Function updateDeltaTime

deps/SDL2/Xcode-iOS/Demos/src/common.c:41–56

static Uint64 prevTime = 0;

double
updateDeltaTime(void)
{
    Uint64 curTime;
    double deltaTime;

    if (prevTime == 0) {
        prevTime = SDL_GetPerformanceCounter();
    }

    curTime = SDL_GetPerformanceCounter();
    deltaTime = (double) (curTime - prevTime) / (double) SDL_GetPerformanceFrequency();
    prevTime = curTime;

    return deltaTime;
}