Question

该程序应打印Fibonacci系列的前50个数字。但只有前47个打印正确，后三个打印不正确。

 /*FreeRTOS.org includes.*/
#include "FreeRTOS.h"
#include "task.h"
#include "queue.h"
#include "stdint.h"
#include "basic_io.h"

static void vSenderTask( void *pvParameters );
static void vReceiverTask( void *pvParameters );
int long resultado;

xQueueHandle xQueue;

int main( void )
{
    xQueue = xQueueCreate( 10, sizeof( long ) );

    if( xQueue != NULL )
    {
        xTaskCreate( vSenderTask, "Sender1", 240, ( long * ) resultado, 2, NULL );
        xTaskCreate( vReceiverTask, "Receiver", 240, ( long * ) resultado, 1, NULL );
        vTaskStartScheduler();
    }
    else
    {
    }
    for( ;; );
    return 0;
}

/*---------------------------------------------------------------------------------------------*/

static void vSenderTask( void *pvParameters )
{
    portBASE_TYPE xStatus;
    const portTickType xTicksToWait = 1000 / portTICK_RATE_MS;
    long s =1;
    long r=0;
    int  k=1;
    uint64_t resultado;
    resultado = ( long ) pvParameters;
    for ( ;; ){
        for (k; k<=61; k++) {
            resultado= s+r;
            s=r;
            r=resultado;

            xStatus = xQueueSendToBack( xQueue, &resultado, xTicksToWait );
        }
        if( xStatus != pdPASS )
        {
            vPrintString( "Could not send to the queue.\n" );
        }
    }
}

/*---------------------------------------------------------------------------------------------*/

static void vReceiverTask( void *pvParameters )
{
    uint64_t resultado;
    portBASE_TYPE xStatus;

    for( ;; )
    {
        if( uxQueueMessagesWaiting( xQueue ) != 10 )
        {
            vPrintString( "Queue should have been full!\n" );
        }

        xStatus = xQueueReceive( xQueue, &resultado , 0 );
        if( xStatus == pdPASS )
        {
            vPrintStringAndNumber( "Received = ", resultado );
        }
        else
        {
            vPrintString( "Could not receive from the queue.\r\n" );
        }
    }
}

/*---------------------------------------------------------------------------------------------*/
void vApplicationMallocFailedHook( void )
{
    /* This function will only be called if an API call to create a task, queue
    or semaphore fails because there is too little heap RAM remaining. */
    for( ;; );
}
/*-----------------------------------------------------------*/

void vApplicationStackOverflowHook( xTaskHandle *pxTask, signed char *pcTaskName )
{
    /*This function will only be called if a task overflows its stack.  Note
    that stack overflow checking does slow down the context switch
    implementation. */
    for( ;; );
}
/*-----------------------------------------------------------*/

void vApplicationIdleHook( void )
{
    /* This example does not use the idle hook to perform any processing. */
}
/*-----------------------------------------------------------*/

void vApplicationTickHook( void )
{
    /* This example does not use the tick hook to perform any processing. */
}

输出结果为：

Received =  1
Received =  1
Received =  2
Received =  3
Received =  5
Received =  8
Received =  13
Received =  21
Received =  34
Received =  55
Received =  89
Received =  144
Received =  233
Received =  377
Received =  610
Received =  987
Received =  1597
Received =  2584
Received =  4181
Received =  6765
Received =  10946
Received =  17711
Received =  28657
Received =  46368
Received =  75025
Received =  121393
Received =  196418
Received =  317811
Received =  514229
Received =  832040
Received =  1346269
Received =  2178309
Received =  3524578
Received =  5702887
Received =  9227465
Received =  14930352
Received =  24157817
Received =  39088169
Received =  63245986
Received =  102334155
Received =  165580141
Received =  267914296
Received =  433494437
Received =  701408733
Received =  1134903170
Received =  1836311903
Received =  2971215073
Received =  512559680
Received =  3483774753
Received =  3996334433

Answer 1

在您的系统上，long为32位。它可以容纳的最大正整数是4294967295。但1836311903 + 2971215073 = 4807526976，这是更大，所以它溢出，你得到512559680（这是4807526976 - 4294967296）。如果你想要超过第47个Fibonacci数，你需要更大的数据类型或进行多精度算术。

斐波纳契系列错误

1 个答案: