From d7736d7eba5cf35398972de687cad11e2b420653 Mon Sep 17 00:00:00 2001
From: Johann Klammer <klammerj@a1.net>
Date: Fri, 11 Mar 2016 21:46:31 +0100
Subject: [PATCH] latch for vvp output

---
 tgt-vvp/draw_net_input.c |  1 +
 tgt-vvp/vvp_scope.c      | 29 +++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/tgt-vvp/draw_net_input.c b/tgt-vvp/draw_net_input.c
index e2f94fb20..d8ce40d88 100644
--- a/tgt-vvp/draw_net_input.c
+++ b/tgt-vvp/draw_net_input.c
@@ -436,6 +436,7 @@ static char* draw_net_input_drive(ivl_nexus_t nex, ivl_nexus_ptr_t nptr)
       if (lpm) switch (ivl_lpm_type(lpm)) {
 
 	  case IVL_LPM_FF:
+	  case IVL_LPM_LATCH:
 	  case IVL_LPM_ABS:
 	  case IVL_LPM_ADD:
 	  case IVL_LPM_ARRAY:
diff --git a/tgt-vvp/vvp_scope.c b/tgt-vvp/vvp_scope.c
index 9bd197df6..53b56dbc6 100644
--- a/tgt-vvp/vvp_scope.c
+++ b/tgt-vvp/vvp_scope.c
@@ -1830,6 +1830,31 @@ static void draw_lpm_ff(ivl_lpm_t net)
       fprintf(vvp_out, ";\n");
 }
 
+/*
+ * Emit a LATCH primitive. This uses the following syntax:
+ *
+ * .latch <width> <data>, <enable>;
+ */
+static void draw_lpm_latch(ivl_lpm_t net)
+{
+      ivl_nexus_t nex;
+
+      unsigned width = ivl_lpm_width(net);
+      fprintf(vvp_out, "L_%p .latch %u ", net, width);
+
+      nex = ivl_lpm_data(net,0);
+      assert(nex);
+      fprintf(vvp_out, "%s", draw_net_input(nex));
+      assert(width_of_nexus(nex) == width);
+
+      nex = ivl_lpm_enable(net);
+      assert(nex);
+      assert(width_of_nexus(nex) == 1);
+      fprintf(vvp_out, ", %s", draw_net_input(nex));
+
+      fprintf(vvp_out, ";\n");
+}
+
 static void draw_lpm_shiftl(ivl_lpm_t net)
 {
       unsigned width = ivl_lpm_width(net);
@@ -2160,6 +2185,10 @@ static void draw_lpm_in_scope(ivl_lpm_t net)
 	    draw_lpm_ff(net);
 	    return;
 
+	  case IVL_LPM_LATCH:
+	    draw_lpm_latch(net);
+	    return;
+
 	  case IVL_LPM_CMP_EEQ:
 	  case IVL_LPM_CMP_EQ:
 	  case IVL_LPM_CMP_EQX: