nativeGen/X86/Cond.hs

    module X86.Cond (
            Cond(..),
            condUnsigned,
            condToSigned,
            condToUnsigned,
            maybeFlipCond
    )

    where

    data Cond
            = ALWAYS        -- What's really used? ToDo
            | EQQ
            | GE
            | GEU
            | GTT
            | GU
            | LE
            | LEU
            | LTT
            | LU
            | NE
            | NEG
            | POS
            | CARRY
            | OFLO
            | PARITY
            | NOTPARITY
            deriving Eq

    condUnsigned :: Cond -> Bool
    condUnsigned GU  = True
    condUnsigned LU  = True
    condUnsigned GEU = True
    condUnsigned LEU = True
    condUnsigned _   = False

    condToSigned :: Cond -> Cond
    condToSigned GU  = GTT
    condToSigned LU  = LTT
    condToSigned GEU = GE
    condToSigned LEU = LE
    condToSigned x   = x

    condToUnsigned :: Cond -> Cond
    condToUnsigned GTT = GU
    condToUnsigned LTT = LU
    condToUnsigned GE  = GEU
    condToUnsigned LE  = LEU
    condToUnsigned x   = x

    -- | @maybeFlipCond c@ returns @Just c'@ if it is possible to flip the
    -- arguments to the conditional @c@, and the new condition should be @c'@.
    maybeFlipCond :: Cond -> Maybe Cond
    maybeFlipCond cond  = case cond of
            EQQ   -> Just EQQ
            NE    -> Just NE
            LU    -> Just GU
            GU    -> Just LU
            LEU   -> Just GEU
            GEU   -> Just LEU
            LTT   -> Just GTT
            GTT   -> Just LTT
            LE    -> Just GE
            GE    -> Just LE
            _other -> Nothing