List是FreeRTOS内部实现的一个简单的双向链表,代码非常简单，这里笔记下注释。
CONTENTS
备注：
List在FreeRTOS中的实现API可能和我们常见的链表的实现方式不同，是因为List并没有被设计为通用链表，它主要是为FreeRTOS内部的scheduler服务的。
List.h：
#ifndef INC_FREERTOS_H
#error FreeRTOS.h must be included before list.h
#endif
#ifndef LIST_H
#define LIST_H
/* 如果在FreeRTOSConfig.h没有定义configLIST_VOLATILE宏,那么这里就用默认的，保证编译通过。详见英文注释 */
#ifndef configLIST_VOLATILE
#define configLIST_VOLATILE
#endif /* configSUPPORT_CROSS_MODULE_OPTIMISATION */
#ifdef __cplusplus
extern "C" {
#endif
/*
是否定义哨兵值，用来判断list的内存空间是否被其他代码意外覆盖了，用来检测程序是否跑飞。
*/
#if( configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES == 0 )
/* Define the macros to do nothing. */
#define listFIRST_LIST_ITEM_INTEGRITY_CHECK_VALUE
#define listSECOND_LIST_ITEM_INTEGRITY_CHECK_VALUE
#define listFIRST_LIST_INTEGRITY_CHECK_VALUE
#define listSECOND_LIST_INTEGRITY_CHECK_VALUE
#define listSET_FIRST_LIST_ITEM_INTEGRITY_CHECK_VALUE( pxItem )
#define listSET_SECOND_LIST_ITEM_INTEGRITY_CHECK_VALUE( pxItem )
#define listSET_LIST_INTEGRITY_CHECK_1_VALUE( pxList )
#define listSET_LIST_INTEGRITY_CHECK_2_VALUE( pxList )
#define listTEST_LIST_ITEM_INTEGRITY( pxItem )
#define listTEST_LIST_INTEGRITY( pxList )
#else
/* Define macros that add new members into the list structures. */
#define listFIRST_LIST_ITEM_INTEGRITY_CHECK_VALUE TickType_t xListItemIntegrityValue1;
#define listSECOND_LIST_ITEM_INTEGRITY_CHECK_VALUE TickType_t xListItemIntegrityValue2;
#define listFIRST_LIST_INTEGRITY_CHECK_VALUE TickType_t xListIntegrityValue1;
#define listSECOND_LIST_INTEGRITY_CHECK_VALUE TickType_t xListIntegrityValue2;
/* Define macros that set the new structure members to known values. */
#define listSET_FIRST_LIST_ITEM_INTEGRITY_CHECK_VALUE( pxItem ) ( pxItem )->xListItemIntegrityValue1 = pdINTEGRITY_CHECK_VALUE
#define listSET_SECOND_LIST_ITEM_INTEGRITY_CHECK_VALUE( pxItem ) ( pxItem )->xListItemIntegrityValue2 = pdINTEGRITY_CHECK_VALUE
#define listSET_LIST_INTEGRITY_CHECK_1_VALUE( pxList ) ( pxList )->xListIntegrityValue1 = pdINTEGRITY_CHECK_VALUE
#define listSET_LIST_INTEGRITY_CHECK_2_VALUE( pxList ) ( pxList )->xListIntegrityValue2 = pdINTEGRITY_CHECK_VALUE
/* Define macros that will assert if one of the structure members does not
contain its expected value. */
#define listTEST_LIST_ITEM_INTEGRITY( pxItem ) configASSERT( ( ( pxItem )->xListItemIntegrityValue1 == pdINTEGRITY_CHECK_VALUE ) && ( ( pxItem )->xListItemIntegrityValue2 == pdINTEGRITY_CHECK_VALUE ) )
#define listTEST_LIST_INTEGRITY( pxList ) configASSERT( ( ( pxList )->xListIntegrityValue1 == pdINTEGRITY_CHECK_VALUE ) && ( ( pxList )->xListIntegrityValue2 == pdINTEGRITY_CHECK_VALUE ) )
#endif /* configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES */
/* 链表中的存储的节点的结构体定义 */
struct xLIST_ITEM
{
/* 头部哨兵值，一般来讲，哨兵值都是在结构体的顶部和尾部，如果哨兵值被修改，那么说明该结构体内存已经被意外修改了。如果哨兵值没有被修改，
基本上说明当前程序是安全的，可以通过多次修改哨兵值的预定值来保证正确性。
*/
listFIRST_LIST_ITEM_INTEGRITY_CHECK_VALUE /*< Set to a known value if configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
/* 节点中存储的值 */
configLIST_VOLATILE TickType_t xItemValue; /*< The value being listed. In most cases this is used to sort the list in descending order. */
