/*
 * Copyright (C) 2009-2012 Thomas Preud'homme <thomas.preud-homme@lip6.fr>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <unistd.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)))
	{
		if (!posix_memalign((void *) &channel->shared_space, CACHE_LINE_SIZE, SHARED_SPACE_SIZE))
		{
			channel->cons_idx = 0;
			channel->prod_idx = 0;
			return channel;
		}
		else
			free(channel);
	}
	return NULL;
}

int end_producer(void *unused __attribute__ ((unused)))
{
	return 0;
}

int destroy_comm_channel(void *channel)
{
	free((void *) ((struct channel *) channel)->shared_space);
	free(channel);
	return 0;
}

void *recv_one_data(struct channel *channel)
{
	void *result;
	unsigned int cons_idx, prod_idx;

	cons_idx = channel->cons_idx;
	prod_idx = channel->prod_idx;
	if (cons_idx == prod_idx)
		while(prod_idx == channel->prod_idx);
	/*
	 * The behaviour of this is not documented but we know the
	 * values inside shared_space won't change during this
	 * affectation
	 */
	result = channel->shared_space[cons_idx];
	cons_idx = (cons_idx + 1) % SHARED_SPACE_VOIDPTR;
	channel->cons_idx = cons_idx;
	return result;
}

ssize_t recv_some_data(struct channel *channel, void **buf, size_t count)
{
	unsigned int n, cons_idx, prod_idx;

	n = 0;
	cons_idx = channel->cons_idx;
	do
	{
		prod_idx = channel->prod_idx;
		for(; cons_idx != prod_idx; cons_idx = (cons_idx + 1) % SHARED_SPACE_VOIDPTR)
		{
			/*
			 * The behaviour of this is not documented but we know
			 * the values inside buf won't change during this affectation
			 */
			*buf++ = channel->shared_space[cons_idx];
			if (++n == count)
			{
				channel->cons_idx = cons_idx;
				return n;
			}
		}
	} while (prod_idx != channel->prod_idx);
	channel->cons_idx = cons_idx;
	return n;
}