/*-
 * Copyright (c) 2002-2004, 2017 The UbixOS Project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are
 * permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this list of
 * conditions, the following disclaimer and the list of authors.  Redistributions in binary
 * form must reproduce the above copyright notice, this list of conditions, the following
 * disclaimer and the list of authors in the documentation and/or other materials provided
 * with the distribution. Neither the name of the UbixOS Project nor the names of its
 * contributors may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
 * THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
 * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <ubixos/spinlock.h>
#include <ubixos/sched.h>

#define atomic_xadd(P, V) __sync_fetch_and_add((P), (V))
#define cmpxchg(P, O, N) __sync_val_compare_and_swap((P), (O), (N))
#define atomic_inc(P) __sync_add_and_fetch((P), 1)
#define atomic_dec(P) __sync_add_and_fetch((P), -1)
#define atomic_add(P, V) __sync_add_and_fetch((P), (V))
#define atomic_set_bit(P, V) __sync_or_and_fetch((P), 1<<(V))
#define atomic_clear_bit(P, V) __sync_and_and_fetch((P), ~(1<<(V)))

#define barrier() asm volatile("": : :"memory")

/* Pause instruction to prevent excess processor bus usage */
#define cpu_relax() asm volatile("pause\n": : :"memory")

void spinLockInit(spinLock_t lock) {
  memset(lock, 0x0, sizeof(spinLock_t));
}

int spinTryLock(spinLock_t lock) {
  if (!cmpxchg(&lock->locked, NULL, LLOCK_FLAG))
    return 0;

  /* Failure! */
  return LOCKED;
}

void spinUnlock(spinLock_t lock) {
  barrier();
  lock->locked = 0x0;
}

void spinLock(spinLock_t lock) {
  while (1) {
    if (!xchg_32(&lock->locked, LOCKED))
      return;
    while (lock->locked == 1)
      sched_yield();
  }
}