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authorupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
committerupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
commit554fd8c5195424bdbcabf5de30fdc183aba391bd (patch)
tree976dc5ab7fddf506dadce60ae936f43f58787092 /libgo/runtime/go-chan-len.c
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Diffstat (limited to 'libgo/runtime/go-chan-len.c')
-rw-r--r--libgo/runtime/go-chan-len.c41
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;
+}