#ifndef SCM_ATOMIC_H
#define SCM_ATOMIC_H

/* Copyright 2016,2018,2025
     Free Software Foundation, Inc.

   This file is part of Guile.

   Guile is free software: you can redistribute it and/or modify it
   under the terms of the GNU Lesser General Public License as published
   by the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   Guile is distributed in the hope that it will be useful, but WITHOUT
   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
   License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with Guile.  If not, see
   <https://www.gnu.org/licenses/>.  */



#include "libguile/gc.h"



/* Atomic boxes
 */
struct scm_atomic_box
{
  scm_t_bits tag;
  SCM value;
};

static inline int
scm_is_atomic_box (SCM x)
{
  return SCM_HAS_TYP7 (x, scm_tc7_atomic_box);
}

static inline struct scm_atomic_box *
scm_to_atomic_box (SCM x)
{
  if (!scm_is_atomic_box (x))
    abort ();
  return (struct scm_atomic_box *) SCM_UNPACK_POINTER (x);
}

static inline SCM
scm_from_atomic_box (struct scm_atomic_box *box)
{
  return SCM_PACK_POINTER (box);
}

static inline SCM*
scm_atomic_box_loc (struct scm_atomic_box *box)
{
  return &box->value;
}

#define SCM_VALIDATE_ATOMIC_BOX(pos, var) \
  do { \
    SCM_ASSERT_TYPE (scm_is_atomic_box (var), var, pos, FUNC_NAME, \
                     "atomic box");                                \
  } while (0)



SCM_INTERNAL SCM scm_make_atomic_box (SCM init);
SCM_INTERNAL SCM scm_atomic_box_p (SCM obj);
SCM_INTERNAL SCM scm_atomic_box_ref (SCM box);
SCM_INTERNAL SCM scm_atomic_box_set_x (SCM box, SCM val);
SCM_INTERNAL SCM scm_atomic_box_swap_x (SCM box, SCM val);
SCM_INTERNAL SCM scm_atomic_box_compare_and_swap_x (SCM box, SCM expected, SCM desired);
SCM_INTERNAL void scm_i_atomic_box_print (SCM box, SCM port, scm_print_state *pstate);

SCM_INTERNAL void scm_register_atomic (void);

#endif  /* SCM_ATOMIC_H */