ice40: Start working on a packer, currently not tested

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

1 files changed, 79 insertions, 0 deletions

diff --git a/ice40/pack.cc b/ice40/pack.cc
new file mode 100644
index 00000000..692bfba2
--- /dev/null
+++ b/ice40/pack.cc
@@ -0,0 +1,79 @@
+/*
+ *  nextpnr -- Next Generation Place and Route
+ *
+ *  Copyright (C) 2018  Clifford Wolf <clifford@clifford.at>
+ *  Copyright (C) 2018  David Shah <dave@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 "pack.h"
+#include "cells.h"
+#include "design_utils.h"
+#include "log.h"
+
+#include <unordered_set>
+
+// Pack LUTs and LUT-FF pairs
+static void pack_lut_lutffs(Design *design)
+{
+    std::unordered_set<IdString> packed_cells;
+    for (auto cell : design->cells) {
+        CellInfo *ci = cell.second;
+        if (is_lut(ci)) {
+            CellInfo *packed = create_ice_cell(design, "ICESTORM_LC",
+                                               std::string(ci->name) + "_LC");
+            packed_cells.insert(ci->name);
+            // See if we can pack into a DFF
+            // TODO: LUT cascade
+            NetInfo *o = ci->ports.at("O").net;
+            CellInfo *dff = net_only_drives(o, is_ff, "D", true);
+            if (dff) {
+                lut_to_lc(ci, packed, false);
+                dff_to_lc(dff, packed, false);
+                packed_cells.insert(dff->name);
+            } else {
+                lut_to_lc(ci, packed, true);
+            }
+        }
+    }
+    for (auto pcell : packed_cells) {
+        design->cells.erase(pcell);
+    }
+}
+
+// Pack FFs not packed as LUTFFs
+static void pack_nonlut_ffs(Design *design)
+{
+    std::unordered_set<IdString> packed_cells;
+    for (auto cell : design->cells) {
+        CellInfo *ci = cell.second;
+        if (is_ff(ci)) {
+            CellInfo *packed = create_ice_cell(design, "ICESTORM_LC",
+                                               std::string(ci->name) + "_LC");
+            packed_cells.insert(ci->name);
+            dff_to_lc(ci, packed, true);
+        }
+    }
+    for (auto pcell : packed_cells) {
+        design->cells.erase(pcell);
+    }
+}
+
+// Main pack function
+void pack_design(Design *design)
+{
+    pack_lut_lutffs(design);
+    pack_nonlut_ffs(design);
+}