FreeRTOS V7.0.2 源码+注释

/* FreeRTOS V7.0.2 - Copyright (C) 2011 Real Time Engineers Ltd. *************************************************************************** * * * FreeRTOS tutorial books are available in pdf and paperback. * * Complete, revised, and edited pdf reference manuals are also * * available. * * * * Purchasing FreeRTOS documentation will not only help you, by * * ensuring you get running as quickly as possible and with an * * in-depth knowledge of how to use FreeRTOS, it will also help * * the FreeRTOS project to continue with its mission of providing * * professional grade, cross platform, de facto standard solutions * * for microcontrollers - completely free of charge! * * * * >>> See http://www.FreeRTOS.org/Documentation for details. <<< * * * * Thank you for using FreeRTOS, and thank you for your support! * * * *************************************************************************** This file is part of the FreeRTOS distribution. FreeRTOS is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License (version 2) as published by the Free Software Foundation AND MODIFIED BY the FreeRTOS exception. >>>NOTE<<< The modification to the GPL is included to allow you to distribute a combined work that includes FreeRTOS without being obliged to provide the source code for proprietary components outside of the FreeRTOS kernel. FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License and the FreeRTOS license exception along with FreeRTOS; if not it can be viewed here: http://www.freertos.org/a00114.html and also obtained by writing to Richard Barry, contact details for whom are available on the FreeRTOS WEB site. 1 tab == 4 spaces! http://www.FreeRTOS.org - Documentation, latest information, license and contact details. http://www.SafeRTOS.com - A version that is certified for use in safety critical systems. http://www.OpenRTOS.com - Commercial support, development, porting, licensing and training services. */ #include <stdio.h> #include <stdlib.h> #include <string.h> /* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE prevents task.h from redefining all the API functions to use the MPU wrappers. That should only be done when task.h is included from an application file. */ #define MPU_WRAPPERS_INCLUDED_FROM_API_FILE #include "FreeRTOS.h" #include "task.h" #include "timers.h" #include "StackMacros.h" #undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE /* * Macro to define the amount of stack available to the idle task. */ #define tskIDLE_STACK_SIZE configMINIMAL_STACK_SIZE /* * Task control block. A task control block (TCB) is allocated to each task, * and stores the context of the task. */ typedef struct tskTaskControlBlock { volatile portSTACK_TYPE *pxTopOfStack; //指向堆栈顶/*< Points to the location of the last item placed on the tasks stack. THIS MUST BE THE FIRST MEMBER OF THE STRUCT. */ #if ( portUSING_MPU_WRAPPERS == 1 ) xMPU_SETTINGS xMPUSettings; /*< The MPU settings are defined as part of the port layer. THIS MUST BE THE SECOND MEMBER OF THE STRUCT. */ #endif xListItem xGenericListItem; //通过它将任务连入就绪链表或者延时链表或者挂起链表中/*< List item used to place the TCB in ready and blocked queues. */ xListItem xEventListItem; //通过它把任务连入事件等待链表/*< List item used to place the TCB in event lists. */ unsigned portBASE_TYPE uxPriority; //uxPriority中存储任务的初始优先级 /*< The priority of the task where 0 is the lowest priority. */ portSTACK_TYPE *pxStack; //pxStack里存储堆栈的起始地址/*< Points to the start of the stack. */ signed char pcTaskName[ configMAX_TASK_NAME_LEN ];/*< Descriptive name given to the task when created. Facilitates debugging only. */ #if ( portSTACK_GROWTH > 0 ) portSTACK_TYPE *pxEndOfStack; //pxEndOfStack存储堆栈的结束的指针来检查堆栈溢出/*< Used for stack overflow checking on architectures where the stack grows up from low memory. */ #endif #if ( portCRITICAL_NESTING_IN_TCB == 1 ) unsigned portBASE_TYPE uxCriticalNesting;//中断嵌套计数器 #endif #if ( configUSE_TRACE_FACILITY == 1 ) unsigned portBASE_TYPE uxTCBNumber; //用于trace，debug时候提供方便/*< This is used for tracing the scheduler and making debugging easier only. */ #endif #if ( configUSE_MUTEXES == 1 ) unsigned portBASE_TYPE uxBasePriority; //uxBasePriority中存储任务的初始优先级，当任务临时提升到“继承的”优先级时，它使用uxBasePriority去记住原来的优先级/*< The priority last assigned to the task - used by the priority inheritance mechanism. */ #endif #if ( configUSE_APPLICATION_TASK_TAG == 1 ) pdTASK_HOOK_CODE pxTaskTag; #endif #if ( configGENERATE_RUN_TIME_STATS == 1 ) unsigned long ulRunTimeCounter; //计算任务利用CPU的时间/*< Used for calculating how much CPU time each task is utilising. */ #endif } tskTCB; /* * Some kernel aware debuggers require data to be viewed to be global, rather * than file scope. */ #ifdef portREMOVE_STATIC_QUALIFIER #define static #endif /*lint -e956 */ PRIVILEGED_DATA tskTCB * volatile pxCurrentTCB = NULL; /* Lists for ready and blocked tasks. --------------------*/ PRIVILEGED_DATA static xList pxReadyTasksLists[ configMAX_PRIORITIES ]; //所有就绪状态的任务根据任务优先级加到对应的就绪链表中。系统为每个优先级定义了一个xList。/*< Prioritised ready tasks. */ PRIVILEGED_DATA static xList xDelayedTaskList1; //延时链表，计数没溢出/*< Delayed tasks. */ PRIVILEGED_DATA static xList xDelayedTaskList2; //延时链表，计数溢出/*< Delayed tasks (two lists are used - one for delays that have overflowed the current tick count. */ PRIVILEGED_DATA static xList * volatile pxDelayedTaskList ; //指向当前正在被用的延时链表/*< Points to the delayed task list currently being used. */ PRIVILEGED_DATA static xList * volatile pxOverflowDelayedTaskList; //指向当前正在被用的有溢出的延时链表/*< Points to the delayed task list currently being used to hold tasks that have overflowed the current tick count. */ PRIVILEGED_DATA static xList xPendingReadyList; //这个链表用在调度器被lock（就是禁止调度了）的时期，如果一个任务从非就绪状态变为就绪状态，它不直接加到就绪链表中，而是加到这个pending链表中。等调度器重新启动(unlock)的时候再检查这个链表，把里面的任务加到就绪链表中/*< Tasks that have been readied while the scheduler was suspended. They will be moved to the ready queue when the scheduler is resumed. */ #if ( INCLUDE_vTaskDelete == 1 ) PRIVILEGED_DATA static xList xTasksWaitingTermination; /*< Tasks that have been deleted - but the their memory not yet freed. */ PRIVILEGED_DATA static volatile unsigned portBASE_TYPE uxTasksDeleted = ( unsigned portBASE_TYPE ) 0U; //一个任务被删除的时候加入到xTasksWaitingTermination链表中，uxTasksDeleted跟踪系统中有多少任务被删除（即加到xTasksWaitingTermination链表的任务数目） #endif #if ( INCLUDE_vTaskSuspend == 1 ) PRIVILEGED_DATA static xList xSuspendedTaskList; /*< Tasks that are currently suspended