/* SPDX-License-Identifier: BSD-2-Clause */

/**
 * @file
 *
 * @ingroup RTEMSBSPGCCAtomics
 *
 * @brief Implementation of GCC Atomic Helper
 *
 * This implementation is used on BSPs with older cores which do not
 * have atomic instructions. If the CPU core has atomic instructions,
 * GCC will do the right thing.
 *
 * https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html
 * describes the interface for __atomic_test_and_set with the *mem
 * being precisely one byte.
 */

/*
 *  COPYRIGHT (c) 2025. On-Line Applications Research Corporation (OAR).
 *
 * 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.
 *
 * 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
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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 */

#include <stdbool.h>

#include <rtems.h>

bool __atomic_test_and_set( volatile void *mem, int access )
{
  (void) access;

  volatile uint8_t     *lock = (volatile uint8_t *) mem;
  rtems_interrupt_level level;
  uint8_t               value;

  rtems_interrupt_disable( level );

  value = *lock;
  *lock = 1;

  rtems_interrupt_enable( level );

  return value;
}