src/arch/riscv/include/atomic.h

/*
 * Copyright (c) 2013, The Regents of the University of California (Regents).
 * All Rights Reserved.
 *
 * 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 Regents nor the
 *    names of its contributors may be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * IN NO EVENT SHALL REGENTS BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,
 * SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING
 * OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF REGENTS HAS
 * BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * REGENTS SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE. THE SOFTWARE AND ACCOMPANYING DOCUMENTATION, IF ANY, PROVIDED
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 */

#ifndef _RISCV_ATOMIC_H
#define _RISCV_ATOMIC_H

#include <arch/encoding.h>

#define disable_irqsave() clear_csr(mstatus, MSTATUS_MIE)
#define enable_irqrestore(flags) set_csr(mstatus, (flags) & MSTATUS_MIE)

typedef struct { int lock; } spinlock_t;
#define SPINLOCK_INIT {0}

#define atomic_set(ptr, val) (*(volatile typeof(*(ptr)) *)(ptr) = val)
#define atomic_read(ptr) (*(volatile typeof(*(ptr)) *)(ptr))

#ifdef PK_ENABLE_ATOMICS
# define atomic_add(ptr, inc) __sync_fetch_and_add(ptr, inc)
# define atomic_swap(ptr, swp) __sync_lock_test_and_set(ptr, swp)
# define atomic_cas(ptr, cmp, swp) __sync_val_compare_and_swap(ptr, cmp, swp)
#else
# define atomic_add(ptr, inc) ({ \
  long flags = disable_irqsave(); \
  typeof(ptr) res = *(volatile typeof(ptr))(ptr); \
  *(volatile typeof(ptr))(ptr) = res + (inc); \
  enable_irqrestore(flags); \
  res; })
# define atomic_swap(ptr, swp) ({ \
  long flags = disable_irqsave(); \
  typeof(*ptr) res = *(volatile typeof(ptr))(ptr); \
  *(volatile typeof(ptr))(ptr) = (swp); \
  enable_irqrestore(flags); \
  res; })
# define atomic_cas(ptr, cmp, swp) ({ \
  long flags = disable_irqsave(); \
  typeof(ptr) res = *(volatile typeof(ptr))(ptr); \
  if (res == (cmp)) *(volatile typeof(ptr))(ptr) = (swp); \
  enable_irqrestore(flags); \
  res; })
#endif

#endif