Create empty relocations section

lib/Language/Elna/Architecture/RiscV.hs

@@ -1,5 +1,6 @@
 module Language.Elna.Architecture.RiscV
     ( BaseOpcode(..)
+    , RelocationType(..)
     , Funct3(..)
     , Funct7(..)
     , Funct12(..)
@@ -15,6 +16,7 @@ module Language.Elna.Architecture.RiscV
 
 import qualified Data.ByteString.Builder as ByteString.Builder
 import Data.Bits (Bits(..))
+import Data.Text (Text)
 import Data.Word (Word8, Word32)
 
 data XRegister
@@ -137,8 +139,18 @@ data Type
     | U XRegister Word32
     | J XRegister Word32
     | Type XRegister Funct3 XRegister Funct12 -- Privileged.
+    deriving Eq
 
-data Instruction = Instruction BaseOpcode Type
+data RelocationType
+    = Lower12I XRegister Funct3 XRegister Text
+    | Lower12S Text Funct3 XRegister XRegister
+    | Higher20 XRegister Text -- Type U.
+    deriving Eq
+
+data Instruction
+    = Instruction BaseOpcode Type
+    | RelocatableInstruction BaseOpcode RelocationType
+    deriving Eq
 
 xRegister :: XRegister -> Word8
 xRegister Zero = 0
@@ -285,8 +297,17 @@ type' (Type rd funct3' rs1 funct12')
     .|. (fromIntegral (xRegister rs1) `shiftL` 15)
     .|. (fromIntegral (funct12 funct12') `shiftL` 20);
 
+relocationType :: RelocationType -> Word32
+relocationType (Lower12I rd funct3' rs1 _) = type' $ I rd funct3' rs1 0
+relocationType (Lower12S _ funct3' rs1 rs2) = type' $ S 0 funct3' rs1 rs2
+relocationType (Higher20 rd _) = type' $ U rd 0
+
 instruction :: Instruction -> ByteString.Builder.Builder
-instruction (Instruction base instructionType)
-    = ByteString.Builder.word32LE
-    $ fromIntegral (baseOpcode base)
-    .|. type' instructionType
+instruction = \case
+    (Instruction base instructionType) -> go base $ type' instructionType
+    (RelocatableInstruction base instructionType) -> go base $ relocationType instructionType
+  where
+    go base instructionType
+        = ByteString.Builder.word32LE
+        $ fromIntegral (baseOpcode base)
+        .|. instructionType