/* 双向链表，存储指向下一个和上一个的指针 */
struct xLIST_ITEM * configLIST_VOLATILE pxNext; /*< Pointer to the next ListItem_t in the list. */
struct xLIST_ITEM * configLIST_VOLATILE pxPrevious; /*< Pointer to the previous ListItem_t in the list. */
/* 该节点存储的值的来源，或者该节点作为一个变量存放到更大的结构体中时，该结构体的内存的指针 */
void * pvOwner; /*< Pointer to the object (normally a TCB) that contains the list item. There is therefore a two way link between the object containing the list item and the list item itself. */
/* 该节点属于哪一个链表 */
void * configLIST_VOLATILE pvContainer; /*< Pointer to the list in which this list item is placed (if any). */
/* 尾部哨兵值 */
listSECOND_LIST_ITEM_INTEGRITY_CHECK_VALUE /*< Set to a known value if configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
};
typedef struct xLIST_ITEM ListItem_t; /* For some reason lint wants this as two separate definitions. */
/*简化版本的xLIST_ITEM，用来减小内存占用。
注意xMINI_LIST_ITEM和xLIST_ITEM在结构体内部变量的定义上是相同的，因此xLIST_ITEM可以强转为xMINI_LIST_ITEM，而不会导致内存越界，并且能保证内部变量的值的正确性.
*/
struct xMINI_LIST_ITEM
{
listFIRST_LIST_ITEM_INTEGRITY_CHECK_VALUE /*< Set to a known value if configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
configLIST_VOLATILE TickType_t xItemValue;
struct xLIST_ITEM * configLIST_VOLATILE pxNext;
struct xLIST_ITEM * configLIST_VOLATILE pxPrevious;
};
typedef struct xMINI_LIST_ITEM MiniListItem_t;
/* 链表结构体，这里的链表的实现是环形链表 */
typedef struct xLIST
{
/* 前部哨兵值 */
listFIRST_LIST_INTEGRITY_CHECK_VALUE /*< Set to a known value if configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
/* 当前链表中一共有多少个节点 */
configLIST_VOLATILE UBaseType_t uxNumberOfItems;
/* 用来遍历当前链表节点的指针，该指针指向的节点不是固定的 */
ListItem_t * configLIST_VOLATILE pxIndex; /*< Used to walk through the list. Points to the last item returned by a call to listGET_OWNER_OF_NEXT_ENTRY (). */
/* 链表的最后一个节点的下一个节点，这里的xListEnd不存储任何有效值。这里用MiniListItem_t而不是用xLIST_ITEM是为了节省一点内存。 */
/* 由于链表为环形链表，因此这个节点也是第一个节点的上一个节点 */
/* 最后一个节点 -> xListEnd -> 第一个节点 */
MiniListItem_t xListEnd; /*< List item that contains the maximum possible item value meaning it is always at the end of the list and is therefore used as a marker. */
/* 尾部哨兵值 */
listSECOND_LIST_INTEGRITY_CHECK_VALUE /*< Set to a known value if configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
} List_t;
/*
* Access macro to set the owner of a list item. The owner of a list item
* is the object (usually a TCB) that contains the list item.
*
* \page listSET_LIST_ITEM_OWNER listSET_LIST_ITEM_OWNER
* \ingroup LinkedList
*/
/* 设置链表节点所属的链表 */
#define listSET_LIST_ITEM_OWNER( pxListItem, pxOwner ) ( ( pxListItem )->pvOwner = ( void * ) ( pxOwner ) )
/*
* Access macro to get the owner of a list item. The owner of a list item
* is the object (usually a TCB) that contains the list item.
*
* \page listSET_LIST_ITEM_OWNER listSET_LIST_ITEM_OWNER
* \ingroup LinkedList
*/
/* 返回链表节点所属的链表 */
#define listGET_LIST_ITEM_OWNER( pxListItem ) ( ( pxListItem )->pvOwner )
/*
* Access macro to set the value of the list item. In most cases the value is
* used to sort the list in descending order.
