End-of-stream emulator WIP

1 files changed, 343 insertions, 0 deletions

diff --git a/fig-emulator-gb/src/Fig/Emulator/GB/CPU/Instruction.hs b/fig-emulator-gb/src/Fig/Emulator/GB/CPU/Instruction.hs
new file mode 100644
index 0000000..b74a8ee
--- /dev/null
+++ b/fig-emulator-gb/src/Fig/Emulator/GB/CPU/Instruction.hs
@@ -0,0 +1,343 @@
+module Fig.Emulator.GB.CPU.Instruction where
+
+import Fig.Prelude
+import Prelude (Integral, fromIntegral, error)
+
+import Data.Word (Word8, Word16)
+
+import Fig.Emulator.GB.Utils
+import Fig.Emulator.GB.Bus as Bus
+
+newtype DecodeError = DecodeError Text
+  deriving Show
+instance Exception DecodeError
+instance Pretty DecodeError where
+  pretty (DecodeError b) = mconcat
+    [ "instruction decoding error: "
+    , b
+    ]
+
+class ExtractFromOpcode t where
+  ext :: Integral i => i -> t
+
+data R8 = R8B | R8C | R8D | R8E | R8H | R8L | R8MemHL | R8A
+  deriving (Show)
+instance ExtractFromOpcode R8 where
+  ext i = case (fromIntegral i :: Int) of
+    0 -> R8B
+    1 -> R8C
+    2 -> R8D
+    3 -> R8E
+    4 -> R8H
+    5 -> R8L
+    6 -> R8MemHL
+    7 -> R8A
+    _ -> error "unreachable"
+
+data R16 = R16BC | R16DE | R16HL | R16SP
+  deriving (Show)
+instance ExtractFromOpcode R16 where
+  ext i = case (fromIntegral i :: Int) of
+    0 -> R16BC
+    1 -> R16DE
+    2 -> R16HL
+    3 -> R16SP
+    _ -> error "unreachable"
+
+data R16Stk = R16StkBC | R16StkDE | R16StkHL | R16StkAF
+  deriving (Show)
+instance ExtractFromOpcode R16Stk where
+  ext i = case (fromIntegral i :: Int) of
+    0 -> R16StkBC
+    1 -> R16StkDE
+    2 -> R16StkHL
+    3 -> R16StkAF
+    _ -> error "unreachable"
+
+data R16Mem = R16MemBC | R16MemDE | R16MemHLPlus | R16MemHLMinus
+  deriving (Show)
+instance ExtractFromOpcode R16Mem where
+  ext i = case (fromIntegral i :: Int) of
+    0 -> R16MemBC
+    1 -> R16MemDE
+    2 -> R16MemHLPlus
+    3 -> R16MemHLMinus
+    _ -> error "unreachable"
+
+data Cond = CondNz | CondZ | CondNc | CondC
+  deriving (Show)
+instance ExtractFromOpcode Cond where
+  ext i = case (fromIntegral i :: Int) of
+    0 -> CondNz
+    1 -> CondZ
+    2 -> CondNc
+    3 -> CondC
+    _ -> error "unreachable"
+
+newtype B3 = B3 Int
+  deriving (Show)
+instance ExtractFromOpcode B3 where
+  ext i = B3 $ fromIntegral i
+
+newtype Tgt3 = Tgt3 Int
+  deriving (Show)
+instance ExtractFromOpcode Tgt3 where
+  ext i = Tgt3 $ fromIntegral i
+
+newtype Imm8 = Imm8 Word8
+  deriving (Show)
+readImm8 :: (MonadIO m, MonadThrow m) => Bus.Bus m -> Addr -> m Imm8
+readImm8 b a = Bus.read b a >>= \case
+  Just i -> pure $ Imm8 i
+  Nothing -> throwM . DecodeError $ mconcat
+    [ "failed to read immediate at unmapped address"
+    , pretty a
+    ]
+
+newtype Imm16 = Imm16 Word16
+  deriving (Show)
+readImm16 :: (MonadIO m, MonadThrow m) => Bus.Bus m -> Addr -> m Imm16
+readImm16 b a = do
+  mlo <- Bus.read b a
+  mhi <- Bus.read b $ a + 1
+  case (mlo, mhi) of
+    (Just lo, Just hi) -> pure . Imm16 $ w8w8 hi lo
+    _otherwise -> throwM . DecodeError $ mconcat
+      [ "failed to read 16-bit immediate at unmapped address"
+      , pretty a
+      ]
+
+data Instruction
+  -- Block 0
+  = Nop
+
