text: /***************************************************************************//**
   * # License
   * 
   * The licensor of this software is Silicon Laboratories Inc. Your use of this
   * software is governed by the terms of Silicon Labs Master Software License
   * Agreement (MSLA) available at
   * www.silabs.com/about-us/legal/master-software-license-agreement. This
   * software is Third Party Software licensed by Silicon Labs from a third party
   * and is governed by the sections of the MSLA applicable to Third Party
   * Software and the additional terms set forth below.
   * 
   ******************************************************************************/
  
  /*
      FreeRTOS V9.0.0 - Copyright (C) 2016 Real Time Engineers Ltd.
      All rights reserved
  
      VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
  
      This file is part of the FreeRTOS distribution.
  
      FreeRTOS is free software; you can redistribute it and/or modify it under
      the terms of the GNU General Public License (version 2) as published by the
      Free Software Foundation >>>> AND MODIFIED BY <<<< the FreeRTOS exception.
  
      ***************************************************************************
      >>!   NOTE: The modification to the GPL is included to allow you to     !<<
      >>!   distribute a combined work that includes FreeRTOS without being   !<<
      >>!   obliged to provide the source code for proprietary components     !<<
      >>!   outside of the FreeRTOS kernel.                                   !<<
      ***************************************************************************
  
      FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
      WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
      FOR A PARTICULAR PURPOSE.  Full license text is available on the following
      link: http://www.freertos.org/a00114.html
  
      ***************************************************************************
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  */
  
  #ifndef CO_ROUTINE_H
  #define CO_ROUTINE_H
  
  #ifndef INC_FREERTOS_H
  	#error "include FreeRTOS.h must appear in source files before include croutine.h"
  #endif
  
  #include "list.h"
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /* Used to hide the implementation of the co-routine control block.  The
  control block structure however has to be included in the header due to
  the macro implementation of the co-routine functionality. */
  typedef void * CoRoutineHandle_t;
  
  /* Defines the prototype to which co-routine functions must conform. */
  typedef void (*crCOROUTINE_CODE)( CoRoutineHandle_t, UBaseType_t );
  
  typedef struct corCoRoutineControlBlock
  {
  	crCOROUTINE_CODE 	pxCoRoutineFunction;
  	ListItem_t			xGenericListItem;	/*< List item used to place the CRCB in ready and blocked queues. */
  	ListItem_t			xEventListItem;		/*< List item used to place the CRCB in event lists. */
  	UBaseType_t 		uxPriority;			/*< The priority of the co-routine in relation to other co-routines. */
  	UBaseType_t 		uxIndex;			/*< Used to distinguish between co-routines when multiple co-routines use the same co-routine function. */
  	uint16_t 			uxState;			/*< Used internally by the co-routine implementation. */
  } CRCB_t; /* Co-routine control block.  Note must be identical in size down to uxPriority with TCB_t. */
  
  /**
   * croutine. h
   *<pre>
   BaseType_t xCoRoutineCreate(
                                   crCOROUTINE_CODE pxCoRoutineCode,
                                   UBaseType_t uxPriority,
                                   UBaseType_t uxIndex
                                 );</pre>
   *
   * Create a new co-routine and add it to the list of co-routines that are
   * ready to run.
   *
   * @param pxCoRoutineCode Pointer to the co-routine function.  Co-routine
   * functions require special syntax - see the co-routine section of the WEB
   * documentation for more information.
   *
   * @param uxPriority The priority with respect to other co-routines at which
   *  the co-routine will run.
   *
   * @param uxIndex Used to distinguish between different co-routines that
   * execute the same function.  See the example below and the co-routine section
   * of the WEB documentation for further information.
   *
   * @return pdPASS if the co-routine was successfully created and added to a ready
   * list, otherwise an error code defined with ProjDefs.h.
   *
   * Example usage:
     <pre>
   // Co-routine to be created.
   void vFlashCoRoutine( CoRoutineHandle_t xHandle, UBaseType_t uxIndex )
   {
   // Variables in co-routines must be declared static if they must maintain value across a blocking call.
   // This may not be necessary for const variables.
   static const char cLedToFlash[ 2 ] = { 5, 6 };
   static const TickType_t uxFlashRates[ 2 ] = { 200, 400 };
  
