/*
 * FreeRTOS V202111.00
 * 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 xQueuePeekFromISR( QueueHandle_t xQueue,
                              void * const pvBuffer )

/*@requires [1/2]queuehandle(xQueue, ?N, ?M, ?is_isr) &*& is_isr == true &*&
 *  chars(pvBuffer, M, ?x);@*/

/*@ensures [1/2]queuehandle(xQueue, N, M, is_isr) &*&
 *  (result == pdPASS ? chars(pvBuffer, M, _) : chars(pvBuffer, M, x));@*/
{
    BaseType_t xReturn;
    UBaseType_t uxSavedInterruptStatus;
    int8_t * pcOriginalReadPosition;

    #ifdef VERIFAST /*< const pointer declaration */
        Queue_t * pxQueue = xQueue;
    #else
        Queue_t * const pxQueue = xQueue;

        configASSERT( pxQueue );
        configASSERT( !( ( pvBuffer == NULL ) && ( pxQueue->uxItemSize != ( UBaseType_t ) 0U ) ) );
        configASSERT( pxQueue->uxItemSize != 0 ); /* Can't peek a semaphore. */
    #endif

    /* RTOS ports that support interrupt nesting have the concept of a maximum
     * system call (or maximum API call) interrupt priority.  Interrupts that are
     * above the maximum system call priority are kept permanently enabled, even
     * when the RTOS kernel is in a critical section, but cannot make any calls to
     * FreeRTOS API functions.  If configASSERT() is defined in FreeRTOSConfig.h
     * then portASSERT_IF_INTERRUPT_PRIORITY_INVALID() will result in an assertion
     * failure if a FreeRTOS API function is called from an interrupt that has been
     * assigned a priority above the configured maximum system call priority.
     * Only FreeRTOS functions that end in FromISR can be called from interrupts
     * that have been assigned a priority at or (logically) below the maximum
     * system call interrupt priority.  FreeRTOS maintains a separate interrupt
     * safe API to ensure interrupt entry is as fast and as simple as possible.
     * More information (albeit Cortex-M specific) is provided on the following
     * link: https://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html */
    portASSERT_IF_INTERRUPT_PRIORITY_INVALID();

    uxSavedInterruptStatus = portSET_INTERRUPT_MASK_FROM_ISR();
    /*@assert queue(pxQueue, ?Storage, N, M, ?W, ?R, ?K, ?is_locked, ?abs);@*/
    {
        /* Cannot block in an ISR, so check there is data available. */
        if( pxQueue->uxMessagesWaiting > ( UBaseType_t ) 0 )
        {
            traceQUEUE_PEEK_FROM_ISR( pxQueue );

            /* Remember the read position so it can be reset as nothing is
             * actually being removed from the queue. */
            pcOriginalReadPosition = pxQueue->u.xQueue.pcReadFrom;
            /*@close queue(pxQueue, Storage, N, M, W, R, K, is_locked, abs);@*/
            prvCopyDataFromQueue( pxQueue, pvBuffer );
            pxQueue->u.xQueue.pcReadFrom = pcOriginalReadPosition;
            /*@close queue(pxQueue, Storage, N, M, W, R, K, is_locked, abs);@*/

            xReturn = pdPASS;
        }
        else
        {
            xReturn = pdFAIL;
            traceQUEUE_PEEK_FROM_ISR_FAILED( pxQueue );
        }
    }
    /*@close queue(pxQueue, Storage, N, M, W, R, K, is_locked, abs);@*/
    portCLEAR_INTERRUPT_MASK_FROM_ISR( uxSavedInterruptStatus );

    return xReturn;
}