Minial LPM to support continuous assignments

tgt-vhdl/Makefile.in

@@ -50,7 +50,7 @@ dep:
 	mv $*.d dep
 
 O = vhdl.o vhdl_element.o vhdl_type.o vhdl_syntax.o scope.o process.o \
-	stmt.o expr.o \
+	stmt.o expr.o lpm.o 
 
 ifeq (@WIN32@,yes)
   TGTLDFLAGS=-L.. -livl

tgt-vhdl/lpm.cc

@@ -0,0 +1,58 @@
+/*
+ *  VHDL code generation for LPM devices.
+ *
+ *  Copyright (C) 2008  Nick Gasson (nick@nickg.me.uk)
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "vhdl_target.h"
+
+#include <iostream>
+#include <cassert>
+
+static int draw_binop_lpm(vhdl_arch *arch, ivl_lpm_t lpm, vhdl_binop_t op)
+{
+   vhdl_expr *lhs = nexus_to_var_ref(arch, ivl_lpm_data(lpm, 0));
+   if (NULL == lhs)
+      return 1;
+
+   vhdl_expr *rhs = nexus_to_var_ref(arch, ivl_lpm_data(lpm, 1));
+   if (NULL == rhs)
+      return 1;
+
+   vhdl_var_ref *out = nexus_to_var_ref(arch, ivl_lpm_q(lpm, 0));
+   if (NULL == out)
+      return 1;
+
+   vhdl_type *result_type = new vhdl_type(*lhs->get_type());
+   vhdl_binop_expr *expr = new vhdl_binop_expr(lhs, op, rhs, result_type);
+
+   arch->add_stmt(new vhdl_cassign_stmt(out, expr));
+      
+   return 0;
+}
+
+int draw_lpm(vhdl_arch *arch, ivl_lpm_t lpm)
+{
+   switch (ivl_lpm_type(lpm)) {
+   case IVL_LPM_ADD:
+      return draw_binop_lpm(arch, lpm, VHDL_BINOP_ADD);
+   default:
+      error("Unsupported LPM type: %d", ivl_lpm_type(lpm));
+      return 1;
+   }
+}
+

tgt-vhdl/scope.cc

@@ -29,7 +29,7 @@
  * Given a nexus and an architecture, find the first signal
  * that is connected to the nexus, if there is one.
  */
-static vhdl_var_ref *nexus_to_var_ref(vhdl_arch *arch, ivl_nexus_t nexus)
+vhdl_var_ref *nexus_to_var_ref(vhdl_arch *arch, ivl_nexus_t nexus)
 {
    int nptrs = ivl_nexus_ptrs(nexus);
    for (int i = 0; i < nptrs; i++) {
@@ -188,6 +188,16 @@ static void declare_signals(vhdl_arch *arch, ivl_scope_t scope)
    }
 }
 
+/*
+ * Generate VHDL for LPM instances in a module.
+ */
+static void declare_lpm(vhdl_arch *arch, ivl_scope_t scope)
+{
+   int nlpms = ivl_scope_lpms(scope);
+   for (int i = 0; i < nlpms; i++)
+      draw_lpm(arch, ivl_scope_lpm(scope, i));
+}
+
 /*
  * Create a VHDL entity for scopes of type IVL_SCT_MODULE.
  */
@@ -215,6 +225,9 @@ static vhdl_entity *create_entity_for(ivl_scope_t scope)
 
    // Similarly, add all the primitive logic gates
    declare_logic(arch, scope);
+
+   // ...and all the LPM devices
+   declare_lpm(arch, scope);
    
    // Build a comment to add to the entity/architecture
    std::ostringstream ss;

tgt-vhdl/vhdl_target.h

@@ -15,12 +15,14 @@ int draw_scope(ivl_scope_t scope, void *_parent);
 int draw_process(ivl_process_t net, void *cd);
 int draw_stmt(vhdl_process *proc, stmt_container *container,
               ivl_statement_t stmt);
+int draw_lpm(vhdl_arch *arch, ivl_lpm_t lpm);
 
 vhdl_expr *translate_expr(ivl_expr_t e);
 
 void remember_entity(vhdl_entity *ent);
 vhdl_entity *find_entity(const std::string &tname);
 
+vhdl_var_ref *nexus_to_var_ref(vhdl_arch *arch, ivl_nexus_t nexus);
 
 void remember_signal(ivl_signal_t sig, const vhdl_entity *ent);
 void rename_signal(ivl_signal_t sig, const std::string &renamed);