Ilya Rezvov
44 lines
1.3 KiB
Haskell
44 lines
1.3 KiB
Haskell
{-# LANGUAGE FlexibleContexts #-}
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module Language.Wasm.FloatUtils (
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wordToFloat,
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floatToWord,
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wordToDouble,
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doubleToWord,
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makeNaN,
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doubleToFloat
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) where
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import Data.Word (Word32, Word64)
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import Data.Bits ((.|.), (.&.), shiftR)
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import Data.Array.ST (newArray, readArray, MArray, STUArray)
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import Data.Array.Unsafe (castSTUArray)
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import GHC.ST (runST, ST)
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-- brough from https://stackoverflow.com/questions/6976684/converting-ieee-754-floating-point-in-haskell-word32-64-to-and-from-haskell-floa
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wordToFloat :: Word32 -> Float
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wordToFloat x = runST (cast x)
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floatToWord :: Float -> Word32
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floatToWord x = runST (cast x)
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wordToDouble :: Word64 -> Double
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wordToDouble x = runST (cast x)
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doubleToWord :: Double -> Word64
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doubleToWord x = runST (cast x)
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{-# INLINE cast #-}
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cast :: (MArray (STUArray s) a (ST s),
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MArray (STUArray s) b (ST s)) => a -> ST s b
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cast x = newArray (0 :: Int, 0) x >>= castSTUArray >>= flip readArray 0
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makeNaN :: Word64 -> Double
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makeNaN w = wordToDouble $ 0x7FF0000000000000 .|. (0x000FFFFFFFFFFFFF .&. w)
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doubleToFloat :: Double -> Float
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doubleToFloat d =
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let w = doubleToWord d in
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if 0x7FF0000000000000 == (w .&. 0x7FF0000000000000) && (w .&. 0x0007FFFFFFFFFFFF) /= 0
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then wordToFloat $ fromIntegral $ ((0x8000000000000000 .&. w) `shiftR` 32) .|. 0x7F800000 .|. (0x7FFFFF .&. w)
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else realToFrac d |