472 lines
16 KiB
C
472 lines
16 KiB
C
/*
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FreeRTOS.org V4.1.0 - Copyright (C) 2003-2006 Richard Barry.
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This file is part of the FreeRTOS.org distribution.
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FreeRTOS.org is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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FreeRTOS.org is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with FreeRTOS.org; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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A special exception to the GPL can be applied should you wish to distribute
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a combined work that includes FreeRTOS.org, without being obliged to provide
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the source code for any proprietary components. See the licensing section
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of http://www.FreeRTOS.org for full details of how and when the exception
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can be applied.
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***************************************************************************
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See http://www.FreeRTOS.org for documentation, latest information, license
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and contact details. Please ensure to read the configuration and relevant
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port sections of the online documentation.
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***************************************************************************
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*/
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#ifndef QUEUE_H
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#define QUEUE_H
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typedef void * xQueueHandle;
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/**
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* queue. h
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* <pre>
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xQueueHandle xQueueCreate(
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unsigned portBASE_TYPE uxQueueLength,
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unsigned portBASE_TYPE uxItemSize
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);
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* </pre>
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*
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* Creates a new queue instance. This allocates the storage required by the
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* new queue and returns a handle for the queue.
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*
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* @param uxQueueLength The maximum number of items that the queue can contain.
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*
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* @param uxItemSize The number of bytes each item in the queue will require.
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* Items are queued by copy, not by reference, so this is the number of bytes
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* that will be copied for each posted item. Each item on the queue must be
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* the same size.
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*
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* @return If the queue is successfully create then a handle to the newly
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* created queue is returned. If the queue cannot be created then 0 is
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* returned.
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*
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* Example usage:
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<pre>
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struct AMessage
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{
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portCHAR ucMessageID;
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portCHAR ucData[ 20 ];
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};
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void vATask( void *pvParameters )
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{
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xQueueHandle xQueue1, xQueue2;
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// Create a queue capable of containing 10 unsigned long values.
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xQueue1 = xQueueCreate( 10, sizeof( unsigned portLONG ) );
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if( xQueue1 == 0 )
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{
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// Queue was not created and must not be used.
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}
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// Create a queue capable of containing 10 pointers to AMessage structures.
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// These should be passed by pointer as they contain a lot of data.
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xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) );
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if( xQueue2 == 0 )
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{
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// Queue was not created and must not be used.
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}
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// ... Rest of task code.
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}
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</pre>
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* \defgroup xQueueCreate xQueueCreate
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* \ingroup QueueManagement
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*/
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xQueueHandle xQueueCreate( unsigned portBASE_TYPE uxQueueLength, unsigned portBASE_TYPE uxItemSize );
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/**
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* queue. h
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* <pre>
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portBASE_TYPE xQueueSend(
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xQueueHandle xQueue,
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const void * pvItemToQueue,
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portTickType xTicksToWait
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);
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* </pre>
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*
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* Post an item on a queue. The item is queued by copy, not by reference.
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* This function must not be called from an interrupt service routine.
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* See xQueueSendFromISR () for an alternative which may be used in an ISR.
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*
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* @param xQueue The handle to the queue on which the item is to be posted.
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*
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* @param pvItemToQueue A pointer to the item that is to be placed on the
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* queue. The size of the items the queue will hold was defined when the
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* queue was created, so this many bytes will be copied from pvItemToQueue
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* into the queue storage area.
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*
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* @param xTicksToWait The maximum amount of time the task should block
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* waiting for space to become available on the queue, should it already
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* be full. The call will return immediately if this is set to 0. The
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* time is defined in tick periods so the constant portTICK_RATE_MS
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* should be used to convert to real time if this is required.
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*
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* @return pdTRUE if the item was successfully posted, otherwise errQUEUE_FULL.