       // Must start every co-routine with a call to crSTART();
       crSTART( xHandle );
  
       for( ;; )
       {
           // This co-routine just delays for a fixed period, then toggles
           // an LED.  Two co-routines are created using this function, so
           // the uxIndex parameter is used to tell the co-routine which
           // LED to flash and how int32_t to delay.  This assumes xQueue has
           // already been created.
           vParTestToggleLED( cLedToFlash[ uxIndex ] );
           crDELAY( xHandle, uxFlashRates[ uxIndex ] );
       }
  
       // Must end every co-routine with a call to crEND();
       crEND();
   }
  
   // Function that creates two co-routines.
   void vOtherFunction( void )
   {
   uint8_t ucParameterToPass;
   TaskHandle_t xHandle;
  
       // Create two co-routines at priority 0.  The first is given index 0
       // so (from the code above) toggles LED 5 every 200 ticks.  The second
       // is given index 1 so toggles LED 6 every 400 ticks.
       for( uxIndex = 0; uxIndex < 2; uxIndex++ )
       {
           xCoRoutineCreate( vFlashCoRoutine, 0, uxIndex );
       }
   }
     </pre>
   * \defgroup xCoRoutineCreate xCoRoutineCreate
   * \ingroup Tasks
   */
  BaseType_t xCoRoutineCreate( crCOROUTINE_CODE pxCoRoutineCode, UBaseType_t uxPriority, UBaseType_t uxIndex );
  
  
  /**
   * croutine. h
   *<pre>
   void vCoRoutineSchedule( void );</pre>
   *
   * Run a co-routine.
   *
   * vCoRoutineSchedule() executes the highest priority co-routine that is able
   * to run.  The co-routine will execute until it either blocks, yields or is
   * preempted by a task.  Co-routines execute cooperatively so one
   * co-routine cannot be preempted by another, but can be preempted by a task.
   *
   * If an application comprises of both tasks and co-routines then
   * vCoRoutineSchedule should be called from the idle task (in an idle task
   * hook).
   *
   * Example usage:
     <pre>
   // This idle task hook will schedule a co-routine each time it is called.
   // The rest of the idle task will execute between co-routine calls.
   void vApplicationIdleHook( void )
   {
  	vCoRoutineSchedule();
   }
  
   // Alternatively, if you do not require any other part of the idle task to
   // execute, the idle task hook can call vCoRoutineScheduler() within an
   // infinite loop.
   void vApplicationIdleHook( void )
   {
      for( ;; )
      {
          vCoRoutineSchedule();
      }
   }
   </pre>
   * \defgroup vCoRoutineSchedule vCoRoutineSchedule
   * \ingroup Tasks
   */
  void vCoRoutineSchedule( void );
  
  /**
   * croutine. h
   * <pre>
   crSTART( CoRoutineHandle_t xHandle );</pre>
   *
   * This macro MUST always be called at the start of a co-routine function.
   *
   * Example usage:
     <pre>
   // Co-routine to be created.
   void vACoRoutine( CoRoutineHandle_t xHandle, UBaseType_t uxIndex )
   {
   // Variables in co-routines must be declared static if they must maintain value across a blocking call.
   static int32_t ulAVariable;
  
       // Must start every co-routine with a call to crSTART();
       crSTART( xHandle );
  
       for( ;; )
       {
            // Co-routine functionality goes here.
       }
  
       // Must end every co-routine with a call to crEND();
       crEND();
   }</pre>
   * \defgroup crSTART crSTART
   * \ingroup Tasks
   */
  #define crSTART( pxCRCB ) switch( ( ( CRCB_t * )( pxCRCB ) )->uxState ) { case 0:
  
