From fc1959bd9887ecc4d4ceb62a53e87abc6f49ef00 Mon Sep 17 00:00:00 2001
From: Nathan Ringo <nathan@remexre.com>
Date: Mon, 23 Sep 2024 21:46:34 -0500
Subject: Adds README, moves fpga stuff to a subdirectory.

---
 fpga/src/App.bs | 154 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 154 insertions(+)
 create mode 100644 fpga/src/App.bs

(limited to 'fpga/src/App.bs')

diff --git a/fpga/src/App.bs b/fpga/src/App.bs
new file mode 100644
index 0000000..cbe6454
--- /dev/null
+++ b/fpga/src/App.bs
@@ -0,0 +1,154 @@
+package App where
+
+import BRAM
+import GetPut
+
+interface App =
+  led :: Bit 1
+
+hexToBits :: Bit 8 -> Maybe (Bit 4)
+hexToBits 0x30 = Just 0b0000
+hexToBits 0x31 = Just 0b0001
+hexToBits 0x32 = Just 0b0010
+hexToBits 0x33 = Just 0b0011
+hexToBits 0x34 = Just 0b0100
+hexToBits 0x35 = Just 0b0101
+hexToBits 0x36 = Just 0b0110
+hexToBits 0x37 = Just 0b0111
+hexToBits 0x38 = Just 0b1000
+hexToBits 0x39 = Just 0b1001
+hexToBits 0x41 = Just 0b1010
+hexToBits 0x42 = Just 0b1011
+hexToBits 0x43 = Just 0b1100
+hexToBits 0x44 = Just 0b1101
+hexToBits 0x45 = Just 0b1110
+hexToBits 0x46 = Just 0b1111
+hexToBits 0x61 = Just 0b1010
+hexToBits 0x62 = Just 0b1011
+hexToBits 0x63 = Just 0b1100
+hexToBits 0x64 = Just 0b1101
+hexToBits 0x65 = Just 0b1110
+hexToBits 0x66 = Just 0b1111
+hexToBits _ = Nothing
+
+bitsToHex :: Bit 4 -> Bit 8
+bitsToHex b =
+  if b < 10
+  then 0x30 + (0 ++ b)
+  else 0x41 + (0 ++ (b - 10))
+
+data State
+  = WaitingForAddrHiNybble
+  | WaitingForAddrLoNybble (Bit 4)
+  | WaitingForRW (Bit 8)
+  | WaitingForRead
+  | WritingData3 (Bit 12)
+  | WritingData2 (Bit 8)
+  | WritingData1 (Bit 4)
+  | WritingCR
+  | WritingLF
+  | WaitingForValueNybble1 (Bit 8)
+  | WaitingForValueNybble2 (Bit 8) (Bit 4)
+  | WaitingForValueNybble3 (Bit 8) (Bit 8)
+  | WaitingForValueNybble4 (Bit 8) (Bit 12)
+  deriving (Bits)
+
+mkApp :: Get (Bit 8) -> Put (Bit 8) -> Module App
+mkApp uartRecv uartSend =
+  module
+    led :: Reg (Bit 1) <- mkReg 1
+    state :: Reg State <- mkReg WaitingForAddrHiNybble
+    ebr :: BRAM2Port (Bit 8) (Bit 16) <- mkBRAM2Server
+      (defaultValue { memorySize = 256 })
+
+    rules
+      "get_hi_nybble": when WaitingForAddrHiNybble <- state ==> do
+        byte <- uartRecv.get
+        case hexToBits byte of
+          Just hiNybble -> do
+            uartSend.put byte
+            state := WaitingForAddrLoNybble hiNybble
+          Nothing -> return ()
+      "get_lo_nybble": when WaitingForAddrLoNybble hiNybble <- state ==> do
+        byte <- uartRecv.get
+        case hexToBits byte of
+          Just loNybble -> do
+            uartSend.put byte
+            state := WaitingForRW (hiNybble ++ loNybble)
+            led := 0
+          Nothing -> return ()
+      "get_rw": when WaitingForRW addr <- state ==> do
+        byte <- uartRecv.get
+        case byte of
+          0x72 {- r -} -> do
+            uartSend.put byte
+            ebr.portA.request.put (BRAMRequest
+              { write = False
+              ; responseOnWrite = _
+              ; address = addr
+              ; datain = _
+              })
+            state := WaitingForRead
+          0x77 {- w -} -> do
+            uartSend.put byte
+            state := WaitingForValueNybble1 addr
+          _ -> return ()
+      "get_read": when WaitingForRead <- state ==> do
+        resp <- ebr.portA.response.get
+        uartSend.put (bitsToHex resp[15:12])
+        state := WritingData3 resp[11:0]
+      "write_data_3": when WritingData3 resp <- state ==> do
+        uartSend.put (bitsToHex resp[11:8])
+        state := WritingData2 resp[7:0]
+      "write_data_2": when WritingData2 resp <- state ==> do
+        uartSend.put (bitsToHex resp[7:4])
+        state := WritingData1 resp[3:0]
+      "write_data_1": when WritingData1 resp <- state ==> do
+        uartSend.put (bitsToHex resp)
+        state := WritingCR
+      "write_cr": when WritingCR <- state ==> do
+        uartSend.put 0x0d
+        state := WritingLF
+      "write_lf": when WritingLF <- state ==> do
+        uartSend.put 0x0a
+        state := WaitingForAddrHiNybble
+        led := 1
+      "get_nybble_1": when WaitingForValueNybble1 addr <- state ==> do
+        byte <- uartRecv.get
+        case hexToBits byte of
+          Just nybble -> do
+            uartSend.put byte
+            state := WaitingForValueNybble2 addr nybble
+          Nothing -> return ()
+      "get_nybble_2": when WaitingForValueNybble2 addr value <- state ==> do
+        byte <- uartRecv.get
+        case hexToBits byte of
+          Just nybble -> do
+            uartSend.put byte
+            state := WaitingForValueNybble3 addr (value ++ nybble)
+          Nothing -> return ()
+      "get_nybble_3": when WaitingForValueNybble3 addr value <- state ==> do
+        byte <- uartRecv.get
+        case hexToBits byte of
+          Just nybble -> do
+            uartSend.put byte
+            state := WaitingForValueNybble4 addr (value ++ nybble)
+          Nothing -> return ()
+      "get_nybble_4": when WaitingForValueNybble4 addr value <- state ==> do
+        byte <- uartRecv.get
+        case hexToBits byte of
+          Just nybble -> do
+            uartSend.put byte
+            ebr.portA.request.put (BRAMRequest
+              { write = True
+              ; responseOnWrite = False
+              ; address = addr
+              ; datain = value ++ nybble
+              })
+            state := WritingCR
+          Nothing -> return ()
+
+    interface App
+      led = led
+
+-- vim: set ft=haskell :
-- 
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