404 lines
17 KiB
C
404 lines
17 KiB
C
/*
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FreeRTOS V8.1.2 - Copyright (C) 2014 Real Time Engineers Ltd.
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All rights reserved
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VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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***************************************************************************
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* *
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* FreeRTOS provides completely free yet professionally developed, *
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* robust, strictly quality controlled, supported, and cross *
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* platform software that has become a de facto standard. *
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* *
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* Help yourself get started quickly and support the FreeRTOS *
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* project by purchasing a FreeRTOS tutorial book, reference *
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* manual, or both from: http://www.FreeRTOS.org/Documentation *
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* *
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* Thank you! *
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* *
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***************************************************************************
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This file is part of the FreeRTOS distribution.
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FreeRTOS is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License (version 2) as published by the
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Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.
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>>! NOTE: The modification to the GPL is included to allow you to !<<
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>>! distribute a combined work that includes FreeRTOS without being !<<
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>>! obliged to provide the source code for proprietary components !<<
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>>! outside of the FreeRTOS kernel. !<<
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FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. Full license text is available from the following
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link: http://www.freertos.org/a00114.html
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1 tab == 4 spaces!
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***************************************************************************
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* *
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* Having a problem? Start by reading the FAQ "My application does *
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* not run, what could be wrong?" *
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* *
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* http://www.FreeRTOS.org/FAQHelp.html *
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* *
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***************************************************************************
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http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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license and Real Time Engineers Ltd. contact details.
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http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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compatible FAT file system, and our tiny thread aware UDP/IP stack.
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http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
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licenses offer ticketed support, indemnification and middleware.
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http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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engineered and independently SIL3 certified version for use in safety and
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mission critical applications that require provable dependability.
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1 tab == 4 spaces!
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*/
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/*
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* This is the list implementation used by the scheduler. While it is tailored
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* heavily for the schedulers needs, it is also available for use by
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* application code.
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*
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* list_ts can only store pointers to list_item_ts. Each ListItem_t contains a
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* numeric value (xItemValue). Most of the time the lists are sorted in
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* descending item value order.
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*
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* Lists are created already containing one list item. The value of this
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* item is the maximum possible that can be stored, it is therefore always at
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* the end of the list and acts as a marker. The list member pxHead always
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* points to this marker - even though it is at the tail of the list. This
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* is because the tail contains a wrap back pointer to the true head of
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* the list.
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*
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* In addition to it's value, each list item contains a pointer to the next
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* item in the list (pxNext), a pointer to the list it is in (pxContainer)
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* and a pointer to back to the object that contains it. These later two
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* pointers are included for efficiency of list manipulation. There is
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* effectively a two way link between the object containing the list item and
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* the list item itself.
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*
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*
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* \page ListIntroduction List Implementation
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* \ingroup FreeRTOSIntro
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*/
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#ifndef LIST_H
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#define LIST_H
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/*
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* The list structure members are modified from within interrupts, and therefore
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* by rights should be declared volatile. However, they are only modified in a
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* functionally atomic way (within critical sections of with the scheduler
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* suspended) and are either passed by reference into a function or indexed via
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* a volatile variable. Therefore, in all use cases tested so far, the volatile
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* qualifier can be omitted in order to provide a moderate performance
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* improvement without adversely affecting functional behaviour. The assembly
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* instructions generated by the IAR, ARM and GCC compilers when the respective
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* compiler's options were set for maximum optimisation has been inspected and
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* deemed to be as intended. That said, as compiler technology advances, and
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* especially if aggressive cross module optimisation is used (a use case that
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* has not been exercised to any great extend) then it is feasible that the
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* volatile qualifier will be needed for correct optimisation. It is expected
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* that a compiler removing essential code because, without the volatile
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* qualifier on the list structure members and with aggressive cross module
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* optimisation, the compiler deemed the code unnecessary will result in
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* complete and obvious failure of the scheduler. If this is ever experienced
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* then the volatile qualifier can be inserted in the relevant places within the
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* list structures by simply defining configLIST_VOLATILE to volatile in
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* FreeRTOSConfig.h (as per the example at the bottom of this comment block).
