nativeGen/PprBase.hs

    -----------------------------------------------------------------------------
    --
    -- Pretty-printing assembly language
    --
    -- (c) The University of Glasgow 1993-2005
    --
    -----------------------------------------------------------------------------

    module PprBase (
            castFloatToWord8Array,
            castDoubleToWord8Array,
            floatToBytes,
            doubleToBytes
    )

    where

    import qualified Data.Array.Unsafe as U ( castSTUArray )
    import Data.Array.ST

    import Control.Monad.ST

    import Data.Word

    -- -----------------------------------------------------------------------------
    -- Converting floating-point literals to integrals for printing

    castFloatToWord8Array :: STUArray s Int Float -> ST s (STUArray s Int Word8)
    castFloatToWord8Array = U.castSTUArray

    castDoubleToWord8Array :: STUArray s Int Double -> ST s (STUArray s Int Word8)
    castDoubleToWord8Array = U.castSTUArray

    -- floatToBytes and doubleToBytes convert to the host's byte
    -- order.  Providing that we're not cross-compiling for a
    -- target with the opposite endianness, this should work ok
    -- on all targets.

    -- ToDo: this stuff is very similar to the shenanigans in PprAbs,
    -- could they be merged?

    floatToBytes :: Float -> [Int]
    floatToBytes f
       = runST (do
            arr <- newArray_ ((0::Int),3)
            writeArray arr 0 f
            arr <- castFloatToWord8Array arr
            i0 <- readArray arr 0
            i1 <- readArray arr 1
            i2 <- readArray arr 2
            i3 <- readArray arr 3
            return (map fromIntegral [i0,i1,i2,i3])
         )

    doubleToBytes :: Double -> [Int]
    doubleToBytes d
       = runST (do
            arr <- newArray_ ((0::Int),7)
            writeArray arr 0 d
            arr <- castDoubleToWord8Array arr
            i0 <- readArray arr 0
            i1 <- readArray arr 1
            i2 <- readArray arr 2
            i3 <- readArray arr 3
            i4 <- readArray arr 4
            i5 <- readArray arr 5
            i6 <- readArray arr 6
            i7 <- readArray arr 7
            return (map fromIntegral [i0,i1,i2,i3,i4,i5,i6,i7])
         )