gcc/libgo/runtime/go-chan-cap.c

42 lines
941 B
C

/* go-chan-cap.c -- the cap 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 cap function applied to a channel--the size of 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. */
int
__go_chan_cap (struct __go_channel *channel)
{
int i;
int ret;
if (channel == NULL)
return 0;
i = pthread_mutex_lock (&channel->lock);
__go_assert (i == 0);
if (channel->num_entries == 0)
ret = 0;
else
{
/* One slot is always unused. We added 1 when we created the
channel. */
ret = channel->num_entries - 1;
}
i = pthread_mutex_unlock (&channel->lock);
__go_assert (i == 0);
return ret;
}