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src/Mima/Instruction.hs

@@ -7,7 +7,6 @@ module Mima.Instruction
   , wordToInstruction
   ) where
 
-import           Data.Bits
 import qualified Data.Map as Map
 import qualified Data.Text as T
 import           Data.Word
@@ -65,14 +64,6 @@ instance ToText Instruction where
   toText (SmallInstruction oc addr) = toText oc <> " " <> toText addr
   toText (LargeInstruction oc)      = toText oc
 
-upperOpcode :: MimaWord -> Word32
-upperOpcode mw = shiftR (toWord32 mw) 20 .&. 0xF
-
-lowerOpcode :: MimaWord -> Word32
-lowerOpcode mw = shiftR (toWord32 mw) 16 .&. 0xF
-
-address :: MimaWord -> MimaAddress
-address = fromWord32 . toWord32 -- no shifting required
 
 wordToInstruction :: MimaWord -> Either T.Text Instruction
 wordToInstruction mw = if upperOpcode mw == 0xF

src/Mima/State.hs

@@ -73,7 +73,7 @@ step ms = do
     (LargeInstruction oc)           -> executeLargeOpcode oc ms
 
 executeSmallOpcode :: SmallOpcode -> MimaAddress -> MimaState -> Either ExecException MimaState
-executeSmallOpcode LDC addr ms = incrementIp ms{msAcc = fromWord32 $ toWord32 addr}
+executeSmallOpcode LDC addr ms = incrementIp ms{msAcc = addressToWord addr}
 executeSmallOpcode LDV addr ms = incrementIp ms{msAcc = readAt addr (msMemory ms)}
 executeSmallOpcode STV addr ms = incrementIp ms{msMemory = writeAt addr (msAcc ms) (msMemory ms)}
 executeSmallOpcode ADD addr ms = incrementIp ms{msAcc = addWords (msAcc ms) (readAt addr $ msMemory ms)}

src/Mima/Word.hs

@@ -1,12 +1,15 @@
 {-# LANGUAGE OverloadedStrings #-}
 
 module Mima.Word
-  ( Word32Based(..)
-  , MimaWord
+  ( MimaWord
   , wordFromBool
   , topBit
+  , upperOpcode
+  , lowerOpcode
+  , address
   , addWords
   , MimaAddress
+  , addressToWord
   ) where
 
 import           Data.Bits
@@ -77,6 +80,15 @@ wordFromBool True  = complement zeroBits
 topBit :: MimaWord -> Bool
 topBit mw = testBit (toWord32 mw) (wordSize - 1)
 
+upperOpcode :: MimaWord -> Word32
+upperOpcode mw = shiftR (toWord32 mw) 20 .&. 0xF
+
+lowerOpcode :: MimaWord -> Word32
+lowerOpcode mw = shiftR (toWord32 mw) 16 .&. 0xF
+
+address :: MimaWord -> MimaAddress
+address = fromWord32 . toWord32
+
 addWords :: MimaWord -> MimaWord -> MimaWord
 addWords mw1 mw2 = fromWord32 $ toWord32 mw1 + toWord32 mw2
 
@@ -110,3 +122,6 @@ instance Enum MimaAddress where
         else error $ "Enum.toEnum{MimaAddress}: tag (" ++ show i
                      ++ ") is out of bounds " ++ show (lower, upper)
   fromEnum = fromEnum . toWord32
+
+addressToWord :: MimaAddress -> MimaWord
+addressToWord = fromWord32 . toWord32