162 lines
4.8 KiB
C
162 lines
4.8 KiB
C
/*
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* Copyright 2010 Stefan Lankes, Chair for Operating Systems,
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* RWTH Aachen University
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* This file is part of MetalSVM.
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*/
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/**
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* @author Stefan Lankes
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* @file arch/x86/include/asm/atomic.h
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* @brief Functions for atomic operations
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*
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* This file defines functions for atomic operations on int32 variables
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* which will be used in locking-mechanisms.
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*/
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#ifndef __ARCH_ATOMIC_H__
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#define __ARCH_ATOMIC_H__
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#include <metalsvm/stddef.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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#if MAX_CORES > 1
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#define LOCK "lock ; "
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#else
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#define LOCK ""
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#endif
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/** @brief Makro for initialization of atomic_int32_t vars
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*
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* Whenever you use an atomic_int32_t variable, init it with
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* this macro first.\n
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* Example: atomic_int32_t myAtomicVar = ATOMIC_INIT(123);
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*
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* @param i The number value you want to init it with.
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*/
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#define ATOMIC_INIT(i) { (i) }
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/** @brief Standard-datatype for atomic operations
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*
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* It just consists of an int32_t variable internally, marked as volatile.
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*/
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typedef struct { volatile int32_t counter; } atomic_int32_t;
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/** @brief Atomic test and set operation for int32 vars.
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*
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* This function will atomically exchange the value of an atomic variable and
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* return its old value. Is used in locking-operations.\n
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* \n
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* Intel manuals: If a memory operand is referenced, the processor's locking
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* protocol is automatically implemented for the duration of the exchange
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* operation, regardless of the presence or absence of the LOCK prefix.
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*
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* @param d Pointer to the atomic_int_32_t with the value you want to exchange
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* @param ret the value you want the var test for
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*
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* @return The old value of the atomic_int_32_t var before exchange
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*/
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inline static int32_t atomic_int32_test_and_set(atomic_int32_t* d, int32_t ret) {
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asm volatile ("xchgl %0, %1" : "=r"(ret) : "m"(d->counter), "0"(ret) : "memory");
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return ret;
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}
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/** @brief Atomic addition of values to atomic_int32_t vars
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*
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* This function lets you add values in an atomic operation
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*
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* @param d Pointer to the atomit_int32_t var you want do add a value to
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* @param i The value you want to increment by
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*
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* @return The mathematical result
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*/
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inline static int32_t atomic_int32_add(atomic_int32_t *d, int32_t i)
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{
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int32_t res = i;
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asm volatile(LOCK "xaddl %0, %1" : "=r"(i) : "m"(d->counter), "0"(i) : "memory");
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return res+i;
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}
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/** @brief Atomic subtraction of values from atomic_int32_t vars
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*
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* This function lets you subtract values in an atomic operation.\n
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* This function is just for convenience. It uses atomic_int32_add(d, -i)
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*
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* @param d Pointer to the atomic_int32_t var you want to subtract from
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* @param i The value you want to subtract by
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*
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* @return The mathematical result
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*/
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inline static int32_t atomic_int32_sub(atomic_int32_t *d, int32_t i)
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{
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return atomic_int32_add(d, -i);
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}
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/** @brief Atomic increment by one
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*
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* The atomic_int32_t var will be atomically incremented by one.\n
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* This function is just for convenience. It uses atomic_int32_add(d, 1)
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*
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* @param d The atomic_int32_t var you want to increment
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* @return The mathematical result
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*/
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inline static int32_t atomic_int32_inc(atomic_int32_t* d) {
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return atomic_int32_add(d, 1);
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}
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/** @brief Atomic decrement by one
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*
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* The atomic_int32_t var will be atomically decremented by one.\n
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* This function is just for convenience. It uses atomic_int32_add(d, -1)
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*
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* @param d The atomic_int32_t var you want to decrement
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* @return The mathematical result
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*/
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inline static int32_t atomic_int32_dec(atomic_int32_t* d) {
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return atomic_int32_add(d, -1);
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}
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/** @brief Read out an atomic_int32_t var
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*
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* This function is for convenience: It looks into the atomic_int32_t struct
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* and returns the internal value for you.
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*
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* @param d Pointer to the atomic_int32_t var you want to read out
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* @return It's number value
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*/
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inline static int32_t atomic_int32_read(atomic_int32_t *d) {
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return d->counter;
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}
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/** @brief Set the value of an atomic_int32_t var
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*
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* This function is for convenience: It sets the internal value of
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* an atomic_int32_t var for you.
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*
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* @param d Pointer to the atomic_int32_t var you want to set
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* @param v The value to set
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*/
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inline static void atomic_int32_set(atomic_int32_t *d, int32_t v) {
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atomic_int32_test_and_set(d, v);
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}
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#ifdef __cplusplus
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}
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#endif
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#endif
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