to the nearest
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- power of ten allowed them to advertise their drives were bigger. This
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- was sorta annoying.
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-
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- Then drives got big. Really, really big. This was good.
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-
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- Except that the small rounding error perpretrated by the drive
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- manufacturers suffered the fate of a small error, and became a large
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- error. This was bad.
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-
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- So, a committee was formed. And it arrived at a committee-like decision,
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- which satisfied noone, confused everyone, and made the world an uglier
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- place. As with all committees, this was meh.
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-
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- And the drive manufacturers happily continued selling drives that are
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- increasingly smaller than you'd expect, if you don't count on your
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- fingers. But that are increasingly bigger.
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-
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- Thus, I use units here that I loathe. Because if I didn't, people would
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- be confused that their drives seem the wrong size, and other people would
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- complain at me for not being standards compliant. And we call this
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- progress?
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-}
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{- approximate display of a particular number of bytes -}
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roughSize :: Bool -> Integer -> String
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roughSize short i
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| i < 0 = "-" ++ roughSize short (negate i)
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| i >= at 8 = units 8 "yottabyte" "YB"
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| i >= at 7 = units 7 "zettabyte" "ZB"
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| i >= at 6 = units 6 "exabyte" "EB"
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| i >= at 5 = units 5 "petabyte" "PB"
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| i >= at 4 = units 4 "terabyte" "TB"
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| i >= at 3 = units 3 "gigabyte" "GB"
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| i >= at 2 = units 2 "megabyte" "MB"
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| i >= at 1 = units 1 "kilobyte" "kB"
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| otherwise = units 0 "byte" "B"
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where
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at :: Integer -> Integer
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at n = 1000^n
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chop :: Integer -> Integer
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chop d = round $ (fromInteger i :: Double) / fromInteger (at d)
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units d u u' = let num = chop d in
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show num ++ " " ++
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(if short then u' else plural num u)
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plural n u
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| n == 1 = u
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| otherwise = u ++ "s"
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