游戏助手（如XX助手）有一项游戏加速功能，实现原理其实非常简单，直接hook gettimeofday。

实现tweak代码如下：

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//  speedup.xm
//  create by creantan on 14-10-23
static int (*orig_gettimeofday)(struct timeval * __restrict, void * __restrict);
static int mygettimeofday(struct timeval*tv,struct timezone *tz ) {
    int ret = orig_gettimeofday(tv,tz);
    if (ret == 0) {
        tv->tv_usec *= SPEEDLEVEL;
        tv->tv_sec *= SPEEDLEVEL;
    }
    return ret;
}
%ctor {
    MSHookFunction((void *)MSFindSymbol(NULL,"_gettimeofday"), (void *)mygettimeofday, (void **)&orig_gettimeofday);
}