forked from Yehowshua/RiscV-Formal
33 lines
816 B
Haskell
33 lines
816 B
Haskell
{-# LANGUAGE DataKinds #-}
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{-# LANGUAGE NumericUnderscores #-}
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module Fetch(
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fetchInstruction,
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FetchResult(..)) where
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import Clash.Prelude
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( Eq((==)),
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KnownNat,
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Bool(False, True),
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(!!),
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Bits(shiftR, (.&.)) )
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import Types(Mem, Addr, Insn)
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import Util(endianSwapWord)
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import Bus(ReadResponse, WriteResponse, read)
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data FetchResult = Instruction Insn
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| Misaligned Addr
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fetchInstruction :: KnownNat n => Mem n -> Addr -> FetchResult
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fetchInstruction mem addr =
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let
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isWordAligned = addr .&. 3 == 0
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addrWordAligned = addr `shiftR` 2
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insn = mem !! addrWordAligned
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-- TODO : check if instruction is word aligned and create type
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-- to capture if its not.
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in
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case isWordAligned of
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True -> Instruction insn
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False -> Misaligned addr
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