/***********************
 * Message Definitions *
 ***********************/

#include <stdint.h>

#define MSG_HEADER       0x1234

#define MSG_VALID_DEVICE 0x0001  // device id is valid
#define MSG_VALID_WORLD  0x0002  // world time is valid
#define MSG_VALID_START  0x0004  // start time is valid
#define MSG_VALID_PERIOD 0x0008  // period is valid
#define MSG_VALID_SYNC   0x8000  // begin time sync

#pragma pack(1)

typedef enum {
	MSG_ID_INIT,       // Device initialization
	MSG_ID_SYNC,       // Time synchronization
	MSG_ID_EVENT,      // Event occurred
	MSG_MAX_ID,        // Maximum message ID
} msgid_t;

typedef struct {
	uint32_t seconds;  // Seconds since 1970
	uint32_t nanosec;  // Nanoseconds since 'seconds'
} ntime_t;

typedef struct {
	uint16_t header;   // Message Header
	uint16_t msgid;    // Message ID
	uint16_t length;   // Body length
	uint16_t cksum;    // Body checksum
} header_t;

typedef struct {
	uint16_t valid;    // Message valid bits
	uint16_t device;   // Device ID to use
	ntime_t  world;    // World time (since 1970)
	ntime_t  start;    // Transmit start time 
	ntime_t  period;   // Transmit period
} init_msg_t;

typedef struct {
	uint32_t seq;      // Current sequence counter
	ntime_t  time;     // Time of previous message
} sync_msg_t;

typedef struct {
	uint16_t device;   // Device ID
	uint16_t event;    // Event ID
	ntime_t  world;    // UTC Time of event
	ntime_t  local;    // Time since turn-on
} event_msg_t;

#pragma pack()