Merge branch 'master' of gitlab.com:SymbioticEDA/nextpnr

3 files changed, 131 insertions, 1 deletions

diff --git a/common/place_sa.cc b/common/place_sa.cc
index 55ec9b9a..0a60adc8 100644
--- a/common/place_sa.cc
+++ b/common/place_sa.cc
@@ -101,6 +101,7 @@ class SAPlacer
                 }
 
                 cell->bel = bel;
+                cell->belStrength = STRENGTH_USER;
                 ctx->bindBel(bel, cell->name);
                 locked_bels.insert(bel);
                 placed_cells++;
@@ -215,9 +216,9 @@ class SAPlacer
         }
         // Final post-pacement validitiy check
         for (auto bel : ctx->getBels()) {
+            IdString cell = ctx->getBelCell(bel, false);
             if (!checker->isBelLocationValid(bel)) {
                 std::string cell_text = "no cell";
-                IdString cell = ctx->getBelCell(bel, false);
                 if (cell != IdString())
                     cell_text = std::string("cell '") + cell.str(ctx) + "'";
                 log_error("post-placement validity check failed for Bel '%s' "
@@ -277,6 +278,7 @@ class SAPlacer
                 all_placed = true;
             }
             cell->bel = best_bel;
+            cell->belStrength = STRENGTH_WEAK;
             ctx->bindBel(cell->bel, cell->name);
 
             // Back annotate location
diff --git a/common/timing.cc b/common/timing.cc
new file mode 100644
index 00000000..47c82a03
--- /dev/null
+++ b/common/timing.cc
@@ -0,0 +1,96 @@
+/*
+ *  nextpnr -- Next Generation Place and Route
+ *
+ *  Copyright (C) 2018  David Shah <david@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
+ *  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 "timing.h"
+#include <algorithm>
+#include <unordered_map>
+#include <utility>
+#include "log.h"
+
+NEXTPNR_NAMESPACE_BEGIN
+
+static delay_t follow_net(Context *ctx, NetInfo *net, int path_length,
+                          delay_t slack);
+
+// Follow a path, returning budget to annotate
+static delay_t follow_user_port(Context *ctx, PortRef &user, int path_length,
+                                delay_t slack)
+{
+    delay_t value;
+    if (ctx->getPortClock(user.cell, user.port) != IdString()) {
+        // At the end of a timing path (arguably, should check setup time
+        // here too)
+        value = slack / path_length;
+    } else {
+        // Default to the path ending here, if no further paths found
+        value = slack / path_length;
+        // Follow outputs of the user
+        for (auto port : user.cell->ports) {
+            if (port.second.type == PORT_OUT) {
+                delay_t comb_delay;
+                // Look up delay through this path
+                bool is_path = ctx->getCellDelay(user.cell, user.port,
+                                                 port.first, comb_delay);
+                if (is_path) {
+                    NetInfo *net = port.second.net;
+                    if (net) {
+                        delay_t path_budget = follow_net(ctx, net, path_length,
+                                                         slack - comb_delay);
+                        value = std::min(value, path_budget);
+                    }
+                }
+            }
+        }
+    }
+
+    if (value < user.budget) {
+        user.budget = value;
+    }
+}
+
+static delay_t follow_net(Context *ctx, NetInfo *net, int path_length,
+                          delay_t slack)
+{
+    delay_t net_budget = slack / path_length;
+    for (auto &usr : net->users) {
+        net_budget = std::min(
+                net_budget, follow_user_port(ctx, usr, path_length + 1, slack));
+    }
+    return net_budget;
+}
+
+void assign_budget(Context *ctx, float default_clock)
+{
+    for (auto cell : ctx->cells) {
+        for (auto port : cell.second->ports) {
+            if (port.second.type == PORT_OUT) {
+                IdString clock_domain =
+                        ctx->getPortClock(cell.second, port.first);
+                if (clock_domain != IdString()) {
+                    delay_t slack = delay_t(
+                            1.0e12 / default_clock); // TODO: clock constraints
+                    if (port.second.net)
+                        follow_net(ctx, port.second.net, 0, slack);
+                }
+            }
+        }
+    }
+}
+
+NEXTPNR_NAMESPACE_END
diff --git a/common/timing.h b/common/timing.h
new file mode 100644
index 00000000..03ae048d
--- /dev/null
+++ b/common/timing.h
@@ -0,0 +1,32 @@
+/*
+ *  nextpnr -- Next Generation Place and Route
+ *
+ *  Copyright (C) 2018  David Shah <david@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
+ *  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.
+ *
+ */
+
+#ifndef TIMING_H
+#define TIMING_H
+
+#include "nextpnr.h"
+
+NEXTPNR_NAMESPACE_BEGIN
+
+// Assign "budget" values for all user ports in the design
+void assign_budget(Context *ctx, float default_clock = 12e6);
+
+NEXTPNR_NAMESPACE_END
+
+#endif