From ed698deeaa65b48f67e87618bc8ae4a3eac1c80a Mon Sep 17 00:00:00 2001
From: Stephen Williams <steve@icarus.com>
Date: Sun, 24 Jun 2007 18:17:37 -0700
Subject: [PATCH] Add support for collapsed/aliased arrays.

Arrays of nets that have all their words collapsed together can become
a collapsed array as a whole. Add support for this case in the vvp code
generator and runtime.
---
 tgt-vvp/vvp_scope.c | 37 ++++++++++++++++++++++++++++++-------
 vvp/README.txt      |  6 ++++++
 vvp/array.cc        | 36 ++++++++++++++++++++++++++++++++++++
 vvp/compile.h       |  1 +
 vvp/parse.y         |  3 +++
 5 files changed, 76 insertions(+), 7 deletions(-)

diff --git a/tgt-vvp/vvp_scope.c b/tgt-vvp/vvp_scope.c
index e12c7f04b..6e977979c 100644
--- a/tgt-vvp/vvp_scope.c
+++ b/tgt-vvp/vvp_scope.c
@@ -1070,6 +1070,7 @@ static void draw_net_in_scope(ivl_signal_t sig)
 		  } else {
 			/* If this is an isolated word, it uses its
 			   own name. */
+			assert(word_count == 1);
 			fprintf(vvp_out, "v%p_%u .net%s%s \"%s\", %d %d, %s;"
 				" %u drivers%s\n",
 				sig, iword, vec8, datatype_flag,
@@ -1081,15 +1082,37 @@ static void draw_net_in_scope(ivl_signal_t sig)
 		  nex_data->net = sig;
 		  nex_data->net_word = iword;
 
+	    } else if (dimensions > 0) {
+
+		    /* In this case, we have an alias to an existing
+		       signal array. this typically is an instance of
+		       port collapsing that the elaborator combined to
+		       discover that the entire array can be collapsed,
+		       so the word count for the signal and the alias
+		       *must* match. */
+		  assert(word_count == ivl_signal_array_count(nex_data->net));
+
+		  if (iword == 0) {
+			fprintf(vvp_out, "v%p .array \"%s\", v%p; Alias to %s\n",
+				sig, vvp_mangle_name(ivl_signal_basename(sig)),
+				nex_data->net, ivl_signal_basename(nex_data->net));
+		  }
+		    /* An alias for the individual words? */
+#if 0
+		  fprintf(vvp_out, "v%p_%u .alias%s v%p, %d %d, v%p_%u;\n",
+			  sig, iword, datatype_flag, sig,
+			  msb, lsb, nex_data->net, nex_data->net_word);
+#endif
 	    } else {
+		    /* Finally, we may have an alias that is a word
+		       connected to another word. Again, this is a
+		       case of port collapsing. */
 
-		  assert(word_count == 1);
-
-		    /* Detect that this is an alias of nex_data->net. Create
-		    a different kind of node that refers to the alias
-		    source data instead of holding our own data. */
-		  fprintf(vvp_out, "v%p_0 .alias%s \"%s\", %d %d, v%p_%u;\n",
-			  sig, datatype_flag,
+		    /* For the alias, create a different kind of node
+		       that refers to the alias source data instead of
+		       holding our own data. */
+		  fprintf(vvp_out, "v%p_%u .alias%s \"%s\", %d %d, v%p_%u;\n",
+			  sig, iword, datatype_flag,
 			  vvp_mangle_name(ivl_signal_basename(sig)),
 			  msb, lsb, nex_data->net, nex_data->net_word);
 	    }
diff --git a/vvp/README.txt b/vvp/README.txt
index 667d23739..a9efba5b4 100644
--- a/vvp/README.txt
+++ b/vvp/README.txt
@@ -380,6 +380,12 @@ declared seperately, this statement collects them together:
 the .var or .net statements after this array statement, that have the
 same "name" are collected, in order, as words.
 
+The syntax below is different, in that it creates an alias for an
+existing array. The dimensions and storage are taken from the .array
+at <src>.
+
+        <label> .array "name", <src> ;
+
 MEMORY STATEMENTS:
 
 Memories are arrays of words, each word a vvp_vector4_t vector of the
diff --git a/vvp/array.cc b/vvp/array.cc
index e50db604b..3ee4290f7 100644
--- a/vvp/array.cc
+++ b/vvp/array.cc
@@ -465,6 +465,42 @@ void compile_array_port(char*label, char*array, char*addr)
 	// The input_connect arranges for the array string to be free'ed.
 }
 
+void compile_array_alias(char*label, char*name, char*src)
+{
+      vvp_array_t mem = array_find(src);
+      assert(mem);
+
+      struct __vpiArray*obj = (struct __vpiArray*)
+	    malloc(sizeof (struct __vpiArray));
+
+      obj->base.vpi_type = &vpip_arraymem_rt;
+      obj->scope = vpip_peek_current_scope();
+      obj->name  = vpip_name_string(name);
+      obj->array_count = mem->array_count;
+
+	// XXXX Need to set an accurate range of addreses.
+      vpip_make_dec_const(&obj->first_addr, mem->first_addr.value);
+      vpip_make_dec_const(&obj->last_addr, mem->last_addr.value);
+
+	// Share the words with the source array.
+      obj->words = mem->words;
+
+      obj->ports_ = 0;
+
+      assert(array_table);
+      assert(!array_find(label));
+      symbol_value_t v;
+      v.ptr = obj;
+      sym_set_value(array_table, label, v);
+
+      compile_vpi_symbol(label, &obj->base);
+      vpip_attach_to_current_scope(&obj->base);
+
+      free(label);
+      free(name);
+      free(src);
+}
+
 /*
  * $Log: array.cc,v $
  * Revision 1.2  2007/04/10 01:26:16  steve
diff --git a/vvp/compile.h b/vvp/compile.h
index cf17313b5..ae6c90ab9 100644
--- a/vvp/compile.h
+++ b/vvp/compile.h
@@ -251,6 +251,7 @@ extern void compile_real_array(char*label, char*name,
 			       int msb, int lsb);
 extern void compile_net_array(char*label, char*name,
 			      int last, int first);
+extern void compile_array_alias(char*label, char*name, char*src);
 
 extern void compile_array_port(char*label, char*name, char*addr);
 
diff --git a/vvp/parse.y b/vvp/parse.y
index fc8e82331..5d31b1e1c 100644
--- a/vvp/parse.y
+++ b/vvp/parse.y
@@ -196,6 +196,9 @@ statement
         | T_LABEL K_ARRAY_PORT T_SYMBOL ',' T_SYMBOL ';'
 		{ compile_array_port($1, $3, $5); }
 
+        | T_LABEL K_ARRAY T_STRING ',' T_SYMBOL ';'
+                { compile_array_alias($1, $3, $5); }
+
  /* The .ufunc functor is for implementing user defined functions, or
      other thread code that is automatically invoked if any of the
      bits in the symbols list change. */