SDL_GetTicks (3) - Linux Manuals
SDL_GetTicks: Get the number of milliseconds since the SDL library initialization.
NAME
SDL_GetTicks - Get the number of milliseconds since the SDL library initialization.SYNOPSIS
#include "SDL.h"
DESCRIPTION
Get the number of milliseconds since the SDL library initialization. Note that this value wraps if the program runs for more than ~49 days.
SEE ALSO
SDL_Delay