static void
taskscheduler(void)
{//协程调度函数
int i;
Task *t;
taskdebug("scheduler enter");
for(;;){
if(taskcount == 0)
exit(taskexitval);
t = taskrunqueue.head;//从头部开始唤起
if(t == nil){
fprint(2, "no runnable tasks! %d tasks stalled\n", taskcount);
exit(1);
}
deltask(&taskrunqueue, t);//从待调度链表中移出来，调度它运行
t->ready = 0;
taskrunning = t;//标记正在执行的协程
tasknswitch++;
taskdebug("run %d (%s)", t->id, t->name);
contextswitch(&taskschedcontext, &t->context);//真正进行上下文切换，这样就切换到了其他协程运行，比如taskmainstart
//print("back in scheduler\n");
taskrunning = nil;//把刚刚被切换的协程的指向改为空。
if(t->exiting){
if(!t->system)
taskcount--;
i = t->alltaskslot;
alltask[i] = alltask[--nalltask];
alltask[i]->alltaskslot = i;
free(t);
}
}
}
static void
taskscheduler(void)
{
int i;
Task *t;
taskdebug("scheduler enter");
for(;;){
if(taskcount == 0)
exit(taskexitval);
t = taskrunqueue.head;
if(t == nil){
fprint(2, "no runnable tasks! %d tasks stalled\n", taskcount);
exit(1);
}
deltask(&taskrunqueue, t);
t->ready = 0;
taskrunning = t;
tasknswitch++;
taskdebug("run %d (%s)", t->id, t->name);
contextswitch(&taskschedcontext, &t->context);
//print("back in scheduler\n");
taskrunning = (Task*) nil;
if(t->exiting){
if(!t->system)
taskcount--;
i = t->alltaskslot;
alltask[i] = alltask[--nalltask];
alltask[i]->alltaskslot = i;
free(t);
}
}
}
static void
taskscheduler(void)
{
int i;
Task *t;
for (; ;) {
if (taskcount == 0)
exit(taskexitval);
t = taskrunqueue.head;
if (t == nil) {
fprintf(stderr, "no runnable tasks! %d tasks stalled\n", taskcount);
exit(1);
}
deltask(&taskrunqueue, t);
t->ready = 0;
taskrunning = t;
tasknswitch++;
contextswitch(&taskschedcontext, &t->context);
taskrunning = nil;
if (t->exiting) {
if (!t->system)
taskcount--;
i = t->alltaskslot;
alltask[i] = alltask[--nalltask];
alltask[i]->alltaskslot = i;
free(t);
}
}
}
static void
taskscheduler(void)
{
int i;
Task *t;
taskdebug("scheduler enter");
for(;;){
// 当前除了系统协程外没有其他协程, 退出
if(taskcount == 0)
exit(taskexitval);
// 处理的顺序是 FIFO
t = taskrunqueue.head;
if(t == nil){
fprint(2, "no runnable tasks! %d tasks stalled\n", taskcount);
exit(1);
}
// 从就绪队列里面去掉这个协程
deltask(&taskrunqueue, t);
t->ready = 0;
// 把拿出来的就绪任务设置为当前正在执行的任务
taskrunning = t;
// 协程调度计数 +1
tasknswitch++;
taskdebug("run %d (%s)", t->id, t->name);
// 切换到刚拿到的协程, 调度的核心
// 使用 taskschedcontext 保留老的堆栈状态, 把 t->context 设置为新的执行上下文
// 后面通过 taskswitch 切换回调度协程
contextswitch(&taskschedcontext, &t->context);
//print("back in scheduler\n");
taskrunning = nil;
if(t->exiting){ // 协程执行完退出
// 系统协程不计数
if(!t->system)
taskcount--;
// 把数组中最后一个任务放到要删除的任务的位置
// 这里判断一下当前任务是不是已经在数据尾部会更加优雅?
i = t->alltaskslot;
alltask[i] = alltask[--nalltask];
alltask[i]->alltaskslot = i;
// 释放任务
free(t);
}
}
}
static
DECL_SYMBOL_ACTION(emulate_reset_computer)
{
/* Upon restart, save volatile RAMs and reload all ROMs,
in case they were overwritten by a bug or something. ;) */
if (task == csa_WRITE) {
memory_volatile_save();
memory_complete_load();
stateflag &= ~ST_INTERRUPT;
reset9901();
init9900();
hold9900pin(INTPIN_RESET);
contextswitch(0);
}
return 1;
}
// 协程切换
void
taskswitch(void)
{
needstack(0);
contextswitch(&taskrunning->context, &taskschedcontext);
}
void
taskswitch(void)
{//主动进行协程切换，其实就是切换到main协程，到那里去进行实际的切换
needstack(0);//检测堆栈溢出
contextswitch(&taskrunning->context, &taskschedcontext);
}