/*
 * Copyright 2010, Lucian Adrian Grijincu, lucian.grijincu@gmail.com.
 * Distributed under the terms of the MIT License.
 */


#include <pthread.h>

#include <arch_cpu_defs.h>

#include "pthread_private.h"


#define UNLOCKED        0
#define LOCKED          1


int
pthread_spin_init(pthread_spinlock_t* lock, int pshared)
{
        // This implementation of spinlocks doesn't differentiate
        // between spin locks used by threads in the same process or
        // between threads of different processes.

        lock->lock = UNLOCKED;
        return 0;
}


int
pthread_spin_destroy(pthread_spinlock_t* lock)
{
        return 0;
}


int
pthread_spin_lock(pthread_spinlock_t* lock)
{
        while (atomic_test_and_set((int32*)&lock->lock, LOCKED, UNLOCKED)
                        == LOCKED) {
                SPINLOCK_PAUSE(); // spin
                        // TODO: On UP machines we should thread_yield() in the loop.
        }
        return 0;
}


int
pthread_spin_trylock(pthread_spinlock_t* lock)
{
        if (atomic_test_and_set((int32*)&lock->lock, LOCKED, UNLOCKED) == LOCKED)
                return EBUSY;
        return 0;
}


int
pthread_spin_unlock(pthread_spinlock_t* lock)
{
        lock->lock = UNLOCKED;
        return 0;
}