  /**
   * croutine. h
   * <pre>
   crEND();</pre>
   *
   * This macro MUST always be called at the end of a co-routine function.
   *
   * Example usage:
     <pre>
   // Co-routine to be created.
   void vACoRoutine( CoRoutineHandle_t xHandle, UBaseType_t uxIndex )
   {
   // Variables in co-routines must be declared static if they must maintain value across a blocking call.
   static int32_t ulAVariable;
  
       // Must start every co-routine with a call to crSTART();
       crSTART( xHandle );
  
       for( ;; )
       {
            // Co-routine functionality goes here.
       }
  
       // Must end every co-routine with a call to crEND();
       crEND();
   }</pre>
   * \defgroup crSTART crSTART
   * \ingroup Tasks
   */
  #define crEND() }
  
  /*
   * These macros are intended for internal use by the co-routine implementation
   * only.  The macros should not be used directly by application writers.
   */
  #define crSET_STATE0( xHandle ) ( ( CRCB_t * )( xHandle ) )->uxState = (__LINE__ * 2); return; case (__LINE__ * 2):
  #define crSET_STATE1( xHandle ) ( ( CRCB_t * )( xHandle ) )->uxState = ((__LINE__ * 2)+1); return; case ((__LINE__ * 2)+1):
  
  /**
   * croutine. h
   *<pre>
   crDELAY( CoRoutineHandle_t xHandle, TickType_t xTicksToDelay );</pre>
   *
   * Delay a co-routine for a fixed period of time.
   *
   * crDELAY can only be called from the co-routine function itself - not
   * from within a function called by the co-routine function.  This is because
   * co-routines do not maintain their own stack.
   *
   * @param xHandle The handle of the co-routine to delay.  This is the xHandle
   * parameter of the co-routine function.
   *
   * @param xTickToDelay The number of ticks that the co-routine should delay
   * for.  The actual amount of time this equates to is defined by
   * configTICK_RATE_HZ (set in FreeRTOSConfig.h).  The constant portTICK_PERIOD_MS
   * can be used to convert ticks to milliseconds.
   *
   * Example usage:
     <pre>
   // Co-routine to be created.
   void vACoRoutine( CoRoutineHandle_t xHandle, UBaseType_t uxIndex )
   {
   // Variables in co-routines must be declared static if they must maintain value across a blocking call.
   // This may not be necessary for const variables.
   // We are to delay for 200ms.
   static const xTickType xDelayTime = 200 / portTICK_PERIOD_MS;
  
       // Must start every co-routine with a call to crSTART();
       crSTART( xHandle );
  
       for( ;; )
       {
          // Delay for 200ms.
          crDELAY( xHandle, xDelayTime );
  
          // Do something here.
       }
  
       // Must end every co-routine with a call to crEND();
       crEND();
   }</pre>
   * \defgroup crDELAY crDELAY
   * \ingroup Tasks
   */
  #define crDELAY( xHandle, xTicksToDelay )												\
  	if( ( xTicksToDelay ) > 0 )															\
  	{																					\
  		vCoRoutineAddToDelayedList( ( xTicksToDelay ), NULL );							\
  	}																					\
  	crSET_STATE0( ( xHandle ) );
  
