ecp5: Global routing algorithm up to TAPs

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

ecp5/globals.cc

@@ -17,8 +17,14 @@
  *
  */
 
-#include "nextpnr.h"
 #include <algorithm>
+#include <iomanip>
+#include <queue>
+#include "nextpnr.h"
+
+#include "log.h"
+
+#define fmt_str(x) (static_cast<const std::ostringstream &>(std::ostringstream() << x).str())
 
 NEXTPNR_NAMESPACE_BEGIN
 
@@ -26,15 +32,16 @@ class Ecp5GlobalRouter
 {
   public:
     Ecp5GlobalRouter(Context *ctx) : ctx(ctx){};
-  private:
 
-    bool is_clock_port(const PortRef &user) {
+  private:
+    bool is_clock_port(const PortRef &user)
+    {
         if (user.cell->type == ctx->id("TRELLIS_LC") && user.port == ctx->id("CLK"))
             return true;
         return false;
     }
 
-    std::vector<NetInfo*> get_clocks()
+    std::vector<NetInfo *> get_clocks()
     {
         std::unordered_map<IdString, int> clockCount;
         for (auto &net : ctx->nets) {
@@ -45,13 +52,11 @@ class Ecp5GlobalRouter
                     clockCount[ni->name]++;
             }
         }
-        std::vector<NetInfo*> clocks;
+        std::vector<NetInfo *> clocks;
         while (clocks.size() < 16) {
-            auto max = std::max_element(clockCount.begin(), clockCount.end(), [](
+            auto max = std::max_element(clockCount.begin(), clockCount.end(),
-                    const decltype(clockCount)::value_type &a, const decltype(clockCount)::value_type &b
+                                        [](const decltype(clockCount)::value_type &a,
-                    ) {
+                                           const decltype(clockCount)::value_type &b) { return a.second < b.second; });
-                return a.second < b.second;
-            });
             if (max == clockCount.end() || max->second < 3)
                 break;
             clocks.push_back(ctx->nets.at(max->first).get());
@@ -77,6 +82,66 @@ class Ecp5GlobalRouter
         return *(ctx->getPipsUphill(tap_wire).begin());
     }
 
+    void route_logic_tile_global(IdString net, int global_index, PortRef user)
+    {
+        WireId userWire = ctx->getBelPinWire(user.cell->bel, ctx->portPinFromId(user.port));
+        WireId globalWire;
+        IdString global_name = ctx->id(fmt_str("G_HPBX" << std::setw(2) << std::setfill('0') << global_index << "00"));
+        std::queue<WireId> upstream;
+        std::unordered_map<WireId, PipId> backtrace;
+        upstream.push(userWire);
+        bool already_routed = false;
+        // Search back from the pin until we reach the global network
+        while (true) {
+            WireId next = upstream.front();
+            upstream.pop();
+
+            if (ctx->getBoundWireNet(next) == net) {
+                already_routed = true;
+                globalWire = next;
+                break;
+            }
+
+            if (ctx->getWireBasename(next) == global_name) {
+                globalWire = next;
+                break;
+            }
+            if (ctx->checkWireAvail(next)) {
+                for (auto pip : ctx->getPipsUphill(next)) {
+                    WireId src = ctx->getPipSrcWire(pip);
+                    backtrace[src] = pip;
+                    upstream.push(src);
+                }
+            }
+            if (upstream.size() > 3000) {
+                log_error("failed to route HPBX%02d00 to %s.%s\n", global_index,
+                          ctx->getBelName(user.cell->bel).c_str(ctx), user.port.c_str(ctx));
+            }
+        }
+        // Set all the pips we found along the way
+        WireId cursor = userWire;
+        while (true) {
+            auto fnd = backtrace.find(cursor);
+            if (fnd == backtrace.end())
+                break;
+            ctx->bindPip(fnd->second, net, STRENGTH_LOCKED);
+            cursor = ctx->getPipSrcWire(fnd->second);
+        }
+        // If the global network inside the tile isn't already set up,
+        // we also need to bind the buffers along the way
+        if (!already_routed) {
+            ctx->bindWire(cursor, net, STRENGTH_LOCKED);
+            PipId tap_pip = find_tap_pip(cursor);
+            IdString tap_net = ctx->getBoundPipNet(tap_pip);
+            if (tap_net == IdString()) {
+                ctx->bindPip(tap_pip, net, STRENGTH_LOCKED);
+                // TODO: SPINE
+            } else {
+                NPNR_ASSERT(tap_net == net);
+            }
+        }
+    }
+
     Context *ctx;
 };