code:timeout - ikarishinjieva/unixV6-code-analyze-chs GitHub Wiki

3833

3834 /*

3835  * timeout is called to arrange that

3836  * fun(arg) is called in tim/HZ seconds.

3837  * An entry is sorted into the callout

3838  * structure. The time in each structure

3839  * entry is the number of HZ’s more

3840  * than the previous entry.

3841  * In this way, decrementing the

3842  * first entry has the effect of

3843  * updating all entries.

3844  */

3845 timeout(fun, arg, tim)

3846 {

3847     register struct callo *p1, *p2;

3848     register t;

3849     int s;

3850

3851     t = tim;

3852     s = PS->integ;

3853     p1 = &callout[0];

3854     spl7();

• 关中断
• 防止 时钟中断 处理 事件执行队列

3855     while(p1->c_func != 0 && p1->c_time <= t) {

3856          t =- p1->c_time;

3857          p1++;

3858     }

3859     p1->c_time =- t;

• 在事件执行队列中，寻找 插入事件 的合适位置

3860     p2 = p1;

3861     while(p2->c_func != 0)

3862          p2++;

3863     while(p2 >= p1) {

3864          (p2+1)->c_time = p2->c_time;

3865          (p2+1)->c_func = p2->c_func;

3866          (p2+1)->c_arg = p2->c_arg;

3867          p2--;

3868     }

3869     p1->c_time = t;

3870     p1->c_func = fun;

3871     p1->c_arg = arg;

• 插入事件

3872     PS->integ = s;

• 还原 PS
• 相当于 开中断

3873 }

3874 /* ------------------------- */

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• clock

• code:ttstart