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diff --git a/common/kernel/design_utils.h b/common/kernel/design_utils.h
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+/*
+ *  nextpnr -- Next Generation Place and Route
+ *
+ *  Copyright (C) 2018  Claire Xenia Wolf <claire@yosyshq.com>
+ *  Copyright (C) 2018  gatecat <gatecat@ds0.me>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#include "nextpnr.h"
+
+#ifndef DESIGN_UTILS_H
+#define DESIGN_UTILS_H
+
+#include <algorithm>
+
+NEXTPNR_NAMESPACE_BEGIN
+
+/*
+Utilities for design manipulation, intended for use inside packing algorithms
+ */
+
+// Disconnect a net (if connected) from old, and connect it to rep
+void replace_port(CellInfo *old_cell, IdString old_name, CellInfo *rep_cell, IdString rep_name);
+
+// If a net drives a given port of a cell matching a predicate (in many
+// cases more than one cell type, e.g. SB_DFFxx so a predicate is used), return
+// the first instance of that cell (otherwise nullptr). If exclusive is set to
+// true, then this cell must be the only load. If ignore_cell is set, that cell
+// is not considered
+template <typename F1>
+CellInfo *net_only_drives(const Context *ctx, NetInfo *net, F1 cell_pred, IdString port, bool exclusive = false,
+                          CellInfo *exclude = nullptr)
+{
+    if (net == nullptr)
+        return nullptr;
+    if (exclusive) {
+        if (exclude == nullptr) {
+            if (net->users.entries() != 1)
+                return nullptr;
+        } else {
+            if (net->users.entries() > 2) {
+                return nullptr;
+            } else if (net->users.entries() == 2) {
+                bool found = false;
+                for (auto &usr : net->users) {
+                    if (usr.cell == exclude)
+                        found = true;
+                }
+                if (!found)
+                    return nullptr;
+            }
+        }
+    }
+    for (const auto &load : net->users) {
+        if (load.cell != exclude && cell_pred(ctx, load.cell) && load.port == port) {
+            return load.cell;
+        }
+    }
+    return nullptr;
+}
+
+// If a net is driven by a given port of a cell matching a predicate, return
+// that cell, otherwise nullptr
+template <typename F1> CellInfo *net_driven_by(const Context *ctx, const NetInfo *net, F1 cell_pred, IdString port)
+{
+    if (net == nullptr)
+        return nullptr;
+    if (net->driver.cell == nullptr)
+        return nullptr;
+    if (cell_pred(ctx, net->driver.cell) && net->driver.port == port) {
+        return net->driver.cell;
+    } else {
+        return nullptr;
+    }
+}
+
+// Check if a port is used
+inline bool port_used(CellInfo *cell, IdString port_name)
+{
+    auto port_fnd = cell->ports.find(port_name);
+    return port_fnd != cell->ports.end() && port_fnd->second.net != nullptr;
+}
+
+void print_utilisation(const Context *ctx);
+
+NEXTPNR_NAMESPACE_END
+
+#endif