proc_switch(): rename from proc_schedule(). Split out the real cooperative scheduler.

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

diff --git a/bertos/kern/preempt.c b/bertos/kern/preempt.c
index cde336510ee0e36cf6644f9bc5f92e5f0e74dc98..e24da145ba1c38ee09fc9363060c9bb0e46aec39 100644 (file)
--- a/bertos/kern/preempt.c
+++ b/bertos/kern/preempt.c
@@ -31,10 +31,23 @@
  *
  * \brief Simple preemptive multitasking scheduler.
  *
+ * All voluntary and preemptive context switching happens on exit from
+ * a common interrupt (signal) dispatcher.  Preemption on quantum timeout
+ * is regulated by a soft-timer.  Other kinds of preemption could happen
+ * if an interrupt sends a signal to a higher priority process (but this
+ * is still unimplemented).
+ *
+ * In the POSIX implementaiton, context switching is done by the portable
+ * SVR4 swapcontext() facility.
+ *
  * \version $Id: proc.c 1616 2008-08-10 19:41:26Z bernie $
  * \author Bernie Innocenti <bernie@codewiz.org>
  */
 
+#include <cfg/cfg_kern.h>
+
+#if CONFIG_KERN_PREEMPT
+
 #include "proc_p.h"
 #include "proc.h"
 
@@ -44,61 +57,74 @@
 #include <cpu/irq.h>   // IRQ_DISABLE()...
 #include <drv/timer.h>
 #include <cfg/module.h>
+#include <cfg/depend.h>    // CONFIG_DEPEND()
+
+// Check config dependencies
+CONFIG_DEPEND(CONFIG_KERN_PREEMPT,    CONFIG_KERN_SCHED && CONFIG_TIMER_EVENTS && CONFIG_KERN_IRQ);
 
+MOD_DEFINE(preempt)
 
 int preempt_forbid_cnt;
 
-Timer preempt_timer;
+static Timer preempt_timer;
 
 
 // fwd decl from idle.c
 void idle_init(void);
 
 
-void proc_preempt(void)
+void proc_schedule(void)
 {
        IRQ_DISABLE;
 
+       ASSERT(preempt_forbid_cnt == 0);
        LIST_ASSERT_VALID(&ProcReadyList);
        CurrentProcess = (struct Process *)list_remHead(&ProcReadyList);
-       LIST_ASSERT_VALID(&ProcReadyList);
        ASSERT2(CurrentProcess, "no idle proc?");
 
        IRQ_ENABLE;
 
-       TRACEMSG("new proc: %p:%s", CurrentProcess, CurrentProcess ? CurrentProcess->monitor.name : "---");
-       monitor_report();
+       TRACEMSG("launching %p:%s", CurrentProcess, proc_currentName());
 }
 
-void proc_preempt_timer(UNUSED_ARG(void *, param))
+void proc_preempt(UNUSED_ARG(void *, param)
 {
-       /* Abort if task preemption is disabled */
-       if (preempt_forbid_cnt)
-               return;
-
-       IRQ_DISABLE;
-/*
-       if (!CurrentProcess->forbid_cnt)
+       if (!preempt_forbid_cnt)
        {
-               TRACEMSG("preempting %p:%s", CurrentProcess, CurrentProcess->monitor.name);
+               IRQ_DISABLE;
+
+               #if CONFIG_KERN_PRI
+                       Process *rival = (Process *)LIST_HEAD(&ProcReadyList);
+                       if (rival && rival->link.pri >= CurrentProcess->link.pri)
+                       {
+               #endif
+
+               TRACEMSG("preempting %p:%s", CurrentProcess, proc_currentName());
+
+// FIXME: this still break havocs, probably because of some reentrancy issue
+#if 0
                SCHED_ENQUEUE(CurrentProcess);
-               proc_preempt();
+               proc_schedule();
+#endif
+               #if CONFIG_KERN_PRI
+                       }
+               #endif
+
+               IRQ_ENABLE;
        }
-*/
-       IRQ_ENABLE;
 
        timer_setDelay(&preempt_timer, CONFIG_KERN_QUANTUM);
        timer_add(&preempt_timer);
 }
 
-void proc_schedule(void)
+void proc_switch(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();
+       IRQ_ASSERT_ENABLED();
        ASSERT(preempt_forbid_cnt == 0);
 
        // Will invoke proc_preempt() in interrupt context
@@ -113,7 +139,7 @@ void proc_yield(void)
        SCHED_ENQUEUE(CurrentProcess);
        IRQ_ENABLE;
 
-       proc_schedule();
+       proc_switch();
 }
 
 void proc_entry(void (*user_entry)(void))
@@ -134,4 +160,8 @@ void preempt_init(void)
        timer_add(&preempt_timer);
 
        idle_init();
+
+       MOD_INIT(preempt);
 }
+
+#endif // CONFIG_KERN_PREEMPT