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|
module Fig.Emulator.GB.Component.ROM
( compROM
) where
import Fig.Prelude
import Prelude (fromIntegral)
import qualified Data.Vector as V
import qualified Data.ByteString as BS
import Fig.Emulator.GB.Bus
newtype ROMError = ROMError Text
deriving Show
instance Exception ROMError
instance Pretty ROMError where
pretty (ROMError b) = mconcat
[ "internal ROM error: "
, b
]
-- | Initialize base ROM (no mapper) from a ByteString
compROM :: ByteString -> Component
compROM bs = Component
{ compState = V.fromList $ BS.unpack bs
, compMatches = \a ->
a >= start && a < end
, compUpdate = \s _ -> pure s
, compWrite = \s _ad _v ->
pure s
-- throwM . ROMError $ mconcat
-- [ "tried to write to ROM at ", pretty ad
-- ]
, compRead = \s ad -> do
let offset = fromIntegral . unAddr $ ad - start
case s V.!? offset of
Nothing -> throwM . ROMError $ mconcat
[ "address ", pretty ad, " out of bounds"
]
Just v -> pure v
}
where
start = 0x0000
-- end = 0x4000
end = 0x8000
|
