n_clock_sync.h File Reference

Clock synchronization estimator for networked games. More...

#include "n_common.h"

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Data Structures
struct	N_CLOCK_SYNC
	clock synchronization estimator More...

Macros
#define	N_CLOCK_SYNC_INTERVAL   3.0
	default interval between sync requests in seconds
#define	N_CLOCK_SYNC_SAMPLE_COUNT   11
	number of samples for the median filter

Functions
void	n_clock_sync_delete (N_CLOCK_SYNC **cs)
	free a clock sync estimator
void	n_clock_sync_mark_sent (N_CLOCK_SYNC *cs, double local_now)
	mark that a sync request was just sent
N_CLOCK_SYNC *	n_clock_sync_new (void)
	allocate and initialize a new clock sync estimator
int	n_clock_sync_process_response (N_CLOCK_SYNC *cs, double client_send_time, double server_time, double local_now)
	record a sync response: client_send_time is the local time the request was sent, server_time is the server's timestamp from the response, local_now is the current local time when the response was received.
double	n_clock_sync_server_time (const N_CLOCK_SYNC *cs, double local_now)
	get estimated server time given a local time value
int	n_clock_sync_should_send (const N_CLOCK_SYNC *cs, double local_now)
	check if it's time to send a new sync request (returns TRUE/FALSE)

Detailed Description

Clock synchronization estimator for networked games.

Estimates the time offset between a local clock and a remote clock using periodic sync request/response pairs. The offset is computed as the median of recent samples to reject outliers caused by network jitter.

Usage:

N_CLOCK_SYNC *cs = n_clock_sync_new();
 
// Periodically:
if (n_clock_sync_should_send(cs, local_now)) {
    n_clock_sync_mark_sent(cs, local_now);
    send_sync_request(local_now);  // include local_now in request
}
 
// On response:
n_clock_sync_process_response(cs, client_send_time, server_time, local_now);
 
// Convert local time to estimated server time:
double srv_time = n_clock_sync_server_time(cs, local_now);
 
n_clock_sync_delete(&cs);

Author

Castagnier Mickael

Version

1.0

Date

12/03/2026

Definition in file n_clock_sync.h.