1 files changed, 127 insertions, 0 deletions
diff --git a/libgo/runtime/go-rec-nb-small.c b/libgo/runtime/go-rec-nb-small.c
new file mode 100644
index 0000000000..9983d34644
--- /dev/null
+++ b/libgo/runtime/go-rec-nb-small.c
@@ -0,0 +1,127 @@
+/* go-rec-nb-small.c -- nonblocking receive of something smal on 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 <stdint.h>
+
+#include "go-assert.h"
+#include "go-panic.h"
+#include "channel.h"
+
+/* Prepare to receive something on a nonblocking channel.  */
+
+int
+__go_receive_nonblocking_acquire (struct __go_channel *channel)
+{
+  int i;
+  _Bool has_data;
+
+  i = pthread_mutex_lock (&channel->lock);
+  __go_assert (i == 0);
+
+  while (channel->selected_for_receive)
+    {
+      i = pthread_cond_wait (&channel->cond, &channel->lock);
+      __go_assert (i == 0);
+    }
+
+  if (channel->is_closed
+      && (channel->num_entries == 0
+	  ? channel->next_store == 0
+	  : channel->next_fetch == channel->next_store))
+    {
+      if (channel->saw_close)
+	{
+	  ++channel->closed_op_count;
+	  if (channel->closed_op_count >= MAX_CLOSED_OPERATIONS)
+	    {
+	      i = pthread_mutex_unlock (&channel->lock);
+	      __go_assert (i == 0);
+	      __go_panic_msg ("too many operations on closed channel");
+	    }
+	}
+      channel->saw_close = 1;
+      __go_unlock_and_notify_selects (channel);
+      return RECEIVE_NONBLOCKING_ACQUIRE_CLOSED;
+    }
+
+  if (channel->num_entries > 0)
+    has_data = channel->next_fetch != channel->next_store;
+  else
+    {
+      if (channel->waiting_to_receive)
+	{
+	  /* Some other goroutine is already waiting for data on this
+	     channel, so we can't pick it up.  */
+	  has_data = 0;
+	}
+      else if (channel->next_store > 0)
+	{
+	  /* There is data on the channel.  */
+	  has_data = 1;
+	}
+      else if (__go_synch_with_select (channel, 0))
+	{
+	  /* We synched up with a select sending data, so there will
+	     be data for us shortly.  Tell the select to go, and then
+	     wait for the data.  */
+	  __go_broadcast_to_select (channel);
+
+	  while (channel->next_store == 0)
+	    {
+	      i = pthread_cond_wait (&channel->cond, &channel->lock);
+	      __go_assert (i == 0);
+	    }
+
+	  has_data = 1;
+	}
+      else
+	{
+	  /* Otherwise there is no data.  */
+	  has_data = 0;
+	}
+
+      if (has_data)
+	{
+	  channel->waiting_to_receive = 1;
+	  __go_assert (channel->next_store == 1);
+	}
+    }
+
+  if (!has_data)
+    {
+      i = pthread_mutex_unlock (&channel->lock);
+      __go_assert (i == 0);
+      return RECEIVE_NONBLOCKING_ACQUIRE_NODATA;
+    }
+
+  return RECEIVE_NONBLOCKING_ACQUIRE_DATA;
+}
+
+/* Receive something 64 bits or smaller on a nonblocking channel.  */
+
+struct __go_receive_nonblocking_small
+__go_receive_nonblocking_small (struct __go_channel *channel)
+{
+  struct __go_receive_nonblocking_small ret;
+
+  __go_assert (channel->element_size <= sizeof (uint64_t));
+
+  int data = __go_receive_nonblocking_acquire (channel);
+  if (data != RECEIVE_NONBLOCKING_ACQUIRE_DATA)
+    {
+      ret.__val = 0;
+      ret.__success = data == RECEIVE_NONBLOCKING_ACQUIRE_CLOSED;
+      return ret;
+    }
+
+  ret.__val = channel->data[channel->next_fetch];
+
+  __go_receive_release (channel);
+
+  ret.__success = 1;
+
+  return ret;
+}