+  | LdR16Imm16 !R16 !Imm16
+  | LdR16MemA !R16Mem
+  | LdAR16Mem !R16Mem
+  | LdImm16Sp !Imm16
+
+  | IncR16 !R16
+  | DecR16 !R16
+  | AddHlR16 !R16
+
+  | IncR8 !R8
+  | DecR8 !R8
+
+  | LdR8Imm8 !R8 !Imm8
+
+  | Rlca
+  | Rrca
+  | Rla
+  | Rra
+  | Daa
+  | Cpl
+  | Scf
+  | Ccf
+
+  | JrImm8 !Imm8
+  | JrCondImm8 !Cond !Imm8
+
+  | Stop
+
+  -- Block 1
+  | LdR8R8 !R8 !R8
+
+  | Halt
+
+  -- Block 2
+  | AddAR8 !R8
+  | AdcAR8 !R8
+  | SubAR8 !R8
+  | SbcAR8 !R8
+  | AndAR8 !R8
+  | XorAR8 !R8
+  | OrAR8 !R8
+  | CpAR8 !R8
+
+  -- Block 3
+  | AddAImm8 !Imm8
+  | AdcAImm8 !Imm8
+  | SubAImm8 !Imm8
+  | SbcAImm8 !Imm8
+  | AndAImm8 !Imm8
+  | XorAImm8 !Imm8
+  | OrAImm8 !Imm8
+  | CpAImm8 !Imm8
+
+  | RetCond !Cond
+  | Ret
+  | Reti
+  | JpCondImm16 !Cond !Imm16
+  | JpImm16 !Imm16
+  | JpHl
+  | CallCondImm16 !Cond !Imm16
+  | CallImm16 !Imm16
+  | RstTgt3 !Tgt3
+
+  | PopR16Stk !R16Stk
+  | PushR16Stk !R16Stk
+
+  | LdhCA
+  | LdhImm8A !Imm8
+  | LdImm16A !Imm16
+  | LdhAC
+  | LdhAImm8 !Imm8
+  | LdAImm16 !Imm16
+
+  | AddSpImm8 !Imm8
+  | LdHlSpPlusImm8 !Imm8
+  | LdSpHl
+
+  | Di
+  | Ei
+
+  -- 0xcb prefixed 16-bit instructions
+  | CbRlcR8 !R8
+  | CbRrcR8 !R8
+  | CbRlR8 !R8
+  | CbRrR8 !R8
+  | CbSlaR8 !R8
+  | CbSraR8 !R8
+  | CbSwapR8 !R8
+  | CbSrlR8 !R8
+
+  | CbBitB3R8 !B3 !R8
+  | CbResB3R8 !B3 !R8
+  | CbSetB3R8 !B3 !R8
+  deriving (Show)
+
+readInstruction ::
+  (MonadIO m, MonadThrow m) =>
+  Bus.Bus m -> Addr ->
+  m (Instruction, Addr)
+readInstruction b a = do
+  op <- Bus.read b a >>= \case
+    Just o -> pure o
+    Nothing -> throwM . DecodeError $ mconcat
+      [ "failed to read opcode at unmapped address "
+      , pretty a
+      ]
+  let blk = w8bits2 7 op
+  let bot3 = w8bits3 2 op
+  let bot4 = w8bits4 3 op
+  let no i = pure (i, a + 1)
+  let imm8 f = do
+        x <- readImm8 b $ a + 1
+        pure (f x, a + 2)
+  let imm16 f = do
+        x <- readImm16 b $ a + 1
+        pure (f x, a + 3)
+  case (op, blk, bot4, bot3) of
+    -- Block 0
+    (0b00000000, _, _, _) -> no Nop
+
+    (_, 0b00, 0b0001, _) -> imm16 $ LdR16Imm16 (ext $ w8bits2 5 op)
+    (_, 0b00, 0b0010, _) -> no $ LdR16MemA (ext $ w8bits2 5 op)
+    (_, 0b00, 0b1010, _) -> no $ LdAR16Mem (ext $ w8bits2 5 op)
+    (0b00001000, _, _, _) -> imm16 LdImm16Sp
+
+    (_, 0b00, 0b0011, _) -> no $ IncR16 (ext $ w8bits2 5 op)
+    (_, 0b00, 0b1011, _) -> no $ DecR16 (ext $ w8bits2 5 op)
+    (_, 0b00, 0b1001, _) -> no $ AddHlR16 (ext $ w8bits2 5 op)
+
+    (_, 0b00, _, 0b100) -> no $ IncR8 (ext $ w8bits3 5 op)
+    (_, 0b00, _, 0b101) -> no $ DecR8 (ext $ w8bits3 5 op)
+
+    (_, 0b00, _, 0b110) -> imm8 $ LdR8Imm8 (ext $ w8bits3 5 op)
+
+    (0b00000111, _, _, _) -> no Rlca
+    (0b00001111, _, _, _) -> no Rrca
+    (0b00010111, _, _, _) -> no Rla
+    (0b00011111, _, _, _) -> no Rra
+    (0b00100111, _, _, _) -> no Daa
+    (0b00101111, _, _, _) -> no Cpl
+    (0b00110111, _, _, _) -> no Scf
+    (0b00111111, _, _, _) -> no Ccf
+
+    (0b00011000, _, _, _) -> imm8 JrImm8
+    (0b00010000, _, _, _) -> no Stop
+    (_, 0b00, _, 0b000) -> imm8 $ JrCondImm8 (ext $ w8bits2 4 op)
+
+    -- Block 1
+    (0b01110110, _, _, _) -> no Halt