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* If configLIST_VOLATILE is not defined then the preprocessor directives below
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* will simply #define configLIST_VOLATILE away completely.
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*
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* To use volatile list structure members then add the following line to
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* FreeRTOSConfig.h (without the quotes):
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* "#define configLIST_VOLATILE volatile"
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*/
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#ifndef configLIST_VOLATILE
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#define configLIST_VOLATILE
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#endif /* configSUPPORT_CROSS_MODULE_OPTIMISATION */
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*
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* Definition of the only type of object that a list can contain.
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*/
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struct xLIST_ITEM
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{
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configLIST_VOLATILE TickType_t xItemValue; /*< The value being listed. In most cases this is used to sort the list in descending order. */
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struct xLIST_ITEM * configLIST_VOLATILE pxNext; /*< Pointer to the next ListItem_t in the list. */
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struct xLIST_ITEM * configLIST_VOLATILE pxPrevious; /*< Pointer to the previous ListItem_t in the list. */
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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. */
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void * configLIST_VOLATILE pvContainer; /*< Pointer to the list in which this list item is placed (if any). */
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};
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typedef struct xLIST_ITEM ListItem_t; /* For some reason lint wants this as two separate definitions. */
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struct xMINI_LIST_ITEM
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{
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configLIST_VOLATILE TickType_t xItemValue;
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struct xLIST_ITEM * configLIST_VOLATILE pxNext;
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struct xLIST_ITEM * configLIST_VOLATILE pxPrevious;
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};
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typedef struct xMINI_LIST_ITEM MiniListItem_t;
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/*
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* Definition of the type of queue used by the scheduler.
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*/
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typedef struct xLIST
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{
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configLIST_VOLATILE UBaseType_t uxNumberOfItems;
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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 (). */
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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. */
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} List_t;
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/*
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* Access macro to set the owner of a list item. The owner of a list item
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* is the object (usually a TCB) that contains the list item.
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*
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* \page listSET_LIST_ITEM_OWNER listSET_LIST_ITEM_OWNER
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* \ingroup LinkedList
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*/
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#define listSET_LIST_ITEM_OWNER( pxListItem, pxOwner ) ( ( pxListItem )->pvOwner = ( void * ) ( pxOwner ) )
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/*
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* Access macro to get the owner of a list item. The owner of a list item
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* is the object (usually a TCB) that contains the list item.
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*
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* \page listSET_LIST_ITEM_OWNER listSET_LIST_ITEM_OWNER
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* \ingroup LinkedList
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*/
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#define listGET_LIST_ITEM_OWNER( pxListItem ) ( ( pxListItem )->pvOwner )
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/*
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* Access macro to set the value of the list item. In most cases the value is
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* used to sort the list in descending order.
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*
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* \page listSET_LIST_ITEM_VALUE listSET_LIST_ITEM_VALUE
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* \ingroup LinkedList
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*/
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#define listSET_LIST_ITEM_VALUE( pxListItem, xValue ) ( ( pxListItem )->xItemValue = ( xValue ) )
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/*
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* Access macro to retrieve the value of the list item. The value can
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* represent anything - for example the priority of a task, or the time at
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* which a task should be unblocked.
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*
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* \page listGET_LIST_ITEM_VALUE listGET_LIST_ITEM_VALUE
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* \ingroup LinkedList
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*/
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#define listGET_LIST_ITEM_VALUE( pxListItem ) ( ( pxListItem )->xItemValue )
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/*
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* Access macro to retrieve the value of the list item at the head of a given
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* list.
