patch-2.0.21-2.1.0 linux/include/asm-m68k/semaphore.h

• Lines: 69
• Date: Wed Sep 25 10:47:42 1996
• Orig file: lx2.0/v2.0.21/linux/include/asm-m68k/semaphore.h
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file lx2.0/v2.0.21/linux/include/asm-m68k/semaphore.h linux/include/asm-m68k/semaphore.h
@@ -0,0 +1,68 @@
+#ifndef _M68K_SEMAPHORE_H
+#define _M68K_SEMAPHORE_H
+
+#include <linux/linkage.h>
+
+/*
+ * SMP- and interrupt-safe semaphores..
+ *
+ * (C) Copyright 1996 Linus Torvalds
+ *
+ * m68k version by Andreas Schwab
+ */
+
+struct semaphore {
+	int count;
+	int waiting;
+	struct wait_queue * wait;
+};
+
+#define MUTEX ((struct semaphore) { 1, 0, NULL })
+#define MUTEX_LOCKED ((struct semaphore) { 0, 0, NULL })
+
+asmlinkage void down_failed(void /* special register calling convention */);
+asmlinkage void up_wakeup(void /* special register calling convention */);
+
+extern void __down(struct semaphore * sem);
+extern void __up(struct semaphore * sem);
+
+/*
+ * This is ugly, but we want the default case to fall through.
+ * "down_failed" is a special asm handler that calls the C
+ * routine that actually waits. See arch/m68k/lib/semaphore.S
+ */
+extern inline void down(struct semaphore * sem)
+{
+	register struct semaphore *sem1 __asm__ ("%a1") = sem;
+	__asm__ __volatile__(
+		"# atomic down operation\n"
+		"1:\n\t"
+		"lea %%pc@(1b),%%a0\n\t"
+		"subql #1,%0\n\t"
+		"jmi " SYMBOL_NAME_STR(down_failed)
+		: /* no outputs */
+		: "m" (sem->count), "a" (sem1)
+		: "%a0", "%d0", "%d1", "memory");
+}
+
+/*
+ * Note! This is subtle. We jump to wake people up only if
+ * the semaphore was negative (== somebody was waiting on it).
+ * The default case (no contention) will result in NO
+ * jumps for both down() and up().
+ */
+extern inline void up(struct semaphore * sem)
+{
+	register struct semaphore *sem1 __asm__ ("%a1") = sem;
+	__asm__ __volatile__(
+		"# atomic up operation\n\t"
+		"lea %%pc@(1f),%%a0\n\t"
+		"addql #1,%0\n\t"
+		"jls " SYMBOL_NAME_STR(up_wakeup) "\n"
+		"1:"
+		: /* no outputs */
+		: "m" (sem->count), "a" (sem1)
+		: "%a0", "%d0", "%d1", "memory");
+}
+
+#endif