五:FreeRTOS列表與列表項
阿新 • • 發佈:2021-01-28
技術標籤:微控制器STM32# FreeRTOSFreeRTOS
列表和列表項是FreeeRTOS的一個數據結構,FreeRTOS大量使用到了列表與列表項,它是FreeRTOS的基石。
列表和列表項和連結串列類似,都有插入和刪除操作
列表:
列表是FreeRTOS中的一個數據結構,概念上和連結串列有點類似,列表被用來跟蹤FreeRTOS中的任務。列表結構為List_t
typedef struct xLIST { listFIRST_LIST_INTEGRITY_CHECK_VALUE /*< Set to a known value if configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */ configLIST_VOLATILE UBaseType_t uxNumberOfItems; 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 (). */ 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. */ listSECOND_LIST_INTEGRITY_CHECK_VALUE /*< Set to a known value if configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */ } List_t;
列表項:
列表項就是存放在列表中的專案,FreeRTOS提供了兩種列表項:列表項和迷你列表項。這兩個都在檔案list_h中有定義
struct xLIST_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; /*< The value being listed. In most cases this is used to sort the list in descending order. */ 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. */ 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. */ void * configLIST_VOLATILE pvContainer; /*< Pointer to the list in which this list item is placed (if any). */ 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. */ 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;