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memory_ex.cpp
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memory_ex.cpp
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/**
* @file exclusive_mem.cpp
* @author Atakan S.
* @date 01/01/2019
* @version 1.0
* @brief Exclusive memory access for Cortex-M3/M4.
*
* @copyright Copyright (c) 2018 Atakan SARIOGLU ~ www.atakansarioglu.com
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
// Includes.
#include "memory_ex.h"
// The namespace.
namespace memory_exclusive {
using namespace std;
bool MemoryEx::ReadModifyWrite_if(uint32_t &memory, MemoryModifier modifier, TimeoutProvider timeout){
uint32_t memory_val;
do {
// Read the current value.
memory_val = __LDREXW(&memory);
// Call the modifier.
if (modifier(memory_val)) {
// Data memory barrier instruction.
__DMB();
// Try to write.
if (0 == __STREXW(memory_val, &memory)) {
// Data memory barrier instruction.
__DMB();
// Written, return success.
return true;
}
}
}
// Check for timeout.
while (!timeout());
// Failure.
return false;
}
uint32_t MemoryEx::Read(const uint32_t &memory){
// Return the memory value directly since it is atomic.
return memory;
}
void MemoryEx::Write(uint32_t &memory, const uint32_t value){
// Data memory barrier instruction.
__DMB();
// Write the value directly since it is atomic.
memory = value;
}
}