X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=bertos%2Fkern%2Fcoop.c;h=542ed67844a7dc0acddb63196369c68572a50c31;hb=7ce645a0dc4cd3683f854f3aa85a72a86101ddbd;hp=be3d6dfdb0756915bf339ab8e3bc8ab0476a0673;hpb=32d1445272120a254d77ce8d1af1f527da7a2c17;p=bertos.git

diff --git a/bertos/kern/coop.c b/bertos/kern/coop.c
index be3d6dfd..542ed678 100644
--- a/bertos/kern/coop.c
+++ b/bertos/kern/coop.c
@@ -51,92 +51,53 @@
 #include <cpu/frame.h>
 
 /**
- * CPU dependent context switching routines.
+ * Define function prototypes exported outside.
  *
- * Saving and restoring the context on the stack is done by a CPU-dependent
- * support routine which usually needs to be written in assembly.
+ * Required to silent gcc "no previous prototype" warnings.
  */
-EXTERN_C void asm_switch_context(cpu_stack_t **new_sp, cpu_stack_t **save_sp);
-
+void coop_yield(void);
+void coop_switch(void);
+void coop_wakeup(Process *proc);
 
 /**
- * System scheduler: pass CPU control to the next process in
- * the ready queue.
+ * Give the control of the CPU to another process.
+ *
+ * \note Assume the current process has been already added to a wait queue.
+ *
+ * \warning This should be considered an internal kernel function, even if it
+ * is allowed, usage from application code is strongly discouraged.
  */
-static void proc_schedule(void)
+void coop_switch(void)
 {
-	cpu_flags_t flags;
-
-	ATOMIC(LIST_ASSERT_VALID(&proc_ready_list));
-	ASSERT_USER_CONTEXT();
-	IRQ_ASSERT_ENABLED();
-
-	/* Poll on the ready queue for the first ready process */
-	IRQ_SAVE_DISABLE(flags);
-	while (!(current_process = (struct Process *)list_remHead(&proc_ready_list)))
-	{
-		/*
-		 * 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 proc_ready_list. 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.
-		 * \todo If there was a way to write sig_wait() so that it does not
-		 * disable interrupts while waiting, there would not be any
-		 * reason to do this.
-		 */
-		IRQ_ENABLE;
-		CPU_IDLE;
-		MEMORY_BARRIER;
-		IRQ_DISABLE;
-	}
-	IRQ_RESTORE(flags);
+	ATOMIC(proc_schedule());
 }
 
-void proc_switch(void)
+/**
+ * Immediately wakeup a process, dispatching it to the CPU.
+ */
+void coop_wakeup(Process *proc)
 {
-	/* Remember old process to save its context later */
-	Process * const old_process = current_process;
+	ASSERT(proc_preemptAllowed());
+	ASSERT(current_process);
+	IRQ_ASSERT_DISABLED();
 
-	proc_schedule();
-
-	/*
-	 * Optimization: don't switch contexts when the active
-	 * process has not changed.
-	 */
-	if (current_process != old_process)
+	if (prio_proc(proc) >= prio_curr())
 	{
-		cpu_stack_t *dummy;
-
-		#if CONFIG_KERN_MONITOR
-			LOG_INFO("Switch from %p(%s) to %p(%s)\n",
-				old_process,    proc_name(old_process),
-				current_process, proc_currentName());
-		#endif
+		Process *old_process = current_process;
 
-		/* Save context of old process and switch to new process. If there is no
-		 * old process, we save the old stack pointer into a dummy variable that
-		 * we ignore. In fact, this happens only when the old process has just
-		 * exited.
-		 * TODO: Instead of physically clearing the process at exit time, a zombie
-		 * list should be created.
-		 */
-		asm_switch_context(&current_process->stack, old_process ? &old_process->stack : &dummy);
+		SCHED_ENQUEUE(current_process);
+		current_process = proc;
+		proc_switchTo(current_process, old_process);
 	}
-
-	/* This RET resumes the execution on the new process */
+	else
+		SCHED_ENQUEUE_HEAD(proc);
 }
 
 /**
  * Co-operative context switch
  */
-void proc_yield(void)
+void coop_yield(void)
 {
 	ATOMIC(SCHED_ENQUEUE(current_process));
-	proc_switch();
+	coop_switch();
 }