From cf39807bf7b8424b6db0bc07a922a19972786735 Mon Sep 17 00:00:00 2001
From: Christiaan Baaij <christiaan.baaij@gmail.com>
Date: Wed, 9 Sep 2009 12:11:43 +0200
Subject: [PATCH] Add support for multiple alts in case statements

---
 "c\316\273ash/CLasH/VHDL/Generate.hs"  | 20 +++++++++++-------
 "c\316\273ash/CLasH/VHDL/VHDLTools.hs" | 29 ++++++++++++++++++++++++--
 2 files changed, 40 insertions(+), 9 deletions(-)

diff --git "a/c\316\273ash/CLasH/VHDL/Generate.hs" "b/c\316\273ash/CLasH/VHDL/Generate.hs"
index da8be8a..8ed2575 100644
--- "a/c\316\273ash/CLasH/VHDL/Generate.hs"
+++ "b/c\316\273ash/CLasH/VHDL/Generate.hs"
@@ -232,15 +232,21 @@ mkConcSm (bndr, expr@(CoreSyn.Case (CoreSyn.Var scrut) b ty [alt]))
 -- binders in the alts and only variables in the case values and a variable
 -- for a scrutinee. We check the constructor of the second alt, since the
 -- first is the default case, if there is any.
-mkConcSm (bndr, (CoreSyn.Case (CoreSyn.Var scrut) b ty [(_, _, CoreSyn.Var false), (con, _, CoreSyn.Var true)])) = do
+-- mkConcSm (bndr, (CoreSyn.Case (CoreSyn.Var scrut) b ty [(_, _, CoreSyn.Var false), (con, _, CoreSyn.Var true)])) = do
+--   scrut' <- MonadState.lift tsType $ varToVHDLExpr scrut
+--   altcon <- MonadState.lift tsType $ altconToVHDLExpr con
+--   let cond_expr = scrut' AST.:=: altcon
+--   true_expr <- MonadState.lift tsType $ varToVHDLExpr true
+--   false_expr <- MonadState.lift tsType $ varToVHDLExpr false
+--   return ([mkCondAssign (Left bndr) cond_expr true_expr false_expr], [])
+
+mkConcSm (bndr, (CoreSyn.Case (CoreSyn.Var scrut) _ _ (alt:alts))) = do --error "\nVHDL.mkConcSm: Not in normal form: Case statement with more than two alternatives"
   scrut' <- MonadState.lift tsType $ varToVHDLExpr scrut
-  altcon <- MonadState.lift tsType $ altconToVHDLExpr con
-  let cond_expr = scrut' AST.:=: altcon
-  true_expr <- MonadState.lift tsType $ varToVHDLExpr true
-  false_expr <- MonadState.lift tsType $ varToVHDLExpr false
-  return ([mkCondAssign (Left bndr) cond_expr true_expr false_expr], [])
+  altcons <- MonadState.lift tsType $ mapM (altconToVHDLExpr . (\(con,_,_) -> con)) (alts ++ [alt])
+  let cond_exprs = map (\x -> scrut' AST.:=: x) (init altcons)
+  exprs <- MonadState.lift tsType $ mapM (varToVHDLExpr . (\(_,_,CoreSyn.Var expr) -> expr)) (alts ++ [alt])
+  return ([mkAltsAssign (Left bndr) cond_exprs exprs], [])
 
-mkConcSm (_, (CoreSyn.Case (CoreSyn.Var _) _ _ alts)) = error "\nVHDL.mkConcSm: Not in normal form: Case statement with more than two alternatives"
 mkConcSm (_, CoreSyn.Case _ _ _ _) = error "\nVHDL.mkConcSm: Not in normal form: Case statement has does not have a simple variable as scrutinee"
 mkConcSm (bndr, expr) = error $ "\nVHDL.mkConcSM: Unsupported binding in let expression: " ++ pprString bndr ++ " = " ++ pprString expr
 
diff --git "a/c\316\273ash/CLasH/VHDL/VHDLTools.hs" "b/c\316\273ash/CLasH/VHDL/VHDLTools.hs"
index 5fc3473..785b528 100644
--- "a/c\316\273ash/CLasH/VHDL/VHDLTools.hs"
+++ "b/c\316\273ash/CLasH/VHDL/VHDLTools.hs"
@@ -73,7 +73,7 @@ mkAssign dst cond false_expr =
     whenelse = case cond of
       Just (cond_expr, true_expr) -> 
         let 
-          true_wform = AST.Wform [AST.WformElem true_expr Nothing] 
+          true_wform = AST.Wform [AST.WformElem true_expr Nothing]
         in
           [AST.WhenElse true_wform cond_expr]
       Nothing -> []
@@ -85,6 +85,31 @@ mkAssign dst cond false_expr =
   in
     AST.CSSASm assign
 
+mkAltsAssign ::
+  Either CoreBndr AST.VHDLName            -- ^ The signal to assign to
+  -> [AST.Expr]       -- ^ The conditions
+  -> [AST.Expr]       -- ^ The expressions
+  -> AST.ConcSm   -- ^ The Alt assigns
+mkAltsAssign dst conds exprs
+        | (length conds) /= ((length exprs) - 1) = error $ "\nVHDLTools.mkAltsAssign: conditions expression mismatch"
+        | otherwise =
+  let
+    whenelses   = zipWith mkWhenElse conds exprs
+    false_wform = AST.Wform [AST.WformElem (last exprs) Nothing]
+    dst_name  = case dst of
+      Left bndr -> AST.NSimple (varToVHDLId bndr)
+      Right name -> name
+    assign    = dst_name AST.:<==: (AST.ConWforms whenelses false_wform Nothing)
+  in
+    AST.CSSASm assign
+  where
+    mkWhenElse :: AST.Expr -> AST.Expr -> AST.WhenElse
+    mkWhenElse cond true_expr =
+      let
+        true_wform = AST.Wform [AST.WformElem true_expr Nothing]
+      in
+        AST.WhenElse true_wform cond
+
 mkAssocElems :: 
   [AST.Expr]                    -- ^ The argument that are applied to function
   -> AST.VHDLName               -- ^ The binder in which to store the result
@@ -163,7 +188,7 @@ altconToVHDLExpr :: CoreSyn.AltCon -> TypeSession AST.Expr
 altconToVHDLExpr (DataAlt dc) = dataconToVHDLExpr dc
 
 altconToVHDLExpr (LitAlt _) = error "\nVHDL.conToVHDLExpr: Literals not support in case alternatives yet"
-altconToVHDLExpr DEFAULT = error "\nVHDL.conToVHDLExpr: DEFAULT alternative should not occur here!"
+altconToVHDLExpr DEFAULT = return $ AST.PrimLit "undefined" -- error "\nVHDL.conToVHDLExpr: DEFAULT alternative should not occur here!"
 
 -- Turn a datacon (without arguments!) into a VHDL expression.
 dataconToVHDLExpr :: DataCon.DataCon -> TypeSession AST.Expr
-- 
2.30.2