forked from Yehowshua/RiscV-Formal
82 lines
2.4 KiB
Haskell
82 lines
2.4 KiB
Haskell
module Peripherals.Uart (read, write, UartAddr) where
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import Clash.Prelude hiding (read)
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import Types (Byte)
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import Data.Char (ord, chr)
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import Peripherals.UartCFFI (
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initTerminal,
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restoreTerminal,
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getCharFromTerminal,
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writeCharToTerminal,
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isCharAvailable,
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setupSigintHandler,
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wasCtrlCReceived
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)
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import BusTypes (
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TransactionSize(..),
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BusVal(..),
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)
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import GHC.Generics (URec(UAddr), Generic (from))
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-- based on a 16550 UART which has an address space of 8 bytes
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type UartAddr = Unsigned 3
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-- Receiver Buffer Register address (commonly 0x0 for 16550 UART)
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rbrAddr :: UartAddr
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rbrAddr = 0x0
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thrAddr :: UartAddr
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thrAddr = 0x0
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-- Line Status Register address
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lsrAddr :: UartAddr
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lsrAddr = 0x5
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-- Helper function to convert Byte to BusVal based on TransactionSize
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busValFromByte :: TransactionSize -> Byte -> BusVal
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busValFromByte size val = case size of
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SizeByte -> BusByte val
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SizeHalfWord -> BusHalfWord (resize val)
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SizeFullWord -> BusFullWord (resize val)
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SizeDoubleWord -> BusDoubleWord (resize val)
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SizeQuadWord -> BusQuadWord (resize val)
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-- Reads a character from the terminal (RBR equivalent)
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buildRBR :: IO Byte
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buildRBR = do
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c <- getCharFromTerminal
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return $ fromIntegral (ord c) -- Convert Char to Byte
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-- Reads the Line Status Register (LSR) to check character availability
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buildLSR :: IO Byte
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buildLSR = do
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(char_available :: Byte) <- fromIntegral <$> isCharAvailable
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-- highly unlikely that we overflow stdout buffer, so we set
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-- transmit to always ready
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let (transmit_ready :: Byte) = 0b0010_0000
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return (char_available .|. transmit_ready)
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-- Updated 'read' function to handle RBR and LSR reads
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read :: TransactionSize -> UartAddr -> IO BusVal
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read size addr
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| addr == rbrAddr = busValFromByte size <$> buildRBR
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| addr == lsrAddr = busValFromByte size <$> buildLSR
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| otherwise = return $ busValFromByte size 0x00
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extractLowestByte :: BusVal -> Byte
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extractLowestByte (BusByte b) = b
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extractLowestByte (BusHalfWord hw) = resize hw
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extractLowestByte (BusFullWord fw) = resize fw
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extractLowestByte (BusDoubleWord dw) = resize dw
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extractLowestByte (BusQuadWord qw) = resize qw
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byteToChar :: Byte -> Char
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byteToChar = chr . fromIntegral
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write :: BusVal -> UartAddr -> IO ()
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write val addr
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| addr == thrAddr = writeCharToTerminal $ byteToChar $ extractLowestByte val
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| otherwise = return ()
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