From 7dd5c99e19e35f37aeee40ccdd2e076948fd4467 Mon Sep 17 00:00:00 2001
From: Yann Herklotz <git@yannherklotz.com>
Date: Tue, 3 Mar 2020 03:31:47 +0000
Subject: Add case statement to the AST

---
 src/Verismith/Verilog/AST.hs     | 31 +++++++++++++++++++++++++++++++
 src/Verismith/Verilog/CodeGen.hs | 11 ++++++++++-
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/src/Verismith/Verilog/AST.hs b/src/Verismith/Verilog/AST.hs
index f880a5a..680ffa9 100644
--- a/src/Verismith/Verilog/AST.hs
+++ b/src/Verismith/Verilog/AST.hs
@@ -92,6 +92,8 @@ module Verismith.Verilog.AST
     , localParamIdent
     , localParamValue
     -- * Statment
+    , CaseType(..)
+    , CasePair(..)
     , Statement(..)
     , statDelay
     , statDStat
@@ -105,6 +107,10 @@ module Verismith.Verilog.AST
     , stmntCondExpr
     , stmntCondTrue
     , stmntCondFalse
+    , stmntCaseType
+    , stmntCaseExpr
+    , stmntCasePair
+    , stmntCaseDefault
     , forAssign
     , forExpr
     , forIncr
@@ -339,6 +345,7 @@ instance IsString ConstExpr where
 instance Plated ConstExpr where
   plate = uniplate
 
+-- | Task call, which is similar to function calls.
 data Task = Task { _taskName :: {-# UNPACK #-} !Identifier
                  , _taskExpr :: [Expr]
                  } deriving (Eq, Show, Ord, Data, Generic, NFData)
@@ -422,10 +429,27 @@ data Assign = Assign { _assignReg   :: !LVal
                      , _assignExpr  :: !Expr
                      } deriving (Eq, Show, Ord, Data, Generic, NFData)
 
+-- | Type for continuous assignment.
+--
+-- @
+-- assign x = 2'b1;
+-- @
 data ContAssign = ContAssign { _contAssignNetLVal :: {-# UNPACK #-} !Identifier
                              , _contAssignExpr    :: !Expr
                              } deriving (Eq, Show, Ord, Data, Generic, NFData)
 
+-- | Case pair which contains an expression followed by a statement which will
+-- get executed if the expression matches the expression in the case statement.
+data CasePair = CasePair { _casePairExpr :: !Expr
+                         , _casePairStmnt :: !Statement
+                         } deriving (Eq, Show, Ord, Data, Generic, NFData)
+
+-- | Type of case statement, which determines how it is interpreted.
+data CaseType = CaseStandard
+              | CaseX
+              | CaseZ
+              deriving (Eq, Show, Ord, Data, Generic, NFData)
+
 -- | Statements in Verilog.
 data Statement = TimeCtrl { _statDelay :: {-# UNPACK #-} !Delay
                           , _statDStat :: Maybe Statement
@@ -442,6 +466,11 @@ data Statement = TimeCtrl { _statDelay :: {-# UNPACK #-} !Delay
                        , _stmntCondTrue  :: Maybe Statement
                        , _stmntCondFalse :: Maybe Statement
                        }
+           | StmntCase { _stmntCaseType :: !CaseType
+                       , _stmntCaseExpr :: !Expr
+                       , _stmntCasePair :: ![CasePair]
+                       , _stmntCaseDefault :: !(Maybe Statement)
+                       }
            | ForLoop { _forAssign :: !Assign
                      , _forExpr   :: Expr
                      , _forIncr   :: !Assign
@@ -519,6 +548,8 @@ instance Semigroup Verilog where
 instance Monoid Verilog where
     mempty = Verilog mempty
 
+-- | Top level type which contains all the source code and associated
+-- information.
 data SourceInfo = SourceInfo { _infoTop :: {-# UNPACK #-} !Text
                              , _infoSrc :: !Verilog
                              }
diff --git a/src/Verismith/Verilog/CodeGen.hs b/src/Verismith/Verilog/CodeGen.hs
index 303c8a2..74acfe4 100644
--- a/src/Verismith/Verilog/CodeGen.hs
+++ b/src/Verismith/Verilog/CodeGen.hs
@@ -242,7 +242,16 @@ pType Reg  = "reg"
 
 genAssign :: Text -> Assign -> Doc a
 genAssign op (Assign r d e) =
-    hsep [lVal r, pretty op, maybe mempty delay d, expr e]
+    hsep . (lVal r : ) . (pretty op :) $ addMay (delay <$> d) [expr e]
+
+caseType :: CaseType -> Doc a
+caseType CaseStandard = "case"
+caseType CaseX = "casex"
+caseType CaseZ = "casez"
+
+casePair :: CasePair -> Doc a
+casePair (CasePair e s) =
+    vsep [hsep [expr e, colon], indent 2 $ statement s]
 
 statement :: Statement -> Doc a
 statement (TimeCtrl  d stat) = hsep [delay d, defMap stat]
-- 
cgit