/* 
 * Copyright 2010 Stefan Lankes, Chair for Operating Systems,
 *                               RWTH Aachen University
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * This file is part of MetalSVM.
 */

#ifndef __ARCH_ATOMIC_H__
#define __ARCH_ATOMIC_H__

#include <metalsvm/stddef.h>

#ifdef __cplusplus
extern "C" {
#endif

#if MAX_CORES > 1
#define LOCK "lock ; "
#else
#define LOCK ""
#endif

#define ATOMIC_INIT(i)  { (i) }

typedef struct { volatile int32_t counter; } atomic_int32_t;

/*
 * Intel manuals: If a memory operand is referenced, the processor's locking 
 * protocol is automatically implemented for the duration of the exchange 
 * operation, regardless of the presence or absence of the LOCK prefix.
 */
inline static int32_t atomic_int32_test_and_set(atomic_int32_t* d, int32_t ret) {
	asm volatile ("xchgl %0, %1" : "=r"(ret) : "m"(d->counter), "0"(ret) : "memory");
	return ret;
}

inline static int32_t atomic_int32_add(atomic_int32_t *d, int32_t i)
{
	int32_t res = i;
        asm volatile(LOCK "xaddl %0, %1" : "=r"(i) : "m"(d->counter), "0"(i));
	return res+i;
}

inline static int32_t atomic_int32_sub(atomic_int32_t *d, int32_t i)
{
        return atomic_int32_add(d, -i);
}

inline static int32_t atomic_int32_inc(atomic_int32_t* d) {
	return atomic_int32_add(d, 1);
}

inline static int32_t atomic_uint32_dec(atomic_int32_t* d) {
	return atomic_int32_add(d, -1);
}

inline static int32_t atomic_int32_read(atomic_int32_t *d) {
	return d->counter;
}

inline static void atomic_int32_set(atomic_int32_t *d, int32_t v) {
	d->counter = v;
}

#ifdef __cplusplus
}
#endif

#endif