X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=kern%2Fsem.c;h=0f31fa067b9fff651945b60076adaf3e855e05f4;hb=faf2f6bfd5933ff75e6cc01e3d48f9277f731d8f;hp=98646e939047200abe5cd7bf64876aaafc3812c2;hpb=1cc167e20f21d2e81527ca47ccd4a21a6198f86f;p=bertos.git

diff --git a/kern/sem.c b/kern/sem.c
old mode 100755
new mode 100644
index 98646e93..0f31fa06
--- a/kern/sem.c
+++ b/kern/sem.c
@@ -1,9 +1,34 @@
-/*!
+/**
  * \file
  * <!--
- * Copyright 2001,2004 Develer S.r.l. (http://www.develer.com/)
- * Copyright 1999,2000,2001 Bernardo Innocenti <bernie@develer.com>
- * All Rights Reserved.
+ * This file is part of BeRTOS.
+ *
+ * Bertos is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * As a special exception, you may use this file as part of a free software
+ * library without restriction.  Specifically, if other files instantiate
+ * templates or use macros or inline functions from this file, or you compile
+ * this file and link it with other files to produce an executable, this
+ * file does not by itself cause the resulting executable to be covered by
+ * the GNU General Public License.  This exception does not however
+ * 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 Bernardo Innocenti <bernie@develer.com>
+ *
  * -->
  *
  * \brief Semaphore based synchronization services.
@@ -13,32 +38,34 @@
  * \author Bernardo Innocenti <bernie@develer.com>
  */
 
-/*
- * $Log$
- * Revision 1.1  2004/05/23 17:27:00  bernie
- * Import kern/ subdirectory.
- *
- */
-
 #include "sem.h"
-#include "proc.h"
-#include "proc_p.h"
-#include "signal.h"
-#include "hw.h"
+#include <kern/proc.h>
+#include <kern/proc_p.h>
+#include <kern/signal.h>
+#include <cfg/debug.h>
 
+INLINE void sem_verify(struct Semaphore *s)
+{
+	(void)s;
+	ASSERT(s);
+	LIST_ASSERT_VALID(&s->wait_queue);
+	ASSERT(s->nest_count >= 0);
+	ASSERT(s->nest_count < 128);   // heuristic max
+}
 
-/*!
- * \brief Initialize a Semaphore structure
+
+/**
+ * \brief Initialize a Semaphore structure.
  */
 void sem_init(struct Semaphore *s)
 {
-	INITLIST(&s->wait_queue);
+	LIST_INIT(&s->wait_queue);
 	s->owner = NULL;
 	s->nest_count = 0;
 }
 
 
-/*!
+/**
  * \brief Attempt to lock a semaphore without waiting.
  *
  * \return true in case of success, false if the semaphore
@@ -46,23 +73,28 @@ void sem_init(struct Semaphore *s)
  *
  * \note   each call to sem_attempt() must be matched by a
  *         call to sem_release().
+ *
+ * \see sem_obtain() sem_release()
  */
 bool sem_attempt(struct Semaphore *s)
 {
-	DISABLE_INTS;
+	bool result = false;
+
+	proc_forbid();
+	sem_verify(s);
 	if ((!s->owner) || (s->owner == CurrentProcess))
 	{
 		s->owner = CurrentProcess;
 		s->nest_count++;
-		ENABLE_INTS;
-		return true;
+		result = true;
 	}
-	ENABLE_INTS;
-	return false;
+	proc_permit();
+
+	return result;
 }
 
 
-/*!
+/**
  * \brief Lock a semaphore.
  *
  * If the semaphore is already owned by another process, the caller
@@ -76,36 +108,42 @@ bool sem_attempt(struct Semaphore *s)
  *       the most common case: the semaphore is free or locked
  *       by the calling process itself. Rearranging this code
  *       is probably a bad idea.
+ *
+ * \sa sem_release() sem_attempt()
  */
 void sem_obtain(struct Semaphore *s)
 {
-	DISABLE_INTS;
+	proc_forbid();
+	sem_verify(s);
 
 	/* Is the semaphore already locked by another process? */
-	if (s->owner && (s->owner != CurrentProcess))
+	if (UNLIKELY(s->owner && (s->owner != CurrentProcess)))
 	{
 		/* Append calling process to the wait queue */
 		ADDTAIL(&s->wait_queue, (Node *)CurrentProcess);
-		ENABLE_INTS;
 
-		/* We will awake only when the current owner calls
-		 * ReleaseSemaphore(). Then, the semaphore will already
+		/*
+		 * We will wake up only when the current owner calls
+		 * sem_release(). Then, the semaphore will already
 		 * be locked for us.
 		 */
+		proc_permit();
 		proc_schedule();
 	}
 	else
 	{
-		/* The semaphore is free: lock it */
+		ASSERT(LIST_EMPTY(&s->wait_queue));
+
+		/* The semaphore was free: lock it */
 		s->owner = CurrentProcess;
 		s->nest_count++;
-		ENABLE_INTS;
+		proc_permit();
 	}
 }
 
 
-/*!
- * \brief Releases a lock on a previously locked semaphore.
+/**
+ * \brief Release a lock on a previously locked semaphore.
  *
  * If the nesting count of the semaphore reaches zero,
  * the next process waiting for it will be awaken.
@@ -114,31 +152,35 @@ void sem_obtain(struct Semaphore *s)
  *       the most common case: the semaphore has been locked just
  *       once and nobody else was waiting for it. Rearranging
  *       this code is probably a bad idea.
+ *
+ * \sa sem_obtain() sem_attempt()
  */
 void sem_release(struct Semaphore *s)
 {
-	DISABLE_INTS;
+	proc_forbid();
+	sem_verify(s);
+
+	ASSERT(s->owner == CurrentProcess);
 
-	/* Decremement nesting count and check if the semaphore
-	 * has been fully unlocked
+	/*
+	 * Decrement nesting count and check if the semaphore
+	 * has been fully unlocked.
 	 */
 	if (--s->nest_count == 0)
 	{
+		Process *proc;
+
 		/* Disown semaphore */
 		s->owner = NULL;
 
-		/* Anybody still waiting for this semaphore? */
-		if (!ISLISTEMPTY(&s->wait_queue))
+		/* Give semaphore to the first applicant, if any */
+		if (UNLIKELY((proc = (Process *)list_remHead(&s->wait_queue))))
 		{
-			/* Give semaphore to the first applicant */
-			Process *proc = (Process *)s->wait_queue.head;
-			REMOVE((Node *)proc);
 			s->nest_count = 1;
 			s->owner = proc;
 			SCHED_ENQUEUE(proc);
 		}
 	}
 
-	ENABLE_INTS;
+	proc_permit();
 }
-