*
* \page listSET_LIST_ITEM_VALUE listSET_LIST_ITEM_VALUE
* \ingroup LinkedList
*/
/* 设置链表节点内部存储的值 */
#define listSET_LIST_ITEM_VALUE( pxListItem, xValue ) ( ( pxListItem )->xItemValue = ( xValue ) )
/*
* Access macro to retrieve the value of the list item. The value can
* represent anything - for example the priority of a task, or the time at
* which a task should be unblocked.
*
* \page listGET_LIST_ITEM_VALUE listGET_LIST_ITEM_VALUE
* \ingroup LinkedList
*/
/* 获取链表节点内部存储的值 */
#define listGET_LIST_ITEM_VALUE( pxListItem ) ( ( pxListItem )->xItemValue )
/*
* Access macro to retrieve the value of the list item at the head of a given
* list.
*
* \page listGET_LIST_ITEM_VALUE listGET_LIST_ITEM_VALUE
* \ingroup LinkedList
*/
/* 返回链表的第一个节点内部存储的值 */
#define listGET_ITEM_VALUE_OF_HEAD_ENTRY( pxList ) ( ( ( pxList )->xListEnd ).pxNext->xItemValue )
/*
* Return the list item at the head of the list.
*
* \page listGET_HEAD_ENTRY listGET_HEAD_ENTRY
* \ingroup LinkedList
*/
/* 返回链表的第一个节点 */
#define listGET_HEAD_ENTRY( pxList ) ( ( ( pxList )->xListEnd ).pxNext )
/*
* Return the list item at the head of the list.
*
* \page listGET_NEXT listGET_NEXT
* \ingroup LinkedList
*/
/* 返回指定节点的下一个节点 */
#define listGET_NEXT( pxListItem ) ( ( pxListItem )->pxNext )
/*
* Return the list item that marks the end of the list
*
* \page listGET_END_MARKER listGET_END_MARKER
* \ingroup LinkedList
*/
/* 返回链表的最后一个节点的下一个节点 */
#define listGET_END_MARKER( pxList ) ( ( ListItem_t const * ) ( &( ( pxList )->xListEnd ) ) )
/*
* Access macro to determine if a list contains any items. The macro will
* only have the value true if the list is empty.
*
* \page listLIST_IS_EMPTY listLIST_IS_EMPTY
* \ingroup LinkedList
*/
/* 判断链表是否为空 */
#define listLIST_IS_EMPTY( pxList ) ( ( BaseType_t ) ( ( pxList )->uxNumberOfItems == ( UBaseType_t ) 0 ) )
/*
* Access macro to return the number of items in the list.
*/
/* 返回链表的长度 */
#define listCURRENT_LIST_LENGTH( pxList ) ( ( pxList )->uxNumberOfItems )
/*
* Access function to obtain the owner of the next entry in a list.
*
* The list member pxIndex is used to walk through a list. Calling
* listGET_OWNER_OF_NEXT_ENTRY increments pxIndex to the next item in the list
* and returns that entry's pxOwner parameter. Using multiple calls to this
* function it is therefore possible to move through every item contained in
* a list.
*
* The pxOwner parameter of a list item is a pointer to the object that owns
* the list item. In the scheduler this is normally a task control block.
* The pxOwner parameter effectively creates a two way link between the list
* item and its owner.
*
* @param pxTCB pxTCB is set to the address of the owner of the next list item.
* @param pxList The list from which the next item owner is to be returned.
*
* \page listGET_OWNER_OF_NEXT_ENTRY listGET_OWNER_OF_NEXT_ENTRY
* \ingroup LinkedList
*/
/*
返回当前链表下个节点的owner的值
*/
#define listGET_OWNER_OF_NEXT_ENTRY( pxTCB, pxList ) \
{ \
List_t * const pxConstList = ( pxList ); \
/* Increment the index to the next item and return the item, ensuring */ \
/* we don't return the marker used at the end of the list. */ \
( pxConstList )->pxIndex = ( pxConstList )->pxIndex->pxNext; \
if( ( void * ) ( pxConstList )->pxIndex == ( void * ) &( ( pxConstList )->xListEnd ) ) \
{ \
( pxConstList )->pxIndex = ( pxConstList )->pxIndex->pxNext; \
} \
( pxTCB ) = ( pxConstList )->pxIndex->pvOwner; \
}
/*
* Access function to obtain the owner of the first entry in a list. Lists
* are normally sorted in ascending item value order.
