X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=bertos%2Fkern%2Fpreempt.c;h=7ecd481d0cdf57c6d4c3679fc4ccfa43f5cc794e;hb=5691738d997fcb88e9ff1cb905c4e180ece79867;hp=0cbaf7c902dd2d65a03015cecf2b15804853f17e;hpb=8cfe12e5b95974d75b98ec964fc7edaf37919f0e;p=bertos.git

diff --git a/bertos/kern/preempt.c b/bertos/kern/preempt.c
index 0cbaf7c9..7ecd481d 100644
--- a/bertos/kern/preempt.c
+++ b/bertos/kern/preempt.c
@@ -26,31 +26,27 @@
  * invalidate any other reasons why the executable file might be covered by
  * the GNU General Public License.
  *
- * Copyright 2001, 2004 Develer S.r.l. (http://www.develer.com/)
- * Copyright 1999, 2000, 2001, 2008 Bernie Innocenti <bernie@codewiz.org>
+ * Copyright 2008 Bernie Innocenti <bernie@codewiz.org>
  * -->
  *
- * \brief Simple realtime multitasking scheduler.
- *        Context switching is only done cooperatively.
+ * \brief Simple preemptive multitasking scheduler.
  *
  * \version $Id: proc.c 1616 2008-08-10 19:41:26Z bernie $
  * \author Bernie Innocenti <bernie@codewiz.org>
- * \author Stefano Fedrigo <aleph@develer.com>
  */
 
 #include "proc_p.h"
 #include "proc.h"
 
+#include <kern/irq.h>
+#include <kern/monitor.h>
 #include <cpu/frame.h> // CPU_IDLE
+#include <drv/timer.h>
+#include <cfg/module.h>
 
-#include <unistd.h> // XXX alarm()
 
 
-/*
- * The time sharing scheduler forces a task switch when the current
- * process has exhausted its quantum.
- */
-uint16_t Quantum;
+Timer preempt_timer;
 
 /**
  * Disable preemptive task switching.
@@ -83,104 +79,99 @@ void proc_permit(void)
 	--CurrentProcess->forbid_cnt;
 }
 
-static void (*irq_handlers[100])(void); // FIXME
-
 
 void proc_preempt(void)
 {
-	TRACE;
+	IRQ_DISABLE;
 
-	ATOMIC(LIST_ASSERT_VALID(&ProcReadyList));
+	LIST_ASSERT_VALID(&ProcReadyList);
+	CurrentProcess = (struct Process *)list_remHead(&ProcReadyList);
+	LIST_ASSERT_VALID(&ProcReadyList);
+	ASSERT2(CurrentProcess, "no idle proc?");
 
-	IRQ_DISABLE;
-	/* Poll on the ready queue for the first ready process */
-	while (!(CurrentProcess = (struct Process *)list_remHead(&ProcReadyList)))
-	{
-		/*
-		 * Make sure we physically reenable interrupts here, no matter what
-		 * the current task status is. This is important because if we
-		 * are idle-spinning, we must allow interrupts, otherwise no
-		 * process will ever wake up.
-		 *
-		 * During idle-spinning, an interrupt can occur and it may
-		 * modify \p ProcReadyList. To ensure that compiler reload this
-		 * variable every while cycle we call CPU_MEMORY_BARRIER.
-		 * The memory barrier ensure that all variables used in this context
-		 * are reloaded.
-		 */
-		IRQ_ENABLE;
-		CPU_IDLE;
-		MEMORY_BARRIER;
-		IRQ_DISABLE;
-	}
 	IRQ_ENABLE;
+
+	TRACEMSG("new proc: %p:%s", CurrentProcess, CurrentProcess ? CurrentProcess->monitor.name : "---");
+	monitor_report();
 }
 
