/*----------------------------------------------------------------------------
 * Copyright (c) Huawei Technologies Co., Ltd. 2018-2020. All rights reserved.
 * Description: Spinlock Assembly
 * Author: Huawei LiteOS Team
 * Create: 2018-07-11
 * 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 and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list
 * of conditions and the following disclaimer in the documentation and/or other materials
 * provided with the distribution.
 * 3. Neither the name of the copyright holder 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 HOLDER 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 "arch/asm.h"

FUNCTION(ArchSpinLock)
    mov     r2, #1
1:
    ldrex   r1, [r0]
    teq     r1, #0
    wfene
    strexeq r1, r2, [r0]
    teqeq   r1, #0
    bne     1b
    dmb
    bx      lr

/*
 * when spinlock already taken, r1 will read 1 which is same with the
 * 'strex' failure return value, no extra convertion needed.
 */
FUNCTION(ArchSpinTrylock)
    ldrex   r1, [r0]
    teq     r1, #0
    moveq   r2, #1
    strexeq r1, r2, [r0]
    dmb
    mov     r0, r1
    bx      lr

FUNCTION(ArchSpinUnlock)
    dmb
    mov     r1, #0
    str     r1, [r0]
    dsb
    sev
    bx      lr