*
* This function returns the pxOwner member of the first item in the list.
* The pxOwner parameter of a list item is a pointer to the object that owns
* the list item. In the scheduler this is normally a task control block.
* The pxOwner parameter effectively creates a two way link between the list
* item and its owner.
*
* @param pxList The list from which the owner of the head item is to be
* returned.
*
* \page listGET_OWNER_OF_HEAD_ENTRY listGET_OWNER_OF_HEAD_ENTRY
* \ingroup LinkedList
*/
/*
返回当前链表第一个节点的owner的值
*/
#define listGET_OWNER_OF_HEAD_ENTRY( pxList ) ( (&( ( pxList )->xListEnd ))->pxNext->pvOwner )
/*
* Check to see if a list item is within a list. The list item maintains a
* "container" pointer that points to the list it is in. All this macro does
* is check to see if the container and the list match.
*
* @param pxList The list we want to know if the list item is within.
* @param pxListItem The list item we want to know if is in the list.
* @return pdTRUE if the list item is in the list, otherwise pdFALSE.
*/
/* 判断节点是否属于某一个链表 */
#define listIS_CONTAINED_WITHIN( pxList, pxListItem ) ( ( BaseType_t ) ( ( pxListItem )->pvContainer == ( void * ) ( pxList ) ) )
/*
* Return the list a list item is contained within (referenced from).
*
* @param pxListItem The list item being queried.
* @return A pointer to the List_t object that references the pxListItem
*/
/* 返回节点的container */
#define listLIST_ITEM_CONTAINER( pxListItem ) ( ( pxListItem )->pvContainer )
/*
* This provides a crude means of knowing if a list has been initialised, as
* pxList->xListEnd.xItemValue is set to portMAX_DELAY by the vListInitialise()
* function.
*/
/* 判断一个链表是否已经被初始化，由于xListEnd不存储任何有效值，因此可以利用xListEnd来判断 */
#define listLIST_IS_INITIALISED( pxList ) ( ( pxList )->xListEnd.xItemValue == portMAX_DELAY )
/*
* Must be called before a list is used! This initialises all the members
* of the list structure and inserts the xListEnd item into the list as a
* marker to the back of the list.
*
* @param pxList Pointer to the list being initialised.
*
* \page vListInitialise vListInitialise
* \ingroup LinkedList
*/
/* 初始化一个链表 */
void vListInitialise( List_t * const pxList );
/*
* Must be called before a list item is used. This sets the list container to
* null so the item does not think that it is already contained in a list.
*
* @param pxItem Pointer to the list item being initialised.
*
* \page vListInitialiseItem vListInitialiseItem
* \ingroup LinkedList
*/
/* 初始化一个链表节点 */
void vListInitialiseItem( ListItem_t * const pxItem );
/*
* Insert a list item into a list. The item will be inserted into the list in
* a position determined by its item value (descending item value order).
*
* @param pxList The list into which the item is to be inserted.
*
* @param pxNewListItem The item that is to be placed in the list.
*
* \page vListInsert vListInsert
* \ingroup LinkedList
*/
/* 将一个链表节点插入到链表中 */
void vListInsert( List_t * const pxList, ListItem_t * const pxNewListItem );
/*
* Insert a list item into a list. The item will be inserted in a position
* such that it will be the last item within the list returned by multiple
* calls to listGET_OWNER_OF_NEXT_ENTRY.
*
* The list member pvIndex is used to walk through a list. Calling
* listGET_OWNER_OF_NEXT_ENTRY increments pvIndex to the next item in the list.
* Placing an item in a list using vListInsertEnd effectively places the item
* in the list position pointed to by pvIndex. This means that every other
* item within the list will be returned by listGET_OWNER_OF_NEXT_ENTRY before
* the pvIndex parameter again points to the item being inserted.
*
* @param pxList The list into which the item is to be inserted.
*
* @param pxNewListItem The list item to be inserted into the list.
*
* \page vListInsertEnd vListInsertEnd
* \ingroup LinkedList
*/
/* 将一个链表节点插入到链表的尾部 */
void vListInsertEnd( List_t * const pxList, ListItem_t * const pxNewListItem );
/*
* Remove an item from a list. The list item has a pointer to the list that
* it is in, so only the list item need be passed into the function.
*
* @param uxListRemove The item to be removed. The item will remove itself from
* the list pointed to by it's pxContainer parameter.
*
* @return The number of items that remain in the list after the list item has
* been removed.
