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#ifndef _I386_SEMAPHORE_H
#define _I386_SEMAPHORE_H
#include <linux/linkage.h>
/*
* SMP- and interrupt-safe semaphores..
*
* (C) Copyright 1996 Linus Torvalds
*/
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/i386/lib/semaphore.S
*/
extern __inline__ void down(struct semaphore * sem)
{
__asm__ __volatile__(
"# atomic down operation\n\t"
#ifdef __SMP__
"lock ; "
#endif
"decl %0\n\t"
"movl $1f,%%eax\n\t"
"js " SYMBOL_NAME_STR(__down_failed)
"\n1:"
:/* no outputs */
:"m" (sem->count), "c" (sem)
:"ax", "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)
{
__asm__ __volatile__(
"# atomic up operation\n\t"
#ifdef __SMP__
"lock ; "
#endif
"incl %0\n\t"
"movl $1f,%%eax\n\t"
"jle " SYMBOL_NAME_STR(__up_wakeup)
"\n1:"
:/* no outputs */
:"m" (sem->count), "c" (sem)
:"ax", "memory");
}
#endif
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