pass all assert_return tests

src/Language/Wasm/FloatUtils.hs

@@ -0,0 +1,44 @@
+{-# LANGUAGE FlexibleContexts #-}
+
+module Language.Wasm.FloatUtils (
+    wordToFloat,
+    floatToWord,
+    wordToDouble,
+    doubleToWord,
+    makeNaN,
+    doubleToFloat
+) where
+
+import Data.Word (Word32, Word64)
+import Data.Bits ((.|.), (.&.), shiftR)
+import Data.Array.ST (newArray, readArray, MArray, STUArray)
+import Data.Array.Unsafe (castSTUArray)
+import GHC.ST (runST, ST)
+
+-- brough from https://stackoverflow.com/questions/6976684/converting-ieee-754-floating-point-in-haskell-word32-64-to-and-from-haskell-floa
+wordToFloat :: Word32 -> Float
+wordToFloat x = runST (cast x)
+
+floatToWord :: Float -> Word32
+floatToWord x = runST (cast x)
+
+wordToDouble :: Word64 -> Double
+wordToDouble x = runST (cast x)
+
+doubleToWord :: Double -> Word64
+doubleToWord x = runST (cast x)
+
+{-# INLINE cast #-}
+cast :: (MArray (STUArray s) a (ST s),
+         MArray (STUArray s) b (ST s)) => a -> ST s b
+cast x = newArray (0 :: Int, 0) x >>= castSTUArray >>= flip readArray 0
+
+makeNaN :: Word64 -> Double
+makeNaN w = wordToDouble $ 0x7FF0000000000000 .|. (0x000FFFFFFFFFFFFF .&. w)
+
+doubleToFloat :: Double -> Float
+doubleToFloat d =
+    let w = doubleToWord d in
+    if 0x7FF0000000000000 == (w .&. 0x7FF0000000000000) && (w .&. 0x0007FFFFFFFFFFFF) /= 0
+    then wordToFloat $ fromIntegral $ ((0x8000000000000000 .&. w) `shiftR` 32) .|. 0x7F800000 .|. (0x7FFFFF .&. w)
+    else realToFrac d