  /**
   * <pre>
   crQUEUE_SEND(
                    CoRoutineHandle_t xHandle,
                    QueueHandle_t pxQueue,
                    void *pvItemToQueue,
                    TickType_t xTicksToWait,
                    BaseType_t *pxResult
               )</pre>
   *
   * The macro's crQUEUE_SEND() and crQUEUE_RECEIVE() are the co-routine
   * equivalent to the xQueueSend() and xQueueReceive() functions used by tasks.
   *
   * crQUEUE_SEND and crQUEUE_RECEIVE can only be used from a co-routine whereas
   * xQueueSend() and xQueueReceive() can only be used from tasks.
   *
   * crQUEUE_SEND can only be called from the co-routine function itself - not
   * from within a function called by the co-routine function.  This is because
   * co-routines do not maintain their own stack.
   *
   * See the co-routine section of the WEB documentation for information on
   * passing data between tasks and co-routines and between ISR's and
   * co-routines.
   *
   * @param xHandle The handle of the calling co-routine.  This is the xHandle
   * parameter of the co-routine function.
   *
   * @param pxQueue The handle of the queue on which the data will be posted.
   * The handle is obtained as the return value when the queue is created using
   * the xQueueCreate() API function.
   *
   * @param pvItemToQueue A pointer to the data being posted onto the queue.
   * The number of bytes of each queued item is specified when the queue is
   * created.  This number of bytes is copied from pvItemToQueue into the queue
   * itself.
   *
   * @param xTickToDelay The number of ticks that the co-routine should block
   * to wait for space to become available on the queue, should space not be
   * available immediately. The actual amount of time this equates to is defined
   * by configTICK_RATE_HZ (set in FreeRTOSConfig.h).  The constant
   * portTICK_PERIOD_MS can be used to convert ticks to milliseconds (see example
   * below).
   *
   * @param pxResult The variable pointed to by pxResult will be set to pdPASS if
   * data was successfully posted onto the queue, otherwise it will be set to an
   * error defined within ProjDefs.h.
   *
   * Example usage:
     <pre>
   // Co-routine function that blocks for a fixed period then posts a number onto
   // a queue.
   static void prvCoRoutineFlashTask( CoRoutineHandle_t xHandle, UBaseType_t uxIndex )
   {
   // Variables in co-routines must be declared static if they must maintain value across a blocking call.
   static BaseType_t xNumberToPost = 0;
   static BaseType_t xResult;
  
      // Co-routines must begin with a call to crSTART().
      crSTART( xHandle );
  
      for( ;; )
      {
          // This assumes the queue has already been created.
          crQUEUE_SEND( xHandle, xCoRoutineQueue, &xNumberToPost, NO_DELAY, &xResult );
  
          if( xResult != pdPASS )
          {
              // The message was not posted!
          }
  
          // Increment the number to be posted onto the queue.
          xNumberToPost++;
  
          // Delay for 100 ticks.
          crDELAY( xHandle, 100 );
      }
  
      // Co-routines must end with a call to crEND().
      crEND();
   }</pre>
   * \defgroup crQUEUE_SEND crQUEUE_SEND
   * \ingroup Tasks
   */
  #define crQUEUE_SEND( xHandle, pxQueue, pvItemToQueue, xTicksToWait, pxResult )			\
  {																						\
  	*( pxResult ) = xQueueCRSend( ( pxQueue) , ( pvItemToQueue) , ( xTicksToWait ) );	\
  	if( *( pxResult ) == errQUEUE_BLOCKED )												\
  	{																					\
  		crSET_STATE0( ( xHandle ) );													\
  		*pxResult = xQueueCRSend( ( pxQueue ), ( pvItemToQueue ), 0 );					\
  	}																					\
  	if( *pxResult == errQUEUE_YIELD )													\
  	{																					\
  		crSET_STATE1( ( xHandle ) );													\
  		*pxResult = pdPASS;																\
  	}																					\
  }
  
