| /*********************************************************************************************************************** | |
| * DISCLAIMER | |
| * This software is supplied by Renesas Electronics Corporation and is only intended for use with Renesas products. No | |
| * other uses are authorized. This software is owned by Renesas Electronics Corporation and is protected under all | |
| * applicable laws, including copyright laws. | |
| * THIS SOFTWARE IS PROVIDED "AS IS" AND RENESAS MAKES NO WARRANTIES REGARDING | |
| * THIS SOFTWARE, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING BUT NOT LIMITED TO WARRANTIES OF MERCHANTABILITY, | |
| * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. ALL SUCH WARRANTIES ARE EXPRESSLY DISCLAIMED. TO THE MAXIMUM | |
| * EXTENT PERMITTED NOT PROHIBITED BY LAW, NEITHER RENESAS ELECTRONICS CORPORATION NOR ANY OF ITS AFFILIATED COMPANIES | |
| * SHALL BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES FOR ANY REASON RELATED TO THIS | |
| * SOFTWARE, EVEN IF RENESAS OR ITS AFFILIATES HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. | |
| * Renesas reserves the right, without notice, to make changes to this software and to discontinue the availability of | |
| * this software. By using this software, you agree to the additional terms and conditions found by accessing the | |
| * following link: | |
| * http://www.renesas.com/disclaimer | |
| * | |
| * Copyright (C) 2011 Renesas Electronics Corporation. All rights reserved. | |
| ***********************************************************************************************************************/ | |
| /*********************************************************************************************************************** | |
| * File Name : locking.c | |
| * Description : This implements a locking mechanism that can be used by all code. The locking is done atomically so | |
| * common resources can be accessed safely. | |
| ***********************************************************************************************************************/ | |
| /********************************************************************************************************************** | |
| * History : DD.MM.YYYY Version Description | |
| * : 07.03.2012 1.00 First Release | |
| ***********************************************************************************************************************/ | |
| /*********************************************************************************************************************** | |
| Includes <System Includes> , "Project Includes" | |
| ***********************************************************************************************************************/ | |
| /* Fixed-size integer typedefs. */ | |
| #include <stdint.h> | |
| /* bool support. */ | |
| #include <stdbool.h> | |
| /* Has intrinsic support. Includes xchg() which is used in this code. */ | |
| #include <machine.h> | |
| /* Includes board and MCU related header files. */ | |
| #include "platform.h" | |
| /*********************************************************************************************************************** | |
| Macro definitions | |
| ***********************************************************************************************************************/ | |
| /*********************************************************************************************************************** | |
| Typedef definitions | |
| ***********************************************************************************************************************/ | |
| /*********************************************************************************************************************** | |
| Exported global variables (to be accessed by other files) | |
| ***********************************************************************************************************************/ | |
| /*********************************************************************************************************************** | |
| Private global variables and functions | |
| ***********************************************************************************************************************/ | |
| /*********************************************************************************************************************** | |
| * Function Name: R_BSP_Lock | |
| * Description : Attempt to acquire the lock that has been sent in. | |
| * Arguments : plock - | |
| * Pointer to lock structure with lock to try and acquire. | |
| * Return Value : true - | |
| * Lock was acquired. | |
| * false - | |
| * Lock was not acquired. | |
| ***********************************************************************************************************************/ | |
| bool R_BSP_Lock(bsp_lock_t * plock) | |
| { | |
| bool ret = false; | |
| /* Variable used in trying to acquire lock. Using the xchg instruction makes this atomic */ | |
| int32_t is_locked = true; | |
| /* This example uses the RX MCU's atomic xchg() instruction. plock->lock is the lock we are trying to reserve. | |
| The way this works is that 'is_locked' gets the value of the plock->lock and plock->lock gets the value of | |
| 'is_locked' which we just set to 'true'. Basically this is an atomic 'swap' command. If the lock had not yet been | |
| reserved then its value would be 'false' and after the xchg() instruction finished 'is_locked' would have | |
| 'false'. If it had already been reserved then 'is_locked' would have 'true' after the xchg() instruction. Since | |
| plock->lock was already 'true' and we just set it back to 'true' everything is ok. To see if we reserved the lock | |
| we just need to check the value of 'is_locked' after this instruction finishes. */ | |
| /* Try to acquire semaphore to obtain lock */ | |
| xchg(&is_locked, &plock->lock); | |
| /* Check to see if semaphore was successfully taken */ | |
| if (is_locked == false) | |
| { | |
| /* Lock obtained, return success. */ | |
| ret = true; | |
| } | |
| else | |
| { | |
| /* Lock was not obtained, another task already has it. */ | |
| } | |
| return ret; | |
| } /* End of function R_BSP_Lock() */ | |
| /*********************************************************************************************************************** | |
| * Function Name: R_BSP_Unlock | |
| * Description : Release hold on lock. | |
| * Arguments : plock - | |
| * Pointer to lock structure with lock to release. | |
| * Return Value : true - | |
| * Lock was released. | |
| * false - | |
| * Lock was not released. | |
| ***********************************************************************************************************************/ | |
| bool R_BSP_Unlock(bsp_lock_t * plock) | |
| { | |
| /* Set lock back to unlocked. */ | |
| plock->lock = false; | |
| return true; | |
| } /* End of function R_BSP_Unlock() */ | |