*
* \page uxListRemove uxListRemove
* \ingroup LinkedList
*/
/* 将一个链表节点从链表中删除 */
UBaseType_t uxListRemove( ListItem_t * const pxItemToRemove );
#ifdef __cplusplus
}
#endif
#endif
List.c:
#include <stdlib.h>
#include "FreeRTOS.h"
#include "list.h"
/*-----------------------------------------------------------
* PUBLIC LIST API documented in list.h
*----------------------------------------------------------*/
/* 初始化一个链表 */
void vListInitialise( List_t * const pxList )
{
/* The list structure contains a list item which is used to mark the
end of the list. To initialise the list the list end is inserted
as the only list entry. */
/* 将内部指针指向xlistEnd */
pxList->pxIndex = ( ListItem_t * ) &( pxList->xListEnd ); /*lint !e826 !e740 The mini list structure is used as the list end to save RAM. This is checked and valid. */
/* The list end value is the highest possible value in the list to
ensure it remains at the end of the list. */
/* 更改xlistEnd存储的值，用来判断该链表是否已经初始化 */
pxList->xListEnd.xItemValue = portMAX_DELAY;
/* The list end next and previous pointers point to itself so we know
when the list is empty. */
/* 初始化环形链表，这里将xListEnd向前向后均指向自己, 表明内部节点数量为0 */
pxList->xListEnd.pxNext = ( ListItem_t * ) &( pxList->xListEnd ); /*lint !e826 !e740 The mini list structure is used as the list end to save RAM. This is checked and valid. */
pxList->xListEnd.pxPrevious = ( ListItem_t * ) &( pxList->xListEnd );/*lint !e826 !e740 The mini list structure is used as the list end to save RAM. This is checked and valid. */
/* 初始化链表元素值 */
pxList->uxNumberOfItems = ( UBaseType_t ) 0U;
/* Write known values into the list if
configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
/* 设置哨兵值 */
listSET_LIST_INTEGRITY_CHECK_1_VALUE( pxList );
listSET_LIST_INTEGRITY_CHECK_2_VALUE( pxList );
}
/*-----------------------------------------------------------*/
/* 初始化链表节点 */
void vListInitialiseItem( ListItem_t * const pxItem )
{
/* 该节点现在不属于任何链表 */
/* Make sure the list item is not recorded as being on a list. */
pxItem->pvContainer = NULL;
/* 设置哨兵值 */
/* Write known values into the list item if
configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
listSET_FIRST_LIST_ITEM_INTEGRITY_CHECK_VALUE( pxItem );
listSET_SECOND_LIST_ITEM_INTEGRITY_CHECK_VALUE( pxItem );
}
/*-----------------------------------------------------------*/
/* 将链表节点插入链表尾部,注意这里的尾部是指链表结构体中pxIndex指向的节点的后面 */
void vListInsertEnd( List_t * const pxList, ListItem_t * const pxNewListItem )
{
ListItem_t * const pxIndex = pxList->pxIndex;
/* 校验下链表和节点的哨兵值是否正确 */
/* Only effective when configASSERT() is also defined, these tests may catch
the list data structures being overwritten in memory. They will not catch
data errors caused by incorrect configuration or use of FreeRTOS. */
listTEST_LIST_INTEGRITY( pxList );
listTEST_LIST_ITEM_INTEGRITY( pxNewListItem );
/* Insert a new list item into pxList, but rather than sort the list,
makes the new list item the last item to be removed by a call to
listGET_OWNER_OF_NEXT_ENTRY(). */
/* 更新要插入的节点的指针 */
pxNewListItem->pxNext = pxIndex;
pxNewListItem->pxPrevious = pxIndex->pxPrevious;
/* Only used during decision coverage testing. */
mtCOVERAGE_TEST_DELAY();
/* 更新pxIndex指向的节点的指针 */
pxIndex->pxPrevious->pxNext = pxNewListItem;
pxIndex->pxPrevious = pxNewListItem;
/* 更新节点的container，表明该节点属于该链表 */
/* Remember which list the item is in. */
pxNewListItem->pvContainer = ( void * ) pxList;
/* 更新链表中的节点的个数 */
( pxList->uxNumberOfItems )++;
}
/*-----------------------------------------------------------*/
/* 将节点插入到链表中,根据节点内部存储的值进行升序排列 */
void vListInsert( List_t * const pxList, ListItem_t * const pxNewListItem )
{
ListItem_t *pxIterator;
const TickType_t xValueOfInsertion = pxNewListItem->xItemValue;
/* 校验下链表和节点的哨兵值是否正确 */
/* Only effective when configASSERT() is also defined, these tests may catch
the list data structures being overwritten in memory. They will not catch
data errors caused by incorrect configuration or use of FreeRTOS. */
listTEST_LIST_INTEGRITY( pxList );
listTEST_LIST_ITEM_INTEGRITY( pxNewListItem );
/* 寻找比新节点内部存储的值更大的节点 */
/* Insert the new list item into the list, sorted in xItemValue order.