  /**
   * croutine. h
   * <pre>
    crQUEUE_RECEIVE(
                       CoRoutineHandle_t xHandle,
                       QueueHandle_t pxQueue,
                       void *pvBuffer,
                       TickType_t xTicksToWait,
                       BaseType_t *pxResult
                   )</pre>
   *
   * The macro's crQUEUE_SEND() and crQUEUE_RECEIVE() are the co-routine
   * equivalent to the xQueueSend() and xQueueReceive() functions used by tasks.
   *
   * crQUEUE_SEND and crQUEUE_RECEIVE can only be used from a co-routine whereas
   * xQueueSend() and xQueueReceive() can only be used from tasks.
   *
   * crQUEUE_RECEIVE can only be called from the co-routine function itself - not
   * from within a function called by the co-routine function.  This is because
   * co-routines do not maintain their own stack.
   *
   * See the co-routine section of the WEB documentation for information on
   * passing data between tasks and co-routines and between ISR's and
   * co-routines.
   *
   * @param xHandle The handle of the calling co-routine.  This is the xHandle
   * parameter of the co-routine function.
   *
   * @param pxQueue The handle of the queue from which the data will be received.
   * The handle is obtained as the return value when the queue is created using
   * the xQueueCreate() API function.
   *
   * @param pvBuffer The buffer into which the received item is to be copied.
   * The number of bytes of each queued item is specified when the queue is
   * created.  This number of bytes is copied into pvBuffer.
   *
   * @param xTickToDelay The number of ticks that the co-routine should block
   * to wait for data to become available from the queue, should data not be
   * available immediately. The actual amount of time this equates to is defined
   * by configTICK_RATE_HZ (set in FreeRTOSConfig.h).  The constant
   * portTICK_PERIOD_MS can be used to convert ticks to milliseconds (see the
   * crQUEUE_SEND example).
   *
   * @param pxResult The variable pointed to by pxResult will be set to pdPASS if
   * data was successfully retrieved from the queue, otherwise it will be set to
   * an error code as defined within ProjDefs.h.
   *
   * Example usage:
   <pre>
   // A co-routine receives the number of an LED to flash from a queue.  It
   // blocks on the queue until the number is received.
   static void prvCoRoutineFlashWorkTask( CoRoutineHandle_t xHandle, UBaseType_t uxIndex )
   {
   // Variables in co-routines must be declared static if they must maintain value across a blocking call.
   static BaseType_t xResult;
   static UBaseType_t uxLEDToFlash;
  
      // All co-routines must start with a call to crSTART().
      crSTART( xHandle );
  
      for( ;; )
      {
          // Wait for data to become available on the queue.
          crQUEUE_RECEIVE( xHandle, xCoRoutineQueue, &uxLEDToFlash, portMAX_DELAY, &xResult );
  
          if( xResult == pdPASS )
          {
              // We received the LED to flash - flash it!
              vParTestToggleLED( uxLEDToFlash );
          }
      }
  
      crEND();
   }</pre>
   * \defgroup crQUEUE_RECEIVE crQUEUE_RECEIVE
   * \ingroup Tasks
   */
  #define crQUEUE_RECEIVE( xHandle, pxQueue, pvBuffer, xTicksToWait, pxResult )			\
  {																						\
  	*( pxResult ) = xQueueCRReceive( ( pxQueue) , ( pvBuffer ), ( xTicksToWait ) );		\
  	if( *( pxResult ) == errQUEUE_BLOCKED ) 											\
  	{																					\
  		crSET_STATE0( ( xHandle ) );													\
  		*( pxResult ) = xQueueCRReceive( ( pxQueue) , ( pvBuffer ), 0 );				\
  	}																					\
  	if( *( pxResult ) == errQUEUE_YIELD )												\
  	{																					\
  		crSET_STATE1( ( xHandle ) );													\
  		*( pxResult ) = pdPASS;															\
  	}																					\
  }
  
  /**
   * croutine. h
   * <pre>
    crQUEUE_SEND_FROM_ISR(
                              QueueHandle_t pxQueue,
                              void *pvItemToQueue,
                              BaseType_t xCoRoutinePreviouslyWoken
                         )</pre>
   *
   * The macro's crQUEUE_SEND_FROM_ISR() and crQUEUE_RECEIVE_FROM_ISR() are the
   * co-routine equivalent to the xQueueSendFromISR() and xQueueReceiveFromISR()
   * functions used by tasks.
   *
   * crQUEUE_SEND_FROM_ISR() and crQUEUE_RECEIVE_FROM_ISR() can only be used to
   * pass data between a co-routine and and ISR, whereas xQueueSendFromISR() and
   * xQueueReceiveFromISR() can only be used to pass data between a task and and
   * ISR.
   *
   * crQUEUE_SEND_FROM_ISR can only be called from an ISR to send data to a queue
   * that is being used from within a co-routine.
   *
   * See the co-routine section of the WEB documentation for information on
   * passing data between tasks and co-routines and between ISR's and
   * co-routines.
   *
   * @param xQueue The handle to the queue on which the item is to be posted.
   *
   * @param pvItemToQueue A pointer to the item that is to be placed on the
   * queue.  The size of the items the queue will hold was defined when the
   * queue was created, so this many bytes will be copied from pvItemToQueue
   * into the queue storage area.
   *
   * @param xCoRoutinePreviouslyWoken This is included so an ISR can post onto
   * the same queue multiple times from a single interrupt.  The first call
   * should always pass in pdFALSE.  Subsequent calls should pass in
   * the value returned from the previous call.
   *
   * @return pdTRUE if a co-routine was woken by posting onto the queue.  This is
   * used by the ISR to determine if a context switch may be required following
   * the ISR.
   *
   * Example usage:
   <pre>
   // A co-routine that blocks on a queue waiting for characters to be received.
   static void vReceivingCoRoutine( CoRoutineHandle_t xHandle, UBaseType_t uxIndex )
   {
   char cRxedChar;
   BaseType_t xResult;
  
