#ifndef _COMMTECH_H_
#define _COMMTECH_H_ 1

#define CACHE_LINE_SIZE 64

#define likely(x) __builtin_expect(!!(x), 1)
#define unlikely(x) __builtin_expect((x), 0)

__BEGIN_DECLS

struct channel;

/* 
 * @return a pointer on the channel if success, NULL else
 *
 * Create a communication channel. The return value is the address of
 * the channel that has to be passed to init_producer_thread and
 * init_consumer_thread respectively by the producer and consumer thread
 * which want to communicate.
 */
void *create_comm_channel(void);


/* 
 * @param channel The channel to destroy
 * @return 0 if success, -1 else
 *
 * Destroy a communication channel.
 *
 * @comment Must be called after producer and consumer stopped to
 * communicate.
 */
int destroy_comm_channel(void *);

/*
 * @param channel The production channel
 * @return 0 if success, -1 else
 *
 * Notify the communication algorithm that the producer has finished producing
 *
 * @comment Must be called by the producer when it has finished producing
 */
int end_producer(void *);


/* 
 * @param channel Channel from which to receive data
 * @return a data sent by the matching producer
 *
 * Wait until a data sent by the matching producer is available
 *
 * @comment recv_one_data should not be used in conjonction of
 * recv_some_data
 */
void *recv_one_data(struct channel *);



/* 
 * @param channel Channel from which to receive data
 * @param buf The buffer to write received data into
 * @param count The maximum number of data to copy into buf
 * @return Number of data copied into buf
 *
 * Wait until some data sent by the matching producer is available and
 * copy as much data as possible into buf, with a maximum of count.
 *
 * @commentrecv_some_data should not be used in conjonction of recv_one_data
 * @comment count must be a multiple of BUF_SIZE / sizeof(void *) which is
 * equal to SUB_SLOTS
 */
ssize_t recv_some_data(struct channel *, void **, size_t);

__END_DECLS

#endif