End-of-stream emulator WIP

1 files changed, 41 insertions, 0 deletions

diff --git a/fig-emulator-gb/src/Fig/Emulator/GB/Component/Video.hs b/fig-emulator-gb/src/Fig/Emulator/GB/Component/Video.hs
new file mode 100644
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--- /dev/null
+++ b/fig-emulator-gb/src/Fig/Emulator/GB/Component/Video.hs
@@ -0,0 +1,41 @@
+module Fig.Emulator.GB.Component.Video where
+
+import Fig.Prelude
+
+import Fig.Emulator.GB.Bus
+
+newtype VideoError = VideoError Text
+  deriving Show
+instance Exception VideoError
+instance Pretty VideoError where
+  pretty (VideoError b) = mconcat
+    [ "video error: "
+    , b
+    ]
+
+compLCD :: (MonadIO m, MonadThrow m) => Component m
+compLCD = Component
+  { compState = ()
+  , compMatches = \a -> a >= 0xff40 && a <= 0xff4b
+  , compUpdate = pure
+  , compWrite = \s _ _ -> pure s
+  , compRead = \_ (Addr a) -> do
+      let off = a - 0xff40
+      case off of
+        0x0 -> pure 0x00
+        0x1 -> pure 0x00
+        0x2 -> pure 0x00
+        0x3 -> pure 0x00
+        0x4 -> pure 0x00
+        0x5 -> pure 0x00
+        0x6 -> pure 0x00
+        0x7 -> pure 0x00
+        0x8 -> pure 0x00
+        0x9 -> pure 0x00
+        0xa -> pure 0x00
+        0xb -> pure 0x00
+        _ -> throwM $ VideoError $ mconcat
+          [ "address out of bounds for LCD: "
+          , pretty $ Addr a
+          ]
+  }