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#ifndef __SYS_MSG_H
#define __SYS_MSG_H
#include <stdint.h>
#include <stdlib.h>
#include <builtins.h>
#ifdef __cplusplus
extern "C"
{
#endif
typedef void* msg_q_t;
struct msg_t
{
uint32_t type;
uint32_t __reserved__async;
uint64_t data[2];
void* extra_data;
};
// Message queue interfaces.
/** @fn msg_q_create
* @brief Create a new message queue.
*
* @return msg_q_t handle
*/
msg_q_t msg_q_create();
/** @fn msg_q_destroy
* @brief Deallocate a message queue previously allocated with msg_q_create()
*
* @param[in] q - handle to message queue to destroy
*/
void msg_q_destroy( msg_q_t q );
/** @fn msg_q_register
* @brief Assign a name to a message queue.
*
* @param[in] q - handle of message queue to name
* @param[in] name - name
*
* @return Result of msg_sendrecv where zero indicates success
*/
int msg_q_register(msg_q_t q, const char* name);
/** @fn msg_q_resolve
* @brief Given the name of a message queue, return the handle to it.
*
* @param[in] name - name of message queue
*
* @return message queue handle or null if name not found.
*/
msg_q_t msg_q_resolve(const char* name);
// Message interfaces.
/** @fn msg_allocate
* @brief Allocate space for message
* @return Pointer to message
*/
ALWAYS_INLINE
inline msg_t* msg_allocate() { return (msg_t*)malloc(sizeof(msg_t)); }
/** @fn msg_free
* @brief Free a msg_t
* @param[in] msg - message to free
*/
ALWAYS_INLINE
inline void msg_free(msg_t* m) { free(m); }
/** @fn msg_send
* @brief Send a message asynchronously.
*
* This call adds the message queue then returns
* to the caller. Any process waiting for a message
* in the queue will awake with this message.
*
* @param[in] q - message queue
* @param[in] msg - message
* @return Always returns zero.
*/
int msg_send(msg_q_t q, msg_t* msg);
/** @fn msg_sendrecv
* @brief Send a message to a server and get a response synchronously.
*
* The calling [client] thread blocks until the recipient [server] receives
* and replies to the message.
*
* @param[in] q - message queue
* @param[in,out] msg - message
* @return Zero on success, else negative.
*/
int msg_sendrecv(msg_q_t q, msg_t* msg);
/** @fn msg_respond
* @brief Respond to a synchronous message.
*
* This is how server-side code responds to synchronous
* messaging when clients call msg_sendrecv().
*
* @param[in] q - message queue
* @param[in] msg - response message
* @return Zero on success, else negative.
*/
int msg_respond(msg_q_t q, msg_t* msg);
/** @fn msg_wait
* @brief Read a message from the message queue.
*
* If a message is already on the queue, this call will return immediately
* with the message. Otherwise the calling thread will block and wait for
* a message.
*
* @param[in] q - message queue to read
* @return the message posted to the queue
*/
msg_t* msg_wait(msg_q_t q);
/** @fn msg_is_async
* @brief Indicates if message is asynchronous.
*
* Tests the message field "__reserved__async" which appears to be set to 0 to indicate asynchronous, and 1 to indicate synchronous message.
*
* @return true if asynchronous message
*/
ALWAYS_INLINE
inline uint32_t msg_is_async(msg_t* msg)
{ return 0 == msg->__reserved__async; }
#ifdef __cplusplus
}
#endif
#endif
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