spinlock.c

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/*-
 * Copyright (c) 2002-2018 The UbixOS Project.
 * All rights reserved.
 *
 * This was developed by Christopher W. Olsen for the UbixOS Project.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
 *
 * 1) Redistributions of source code must retain the above copyright notice, this list of
 *    conditions, the following disclaimer and the list of authors.
 * 2) 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.
 * 3) 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 AUTHOR 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>
 
void spinLockInit(spinLock_t *lock) {
  *lock = SPIN_LOCK_INITIALIZER;
  }
 
void spinUnlock(spinLock_t *lock) {
  *lock = 0x0;
  /*
  register int unlocked;
  asm volatile(
    "xchgl %0, %1"
    : "=&r" (unlocked), "=m" (*lock) : "0" (0)
    );
  */
  }
 
int spinTryLock(spinLock_t *lock) {
  register int locked;
  asm volatile("xchgl %0, %1"
    : "=&r" (locked), "=m" (*lock) : "0" (1)
    );
  return(!locked);
  }
 
void spinLock(spinLock_t *lock) {
  while (!spinTryLock(lock))
  {
    while (*lock == 1)
        sched_yield();
  }
}
 
void spinLock_scheduler(spinLock_t *lock) {
  while (!spinTryLock(lock))
    while (*lock == 1);
  }
 
 
int spinLockLocked(spinLock_t *lock) {
  return(*lock != 0);
  }
 
 
/***
 END
 ***/