From b0de1a8d7eddb12f9563170d4fe581ecf1cb0ee6 Mon Sep 17 00:00:00 2001
From: Nick Gasson <nick@nickg.me.uk>
Date: Mon, 7 Jul 2008 16:11:45 +0100
Subject: [PATCH] Implement part select for LHS of assignment

---
 tgt-vhdl/stmt.cc        | 33 ++++++++++++++++++++++++++++-----
 tgt-vhdl/vhdl_syntax.cc |  4 ++++
 tgt-vhdl/vhdl_syntax.hh |  3 ++-
 3 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/tgt-vhdl/stmt.cc b/tgt-vhdl/stmt.cc
index fb6d214fb..b7f9ad68d 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, unsigned lval_width = 0)
 {
    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, lval_width-1);
+
          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, lval_width-1);
          
       T *a = new T(lval_ref, rhs);
       container->add_stmt(a);
@@ -198,6 +211,16 @@ 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;
+      }
+
+      unsigned lval_width = ivl_lval_width(lval);
+      
       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 +233,9 @@ 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, lval_width);
          make_vhdl_assignment<T>(proc, vhdif->get_else_container(), sig,
-                                 false_part, blocking);
+                                 false_part, blocking, base, lval_width);
 
          container->add_stmt(vhdif);         
          return NULL;
@@ -222,7 +245,7 @@ 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, lval_width);
       }
    }
    else {
diff --git a/tgt-vhdl/vhdl_syntax.cc b/tgt-vhdl/vhdl_syntax.cc
index d4773fa97..aa5d18eb7 100644
--- a/tgt-vhdl/vhdl_syntax.cc
+++ b/tgt-vhdl/vhdl_syntax.cc
@@ -477,6 +477,10 @@ void vhdl_var_ref::emit(std::ostream &of, int level) const
    of << name_;
    if (slice_) {
       of << "(";
+      if (slice_width_ > 0) {
+         slice_->emit(of, level);
+         of << " + " << slice_width_ << " downto ";
+      }
       slice_->emit(of, level);
       of << ")";
    }
diff --git a/tgt-vhdl/vhdl_syntax.hh b/tgt-vhdl/vhdl_syntax.hh
index c45351d18..0e3968327 100644
--- a/tgt-vhdl/vhdl_syntax.hh
+++ b/tgt-vhdl/vhdl_syntax.hh
@@ -56,10 +56,11 @@ public:
    
    void emit(std::ostream &of, int level) const;
    const std::string &get_name() const { return name_; }
-   void set_slice(vhdl_expr *s) { slice_ = s; }
+   void set_slice(vhdl_expr *s, int w=0) { slice_ = s; slice_width_ = w; }
 private:
    std::string name_;
    vhdl_expr *slice_;
+   unsigned slice_width_;
 };