From ebaa4c7d5db29cc80372868c2dbcf13ec0bdaa50 Mon Sep 17 00:00:00 2001
From: Nick Gasson <nick@nickg.me.uk>
Date: Mon, 7 Jul 2008 11:00:27 +0100
Subject: [PATCH] Implement assignment to part select properly

Previously the base of the lval was ignored, this ensures
the correct assignment is generated.
---
 tgt-vhdl/expr.cc | 20 ++++++++++++++++----
 tgt-vhdl/stmt.cc | 31 ++++++++++++++++++++++++++-----
 2 files changed, 42 insertions(+), 9 deletions(-)

diff --git a/tgt-vhdl/expr.cc b/tgt-vhdl/expr.cc
index 447857bf6..996bbe573 100644
--- a/tgt-vhdl/expr.cc
+++ b/tgt-vhdl/expr.cc
@@ -212,10 +212,22 @@ static vhdl_expr *translate_select(ivl_expr_t e)
 {
    vhdl_expr *from = translate_expr(ivl_expr_oper1(e));
    if (NULL == from)
-      return NULL;   
-   
-   // Hack: resize it to the correct size
-   return from->resize(ivl_expr_width(e));
+      return NULL;
+
+   ivl_expr_t o2 = ivl_expr_oper2(e);
+   if (o2) {
+      vhdl_expr *off = translate_expr(ivl_expr_oper2(e));
+      if (NULL == off)
+         return NULL;
+      
+      vhdl_var_ref *ref = dynamic_cast<vhdl_var_ref*>(from);
+      assert(ref);
+      
+      ref->set_slice(off);
+      return ref;
+   }
+   else   
+      return from;
 }
 
 static vhdl_type *expr_to_vhdl_type(ivl_expr_t e)
diff --git a/tgt-vhdl/stmt.cc b/tgt-vhdl/stmt.cc
index fb6d214fb..f956a48bf 100644
--- a/tgt-vhdl/stmt.cc
+++ b/tgt-vhdl/stmt.cc
@@ -110,14 +110,22 @@ static int draw_noop(vhdl_procedural *proc, stmt_container *container,
  */
 template <class T>
 static T *make_vhdl_assignment(vhdl_procedural *proc, stmt_container *container,
-                               ivl_signal_t sig, vhdl_expr *rhs, bool blocking)
+                               ivl_signal_t sig, vhdl_expr *rhs, bool blocking,
+                               vhdl_expr *base = NULL)
 {
    std::string signame(get_renamed_signal(sig));
 
    vhdl_decl *decl = proc->get_scope()->get_decl(signame);
    assert(decl);
 
-   rhs = rhs->cast(decl->get_type());
+   // TODO: Fix casting when there is a part select
+   if (base == NULL)
+      rhs = rhs->cast(decl->get_type());
+
+   if (base) {
+      vhdl_type integer(VHDL_TYPE_INTEGER);
+      base = base->cast(&integer);
+   }
       
    bool isvar = strip_var(signame) != signame;
 
@@ -154,6 +162,9 @@ static T *make_vhdl_assignment(vhdl_procedural *proc, stmt_container *container,
          vhdl_var_ref *lval_ref = new vhdl_var_ref(renamed.c_str(), NULL);
          vhdl_var_ref *sig_ref = new vhdl_var_ref(signame.c_str(), NULL);
 
+         if (base)
+            lval_ref->set_slice(base);
+
          T *a = new T(lval_ref, sig_ref);
          container->add_stmt(a);
             
@@ -174,6 +185,8 @@ static T *make_vhdl_assignment(vhdl_procedural *proc, stmt_container *container,
          
       // The type here can be null as it is never actually needed
       vhdl_var_ref *lval_ref = new vhdl_var_ref(signame.c_str(), NULL);
+      if (base)
+         lval_ref->set_slice(base);
          
       T *a = new T(lval_ref, rhs);
       container->add_stmt(a);
@@ -198,6 +211,14 @@ static T *make_assignment(vhdl_procedural *proc, stmt_container *container,
    ivl_lval_t lval = ivl_stmt_lval(stmt, 0);
    ivl_signal_t sig;
    if ((sig = ivl_lval_sig(lval))) {
+
+      vhdl_expr *base = NULL;
+      ivl_expr_t e_off = ivl_lval_part_off(lval);
+      if (e_off) {
+         if ((base = translate_expr(e_off)) == NULL)
+            return NULL;
+      }      
+      
       ivl_expr_t rval = ivl_stmt_rval(stmt);
       if (ivl_expr_type(rval) == IVL_EX_TERNARY) {
          // Expand ternary expressions into an if statement
@@ -210,9 +231,9 @@ static T *make_assignment(vhdl_procedural *proc, stmt_container *container,
 
          vhdl_if_stmt *vhdif = new vhdl_if_stmt(test);
          make_vhdl_assignment<T>(proc, vhdif->get_then_container(), sig,
-                                 true_part, blocking);
+                                 true_part, blocking, base);
          make_vhdl_assignment<T>(proc, vhdif->get_else_container(), sig,
-                                 false_part, blocking);
+                                 false_part, blocking, base);
 
          container->add_stmt(vhdif);         
          return NULL;
@@ -222,7 +243,7 @@ static T *make_assignment(vhdl_procedural *proc, stmt_container *container,
          if (NULL == rhs)
             return NULL;
          
-         return make_vhdl_assignment<T>(proc, container, sig, rhs, blocking);
+         return make_vhdl_assignment<T>(proc, container, sig, rhs, blocking, base);
       }
    }
    else {