/*

 * Low-level protocol support for the IPC connection to the engine.

 */

#ifndef IPCCONN_H_

#define IPCCONN_H_

#include <stddef.h>

typedef enum {IPC_NOT_CONNECTED, IPC_LISTENING, IPC_CONNECTED} IpcConnState;

/**

 * Called by flib_init(). Initialize everything related to ipc.

 */

void flib_ipcconn_init();

/**

 * Called by flib_quit(). Free resources and shut down.

 */

void flib_ipcconn_quit();

/**

 * Start listening for a connection from the engine. The system has to be in state

 * IPC_NOT_CONNECTED when calling this function.

 *

 * Returns the port we started listening on, or a negative value if there is an error.

 *

 * We stop listening once a connection has been established, so if you want to start

 * the engine again and talk to it you need to call this function again after the old

 * connection is closed.

 */

int flib_ipcconn_listen();

/**

 * Close the current IPC connection and/or stop listening for an incoming one.

 * This also discards all unread messages.

 */

void flib_ipcconn_close();

/**

 * Determine the current connection state

 */

IpcConnState flib_ipcconn_state();

/**

 * Receive a single message (up to 255 bytes) and copy it into the data buffer.

 * Returns the length of the received message, a negative value if no message could

 * be read.

 */

int flib_ipcconn_recv_message(void *data);

/**

 * Write a single message (up to 255 bytes) to the engine. This call blocks until the

 * message is completely written or the connection is closed or an error occurs.

 *

 * Calling this function in a state other than IPC_CONNECTED will fail immediately.

 * Returns a negative value on failure.

 */

int flib_ipcconn_send_message(void *data, size_t len);

/**

 * Call regularly to allow background work to proceed

 */

void flib_ipcconn_tick();

#endif /* IPCCONN_H_ */