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*
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* Example usage:
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<pre>
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struct AMessage
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{
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portCHAR ucMessageID;
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portCHAR ucData[ 20 ];
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} xMessage;
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unsigned portLONG ulVar = 10UL;
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void vATask( void *pvParameters )
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{
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xQueueHandle xQueue1, xQueue2;
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struct AMessage *pxMessage;
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// Create a queue capable of containing 10 unsigned long values.
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xQueue1 = xQueueCreate( 10, sizeof( unsigned portLONG ) );
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// Create a queue capable of containing 10 pointers to AMessage structures.
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// These should be passed by pointer as they contain a lot of data.
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xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) );
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// ...
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if( xQueue1 != 0 )
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{
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// Send an unsigned long. Wait for 10 ticks for space to become
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// available if necessary.
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if( xQueueSend( xQueue1, ( void * ) &ulVar, ( portTickType ) 10 ) != pdPASS )
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{
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// Failed to post the message, even after 10 ticks.
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}
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}
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if( xQueue2 != 0 )
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{
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// Send a pointer to a struct AMessage object. Don't block if the
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// queue is already full.
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pxMessage = & xMessage;
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xQueueSend( xQueue2, ( void * ) &pxMessage, ( portTickType ) 0 );
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}
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// ... Rest of task code.
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}
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</pre>
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* \defgroup xQueueSend xQueueSend
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* \ingroup QueueManagement
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*/
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signed portBASE_TYPE xQueueSend( xQueueHandle xQueue, const void * pvItemToQueue, portTickType xTicksToWait );
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/**
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* queue. h
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* <pre>
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portBASE_TYPE xQueueReceive(
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xQueueHandle xQueue,
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void *pvBuffer,
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portTickType xTicksToWait
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);</pre>
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*
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* Receive an item from a queue. The item is received by copy so a buffer of
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* adequate size must be provided. The number of bytes copied into the buffer
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* was defined when the queue was created.
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*
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* This function must not be used in an interrupt service routine. See
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* xQueueReceiveFromISR for an alternative that can.
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*
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* @param pxQueue The handle to the queue from which the item is to be
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* received.
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*
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* @param pvBuffer Pointer to the buffer into which the received item will
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* be copied.
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*
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* @param xTicksToWait The maximum amount of time the task should block
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* waiting for an item to receive should the queue be empty at the time
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* of the call. The time is defined in tick periods so the constant
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* portTICK_RATE_MS should be used to convert to real time if this is required.
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*
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* @return pdTRUE if an item was successfully received from the queue,
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* otherwise pdFALSE.
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*
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* Example usage:
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<pre>
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struct AMessage
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{
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portCHAR ucMessageID;
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portCHAR ucData[ 20 ];
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} xMessage;
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xQueueHandle xQueue;
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// Task to create a queue and post a value.
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void vATask( void *pvParameters )
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{
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struct AMessage *pxMessage;
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// Create a queue capable of containing 10 pointers to AMessage structures.
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// These should be passed by pointer as they contain a lot of data.
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xQueue = xQueueCreate( 10, sizeof( struct AMessage * ) );
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if( xQueue == 0 )
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{
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// Failed to create the queue.
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}
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// ...
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// Send a pointer to a struct AMessage object. Don't block if the
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// queue is already full.
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pxMessage = & xMessage;
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xQueueSend( xQueue, ( void * ) &pxMessage, ( portTickType ) 0 );
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// ... Rest of task code.
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}
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// Task to receive from the queue.
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void vADifferentTask( void *pvParameters )
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{
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struct AMessage *pxRxedMessage;
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if( xQueue != 0 )
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{
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// Receive a message on the created queue. Block for 10 ticks if a
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// message is not immediately available.
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if( xQueueReceive( xQueue, &( pxRxedMessage ), ( portTickType ) 10 ) )
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{
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// pcRxedMessage now points to the struct AMessage variable posted
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// by vATask.
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}
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}
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// ... Rest of task code.
