请问系统是怎样找到优先级最高的任务
假设有2个任务，优先级分别是4和5，先后调用rt_thread_startup进入对应优先级的就绪列表。请问以下程序是怎么找到优先级4的线程？程序怎么确定rt_thread_ready_priority_group的值为4？求解...register rt_ubase_t number;
/* find out the highest priority task */
if (rt_thread_ready_priority_group & 0xff)
{
number = rt_lowest_bitmap;
}
else if (rt_thread_ready_priority_group & 0xff00)
{
number = rt_lowest_bitmap[(rt_thread_ready_priority_group >> 8) & 0xff] + 8;
}
else if (rt_thread_ready_priority_group & 0xff0000)
{
number = rt_lowest_bitmap[(rt_thread_ready_priority_group >> 16) & 0xff] + 16;
}
else
{
number = rt_lowest_bitmap[(rt_thread_ready_priority_group >> 24) & 0xff] + 24;
}
#if RT_THREAD_PRIORITY_MAX > 32
highest_ready_priority = (number << 3) + rt_lowest_bitmap];
#else
highest_ready_priority = number;
#endif 理解了，昨天理解错了 rt_thread_ready_priority_group |= thread->number_mask; 这句话。
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