From 23688da201a3b668deaa3e7cc184060b678f2058 Mon Sep 17 00:00:00 2001
From: Andrew Waterman <waterman@eecs.berkeley.edu>
Date: Tue, 31 Jan 2012 17:31:33 -0800
Subject: [PATCH] poll HTIF occasionally

---
 riscv/htif.cc          | 12 ++++++++++++
 riscv/htif.h           |  3 +++
 riscv/riscv-isa-run.cc |  1 +
 riscv/sim.cc           | 13 +++++++++----
 4 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/riscv/htif.cc b/riscv/htif.cc
index ab27f01..7de27c6 100644
--- a/riscv/htif.cc
+++ b/riscv/htif.cc
@@ -7,6 +7,7 @@
 #include <errno.h>
 #include <assert.h>
 #include <stddef.h>
+#include <poll.h>
 
 enum
 {
@@ -79,6 +80,17 @@ void htif_t::nack(uint16_t nack_seqno)
   send_packet(&p);
 }
 
+void htif_t::poll()
+{
+  struct pollfd pfd;
+  pfd.fd = fromhost_fd;
+  pfd.events = POLLIN;
+  pfd.revents = 0;
+
+  if (::poll(&pfd, 1, 0) > 0)
+    wait_for_packet();
+}
+
 int htif_t::wait_for_packet()
 {
   while(1)
diff --git a/riscv/htif.h b/riscv/htif.h
index d7a8c89..805cc4f 100644
--- a/riscv/htif.h
+++ b/riscv/htif.h
@@ -22,6 +22,9 @@ public:
   void wait_for_tohost_write();
   void wait_for_fromhost_write();
 
+  // check to see if there's a pending packet and process it if so
+  void poll();
+
 private:
   sim_t* sim;
   int tohost_fd;
diff --git a/riscv/riscv-isa-run.cc b/riscv/riscv-isa-run.cc
index f73cc55..9217be8 100644
--- a/riscv/riscv-isa-run.cc
+++ b/riscv/riscv-isa-run.cc
@@ -54,4 +54,5 @@ int main(int argc, char** argv)
   // initalize simulator and run to completion
   sim_t s(nprocs, &htif);
   s.run(debug);
+  printf("graceful\n");
 }
diff --git a/riscv/sim.cc b/riscv/sim.cc
index f1c1b3b..d61e600 100644
--- a/riscv/sim.cc
+++ b/riscv/sim.cc
@@ -87,10 +87,15 @@ void sim_t::run(bool debug)
 
   for(running = true; running; )
   {
-    if(!debug)
-      step_all(100,100,false);
-    else
-      interactive();
+    for (int i = 0; i < 1000; i++)
+    {
+      if(!debug)
+        step_all(100,100,false);
+      else
+        interactive();
+    }
+
+    htif->poll();
   }
 }
 
-- 
2.30.2