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*
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* \page listGET_LIST_ITEM_VALUE listGET_LIST_ITEM_VALUE
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* \ingroup LinkedList
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*/
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#define listGET_ITEM_VALUE_OF_HEAD_ENTRY( pxList ) ( ( ( pxList )->xListEnd ).pxNext->xItemValue )
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/*
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* Return the list item at the head of the list.
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*
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* \page listGET_HEAD_ENTRY listGET_HEAD_ENTRY
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* \ingroup LinkedList
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*/
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#define listGET_HEAD_ENTRY( pxList ) ( ( ( pxList )->xListEnd ).pxNext )
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/*
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* Return the list item at the head of the list.
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*
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* \page listGET_NEXT listGET_NEXT
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* \ingroup LinkedList
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*/
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#define listGET_NEXT( pxListItem ) ( ( pxListItem )->pxNext )
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/*
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* Return the list item that marks the end of the list
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*
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* \page listGET_END_MARKER listGET_END_MARKER
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* \ingroup LinkedList
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*/
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#define listGET_END_MARKER( pxList ) ( ( ListItem_t const * ) ( &( ( pxList )->xListEnd ) ) )
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/*
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* Access macro to determine if a list contains any items. The macro will
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* only have the value true if the list is empty.
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*
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* \page listLIST_IS_EMPTY listLIST_IS_EMPTY
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* \ingroup LinkedList
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*/
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#define listLIST_IS_EMPTY( pxList ) ( ( BaseType_t ) ( ( pxList )->uxNumberOfItems == ( UBaseType_t ) 0 ) )
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/*
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* Access macro to return the number of items in the list.
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*/
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#define listCURRENT_LIST_LENGTH( pxList ) ( ( pxList )->uxNumberOfItems )
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/*
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* Access function to obtain the owner of the next entry in a list.
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*
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* The list member pxIndex is used to walk through a list. Calling
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* listGET_OWNER_OF_NEXT_ENTRY increments pxIndex to the next item in the list
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* and returns that entry's pxOwner parameter. Using multiple calls to this
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* function it is therefore possible to move through every item contained in
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* a list.
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*
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* The pxOwner parameter of a list item is a pointer to the object that owns
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* the list item. In the scheduler this is normally a task control block.
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* The pxOwner parameter effectively creates a two way link between the list
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* item and its owner.
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*
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* @param pxTCB pxTCB is set to the address of the owner of the next list item.
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* @param pxList The list from which the next item owner is to be returned.
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*
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* \page listGET_OWNER_OF_NEXT_ENTRY listGET_OWNER_OF_NEXT_ENTRY
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* \ingroup LinkedList
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*/
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#define listGET_OWNER_OF_NEXT_ENTRY( pxTCB, pxList ) \
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{ \
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List_t * const pxConstList = ( pxList ); \
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/* Increment the index to the next item and return the item, ensuring */ \
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/* we don't return the marker used at the end of the list. */ \
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( pxConstList )->pxIndex = ( pxConstList )->pxIndex->pxNext; \
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if( ( void * ) ( pxConstList )->pxIndex == ( void * ) &( ( pxConstList )->xListEnd ) ) \
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{ \
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( pxConstList )->pxIndex = ( pxConstList )->pxIndex->pxNext; \
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} \
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( pxTCB ) = ( pxConstList )->pxIndex->pvOwner; \
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}
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/*
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* Access function to obtain the owner of the first entry in a list. Lists
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* are normally sorted in ascending item value order.
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*
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* This function returns the pxOwner member of the first item in the list.
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* The pxOwner parameter of a list item is a pointer to the object that owns
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* the list item. In the scheduler this is normally a task control block.
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* The pxOwner parameter effectively creates a two way link between the list
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* item and its owner.
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*
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* @param pxList The list from which the owner of the head item is to be
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* returned.
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*
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* \page listGET_OWNER_OF_HEAD_ENTRY listGET_OWNER_OF_HEAD_ENTRY
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* \ingroup LinkedList
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*/
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#define listGET_OWNER_OF_HEAD_ENTRY( pxList ) ( (&( ( pxList )->xListEnd ))->pxNext->pvOwner )
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/*
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* Check to see if a list item is within a list. The list item maintains a
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* "container" pointer that points to the list it is in. All this macro does
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* is check to see if the container and the list match.
