Himbaechel xilinx : DSP packing : Fix identification of cascaded port…

…s and share identification code
lethalbit · Sep 24, 2024 · 9bea22e · 9bea22e
1 parent ad9a54c
commit 9bea22e
Showing 1 changed file with 15 additions and 17 deletions.
diff --git a/himbaechel/uarch/xilinx/pack_dsp_xc7.cc b/himbaechel/uarch/xilinx/pack_dsp_xc7.cc
@@ -26,6 +26,17 @@
 
 NEXTPNR_NAMESPACE_BEGIN
 
+static bool is_cascade_input(const std::string& port_name)
+{
+    return boost::starts_with(port_name, "ACIN") || boost::starts_with(port_name, "BCIN") || boost::starts_with(port_name, "PCIN") ||
+           port_name == "CARRYCASCIN" || port_name == "MULTSIGNIN";
+}
+static bool is_cascade_output(const std::string& port_name)
+{
+    return boost::starts_with(port_name, "ACOUT") || boost::starts_with(port_name, "BCOUT") || boost::starts_with(port_name, "PCOUT") ||
+           port_name == "CARRYCASCOUT" || port_name == "MULTSIGNOUT";
+}
+
 void XC7Packer::walk_dsp(CellInfo *root, CellInfo *current_cell, int constr_z)
 {
     CellInfo *cascaded_cell = nullptr;
@@ -42,7 +53,7 @@ void XC7Packer::walk_dsp(CellInfo *root, CellInfo *current_cell, int constr_z)
 
     // see if any cascade outputs are connected
     for (auto port : current_cell->ports) {
-        if (!boost::contains(port.first.str(ctx), "COUT")) continue;
+        if (!is_cascade_output(port.first.str(ctx))) continue;
         NetInfo *cout_net = port.second.net;
 
         if (cout_net == nullptr || cout_net->users.empty()) continue;
@@ -108,21 +119,8 @@ void XC7Packer::pack_dsps()
             for (auto &port : ci->ports) {
                 std::string n = port.first.str(ctx);
 
-                // According to ug479 :
-                // These signals are dedicated routing paths internal to the DSP48E1 column. They are not accessible via fabric routing resources.
-                if (boost::starts_with(n, "ACIN") || boost::starts_with(n, "BCIN") || boost::starts_with(n, "PCIN")) {
-                    if (port.second.net == nullptr)
-                        continue;
-                    if (port.second.net->name == ctx->id("$PACKER_GND_NET"))
-                        ci->disconnectPort(port.first);
-                }
-                if (n == "CARRYCASCIN") {
-                    if (port.second.net == nullptr)
-                        continue;
-                    if (port.second.net->name == ctx->id("$PACKER_GND_NET"))
-                        ci->disconnectPort(port.first);
-                }
-                if (n == "MULTSIGNIN") {
+                // Cascading inputs do not use routing resources, so disconnect them if constants
+                if (is_cascade_input(n)) {
                     if (port.second.net == nullptr)
                         continue;
                     if (port.second.net->name == ctx->id("$PACKER_GND_NET"))
@@ -157,7 +155,7 @@ void XC7Packer::pack_dsps()
     for (auto ci : all_dsps) {
         bool cascade_input_used = false;
         for (auto port : ci->ports) {
-            if (!boost::contains(port.first.str(ctx), "CIN")) continue;
+            if (!is_cascade_input(port.first.str(ctx))) continue;
             if (port.second.net != nullptr) {
                 cascade_input_used = true;
                 break;