ice40: Refactor PLL/LOCK LUT splicing out into Arch::

1 files changed, 50 insertions, 0 deletions

diff --git a/ice40/arch.cc b/ice40/arch.cc
index d6ef800d..6679217a 100644
--- a/ice40/arch.cc
+++ b/ice40/arch.cc
@@ -2,6 +2,7 @@
  *  nextpnr -- Next Generation Place and Route
  *
  *  Copyright (C) 2018  Clifford Wolf <clifford@symbioticeda.com>
+ *  Copyright (C) 2018  Serge Bazanski <q3k@symbioticeda.com>
  *
  *  Permission to use, copy, modify, and/or distribute this software for any
  *  purpose with or without fee is hereby granted, provided that the above
@@ -805,4 +806,53 @@ void Arch::assignCellInfo(CellInfo *cell)
     }
 }
 
+std::unique_ptr<CellInfo> Arch::spliceLUT(CellInfo *ci, IdString portId, bool onlyNonLUTs)
+{
+     auto port = ci->ports[portId];
+
+     NPNR_ASSERT(port.net != nullptr);
+
+
+     // Create pass-through LUT.
+     std::unique_ptr<CellInfo> pt =
+         create_ice_cell(getCtx(), id("ICESTORM_LC"), ci->name.str(this) + "$nextpnr_ice40_pack_pll_lc");
+     pt->params[id("LUT_INIT")] = "255";  // output is always I3
+
+     // Create LUT output net.
+     std::unique_ptr<NetInfo> out_net = std::unique_ptr<NetInfo>(new NetInfo);
+     out_net->name = id(ci->name.str(this) + "$nextnr_ice40_pack_pll_net");
+     out_net->driver.cell = pt.get();
+     out_net->driver.port = id("O");
+     pt->ports.at(id("O")).net = out_net.get();
+
+     // New users of the original cell's port
+     std::vector<PortRef> new_users;
+     for (const auto &user : port.net->users) {
+         if (onlyNonLUTs && user.cell->type == id("ICESTORM_LC")) {
+             new_users.push_back(user);
+             continue;
+         }
+         // Rewrite pointer into net in user.
+         user.cell->ports[user.port].net = out_net.get();
+         // Add user to net.
+         PortRef pr;
+         pr.cell = user.cell;
+         pr.port = user.port;
+         out_net->users.push_back(pr);
+     }
+
+     // Add LUT to new users.
+     PortRef pr;
+     pr.cell = pt.get();
+     pr.port = id("I3");
+     new_users.push_back(pr);
+     pt->ports.at(id("I3")).net = port.net;
+
+     // Replace users of the original net.
+     port.net->users = new_users;
+
+     nets[out_net->name] = std::move(out_net);
+     return pt;
+}
+
 NEXTPNR_NAMESPACE_END