ice40: Pack constants to LCs

Signed-off-by: David Shah <davey1576@gmail.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/ice40/pack.cc b/ice40/pack.cc
index 47e55b68..eb783f2f 100644
--- a/ice40/pack.cc
+++ b/ice40/pack.cc
@@ -89,9 +89,34 @@ static void pack_nonlut_ffs(Design *design)
     }
 }
 
+// Pack constants (simple implementation)
+static void pack_constants(Design *design) {
+    CellInfo *gnd_cell = create_ice_cell(design, "ICESTORM_LC",
+                                       "$PACKER_GND");
+    gnd_cell->attrs["LUT_INIT"] = "0";
+
+    CellInfo *vcc_cell = create_ice_cell(design, "ICESTORM_LC",
+                                         "$PACKER_VCC");
+    vcc_cell->attrs["LUT_INIT"] = "1";
+
+    for (auto net : design->nets) {
+        NetInfo *ni = net.second;
+        if (ni->driver.cell != nullptr && ni->driver.cell->type == "GND") {
+            ni->driver.cell = gnd_cell;
+            ni->driver.port = "O";
+            design->cells[gnd_cell->name] = gnd_cell;
+        } else if (ni->driver.cell != nullptr && ni->driver.cell->type == "VCC") {
+            ni->driver.cell = vcc_cell;
+            ni->driver.port = "O";
+            design->cells[vcc_cell->name] = vcc_cell;
+        }
+    }
+}
+
 // Main pack function
 void pack_design(Design *design)
 {
+    pack_constants(design);
     pack_lut_lutffs(design);
     pack_nonlut_ffs(design);
 }