/* * Amazon FreeRTOS * Copyright (C) 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved. * * 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. * * http://aws.amazon.com/freertos * http://www.FreeRTOS.org */ /** * @file aws_doubly_linked_list.h * @brief Doubly Linked List implementation. * * A generic implementation of circular Doubly Linked List which consists of a * list head and some list entries (zero in case of an empty list). * * To start with, a structure of type Link_t should be embedded in the structure * which is to be organized as doubly linked list. * @code * typedef struct UserStruct * { * uint32_t ulField1; * uint32_t ulField2; * Link_t xLink; * } UserStruct_t; * @endcode * * A List head should then be defined and initialized. * @code * Link_t xListHead; * listINIT_HEAD( &xListHead ); * @endcode * * listADD can then be used to add nodes to the list. * @code * listADD( &( xListHead ), &( pxUserStruct->xLink ) ); * @endcode * * listFOR_EACH can be used for traversing the list. * @code * Link_t *pxLink; * UserStruct_t *pxUserStruct; * listFOR_EACH( pxLink, &( xListHead ) ) * { * pxUserStruct = listCONTAINER( pxLink, UserStruct_t, xLink ); * } * @endcode * * listFOR_EACH_SAFE should be used if you want to perform destructive operations * (like free) on nodes while traversing the list. * @code * Link_t *pxLink, *pxTempLink; * UserStruct_t *pxUserStruct; * listFOR_EACH( pxLink, pxTempLink, &( xListHead ) ) * { * pxUserStruct = listCONTAINER( pxLink, UserStruct_t, xLink ); * free( pxUserStruct ); * } * @endcode */ #ifndef _AWS_DOUBLY_LINKED_LIST_H_ #define _AWS_DOUBLY_LINKED_LIST_H_ #include #include /** * @brief Struct embedded in any struct to make it a doubly linked * list. * * pxNext in the head points to the first node in the list and pxPrev * in the head points to the last node in the list. In case of empty * list, both pxPrev and pxNext in the head point to the head node itself. */ typedef struct Link { struct Link * pxPrev; /**< Pointer to the previous node. */ struct Link * pxNext; /**< Pointer to the next node. */ } Link_t; /** * @brief Initializes the given list head to an empty list. * * @param[in] pxHead The given list head to initialize. */ #define listINIT_HEAD( pxHead ) \ { \ ( pxHead )->pxPrev = ( pxHead ); \ ( pxHead )->pxNext = ( pxHead ); \ } /** * @brief Adds the given new node to the given list. * * @param[in] pxHead The head of the given list. * @param[in] pxLink The given new node to be added to the given * list. */ #define listADD( pxHead, pxLink ) \ { \ Link_t * pxPrevLink = ( pxHead ); \ Link_t * pxNextLink = ( ( pxHead )->pxNext ); \ \ ( pxLink )->pxNext = pxNextLink; \ pxNextLink->pxPrev = ( pxLink ); \ pxPrevLink->pxNext = ( pxLink ); \ ( pxLink )->pxPrev = ( pxPrevLink ); \ } /** * @brief Removes the given node from the list it is part of. * * If the given node is not a part of any list (i.e. next and previous * nodes are NULL), nothing happens. * * @param[in] pxLink The given node to remove from the list. */ #define listREMOVE( pxLink ) \ { \ /* If the link is part of a list, remove it from the list. */ \ if( ( pxLink )->pxNext != NULL && ( pxLink )->pxPrev != NULL ) \ { \ ( pxLink )->pxPrev->pxNext = ( pxLink )->pxNext; \ ( pxLink )->pxNext->pxPrev = ( pxLink )->pxPrev; \ } \ \ /* Make sure that this link is not part of any list anymore. */ \ ( pxLink )->pxPrev = NULL; \ ( pxLink )->pxNext = NULL; \ } /** * @brief Given the head of a list, checks if the list is empty. * * @param[in] pxHead The head of the given list. */ #define listIS_EMPTY( pxHead ) ( ( ( pxHead ) == NULL ) || ( ( pxHead )->pxNext == ( pxHead ) ) ) /** * @brief Removes the first node from the given list and returns it. * * Removes the first node from the given list and assigns it to the * pxLink parameter. If the list is empty, it assigns NULL to the * pxLink. * * @param[in] pxHead The head of the list from which to remove the * first node. * @param[out] pxLink The output parameter to receive the removed * node. */ #define listPOP( pxHead, pxLink ) \ { \ if( listIS_EMPTY( ( pxHead ) ) ) \ { \ ( pxLink ) = NULL; \ } \ else \ { \ ( pxLink ) = ( pxHead )->pxNext; \ /* If the link is part of a list, remove it from the list. */ \ if( ( pxLink )->pxNext != NULL && ( pxLink )->pxPrev != NULL ) \ { \ ( pxLink )->pxPrev->pxNext = ( pxLink )->pxNext; \ ( pxLink )->pxNext->pxPrev = ( pxLink )->pxPrev; \ } \ \ /* Make sure that this link is not part of any list anymore. */ \ ( pxLink )->pxPrev = NULL; \ ( pxLink )->pxNext = NULL; \ } \ } /** * @brief Merges a list into a given list. * * @param[in] pxHeadResultList The head of the given list into which the * other list should be merged. * @param[in] pxHeadListToMerge The head of the list to be merged into the * given list. */ #define listMERGE( pxHeadResultList, pxHeadListToMerge ) \ { \ if( !listIS_EMPTY( ( pxHeadListToMerge ) ) ) \ { \ /* Setup links between last node of listToMerge and first node of resultList. */ \ ( pxHeadListToMerge )->pxPrev->pxNext = ( pxHeadResultList )->pxNext; \ ( pxHeadResultList )->pxNext->pxPrev = ( pxHeadListToMerge )->pxPrev; \ \ /* Setup links between first node of listToMerge and the head of resultList. */ \ ( pxHeadListToMerge )->pxNext->pxPrev = ( pxHeadResultList ); \ ( pxHeadResultList )->pxNext = ( pxHeadListToMerge )->pxNext; \ /* Empty the merged list. */ \ listINIT_HEAD( ( pxHeadListToMerge ) ); \ } \ } /** * @brief Helper macro to iterate over a list. pxLink contains the link node * in each iteration. */ #define listFOR_EACH( pxLink, pxHead ) \ for( ( pxLink ) = ( pxHead )->pxNext; \ ( pxLink ) != ( pxHead ); \ ( pxLink ) = ( pxLink )->pxNext ) /** * @brief Helper macro to iterate over a list. It is safe to destroy/free the * nodes while iterating. pxLink contains the link node in each iteration. */ #define listFOR_EACH_SAFE( pxLink, pxTempLink, pxHead ) \ for( ( pxLink ) = ( pxHead )->pxNext, ( pxTempLink ) = ( pxLink )->pxNext; \ ( pxLink ) != ( pxHead ); \ ( pxLink ) = ( pxTempLink ), ( pxTempLink ) = ( pxLink )->pxNext ) /** * @brief Given the pointer to the link member (of type Link_t) in a struct, * extracts the pointer to the containing struct. * * @param[in] pxLink The pointer to the link member. * @param[in] type The type of the containing struct. * @param[in] member Name of the link member in the containing struct. */ #define listCONTAINER( pxLink, type, member ) ( ( type * ) ( ( uint8_t * ) ( pxLink ) - ( uint8_t * ) ( &( ( type * ) 0 )->member ) ) ) #endif /* _AWS_DOUBLY_LINKED_LIST_H_ */