1 files changed, 41 insertions, 0 deletions
diff --git a/libgo/runtime/go-chan-len.c b/libgo/runtime/go-chan-len.c
new file mode 100644
index 000000000..5aebae141
--- /dev/null
+++ b/libgo/runtime/go-chan-len.c
@@ -0,0 +1,41 @@
+/* go-chan-len.c -- the len function applied to a channel.
+
+   Copyright 2009 The Go Authors. All rights reserved.
+   Use of this source code is governed by a BSD-style
+   license that can be found in the LICENSE file.  */
+
+#include <stddef.h>
+
+#include "go-assert.h"
+#include "channel.h"
+
+/* Return the len function applied to a channel--the number of
+   elements in the buffer.  This could be done inline but I'm doing it
+   as a function for now to make it easy to change the channel
+   structure.  */
+
+size_t
+__go_chan_len (struct __go_channel *channel)
+{
+  int i;
+  size_t ret;
+
+  if (channel == NULL)
+    return 0;
+
+  i = pthread_mutex_lock (&channel->lock);
+  __go_assert (i == 0);
+
+  if (channel->num_entries == 0)
+    ret = 0;
+  else if (channel->next_fetch == channel->next_store)
+    ret = 0;
+  else
+    ret = ((channel->next_store + channel->num_entries - channel->next_fetch)
+	   % channel->num_entries);
+
+  i = pthread_mutex_unlock (&channel->lock);
+  __go_assert  (i == 0);
+
+  return ret;
+}