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*
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* @param pxList The list we want to know if the list item is within.
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* @param pxListItem The list item we want to know if is in the list.
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* @return pdTRUE if the list item is in the list, otherwise pdFALSE.
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*/
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#define listIS_CONTAINED_WITHIN( pxList, pxListItem ) ( ( BaseType_t ) ( ( pxListItem )->pvContainer == ( void * ) ( pxList ) ) )
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/*
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* Return the list a list item is contained within (referenced from).
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*
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* @param pxListItem The list item being queried.
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* @return A pointer to the List_t object that references the pxListItem
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*/
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#define listLIST_ITEM_CONTAINER( pxListItem ) ( ( pxListItem )->pvContainer )
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/*
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* This provides a crude means of knowing if a list has been initialised, as
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* pxList->xListEnd.xItemValue is set to portMAX_DELAY by the vListInitialise()
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* function.
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*/
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#define listLIST_IS_INITIALISED( pxList ) ( ( pxList )->xListEnd.xItemValue == portMAX_DELAY )
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/*
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* Must be called before a list is used! This initialises all the members
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* of the list structure and inserts the xListEnd item into the list as a
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* marker to the back of the list.
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*
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* @param pxList Pointer to the list being initialised.
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*
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* \page vListInitialise vListInitialise
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* \ingroup LinkedList
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*/
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void vListInitialise( List_t * const pxList );
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/*
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* Must be called before a list item is used. This sets the list container to
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* null so the item does not think that it is already contained in a list.
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*
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* @param pxItem Pointer to the list item being initialised.
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*
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* \page vListInitialiseItem vListInitialiseItem
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* \ingroup LinkedList
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*/
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void vListInitialiseItem( ListItem_t * const pxItem );
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/*
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* Insert a list item into a list. The item will be inserted into the list in
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* a position determined by its item value (descending item value order).
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*
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* @param pxList The list into which the item is to be inserted.
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*
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* @param pxNewListItem The item that is to be placed in the list.
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*
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* \page vListInsert vListInsert
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* \ingroup LinkedList
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*/
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void vListInsert( List_t * const pxList, ListItem_t * const pxNewListItem );
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/*
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* Insert a list item into a list. The item will be inserted in a position
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* such that it will be the last item within the list returned by multiple
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* calls to listGET_OWNER_OF_NEXT_ENTRY.
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*
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* The list member pvIndex is used to walk through a list. Calling
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* listGET_OWNER_OF_NEXT_ENTRY increments pvIndex to the next item in the list.
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* Placing an item in a list using vListInsertEnd effectively places the item
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* in the list position pointed to by pvIndex. This means that every other
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* item within the list will be returned by listGET_OWNER_OF_NEXT_ENTRY before
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* the pvIndex parameter again points to the item being inserted.
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*
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* @param pxList The list into which the item is to be inserted.
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*
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* @param pxNewListItem The list item to be inserted into the list.
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*
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* \page vListInsertEnd vListInsertEnd
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* \ingroup LinkedList
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*/
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void vListInsertEnd( List_t * const pxList, ListItem_t * const pxNewListItem );
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/*
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* Remove an item from a list. The list item has a pointer to the list that
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* it is in, so only the list item need be passed into the function.
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*
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* @param uxListRemove The item to be removed. The item will remove itself from
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* the list pointed to by it's pxContainer parameter.
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*
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* @return The number of items that remain in the list after the list item has
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* been removed.
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*
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* \page uxListRemove uxListRemove
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* \ingroup LinkedList
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*/
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UBaseType_t uxListRemove( ListItem_t * const pxItemToRemove );
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#ifdef __cplusplus
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}
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#endif
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#endif
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