Gowin: use global VCC and VSS nets (#956)

* use global VCC and VSS nets

* derp

* remove init parameter

4 files changed, 22 insertions, 10 deletions

diff --git a/gowin/arch.cc b/gowin/arch.cc
index 6213124f..4400a554 100644
--- a/gowin/arch.cc
+++ b/gowin/arch.cc
@@ -440,7 +440,9 @@ IdString Arch::wireToGlobal(int &row, int &col, const DatabasePOD *db, IdString
 {
     const std::string &wirename = wire.str(this);
     char buf[32];
-    if (wirename == "VCC" || wirename == "GND") {
+    if (wirename == "VCC" || wirename == "VSS") {
+        row = 0;
+        col = 0;
         return wire;
     }
     if (!isdigit(wirename[1]) || !isdigit(wirename[2]) || !isdigit(wirename[3])) {
@@ -949,6 +951,13 @@ Arch::Arch(ArchArgs args) : args(args)
              package_name.c_str(this), speed_id.c_str(this));
 
     // setup db
+    // add global VCC and GND bels
+    addBel(id_GND, id_GND, Loc(0, 0, 998), true);
+    addWire(id_VSS, id_VSS, 0, 0);
+    addBelOutput(id_GND, id_G, id_VSS);
+    addBel(id_VCC, id_VCC, Loc(0, 0, 999), true);
+    addWire(id_VCC, id_VCC, 0, 0);
+    addBelOutput(id_VCC, id_V, id_VCC);
     char buf[32];
     // The reverse order of the enumeration simplifies the creation
     // of MUX2_LUT8s: they need the existence of the wire on the right.
diff --git a/gowin/cells.cc b/gowin/cells.cc
index 8e450b51..c3b21782 100644
--- a/gowin/cells.cc
+++ b/gowin/cells.cc
@@ -65,6 +65,10 @@ std::unique_ptr<CellInfo> create_generic_cell(Context *ctx, IdString type, std::
         new_cell->addOutput(id_O);
     } else if (type == id_GSR) {
         new_cell->addInput(id_GSRI);
+    } else if (type == id_GND) {
+        new_cell->addOutput(id_G);
+    } else if (type == id_VCC) {
+        new_cell->addOutput(id_V);
     } else {
         log_error("unable to create generic cell of type %s\n", type.c_str(ctx));
     }
diff --git a/gowin/constids.inc b/gowin/constids.inc
index 125fdc74..b293293b 100644
--- a/gowin/constids.inc
+++ b/gowin/constids.inc
@@ -787,6 +787,8 @@ X(SUM)
 X(CIN)
 X(COUT)
 X(OF)
+X(V)
+X(G)
 
 // timing
 X(X0)
diff --git a/gowin/pack.cc b/gowin/pack.cc
index 9f0a2478..d31b4a84 100644
--- a/gowin/pack.cc
+++ b/gowin/pack.cc
@@ -611,20 +611,17 @@ static void pack_constants(Context *ctx)
 {
     log_info("Packing constants..\n");
 
-    std::unique_ptr<CellInfo> gnd_cell = create_generic_cell(ctx, id_SLICE, "$PACKER_GND");
-    gnd_cell->params[id_INIT] = Property(0, 1 << 4);
+    std::unique_ptr<CellInfo> gnd_cell = create_generic_cell(ctx, id_GND, "$PACKER_GND");
     auto gnd_net = std::make_unique<NetInfo>(ctx->id("$PACKER_GND_NET"));
     gnd_net->driver.cell = gnd_cell.get();
-    gnd_net->driver.port = id_F;
-    gnd_cell->ports.at(id_F).net = gnd_net.get();
+    gnd_net->driver.port = id_G;
+    gnd_cell->ports.at(id_G).net = gnd_net.get();
 
-    std::unique_ptr<CellInfo> vcc_cell = create_generic_cell(ctx, id_SLICE, "$PACKER_VCC");
-    // Fill with 1s
-    vcc_cell->params[id_INIT] = Property(Property::S1).extract(0, (1 << 4), Property::S1);
+    std::unique_ptr<CellInfo> vcc_cell = create_generic_cell(ctx, id_VCC, "$PACKER_VCC");
     auto vcc_net = std::make_unique<NetInfo>(ctx->id("$PACKER_VCC_NET"));
     vcc_net->driver.cell = vcc_cell.get();
-    vcc_net->driver.port = id_F;
-    vcc_cell->ports.at(id_F).net = vcc_net.get();
+    vcc_net->driver.port = id_V;
+    vcc_cell->ports.at(id_V).net = vcc_net.get();
 
     std::vector<IdString> dead_nets;