1 files changed, 87 insertions, 0 deletions
diff --git a/firmware/octoclock/lib/arp_cache.c b/firmware/octoclock/lib/arp_cache.c
new file mode 100644
index 000000000..558632d7f
--- /dev/null
+++ b/firmware/octoclock/lib/arp_cache.c
@@ -0,0 +1,87 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2009-2011,2014 Ettus Research LLC
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include "arp_cache.h"
+#include <stddef.h>
+
+typedef struct {
+  struct ip_addr	ip;
+  eth_mac_addr_t	mac;
+} arp_cache_t;
+
+#define	NENTRIES 8	// power-of-2
+
+static size_t nentries;
+static size_t victim;
+static arp_cache_t cache[NENTRIES];
+
+void
+arp_cache_init(void)
+{
+  nentries = 0;
+  victim = 0;
+}
+
+// returns non-negative index if found, else -1
+static int
+arp_cache_lookup(const struct ip_addr *ip)
+{
+  int i;
+  for (i = 0; i < nentries; i++)
+    if (cache[i].ip.addr == ip->addr)
+      return i;
+
+  return -1;
+}
+
+static int
+arp_cache_alloc(void)
+{
+  if (nentries < NENTRIES)
+    return nentries++;
+
+  int i = victim;
+  victim = (victim + 1) % NENTRIES;
+  return i;
+}
+
+void 
+arp_cache_update(const struct ip_addr *ip,
+		 const eth_mac_addr_t *mac)
+{
+  int i = arp_cache_lookup(ip);
+  if (i < 0){
+    i = arp_cache_alloc();
+    cache[i].ip = *ip;
+    cache[i].mac = *mac;
+  }
+  else {
+    cache[i].mac = *mac;
+  }
+}
+
+bool
+arp_cache_lookup_mac(const struct ip_addr *ip,
+		     eth_mac_addr_t *mac)
+{
+  int i = arp_cache_lookup(ip);
+  if (i < 0)
+    return false;
+
+  *mac = cache[i].mac;
+  return true;
+}