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}
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</pre>
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* \defgroup xQueueReceive xQueueReceive
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* \ingroup QueueManagement
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*/
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signed portBASE_TYPE xQueueReceive( xQueueHandle xQueue, void *pvBuffer, portTickType xTicksToWait );
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/**
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* queue. h
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* <pre>unsigned portBASE_TYPE uxQueueMessagesWaiting( xQueueHandle xQueue );</pre>
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*
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* Return the number of messages stored in a queue.
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*
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* @param xQueue A handle to the queue being queried.
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*
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* @return The number of messages available in the queue.
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*
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* \page uxQueueMessagesWaiting uxQueueMessagesWaiting
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* \ingroup QueueManagement
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*/
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unsigned portBASE_TYPE uxQueueMessagesWaiting( xQueueHandle xQueue );
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/**
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* queue. h
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* <pre>void vQueueDelete( xQueueHandle xQueue );</pre>
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*
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* Delete a queue - freeing all the memory allocated for storing of items
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* placed on the queue.
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*
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* @param xQueue A handle to the queue to be deleted.
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*
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* \page vQueueDelete vQueueDelete
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* \ingroup QueueManagement
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*/
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void vQueueDelete( xQueueHandle xQueue );
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/**
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* queue. h
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* <pre>
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portBASE_TYPE xQueueSendFromISR(
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xQueueHandle pxQueue,
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const void *pvItemToQueue,
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portBASE_TYPE xTaskPreviouslyWoken
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);
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</pre>
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*
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* Post an item on a queue. It is safe to use this function from within an
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* interrupt service routine.
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*
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* Items are queued by copy not reference so it is preferable to only
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* queue small items, especially when called from an ISR. In most cases
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* it would be preferable to store a pointer to the item being queued.
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*
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* @param xQueue The handle to the queue on which the item is to be posted.
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*
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* @param pvItemToQueue A pointer to the item that is to be placed on the
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* queue. The size of the items the queue will hold was defined when the
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* queue was created, so this many bytes will be copied from pvItemToQueue
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* into the queue storage area.
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*
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* @param cTaskPreviouslyWoken This is included so an ISR can post onto
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* the same queue multiple times from a single interrupt. The first call
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* should always pass in pdFALSE. Subsequent calls should pass in
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* the value returned from the previous call. See the file serial .c in the
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* PC port for a good example of this mechanism.
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*
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* @return pdTRUE if a task was woken by posting onto the queue. This is
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* used by the ISR to determine if a context switch may be required following
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* the ISR.
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*
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* Example usage for buffered IO (where the ISR can obtain more than one value
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* per call):
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<pre>
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void vBufferISR( void )
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{
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portCHAR cIn;
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portBASE_TYPE xTaskWokenByPost;
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// We have not woken a task at the start of the ISR.
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cTaskWokenByPost = pdFALSE;
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// Loop until the buffer is empty.
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do
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{
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// Obtain a byte from the buffer.
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cIn = portINPUT_BYTE( RX_REGISTER_ADDRESS );
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// Post the byte. The first time round the loop cTaskWokenByPost
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// will be pdFALSE. If the queue send causes a task to wake we do
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// not want the task to run until we have finished the ISR, so
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// xQueueSendFromISR does not cause a context switch. Also we
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// don't want subsequent posts to wake any other tasks, so we store
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// the return value back into cTaskWokenByPost so xQueueSendFromISR
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// knows not to wake any task the next iteration of the loop.
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xTaskWokenByPost = xQueueSendFromISR( xRxQueue, &cIn, cTaskWokenByPost );
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} while( portINPUT_BYTE( BUFFER_COUNT ) );
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// Now the buffer is empty we can switch context if necessary.
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if( cTaskWokenByPost )
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{
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taskYIELD ();
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}
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}
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</pre>
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*
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* \defgroup xQueueSendFromISR xQueueSendFromISR
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* \ingroup QueueManagement
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*/
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signed portBASE_TYPE xQueueSendFromISR( xQueueHandle pxQueue, const void *pvItemToQueue, signed portBASE_TYPE xTaskPreviouslyWoken );
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/**
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* queue. h
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* <pre>
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portBASE_TYPE xQueueReceiveFromISR(
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xQueueHandle pxQueue,
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void *pvBuffer,
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portBASE_TYPE *pxTaskWoken
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);
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* </pre>
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*
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* Receive an item from a queue. It is safe to use this function from within an
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* interrupt service routine.