+    (_, 0b01, _, _) -> no $ LdR8R8 (ext $ w8bits3 5 op) (ext $ w8bits3 2 op)
+
+    -- Block 2
+    (_, 0b10, _, _) -> do
+      let ins = case w8bits3 5 op of
+            0b000 -> AddAR8
+            0b001 -> AdcAR8
+            0b010 -> SubAR8
+            0b011 -> SbcAR8
+            0b100 -> AndAR8
+            0b101 -> XorAR8
+            0b110 -> OrAR8
+            0b111 -> CpAR8
+            _ -> error "unreachable"
+      no $ ins (ext $ w8bits3 2 op)
+
+    -- Block 3
+    (0b11000110, _, _, _) -> imm8 AddAImm8
+    (0b11001110, _, _, _) -> imm8 AdcAImm8
+    (0b11010110, _, _, _) -> imm8 SubAImm8
+    (0b11011110, _, _, _) -> imm8 SbcAImm8
+    (0b11100110, _, _, _) -> imm8 AndAImm8
+    (0b11101110, _, _, _) -> imm8 XorAImm8
+    (0b11110110, _, _, _) -> imm8 OrAImm8
+    (0b11111110, _, _, _) -> imm8 CpAImm8
+
+    (0b11001001, _, _, _) -> no Ret
+    (0b11011001, _, _, _) -> no Reti
+    (0b11000011, _, _, _) -> imm16 JpImm16
+    (0b11101001, _, _, _) -> no JpHl
+    (0b11001101, _, _, _) -> imm16 CallImm16
+
+    (0b11100010, _, _, _) -> no LdhCA
+    (0b11100000, _, _, _) -> imm8 LdhImm8A
+    (0b11101010, _, _, _) -> imm16 LdImm16A
+    (0b11110010, _, _, _) -> no LdhAC
+    (0b11110000, _, _, _) -> imm8 LdhAImm8
+    (0b11111010, _, _, _) -> imm16 LdAImm16
+
+    (0b11101000, _, _, _) -> imm8 AddSpImm8
+    (0b11111000, _, _, _) -> imm8 LdHlSpPlusImm8
+    (0b11111001, _, _, _) -> no LdSpHl
+
+    (0b11110011, _, _, _) -> no Di
+    (0b11111011, _, _, _) -> no Ei
+
+    (0b11001011, _, _, _) -> do
+      -- 0xcb prefix
+      op2 <- Bus.read b (a + 1) >>= \case
+        Just o -> pure o
+        Nothing -> throwM . DecodeError $ mconcat
+          [ "failed to read (0xCB-prefixed) opcode at unmapped address "
+          , pretty $ a + 1
+          ]
+      case w8bits2 7 op2 of
+
+        0b00 -> case w8bits3 5 op2 of
+          0b000 -> pure (CbRlcR8 $ ext $ w8bits3 2 op2, a + 2)
+          0b001 -> pure (CbRrcR8 $ ext $ w8bits3 2 op2, a + 2)
+          0b010 -> pure (CbRlR8 $ ext $ w8bits3 2 op2, a + 2)
+          0b011 -> pure (CbRrR8 $ ext $ w8bits3 2 op2, a + 2)
+          0b100 -> pure (CbSlaR8 $ ext $ w8bits3 2 op2, a + 2)
+          0b101 -> pure (CbSraR8 $ ext $ w8bits3 2 op2, a + 2)
+          0b110 -> pure (CbSwapR8 $ ext $ w8bits3 2 op2, a + 2)
+          0b111 -> pure (CbSrlR8 $ ext $ w8bits3 2 op2, a + 2)
+          _ -> error "unreachable"
+        0b01 -> pure (CbBitB3R8 (ext $ w8bits3 5 op2) $ ext $ w8bits3 2 op2, a + 2)
+        0b10 -> pure (CbResB3R8 (ext $ w8bits3 5 op2) $ ext $ w8bits3 2 op2, a + 2)
+        0b11 -> pure (CbSetB3R8 (ext $ w8bits3 5 op2) $ ext $ w8bits3 2 op2, a + 2)
+        _ -> error "unreachable"
+
+    (_, 0b11, _, 0b000) -> no $ RetCond (ext $ w8bits2 4 op)
+    (_, 0b11, _, 0b010) -> imm16 $ JpCondImm16 (ext $ w8bits2 4 op)
+    (_, 0b11, _, 0b100) -> imm16 $ CallCondImm16 (ext $ w8bits2 4 op)
+    (_, 0b11, _, 0b111) -> no $ RstTgt3 (ext $ w8bits3 5 op)
+    (_, 0b11, 0b0001, _) -> no $ PopR16Stk (ext $ w8bits2 5 op)
+    (_, 0b11, 0b0101, _) -> no $ PushR16Stk (ext $ w8bits2 5 op)
+
+    _unknown -> do
+      log $ "unknown opcode: " <> tshow op
+      no Nop