From bbb140c6991f01838009a65c81399694fe8afe3f Mon Sep 17 00:00:00 2001
From: David Shah <davey1576@gmail.com>
Date: Sat, 21 Jul 2018 11:52:41 +0200
Subject: Quick hack to route nets with lowest budget first

---
 common/router1.cc | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

(limited to 'common')

diff --git a/common/router1.cc b/common/router1.cc
index 94c7070e..50022169 100644
--- a/common/router1.cc
+++ b/common/router1.cc
@@ -402,6 +402,21 @@ struct Router
 
 NEXTPNR_NAMESPACE_BEGIN
 
+static void prioritise_nets(Context *ctx, std::vector<IdString> &netsArray)
+{
+    std::unordered_map<IdString, delay_t> netScores;
+    for (auto net_name : netsArray) {
+        delay_t score = std::numeric_limits<delay_t>::max();
+        for (const auto &sink : ctx->nets.at(net_name)->users) {
+            if (sink.budget < score)
+                score = sink.budget;
+        }
+        netScores[net_name] = score;
+    }
+    std::sort(netsArray.begin(), netsArray.end(),
+              [&netScores](IdString a, IdString b) { return netScores[a] < netScores[b]; });
+}
+
 bool router1(Context *ctx)
 {
     try {
@@ -508,7 +523,7 @@ bool router1(Context *ctx)
             bool printNets = ctx->verbose && (netsQueue.size() < 10);
 
             std::vector<IdString> netsArray(netsQueue.begin(), netsQueue.end());
-            ctx->sorted_shuffle(netsArray);
+            prioritise_nets(ctx, netsArray);
             netsQueue.clear();
 
             for (auto net_name : netsArray) {
@@ -560,7 +575,7 @@ bool router1(Context *ctx)
                 int ripCnt = 0;
 
                 std::vector<IdString> ripupArray(ripupQueue.begin(), ripupQueue.end());
-                ctx->sorted_shuffle(ripupArray);
+                prioritise_nets(ctx, ripupArray);
 
                 for (auto net_name : ripupArray) {
                     if (printNets)
-- 
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