metalsvm/arch/x86/include/asm/atomic.h
2011-08-02 15:58:20 +02:00

162 lines
4.8 KiB
C

/*
* 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.
*/
/**
* @author Stefan Lankes
* @file arch/x86/include/asm/atomic.h
* @brief Functions for atomic operations
*
* This file defines functions for atomic operations on int32 variables
* which will be used in locking-mechanisms.
*/
#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
/** @brief Makro for initialization of atomic_int32_t vars
*
* Whenever you use an atomic_int32_t variable, init it with
* this macro first.\n
* Example: atomic_int32_t myAtomicVar = ATOMIC_INIT(123);
*
* @param i The number value you want to init it with.
*/
#define ATOMIC_INIT(i) { (i) }
/** @brief Standard-datatype for atomic operations
*
* It just consists of an int32_t variable internally, marked as volatile.
*/
typedef struct { volatile int32_t counter; } atomic_int32_t;
/** @brief Atomic test and set operation for int32 vars.
*
* This function will atomically exchange the value of an atomic variable and
* return its old value. Is used in locking-operations.\n
* \n
* 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.
*
* @param d Pointer to the atomic_int_32_t with the value you want to exchange
* @param ret the value you want the var test for
*
* @return The old value of the atomic_int_32_t var before exchange
*/
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;
}
/** @brief Atomic addition of values to atomic_int32_t vars
*
* This function lets you add values in an atomic operation
*
* @param d Pointer to the atomit_int32_t var you want do add a value to
* @param i The value you want to increment by
*
* @return The mathematical result
*/
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) : "memory");
return res+i;
}
/** @brief Atomic subtraction of values from atomic_int32_t vars
*
* This function lets you subtract values in an atomic operation.\n
* This function is just for convenience. It uses atomic_int32_add(d, -i)
*
* @param d Pointer to the atomic_int32_t var you want to subtract from
* @param i The value you want to subtract by
*
* @return The mathematical result
*/
inline static int32_t atomic_int32_sub(atomic_int32_t *d, int32_t i)
{
return atomic_int32_add(d, -i);
}
/** @brief Atomic increment by one
*
* The atomic_int32_t var will be atomically incremented by one.\n
* This function is just for convenience. It uses atomic_int32_add(d, 1)
*
* @param d The atomic_int32_t var you want to increment
* @return The mathematical result
*/
inline static int32_t atomic_int32_inc(atomic_int32_t* d) {
return atomic_int32_add(d, 1);
}
/** @brief Atomic decrement by one
*
* The atomic_int32_t var will be atomically decremented by one.\n
* This function is just for convenience. It uses atomic_int32_add(d, -1)
*
* @param d The atomic_int32_t var you want to decrement
* @return The mathematical result
*/
inline static int32_t atomic_int32_dec(atomic_int32_t* d) {
return atomic_int32_add(d, -1);
}
/** @brief Read out an atomic_int32_t var
*
* This function is for convenience: It looks into the atomic_int32_t struct
* and returns the internal value for you.
*
* @param d Pointer to the atomic_int32_t var you want to read out
* @return It's number value
*/
inline static int32_t atomic_int32_read(atomic_int32_t *d) {
return d->counter;
}
/** @brief Set the value of an atomic_int32_t var
*
* This function is for convenience: It sets the internal value of
* an atomic_int32_t var for you.
*
* @param d Pointer to the atomic_int32_t var you want to set
* @param v The value to set
*/
inline static void atomic_int32_set(atomic_int32_t *d, int32_t v) {
atomic_int32_test_and_set(d, v);
}
#ifdef __cplusplus
}
#endif
#endif