use of uninterpreted functions for code generation

cgEx.hs

import Data.SBV

shiftLeft :: SWord32 -> SWord32 -> SWord32
shiftLeft = cgUninterpret "SBV_SHIFTLEFT" cCode hCode
  where cCode = ["#define SBV_SHIFTLEFT(x, y) ((x) << (y))"]
        hCode x y = select [x * literal (bit b) | b <- [0.. bitSize x - 1]] (literal 0) y

tstShiftLeft ::  SWord32 -> SWord32 -> SWord32 -> SWord32
tstShiftLeft x y z = x `shiftLeft` z + y `shiftLeft` z

genCCode :: IO ()
genCCode = compileToC (Just "ddd") "tst" $ do
                [x, y, z] <- cgInputArr 3 "vs"
                cgReturn $ tstShiftLeft x y z