preempt: Cleanup

[bertos.git] / bertos / kern / preempt.c

diff --git a/bertos/kern/preempt.c b/bertos/kern/preempt.c
index f068a8a82c24d314d159e84a045422de18b55475..95ffbea093234e74834f5067f174fa3b90bfc956 100644 (file)
--- a/bertos/kern/preempt.c
+++ b/bertos/kern/preempt.c
@@ -26,55 +26,107 @@
  * 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 <cpu/irq.h>   // IRQ_DISABLE()...
+#include <drv/timer.h>
+#include <cfg/module.h>
 
-/*
- * The time sharing scheduler forces a task switch when the current
- * process has exhausted its quantum.
- */
-uint16_t Quantum;
 
-/**
- * Disable preemptive task switching.
- *
- * The scheduler maintains a per-process nesting counter.  Task switching is
- * effectively re-enabled only when the number of calls to proc_permit()
- * matches the number of calls to proc_forbid().
- *
- * Calling functions that could sleep while task switching is disabled
- * is dangerous, although supported.  Preemptive task switching is
- * resumed while the process is sleeping and disabled again as soon as
- * it wakes up again.
- *
- * \sa proc_permit()
- */
-void proc_forbid(void)
+int preempt_forbid_cnt;
+
+static Timer preempt_timer;
+
+
+// fwd decl from idle.c
+void idle_init(void);
+
+
+void proc_preempt(void)
 {
-       /* No need to protect against interrupts here. */
-       ++CurrentProcess->forbid_cnt;
+       IRQ_DISABLE;
+
+       ASSERT(preempt_forbid_cnt == 0);
+       LIST_ASSERT_VALID(&ProcReadyList);
+       CurrentProcess = (struct Process *)list_remHead(&ProcReadyList);
+       ASSERT2(CurrentProcess, "no idle proc?");
+
+       IRQ_ENABLE;
+
+       TRACEMSG("launching %p:%s", CurrentProcess, proc_currentName());
 }
 
-/**
- * Re-enable preemptive task switching.
- *
- * \sa proc_forbid()
- */
-void proc_permit(void)
+void proc_preempt_timer(UNUSED_ARG(void *, param))
 {
-       /* No need to protect against interrupts here. */
-       --CurrentProcess->forbid_cnt;
+       if (!preempt_forbid_cnt)
+       {
+               IRQ_DISABLE;
+               TRACEMSG("preempting %p:%s", CurrentProcess, proc_currentName());
+#if 0
+               SCHED_ENQUEUE(CurrentProcess);
+               proc_preempt();
+#endif
+               IRQ_ENABLE;
+       }
+
+       timer_setDelay(&preempt_timer, CONFIG_KERN_QUANTUM);
+       timer_add(&preempt_timer);
+}
+
+void proc_schedule(void)
+{
+       ATOMIC(LIST_ASSERT_VALID(&ProcReadyList));
+       TRACEMSG("%p:%s", CurrentProcess, proc_currentName());
+       ATOMIC(LIST_ASSERT_VALID(&ProcReadyList));
+
+       /* Sleeping with IRQs disabled or preemption forbidden is illegal */
+       ASSERT_IRQ_ENABLED();
+       ASSERT(preempt_forbid_cnt == 0);
+
+       // Will invoke proc_preempt() in interrupt context
+       kill(0, SIGUSR1);
+}
+
+void proc_yield(void)
+{
+       TRACEMSG("%p:%s", CurrentProcess, proc_currentName());
+
+       IRQ_DISABLE;
+       SCHED_ENQUEUE(CurrentProcess);
+       IRQ_ENABLE;
+
+       proc_schedule();
+}
+
+void proc_entry(void (*user_entry)(void))
+{
+       user_entry();
+       proc_exit();
+}
+
+void preempt_init(void)
+{
+       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);
+
+       idle_init();
 }