       // All co-routines must start with a call to crSTART().
       crSTART( xHandle );
  
       for( ;; )
       {
           // Wait for data to become available on the queue.  This assumes the
           // queue xCommsRxQueue has already been created!
           crQUEUE_RECEIVE( xHandle, xCommsRxQueue, &uxLEDToFlash, portMAX_DELAY, &xResult );
  
           // Was a character received?
           if( xResult == pdPASS )
           {
               // Process the character here.
           }
       }
  
       // All co-routines must end with a call to crEND().
       crEND();
   }
  
   // An ISR that uses a queue to send characters received on a serial port to
   // a co-routine.
   void vUART_ISR( void )
   {
   char cRxedChar;
   BaseType_t xCRWokenByPost = pdFALSE;
  
       // We loop around reading characters until there are none left in the UART.
       while( UART_RX_REG_NOT_EMPTY() )
       {
           // Obtain the character from the UART.
           cRxedChar = UART_RX_REG;
  
           // Post the character onto a queue.  xCRWokenByPost will be pdFALSE
           // the first time around the loop.  If the post causes a co-routine
           // to be woken (unblocked) then xCRWokenByPost will be set to pdTRUE.
           // In this manner we can ensure that if more than one co-routine is
           // blocked on the queue only one is woken by this ISR no matter how
           // many characters are posted to the queue.
           xCRWokenByPost = crQUEUE_SEND_FROM_ISR( xCommsRxQueue, &cRxedChar, xCRWokenByPost );
       }
   }</pre>
   * \defgroup crQUEUE_SEND_FROM_ISR crQUEUE_SEND_FROM_ISR
   * \ingroup Tasks
   */
  #define crQUEUE_SEND_FROM_ISR( pxQueue, pvItemToQueue, xCoRoutinePreviouslyWoken ) xQueueCRSendFromISR( ( pxQueue ), ( pvItemToQueue ), ( xCoRoutinePreviouslyWoken ) )
  
  
  /**
   * croutine. h
   * <pre>
    crQUEUE_SEND_FROM_ISR(
                              QueueHandle_t pxQueue,
                              void *pvBuffer,
                              BaseType_t * pxCoRoutineWoken
                         )</pre>
   *
   * The macro's crQUEUE_SEND_FROM_ISR() and crQUEUE_RECEIVE_FROM_ISR() are the
   * co-routine equivalent to the xQueueSendFromISR() and xQueueReceiveFromISR()
   * functions used by tasks.
   *
   * crQUEUE_SEND_FROM_ISR() and crQUEUE_RECEIVE_FROM_ISR() can only be used to
   * pass data between a co-routine and and ISR, whereas xQueueSendFromISR() and
   * xQueueReceiveFromISR() can only be used to pass data between a task and and
   * ISR.
   *
   * crQUEUE_RECEIVE_FROM_ISR can only be called from an ISR to receive data
   * from a queue that is being used from within a co-routine (a co-routine
   * posted to the queue).
   *
   * See the co-routine section of the WEB documentation for information on
   * passing data between tasks and co-routines and between ISR's and
   * co-routines.
   *
   * @param xQueue The handle to the queue on which the item is to be posted.
   *
   * @param pvBuffer A pointer to a buffer into which the received item will be
   * placed.  The size of the items the queue will hold was defined when the
   * queue was created, so this many bytes will be copied from the queue into
   * pvBuffer.
   *
   * @param pxCoRoutineWoken A co-routine may be blocked waiting for space to become
   * available on the queue.  If crQUEUE_RECEIVE_FROM_ISR causes such a
   * co-routine to unblock *pxCoRoutineWoken will get set to pdTRUE, otherwise
   * *pxCoRoutineWoken will remain unchanged.
   *
   * @return pdTRUE an item was successfully received from the queue, otherwise
   * pdFALSE.
   *
   * Example usage:
   <pre>
   // A co-routine that posts a character to a queue then blocks for a fixed
   // period.  The character is incremented each time.
   static void vSendingCoRoutine( CoRoutineHandle_t xHandle, UBaseType_t uxIndex )
   {
   // cChar holds its value while this co-routine is blocked and must therefore
   // be declared static.
   static char cCharToTx = 'a';
   BaseType_t xResult;
  
