//----------------------------------------------------------------------------------------------------//
// @func - sched_prio
//! @desc
//! Pre-emptive strict priority scheduler
//! @return
//! - Nothing
//! @note
//! - None
//----------------------------------------------------------------------------------------------------//
void sched_prio ()
{
int i;
signed char ready = -1;
// Enqueue only currently running processes. Else,
// If PROC_DEAD, no need to enqueue
// If PROC_WAIT or PROC_TIMED_WAIT, already enqueued in appropriate wait queue
// If PROC_DELAY, is in one of the timer queues
// If idle_task, then does not need to enter the queue
if (current_process->state == PROC_RUN) {
ptable[current_pid].state = PROC_READY;
if (current_pid != idle_task_pid)
penq (&ready_q[ptable[current_pid].priority], current_pid, 0);
}
SET_CURRENT_PROCESS (-1);
for (i=0; i <= PRIO_LOWEST; i++) {
while (ready_q[i].item_count != 0) {
pdeq (&ready_q[i], &ready, 0);
if (ptable[ready].state == PROC_DEAD) { // Flush out dead processes
ready = -1;
continue;
}
else break;
}
if (ready != -1)
break;
}
if (ready == -1)
ready = idle_task_pid;
#if 0
DBG_PRINT ("XMK: Scheduler: scheduled pid: ");
putnum (ready);
DBG_PRINT ("\r\n");
#endif
ptable[ready].state = PROC_RUN;
SET_CURRENT_PROCESS (ready);
}
void init_idle_task (void)
{
idle_task_pid = proc_create (PRIO_LOWEST); // Idle task (PID 0).
ptable[idle_task_pid].state = PROC_RUN; // Idle task assumed to be running as soon as the kernel starts
#ifndef PPC_CPU_440
ptable[idle_task_pid].pcontext.regs[CTX_INDEX_MSR] = mfmsr () | XIL_EXCEPTION_NON_CRITICAL;
#else
// We set MSR[DS] = 1 here, because that is the TLB scheme we use to
// separate instruction and data space on the 440.
ptable[idle_task_pid].pcontext.regs[CTX_INDEX_MSR] = mfmsr () | XIL_EXCEPTION_NON_CRITICAL | XREG_MSR_TLB_DATA_TS;
#endif
ptable[idle_task_pid].pcontext.regs[CTX_INDEX_PC] = (unsigned int)idle_task;
ptable[idle_task_pid].pcontext.regs[CTX_INDEX_GPR(1)] = mfgpr (1);
ptable[idle_task_pid].pcontext.regs[CTX_INDEX_GPR(2)] = mfgpr (2);
ptable[idle_task_pid].pcontext.regs[CTX_INDEX_GPR(13)]= mfgpr (13);
SET_CURRENT_PROCESS (idle_task_pid);
}
