42 lines
1006 B
C
42 lines
1006 B
C
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/* go-chan-len.c -- the len function applied to a channel.
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Copyright 2009 The Go Authors. All rights reserved.
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Use of this source code is governed by a BSD-style
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license that can be found in the LICENSE file. */
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#include <stddef.h>
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#include "go-assert.h"
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#include "channel.h"
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/* Return the len function applied to a channel--the number of
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elements in the buffer. This could be done inline but I'm doing it
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as a function for now to make it easy to change the channel
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structure. */
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size_t
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__go_chan_len (struct __go_channel *channel)
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{
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int i;
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size_t ret;
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if (channel == NULL)
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return 0;
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i = pthread_mutex_lock (&channel->lock);
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__go_assert (i == 0);
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if (channel->num_entries == 0)
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ret = 0;
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else if (channel->next_fetch == channel->next_store)
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ret = 0;
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else
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ret = ((channel->next_store + channel->num_entries - channel->next_fetch)
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% channel->num_entries);
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i = pthread_mutex_unlock (&channel->lock);
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__go_assert (i == 0);
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return ret;
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}
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