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https://github.com/idris-lang/Idris2.git
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7972c6acbd
* [ new ] Implement bit-rotation operators Whereas `shiftR` and `shiftL` throw bits off the edge, the `rotR` and `rotL` operations wrap the bits around to the start of the bit-stream. * [ test ] visualise bit patterns instead * [ fix ] print bit patterns the right way around --------- Co-authored-by: Guillaume Allais <guillaume.allais@ens-lyon.org>
101 lines
2.7 KiB
Idris
101 lines
2.7 KiB
Idris
import Data.Bits
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import Data.List
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import Data.Stream
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import Data.String
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import Decidable.Equality
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import Data.Fin
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--------------------------------------------------------------------------------
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-- Utilities
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--------------------------------------------------------------------------------
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shl1 : Int -> Int
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shl1 = prim__shl_Int 1
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b8max : Bits8
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b8max = 0xff
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b16max : Bits16
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b16max = 0xffff
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b32max : Bits32
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b32max = 0xffffffff
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b64max : Bits64
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b64max = 18446744073709551615
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-- the only way to create -2^63
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intmin : Int
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intmin = shl1 63
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intmax : Int
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intmax = 0x7fffffffffffffff
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powsOf2 : Num a => Nat -> List a
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powsOf2 n = take n (iterate (*2) 1)
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experiment : FiniteBits a => String -> (a -> a) -> List a -> String
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experiment name f vals
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= unlines
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$ replicate 72 '-'
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:: "-- \{name}"
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:: map (\ l => "\{asString l} \{asString (f l)}") vals
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--------------------------------------------------------------------------------
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-- rotR
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--------------------------------------------------------------------------------
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rotRBits8 : String
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rotRBits8 = experiment "RotR Bits8" (`rotR` 1) (0 :: powsOf2 8 ++ [b8max])
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rotRBits16 : String
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rotRBits16 = experiment "RotR Bits16" (`rotR` 1) (0 :: powsOf2 16 ++ [b16max])
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rotRBits32 : String
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rotRBits32 = experiment "RotR Bits32" (`rotR` 1) (0 :: powsOf2 32 ++ [b32max])
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rotRInt : String
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rotRInt = experiment "RotR Int" (`rotR` 1) (0 :: powsOf2 63 ++ [intmax])
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rotRNegativeInt : String
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rotRNegativeInt = experiment "RotR negative Int" (`rotR` 1) (0 :: map negate (powsOf2 63) ++ [intmin])
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--------------------------------------------------------------------------------
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-- rotL
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--------------------------------------------------------------------------------
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rotLBits8 : String
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rotLBits8 = experiment "RotL Bits8" (`rotL` 1) (0 :: powsOf2 8 ++ [b8max])
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rotLBits16 : String
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rotLBits16 = experiment "RotL Bits16" (`rotL` 1) (0 :: powsOf2 16 ++ [b16max])
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rotLBits32 : String
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rotLBits32 = experiment "RotL Bits32" (`rotL` 1) (0 :: powsOf2 32 ++ [b32max])
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rotLInt : String
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rotLInt = experiment "RotL Int" (`rotL` 1) (0 :: powsOf2 63 ++ [intmax])
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rotLNegativeInt : String
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rotLNegativeInt = experiment "RotL negative Int" (`rotL` 1) (0 :: map negate (powsOf2 62) ++ [intmin])
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--------------------------------------------------------------------------------
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-- Running Tests
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--------------------------------------------------------------------------------
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main : IO ()
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main = do putStrLn rotRBits8
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putStrLn rotRBits16
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putStrLn rotRBits32
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putStrLn rotRInt
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putStrLn rotRNegativeInt
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putStrLn ""
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putStrLn rotLBits8
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putStrLn rotLBits16
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putStrLn rotLBits32
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putStrLn rotLInt
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putStrLn rotLNegativeInt
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