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*
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* @param pxQueue The handle to the queue from which the item is to be
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* received.
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*
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* @param pvBuffer Pointer to the buffer into which the received item will
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* be copied.
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*
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* @param pxTaskWoken A task may be blocked waiting for space to become
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* available on the queue. If xQueueReceiveFromISR causes such a task to
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* unblock *pxTaskWoken will get set to pdTRUE, otherwise *pxTaskWoken will
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* remain unchanged.
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*
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* @return pdTRUE if an item was successfully received from the queue,
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* otherwise pdFALSE.
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*
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* Example usage:
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<pre>
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xQueueHandle xQueue;
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// Function to create a queue and post some values.
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void vAFunction( void *pvParameters )
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{
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portCHAR cValueToPost;
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const portTickType xBlockTime = ( portTickType )0xff;
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// Create a queue capable of containing 10 characters.
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xQueue = xQueueCreate( 10, sizeof( portCHAR ) );
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if( xQueue == 0 )
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{
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// Failed to create the queue.
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}
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// ...
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// Post some characters that will be used within an ISR. If the queue
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// is full then this task will block for xBlockTime ticks.
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cValueToPost = 'a';
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xQueueSend( xQueue, ( void * ) &cValueToPost, xBlockTime );
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cValueToPost = 'b';
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xQueueSend( xQueue, ( void * ) &cValueToPost, xBlockTime );
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// ... keep posting characters ... this task may block when the queue
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// becomes full.
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cValueToPost = 'c';
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xQueueSend( xQueue, ( void * ) &cValueToPost, xBlockTime );
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}
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// ISR that outputs all the characters received on the queue.
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void vISR_Routine( void )
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{
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portBASE_TYPE xTaskWokenByReceive = pdFALSE;
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portCHAR cRxedChar;
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while( xQueueReceiveFromISR( xQueue, ( void * ) &cRxedChar, &xTaskWokenByReceive) )
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{
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// A character was received. Output the character now.
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vOutputCharacter( cRxedChar );
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// If removing the character from the queue woke the task that was
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// posting onto the queue cTaskWokenByReceive will have been set to
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// pdTRUE. No matter how many times this loop iterates only one
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// task will be woken.
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}
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if( cTaskWokenByPost != ( portCHAR ) pdFALSE;
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{
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taskYIELD ();
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}
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}
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</pre>
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* \defgroup xQueueReceiveFromISR xQueueReceiveFromISR
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* \ingroup QueueManagement
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*/
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signed portBASE_TYPE xQueueReceiveFromISR( xQueueHandle pxQueue, void *pvBuffer, signed portBASE_TYPE *pxTaskWoken );
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/*
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* The functions defined above are for passing data to and from tasks. The
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* functions below are the equivalents for passing data to and from
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* co-rtoutines.
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*
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* These functions are called from the co-routine macro implementation and
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* should not be called directly from application code. Instead use the macro
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* wrappers defined within croutine.h.
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*/
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signed portBASE_TYPE xQueueCRSendFromISR( xQueueHandle pxQueue, const void *pvItemToQueue, signed portBASE_TYPE xCoRoutinePreviouslyWoken );
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signed portBASE_TYPE xQueueCRReceiveFromISR( xQueueHandle pxQueue, void *pvBuffer, signed portBASE_TYPE *pxTaskWoken );
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signed portBASE_TYPE xQueueCRSend( xQueueHandle pxQueue, const void *pvItemToQueue, portTickType xTicksToWait );
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signed portBASE_TYPE xQueueCRReceive( xQueueHandle pxQueue, void *pvBuffer, portTickType xTicksToWait );
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#endif
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