-void proc_preempt_timer(void)
+void proc_preempt_timer(UNUSED_ARG(void *, param))
 {
-	// TODO: check Quantum
+	IRQ_DISABLE;
+/*
+	if (!CurrentProcess->forbid_cnt)
+	{
+		TRACEMSG("preempting %p:%s", CurrentProcess, CurrentProcess->monitor.name);
+		LIST_ASSERT_VALID(&ProcReadyList);
+		SCHED_ENQUEUE(CurrentProcess);
+		proc_preempt();
+	}
+*/
+	IRQ_ENABLE;
 
-	alarm(1);
-	ATOMIC(SCHED_ENQUEUE(CurrentProcess));
-	proc_schedule();
+	timer_setDelay(&preempt_timer, CONFIG_KERN_QUANTUM);
+	timer_add(&preempt_timer);
 }
 
 void proc_schedule(void)
 {
+	TRACE;
+
+	// Will invoke proc_preempt() in interrupt context
 	kill(0, SIGUSR1);
 }
 
 void proc_yield(void)
 {
-	ATOMIC(SCHED_ENQUEUE(CurrentProcess));
+	TRACE;
 
+	ASSERT_IRQ_ENABLED();
+	IRQ_DISABLE;
+	SCHED_ENQUEUE(CurrentProcess);
+	LIST_ASSERT_VALID(&ProcReadyList);
 	proc_schedule();
+	IRQ_ENABLE;
 }
 
-/* signal handler */
-void irq_entry(int signum)
+void proc_entry(void (*user_entry)(void))
 {
-	Process *old_process;
-
-	TRACEMSG("storing %p:%s", CurrentProcess, CurrentProcess->monitor.name);
-	CurrentProcess->leaving = false;
-	getcontext(&CurrentProcess->context);
-	/* We get here in two ways: directly, and after setcontext() below */
-
-	if (CurrentProcess->leaving)
-	{
-		TRACEMSG("leaving to %p:%s", CurrentProcess, CurrentProcess->monitor.name);
-		return;
-	}
+	user_entry();
+	proc_exit();
+}
 
-	old_process = CurrentProcess;
 
-	irq_handlers[signum]();
+static cpustack_t idle_stack[CONFIG_PROC_DEFSTACKSIZE / sizeof(cpustack_t)];
 
-	if (old_process != CurrentProcess)
+/*
+ * The idle process
+ *
+ * This process never dies and never sleeps.  It's also quite apathic
+ * and a bit antisocial.
+ *
+ * Having an idle process costs some stack space, but simplifies the
+ * interrupt-driven preemption logic because there is always a user
+ * context to which we can return.
+ */
+static NORETURN void idle(void)
+{
+	for (;;)
 	{
-		TRACEMSG("launching %p:%s", CurrentProcess, CurrentProcess->monitor.name);
-		CurrentProcess->leaving = true;
-		setcontext(&CurrentProcess->context);
-		/* not reached */
+		TRACE;
+		monitor_report();
+		proc_yield(); // FIXME: CPU_IDLE
 	}
-
-	TRACEMSG("keeping %p:%s", CurrentProcess, CurrentProcess->monitor.name);
 }
 
 void preempt_init(void)
 {
-	struct sigaction act;
-	act.sa_handler = irq_entry;
-	sigemptyset(&act.sa_mask);
-	sigaddset(&act.sa_mask, SIGUSR1);
-	sigaddset(&act.sa_mask, SIGALRM);
-	act.sa_flags = SA_RESTART; /* | SA_SIGINFO; */
-
-	irq_handlers[SIGUSR1] = proc_preempt;
-	irq_handlers[SIGALRM] = proc_preempt_timer;
-	sigaction(SIGUSR1, &act, NULL);
-	sigaction(SIGALRM, &act, NULL);
-
-	alarm(1);
+	MOD_CHECK(irq);
+	MOD_CHECK(timer);
+
+	irq_register(SIGUSR1, proc_preempt);
+
+	timer_setSoftint(&preempt_timer, proc_preempt_timer, NULL);
+	timer_setDelay(&preempt_timer, CONFIG_KERN_QUANTUM);
+	timer_add(&preempt_timer);
+
+	proc_new(idle, NULL, sizeof(idle_stack), idle_stack);
 }