83 lines
1.5 KiB
Haskell
83 lines
1.5 KiB
Haskell
{-# language BangPatterns #-}
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module Word16Tree
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( Word16Tree
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, encode
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, exampleSmall
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, example2000
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, example9000
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, expectedSmall
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) where
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import Data.ByteArray.Builder as B
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import Data.Word (Word16)
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import Data.Primitive (ByteArray)
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import qualified Data.Bytes as Bytes
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data Word16Tree
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= Branch !Word16Tree !Word16Tree
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| Leaf {-# UNPACK #-} !Word16
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encode :: Word16Tree -> Builder
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encode (Leaf w) = B.word16PaddedUpperHex w
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encode (Branch a b) =
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B.ascii '('
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<>
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encode a
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<>
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B.ascii ','
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<>
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encode b
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<>
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B.ascii ')'
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expectedSmall :: ByteArray
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expectedSmall = Bytes.toByteArray $ Bytes.fromAsciiString
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"((AB59,(1F33,2E71)),((((FA9A,247B),890C),(0F13,((55BF,7CF1),389B))),1205))"
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exampleSmall :: Word16Tree
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exampleSmall = Branch
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(Branch
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(Leaf 0xAB59)
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(Branch
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(Leaf 0x1F33)
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(Leaf 0x2E71)
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)
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)
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(Branch
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(Branch
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(Branch
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(Branch
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(Leaf 0xFA9A)
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(Leaf 0x247B)
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)
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(Leaf 0x890C)
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)
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(Branch
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(Leaf 0x0F13)
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(Branch
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(Branch
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(Leaf 0x55BF)
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(Leaf 0x7CF1)
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)
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(Leaf 0x389B)
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)
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)
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)
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(Leaf 0x1205)
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)
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example2000 :: Word16Tree
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{-# noinline example2000 #-}
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example2000 = balanced 0 2000
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example9000 :: Word16Tree
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{-# noinline example9000 #-}
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example9000 = balanced 0 9000
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balanced :: Word16 -> Word16 -> Word16Tree
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balanced !off !n
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| n == 0 = Leaf off
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| n == 1 = Leaf (off + 1)
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| otherwise = let x = div n 2 in
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Branch (balanced off x) (balanced (off + x) (n - x))
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