1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
|
{- data size display and parsing
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Utility.DataUnits (
dataUnits,
storageUnits,
memoryUnits,
bandwidthUnits,
oldSchoolUnits,
roughSize,
compareSizes,
readSize
) where
import Data.List
import Data.Char
type ByteSize = Integer
type Name = String
type Abbrev = String
data Unit = Unit ByteSize Abbrev Name
deriving (Ord, Show, Eq)
{- And now a rant:
-
- In the beginning, we had powers of two, and they were good.
-
- Disk drive manufacturers noticed that some powers of two were
- sorta close to some powers of ten, and that rounding down to the nearest
- power of ten allowed them to advertise their drives were bigger. This
- was sorta annoying.
-
- Then drives got big. Really, really big. This was good.
-
- Except that the small rounding error perpretrated by the drive
- manufacturers suffered the fate of a small error, and became a large
- error. This was bad.
-
- So, a committee was formed. And it arrived at a committee-like decision,
- which satisfied noone, confused everyone, and made the world an uglier
- place. As with all committees, this was meh.
-
- And the drive manufacturers happily continued selling drives that are
- increasingly smaller than you'd expect, if you don't count on your
- fingers. But that are increasingly too big for anyone to much notice.
- This caused me to need git-annex.
-
- Thus, I use units here that I loathe. Because if I didn't, people would
- be confused that their drives seem the wrong size, and other people would
- complain at me for not being standards compliant. And we call this
- progress?
-}
dataUnits :: [Unit]
dataUnits = storageUnits ++ memoryUnits
{- Storage units are (stupidly) powers of ten. -}
storageUnits :: [Unit]
storageUnits =
[ Unit (p 8) "YB" "yottabyte"
, Unit (p 7) "ZB" "zettabyte"
, Unit (p 6) "EB" "exabyte"
, Unit (p 5) "PB" "petabyte"
, Unit (p 4) "TB" "terabyte"
, Unit (p 3) "GB" "gigabyte"
, Unit (p 2) "MB" "megabyte"
, Unit (p 1) "kB" "kilobyte" -- weird capitalization thanks to committe
, Unit (p 0) "B" "byte"
]
where
p :: Integer -> Integer
p n = 1000^n
{- Memory units are (stupidly named) powers of 2. -}
memoryUnits :: [Unit]
memoryUnits =
[ Unit (p 8) "YiB" "yobibyte"
, Unit (p 7) "ZiB" "zebibyte"
, Unit (p 6) "EiB" "exbibyte"
, Unit (p 5) "PiB" "pebibyte"
, Unit (p 4) "TiB" "tebibyte"
, Unit (p 3) "GiB" "gigabyte"
, Unit (p 2) "MiB" "mebibyte"
, Unit (p 1) "KiB" "kibibyte"
, Unit (p 0) "B" "byte"
]
where
p :: Integer -> Integer
p n = 2^(n*10)
{- Bandwidth units are only measured in bits if you're some crazy telco. -}
bandwidthUnits :: [Unit]
bandwidthUnits = error "stop trying to rip people off"
{- Do you yearn for the days when men were men and megabytes were megabytes? -}
oldSchoolUnits :: [Unit]
oldSchoolUnits = map mingle $ zip storageUnits memoryUnits
where
mingle (Unit _ a n, Unit s' _ _) = Unit s' a n
{- approximate display of a particular number of bytes -}
roughSize :: [Unit] -> Bool -> ByteSize -> String
roughSize units abbrev i
| i < 0 = '-' : findUnit units' (negate i)
| otherwise = findUnit units' i
where
units' = reverse $ sort units -- largest first
findUnit (u@(Unit s _ _):us) i'
| i' >= s = showUnit i' u
| otherwise = findUnit us i'
findUnit [] i' = showUnit i' (last units') -- bytes
showUnit i' (Unit s a n) = let num = chop i' s in
show num ++ " " ++
(if abbrev then a else plural num n)
chop :: Integer -> Integer -> Integer
chop i' d = round $ (fromInteger i' :: Double) / fromInteger d
plural n u
| n == 1 = u
| otherwise = u ++ "s"
{- displays comparison of two sizes -}
compareSizes :: [Unit] -> Bool -> ByteSize -> ByteSize -> String
compareSizes units abbrev old new
| old > new = roughSize units abbrev (old - new) ++ " smaller"
| old < new = roughSize units abbrev (new - old) ++ " larger"
| otherwise = "same"
{- Parses strings like "10 kilobytes" or "0.5tb". -}
readSize :: [Unit] -> String -> Maybe ByteSize
readSize units input
| null parsednum || null parsedunit = Nothing
| otherwise = Just $ round $ number * fromIntegral multiplier
where
(number, rest) = head parsednum
multiplier = head parsedunit
unitname = takeWhile isAlpha $ dropWhile isSpace rest
parsednum = reads input :: [(Double, String)]
parsedunit = lookupUnit units unitname
lookupUnit _ [] = [1] -- no unit given, assume bytes
lookupUnit [] _ = []
lookupUnit (Unit s a n:us) v
| a ~~ v || n ~~ v = [s]
| plural n ~~ v || a ~~ byteabbrev v = [s]
| otherwise = lookupUnit us v
a ~~ b = map toLower a == map toLower b
plural n = n ++ "s"
byteabbrev a = a ++ "b"
|
