#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

/* Non standard include */
#include <commtech.h>
#include <specific_comm.h>


void *create_comm_channel(void)
{
	struct channel *channel;

	if (!posix_memalign((void **) &channel, CACHE_LINE_SIZE, sizeof(struct channel)))
	{
		channel->receiver_idx = 0;
		channel->state = 0;
		channel->sender_idx = 0;
		return channel;
	}
	return NULL;
}

int destroy_comm_channel(void *channel)
{
	free(channel);
	return 0;
}

/*
 * Copy at max count received data into buf
 * @param buf The buffer in which received data must be copied into
 * @return Number of data received and copied into buf
 *
 * @warning recv_one_data should not be used in conjonction of
 * recv_some_data
 */
void *recv_one_data(struct channel *channel)
{
	static __thread int i;
	void *result;

	if (unlikely(!(channel->receiver_idx % (BUF_SIZE / sizeof(void *)))))
		while (!channel->state);
	result = channel->buf[channel->receiver_idx++];
	i %= (2 * BUF_SIZE) / sizeof(void *);
	if (unlikely(!(channel->receiver_idx % (BUF_SIZE / sizeof(void *)))))
		channel->state = 0;
	return result;
}

/*
 * Copy at max count received data into buf
 * @param buf The buffer in which received data must be copied into
 * @return Number of data received and copied into buf
 *
 * @warning recv_some_data should not be used in conjonction of
 * recv_one_data
 * @warning count must be a multiple of BUF_SIZE
 */
ssize_t recv_some_data(struct channel *channel, void **buf, size_t count)
{
	int nb_read;

	nb_read = 0;
	while (channel->state && nb_read < count)
	{
		int i, n;
		/*
		 * cur->receiver_idx point to the last buffer we have read.
		 * We go to the next cache line "+ (BUF_SIZE / sizeof(void *))"
		 * (because the line is full of void * and then if we are after
		 * the second cache line we correct the pointer to point to the
		 * first one (this is done by the modulo).
		 */
		i = channel->receiver_idx;
		n = channel->receiver_idx + (BUF_SIZE / sizeof(void *));
		channel->receiver_idx = n % ((2 * BUF_SIZE) / sizeof(void *));
		for(; i < n; i++)
		{
			/*
			 * The behaviour of this is not documented but we know
			 * the values inside buf won't change during this affectation
			 */
			*buf++ = channel->buf[i];
		}
		nb_read += BUF_SIZE / sizeof(void *);
		channel->state = 0;
	}
	return nb_read;
}