       // All co-routines must start with a call to crSTART().
       crSTART( xHandle );
  
       for( ;; )
       {
           // Send the next character to the queue.
           crQUEUE_SEND( xHandle, xCoRoutineQueue, &cCharToTx, NO_DELAY, &xResult );
  
           if( xResult == pdPASS )
           {
               // The character was successfully posted to the queue.
           }
  		 else
  		 {
  			// Could not post the character to the queue.
  		 }
  
           // Enable the UART Tx interrupt to cause an interrupt in this
  		 // hypothetical UART.  The interrupt will obtain the character
  		 // from the queue and send it.
  		 ENABLE_RX_INTERRUPT();
  
  		 // Increment to the next character then block for a fixed period.
  		 // cCharToTx will maintain its value across the delay as it is
  		 // declared static.
  		 cCharToTx++;
  		 if( cCharToTx > 'x' )
  		 {
  			cCharToTx = 'a';
  		 }
  		 crDELAY( 100 );
       }
  
       // All co-routines must end with a call to crEND().
       crEND();
   }
  
   // An ISR that uses a queue to receive characters to send on a UART.
   void vUART_ISR( void )
   {
   char cCharToTx;
   BaseType_t xCRWokenByPost = pdFALSE;
  
       while( UART_TX_REG_EMPTY() )
       {
           // Are there any characters in the queue waiting to be sent?
  		 // xCRWokenByPost will automatically be set to pdTRUE if a co-routine
  		 // is woken by the post - ensuring that only a single co-routine is
  		 // woken no matter how many times we go around this loop.
           if( crQUEUE_RECEIVE_FROM_ISR( pxQueue, &cCharToTx, &xCRWokenByPost ) )
  		 {
  			 SEND_CHARACTER( cCharToTx );
  		 }
       }
   }</pre>
   * \defgroup crQUEUE_RECEIVE_FROM_ISR crQUEUE_RECEIVE_FROM_ISR
   * \ingroup Tasks
   */
  #define crQUEUE_RECEIVE_FROM_ISR( pxQueue, pvBuffer, pxCoRoutineWoken ) xQueueCRReceiveFromISR( ( pxQueue ), ( pvBuffer ), ( pxCoRoutineWoken ) )
  
  /*
   * This function is intended for internal use by the co-routine macros only.
   * The macro nature of the co-routine implementation requires that the
   * prototype appears here.  The function should not be used by application
   * writers.
   *
   * Removes the current co-routine from its ready list and places it in the
   * appropriate delayed list.
   */
  void vCoRoutineAddToDelayedList( TickType_t xTicksToDelay, List_t *pxEventList );
  
  /*
   * This function is intended for internal use by the queue implementation only.
   * The function should not be used by application writers.
   *
   * Removes the highest priority co-routine from the event list and places it in
   * the pending ready list.
   */
  BaseType_t xCoRoutineRemoveFromEventList( const List_t *pxEventList );
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* CO_ROUTINE_H */
  