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/*********************************************************************
* @fn osal_msg_receive
*
* @brief
*
* This function is called by a task to retrieve a received command
* message. The calling task must deallocate the message buffer after
* processing the message using the osal_msg_deallocate() call.
*
* @param uint8 task_id - receiving tasks ID
*
* @return *uint8 - message information or NULL if no message
*/
uint8 *osal_msg_receive( uint8 task_id )
{
osal_msg_hdr_t *listHdr;
osal_msg_hdr_t *prevHdr = NULL;
osal_msg_hdr_t *foundHdr = NULL;
halIntState_t intState;
// Hold off interrupts
HAL_ENTER_CRITICAL_SECTION(intState);
// Point to the top of the queue
listHdr = osal_qHead;
// Look through the queue for a message that belongs to the asking task
while ( listHdr != NULL )
{
if ( (listHdr - 1)->dest_id == task_id )
{
if ( foundHdr == NULL )
{
// Save the first one
foundHdr = listHdr;
}
else
{
// Second msg found, stop looking
break;
}
}
if ( foundHdr == NULL )
{
prevHdr = listHdr;
}
listHdr = OSAL_MSG_NEXT( listHdr );
}
// Is there more than one?
if ( listHdr != NULL )
{
// Yes, Signal the task that a message is waiting
osal_set_event( task_id, SYS_EVENT_MSG );
}
else
{
// No more
osal_clear_event( task_id, SYS_EVENT_MSG );
}
// Did we find a message?
if ( foundHdr != NULL )
{
// Take out of the link list
osal_msg_extract( &osal_qHead, foundHdr, prevHdr );
}
// Release interrupts
HAL_EXIT_CRITICAL_SECTION(intState);
return ( (uint8*) foundHdr );
}