If the list already contains a list item with the same item value then the
new list item should be placed after it. This ensures that TCB's which are
stored in ready lists (all of which have the same xItemValue value) get a
share of the CPU. However, if the xItemValue is the same as the back marker
the iteration loop below will not end. Therefore the value is checked
first, and the algorithm slightly modified if necessary. */
if( xValueOfInsertion == portMAX_DELAY )
{
pxIterator = pxList->xListEnd.pxPrevious;
}
else
{
/* *** NOTE ***********************************************************
If you find your application is crashing here then likely causes are
listed below. In addition see http://www.freertos.org/FAQHelp.html for
more tips, and ensure configASSERT() is defined!
http://www.freertos.org/a00110.html#configASSERT
1) Stack overflow -
see http://www.freertos.org/Stacks-and-stack-overflow-checking.html
2) Incorrect interrupt priority assignment, especially on Cortex-M
parts where numerically high priority values denote low actual
interrupt priorities, which can seem counter intuitive. See
http://www.freertos.org/RTOS-Cortex-M3-M4.html and the definition
of configMAX_SYSCALL_INTERRUPT_PRIORITY on
http://www.freertos.org/a00110.html
3) Calling an API function from within a critical section or when
the scheduler is suspended, or calling an API function that does
not end in "FromISR" from an interrupt.
4) Using a queue or semaphore before it has been initialised or
before the scheduler has been started (are interrupts firing
before vTaskStartScheduler() has been called?).
**********************************************************************/
for( pxIterator = ( ListItem_t * ) &( pxList->xListEnd ); pxIterator->pxNext->xItemValue <= xValueOfInsertion; pxIterator = pxIterator->pxNext ) /*lint !e826 !e740 The mini list structure is used as the list end to save RAM. This is checked and valid. */
{
/* There is nothing to do here, just iterating to the wanted
insertion position. */
}
}
/* 更新插入点前后节点的指针，将新的节点插入到链表里面 */
pxNewListItem->pxNext = pxIterator->pxNext;
pxNewListItem->pxNext->pxPrevious = pxNewListItem;
pxNewListItem->pxPrevious = pxIterator;
pxIterator->pxNext = pxNewListItem;
/* Remember which list the item is in. This allows fast removal of the
item later. */
/* 更新节点的container，表明该节点属于该链表 */
pxNewListItem->pvContainer = ( void * ) pxList;
/* 更新链表中的节点的个数 */
( pxList->uxNumberOfItems )++;
}
/*-----------------------------------------------------------*/
/* 将一个节点从链表中删除 */
UBaseType_t uxListRemove( ListItem_t * const pxItemToRemove )
{
/* The list item knows which list it is in. Obtain the list from the list
item. */
/* 获取节点所属的链表 */
List_t * const pxList = ( List_t * ) pxItemToRemove->pvContainer;
/* 更新节点前后的节点的指针，将该节点从链表中移除 */
pxItemToRemove->pxNext->pxPrevious = pxItemToRemove->pxPrevious;
pxItemToRemove->pxPrevious->pxNext = pxItemToRemove->pxNext;
/* Only used during decision coverage testing. */
mtCOVERAGE_TEST_DELAY();
/* 修正下链表中的pxIndex，保证其指向的正确性 */
/* Make sure the index is left pointing to a valid item. */
if( pxList->pxIndex == pxItemToRemove )
{
pxList->pxIndex = pxItemToRemove->pxPrevious;
}
else
{
mtCOVERAGE_TEST_MARKER();
}
/* 将节点所属的链表设置为NULL */
pxItemToRemove->pvContainer = NULL;
/* 更新链表中节点个数 */
( pxList->uxNumberOfItems )--;
return pxList->uxNumberOfItems;
}
/*-----------------------------------------------------------*/
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