使用 TCP 套接字发送数据
FreeRTOS-Plus-TCP 网络教程节选

void vTCPSend( char *pcBufferToTransmit, const size_t xTotalLengthToSend )

{

Socket_t xSocket;

struct freertos_sockaddr xRemoteAddress;

BaseType_t xAlreadyTransmitted = 0, xBytesSent = 0;

TaskHandle_t xRxTask = NULL;

size_t xLenToSend;



    /* Set the IP address (192.168.0.200) and port (1500) of the remote socket


    to which this client socket will transmit. */

    xRemoteAddress.sin_port = FreeRTOS_htons( 1500 );

    xRemoteAddress.sin_addr = FreeRTOS_inet_addr_quick( 192, 168, 0, 200 );



    /* Create a socket. */

    xSocket = FreeRTOS_socket( FREERTOS_AF_INET,

                               FREERTOS_SOCK_STREAM, /* FREERTOS_SOCK_STREAM for TCP. */

                               FREERTOS_IPPROTO_TCP );

    configASSERT( xSocket != FREERTOS_INVALID_SOCKET );



    /* Connect to the remote socket.  The socket has not previously been bound to


       a local port number so will get automatically bound to a local port inside


       the FreeRTOS_connect() function. */

    if( FreeRTOS_connect( xSocket, &xRemoteAddress, sizeof( xRemoteAddress ) ) == 0 )

    {

        /* Keep sending until the entire buffer has been sent. */

        while( xAlreadyTransmitted < xTotalLengthToSend )

        {

            /* How many bytes are left to send? */

            xLenToSend = xTotalLengthToSend - xAlreadyTransmitted;

            xBytesSent = FreeRTOS_send( /* The socket being sent to. */

                                        xSocket,

                                        /* The data being sent. */

                                        &( pcBufferToTransmit[ xAlreadyTransmitted ] ),

                                        /* The remaining length of data to send. */

                                        xLenToSend,

                                        /* ulFlags. */

                                        0 );



            if( xBytesSent >= 0 )

            {

                /* Data was sent successfully. */

                xAlreadyTransmitted += xBytesSent;

            }

            else

            {

                /* Error - break out of the loop for graceful socket close. */

                break;

            }

        }

    }



    /* Initiate graceful shutdown. */

    FreeRTOS_shutdown( xSocket, FREERTOS_SHUT_RDWR );



    /* Wait for the socket to disconnect gracefully (indicated by FreeRTOS_recv()


       returning a -pdFREERTOS_ERRNO_EINVAL error) before closing the socket. */

    while( FreeRTOS_recv( xSocket, pcBufferToTransmit, xTotalLengthToSend, 0 ) >= 0 )

    {

        /* Wait for shutdown to complete.  If a receive block time is used then


           this delay will not be necessary as FreeRTOS_recv() will place the RTOS task


           into the Blocked state anyway. */

        vTaskDelay( pdTICKS_TO_MS( 250 ) );



        /* Note - real applications should implement a timeout here, not just


        loop forever. */

    }



    /* The socket has shut down and is safe to close. */

    FreeRTOS_closesocket( xSocket );

}

void vTCPSend( char *pcBufferToTransmit, const size_t xTotalLengthToSend )

{

Socket_t xSocket;

struct freertos_sockaddr xRemoteAddress;

BaseType_t xAlreadyTransmitted = 0, xBytesSent = 0;

TaskHandle_t xRxTask = NULL;

size_t xLenToSend;



    /* Set the IP address (2001:470:ed44::9c08:38cc:599f:f62a) and port (1500) of the remote socket


       to which this client socket will transmit. */

    xRemoteAddress.sin_port = FreeRTOS_htons( 1500 );

    FreeRTOS_inet_pton6( "2001:470:ed44::9c08:38cc:599f:f62a", (void *) xRemoteAddress.sin_address.xIP_IPv6.ucBytes )



    /* Create a socket. */

    xSocket = FreeRTOS_socket( FREERTOS_AF_INET6,

                               FREERTOS_SOCK_STREAM, /* FREERTOS_SOCK_STREAM for TCP. */

                               FREERTOS_IPPROTO_TCP );

    configASSERT( xSocket != FREERTOS_INVALID_SOCKET );



    /* Connect to the remote socket.  The socket has not previously been bound to


       a local port number so will get automatically bound to a local port inside


       the FreeRTOS_connect() function. */

    if( FreeRTOS_connect( xSocket, &xRemoteAddress, sizeof( xRemoteAddress ) ) == 0 )

    {

        /* Keep sending until the entire buffer has been sent. */

        while( xAlreadyTransmitted < xTotalLengthToSend )

        {

            /* How many bytes are left to send? */

            xLenToSend = xTotalLengthToSend - xAlreadyTransmitted;

            xBytesSent = FreeRTOS_send( /* The socket being sent to. */

                                        xSocket,

                                        /* The data being sent. */

                                        &( pcBufferToTransmit[ xAlreadyTransmitted ] ),

                                        /* The remaining length of data to send. */

                                        xLenToSend,

                                        /* ulFlags. */

                                        0 );



            if( xBytesSent >= 0 )

            {

                /* Data was sent successfully. */

                xAlreadyTransmitted += xBytesSent;

            }

            else

            {

                /* Error - break out of the loop for graceful socket close. */

                break;

            }

        }

    }



    /* Initiate graceful shutdown. */

    FreeRTOS_shutdown( xSocket, FREERTOS_SHUT_RDWR );



    /* Wait for the socket to disconnect gracefully (indicated by FreeRTOS_recv()


       returning a -pdFREERTOS_ERRNO_EINVAL error) before closing the socket. */

    while( FreeRTOS_recv( xSocket, pcBufferToTransmit, xTotalLengthToSend, 0 ) >= 0 )

    {

        /* Wait for shutdown to complete.  If a receive block time is used then


           this delay will not be necessary as FreeRTOS_recv() will place the RTOS task


           into the Blocked state anyway. */

        vTaskDelay( pdTICKS_TO_MS( 250 ) );



        /* Note - real applications should implement a timeout here, not just


           loop forever. */

    }



    /* The socket has shut down and is safe to close. */

    FreeRTOS_closesocket( xSocket );

}