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/*
* FreeRTOS V202107.00
* Copyright (C) Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
* https://www.FreeRTOS.org
* https://github.com/FreeRTOS
*
*/
#include "proof/queue.h"
#include "proof/queuecontracts.h"
BaseType_t xQueuePeek( QueueHandle_t xQueue,
void * const pvBuffer,
TickType_t xTicksToWait )
/*@requires [1/2]queuehandle(xQueue, ?N, ?M, ?is_isr) &*& is_isr == false &*&
* [1/2]queuesuspend(xQueue) &*&
* chars(pvBuffer, M, ?x);@*/
/*@ensures [1/2]queuehandle(xQueue, N, M, is_isr) &*&
* [1/2]queuesuspend(xQueue) &*&
* (result == pdPASS ? chars(pvBuffer, M, _) : chars(pvBuffer, M, x));@*/
{
BaseType_t xEntryTimeSet = pdFALSE;
TimeOut_t xTimeOut;
int8_t * pcOriginalReadPosition;
#ifdef VERIFAST /*< const pointer declaration */
Queue_t * pxQueue = xQueue;
#else
Queue_t * const pxQueue = xQueue;
/* Check the pointer is not NULL. */
configASSERT( ( pxQueue ) );
/* The buffer into which data is received can only be NULL if the data size
* is zero (so no data is copied into the buffer. */
configASSERT( !( ( ( pvBuffer ) == NULL ) && ( ( pxQueue )->uxItemSize != ( UBaseType_t ) 0U ) ) );
/* Cannot block if the scheduler is suspended. */
#if ( ( INCLUDE_xTaskGetSchedulerState == 1 ) || ( configUSE_TIMERS == 1 ) )
{
configASSERT( !( ( xTaskGetSchedulerState() == taskSCHEDULER_SUSPENDED ) && ( xTicksToWait != 0 ) ) );
}
#endif
#endif /* ifdef VERIFAST */
/*lint -save -e904 This function relaxes the coding standard somewhat to
* allow return statements within the function itself. This is done in the
* interest of execution time efficiency. */
for( ; ; )
/*@invariant [1/2]queuehandle(xQueue, N, M, is_isr) &*&
* [1/2]queuesuspend(xQueue) &*&
* chars(pvBuffer, M, x) &*&
* u_integer(&xTicksToWait, _) &*&
* xTIME_OUT(&xTimeOut);@*/
{
taskENTER_CRITICAL();
/*@assert queue(pxQueue, ?Storage, N, M, ?W, ?R, ?K, ?is_locked, ?abs);@*/
{
const UBaseType_t uxMessagesWaiting = pxQueue->uxMessagesWaiting;
/* Is there data in the queue now? To be running the calling task
* must be the highest priority task wanting to access the queue. */
if( uxMessagesWaiting > ( UBaseType_t ) 0 )
{
/* Remember the read position so it can be reset after the data
* is read from the queue as this function is only peeking the
* data, not removing it. */
pcOriginalReadPosition = pxQueue->u.xQueue.pcReadFrom;
/*@close queue(pxQueue, Storage, N, M, W, R, K, is_locked, abs);@*/
prvCopyDataFromQueue( pxQueue, pvBuffer );
traceQUEUE_PEEK( pxQueue );
/* The data is not being removed, so reset the read pointer. */
pxQueue->u.xQueue.pcReadFrom = pcOriginalReadPosition;
/* The data is being left in the queue, so see if there are
* any other tasks waiting for the data. */
if( listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) == pdFALSE )
{
if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
{
/* The task waiting has a higher priority than this task. */
queueYIELD_IF_USING_PREEMPTION();
}
else
{
mtCOVERAGE_TEST_MARKER();
}
}
else
{
mtCOVERAGE_TEST_MARKER();
}
/*@close queue(pxQueue, Storage, N, M, W, R, K, is_locked, abs);@*/
taskEXIT_CRITICAL();
return pdPASS;
}
else
{
if( xTicksToWait == ( TickType_t ) 0 )
{
/* The queue was empty and no block time is specified (or
* the block time has expired) so leave now. */
/*@close queue(pxQueue, Storage, N, M, W, R, K, is_locked, abs);@*/
taskEXIT_CRITICAL();
traceQUEUE_PEEK_FAILED( pxQueue );
return errQUEUE_EMPTY;
}
else if( xEntryTimeSet == pdFALSE )
{
/* The queue was empty and a block time was specified so
* configure the timeout structure ready to enter the blocked
* state. */
vTaskInternalSetTimeOutState( &xTimeOut );
xEntryTimeSet = pdTRUE;
}
else
{
/* Entry time was already set. */
mtCOVERAGE_TEST_MARKER();
}
}
}
/*@close queue(pxQueue, Storage, N, M, W, R, K, is_locked, abs);@*/
taskEXIT_CRITICAL();
/* Interrupts and other tasks can send to and receive from the queue
* now the critical section has been exited. */
/*@close exists<QueueHandle_t>(pxQueue);@*/
vTaskSuspendAll();
prvLockQueue( pxQueue );
/* Update the timeout state to see if it has expired yet. */
if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )
{
/* Timeout has not expired yet, check to see if there is data in the
* queue now, and if not enter the Blocked state to wait for data. */
if( prvIsQueueEmpty( pxQueue ) != pdFALSE )
{
traceBLOCKING_ON_QUEUE_PEEK( pxQueue );
/*@open queue_locked_invariant(xQueue)();@*/
vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToReceive ), xTicksToWait );
/*@close queue_locked_invariant(xQueue)();@*/
prvUnlockQueue( pxQueue );
/*@close exists<QueueHandle_t>(pxQueue);@*/
if( xTaskResumeAll() == pdFALSE )
{
portYIELD_WITHIN_API();
}
else
{
mtCOVERAGE_TEST_MARKER();
}
}
else
{
/* There is data in the queue now, so don't enter the blocked
* state, instead return to try and obtain the data. */
prvUnlockQueue( pxQueue );
#ifdef VERIFAST /*< void cast of unused return value */
/*@close exists<QueueHandle_t>(pxQueue);@*/
xTaskResumeAll();
#else
( void ) xTaskResumeAll();
#endif
}
}
else
{
/* The timeout has expired. If there is still no data in the queue
* exit, otherwise go back and try to read the data again. */
prvUnlockQueue( pxQueue );
#ifdef VERIFAST /*< void cast of unused return value */
/*@close exists<QueueHandle_t>(pxQueue);@*/
xTaskResumeAll();
#else
( void ) xTaskResumeAll();
#endif
if( prvIsQueueEmpty( pxQueue ) != pdFALSE )
{
traceQUEUE_PEEK_FAILED( pxQueue );
return errQUEUE_EMPTY;
}
else
{
mtCOVERAGE_TEST_MARKER();
}
}
} /*lint -restore */
}
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