static void vUDPSendingUsingZeroCopyInterface( void *pvParameters )
{
Socket_t xSocket;
uint8_t *pucBuffer;
struct freertos_sockaddr xDestinationAddress;
BaseType_t lReturned;
uint32_t ulCount = 0UL;
const uint8_t *pucStringToSend = "Zero copy send message number ";
const TickType_t x1000ms = 1000UL / portTICK_PERIOD_MS; /* 15 is added to ensure the number, rn and terminating zero fit. */
const size_t xStringLength = strlen( ( char * ) pucStringToSend ) + 15;
/* Send strings to port 10000 on IP address 192.168.0.50. */
xDestinationAddress.sin_addr = FreeRTOS_inet_addr( "192.168.0.50" );
xDestinationAddress.sin_port = FreeRTOS_htons( 10000 );
/* Create the socket. */
xSocket = FreeRTOS_socket( FREERTOS_AF_INET,
FREERTOS_SOCK_DGRAM,/*FREERTOS_SOCK_DGRAM for UDP.*/
FREERTOS_IPPROTO_UDP );
/* Check the socket was created. */
configASSERT( xSocket != FREERTOS_INVALID_SOCKET );
/* NOTE: FreeRTOS_bind() is not called. This will only work if
ipconfigALLOW_SOCKET_SEND_WITHOUT_BIND is set to 1 in FreeRTOSIPConfig.h. */
for( ;; )
{ /* This RTOS task is going to send using the zero copy interface. The
data being sent is therefore written directly into a buffer that is
passed into, rather than copied into, the FreeRTOS_sendto()
function.
First obtain a buffer of adequate length from the TCP/IP stack into which
the string will be written. */
pucBuffer = FreeRTOS_GetUDPPayloadBuffer_Multi( xStringLength,
portMAX_DELAY,
ipTYPE_IPv4 );
/* Check a buffer was obtained. */
configASSERT( pucBuffer );
/* Create the string that is sent. */
memset( pucBuffer, 0x00, xStringLength );
sprintf( pucBuffer, "%s%lurn", ucStringToSend, ulCount );
/* Pass the buffer into the send function. ulFlags has the
FREERTOS_ZERO_COPY bit set so the TCP/IP stack will take control of the
buffer rather than copy data out of the buffer. */
lReturned = FreeRTOS_sendto( xSocket,
( void * ) pucBuffer,
strlen( ( const char * ) pucBuffer ) + 1,
FREERTOS_ZERO_COPY,
&xDestinationAddress,
sizeof( xDestinationAddress ) );
if( lReturned == 0 )
{ /* The send operation failed, so this RTOS task is still responsible
for the buffer obtained from the TCP/IP stack. To ensure the buffer
is not lost it must either be used again, or, as in this case,
returned to the TCP/IP stack using FreeRTOS_ReleaseUDPPayloadBuffer().
pucBuffer can be safely re-used after this call. */ FreeRTOS_ReleaseUDPPayloadBuffer( ( void * ) pucBuffer );
}
else
{ /* The send was successful so the TCP/IP stack is now managing the
buffer pointed to by pucBuffer, and the TCP/IP stack will
return the buffer once it has been sent. pucBuffer can
be safely re-used. */
}
ulCount++;
/* Wait until it is time to send again. */
vTaskDelay( x1000ms );
}
}
使用 FreeRTOS_sendto() 与零拷贝（和标准相反）调用语义的示例
IPv6 -
static void vUDPSendingUsingZeroCopyInterface( void *pvParameters )
{
Socket_t xSocket;
uint8_t *pucBuffer;
struct freertos_sockaddr xDestinationAddress;
BaseType_t lReturned;
uint32_t ulCount = 0UL;
const uint8_t *pucStringToSend = "Zero copy send message number ";
const TickType_t x1000ms = 1000UL / portTICK_PERIOD_MS; /* 15 is added to ensure the number, rn and terminating zero fit. */
const size_t xStringLength = strlen( ( char * ) pucStringToSend ) + 15;
/* Send strings to port 10000 on IP address 2001::1234. */
BaseType_t rc = FreeRTOS_inet_pton( FREERTOS_AF_INET6, "2001::1234", ( void * ) xDestinationAddress.sin_address.xIP_IPv6.ucBytes );
xDestinationAddress.sin_port = FreeRTOS_htons( 10000 );
xDestinationAddress.sin_family = FREERTOS_AF_INET6;
if( rc == pdPASS )
{ /* Create the socket. */
xSocket = FreeRTOS_socket( FREERTOS_AF_INET6,
FREERTOS_SOCK_DGRAM,/*FREERTOS_SOCK_DGRAM for UDP.*/
FREERTOS_IPPROTO_UDP );
/* Check the socket was created. */
configASSERT( xSocket != FREERTOS_INVALID_SOCKET );
/* NOTE: FreeRTOS_bind() is not called. This will only work if
ipconfigALLOW_SOCKET_SEND_WITHOUT_BIND is set to 1 in FreeRTOSIPConfig.h. */
for( ;; )
{ /* This RTOS task is going to send using the zero copy interface. The
data being sent is therefore written directly into a buffer that is
passed into, rather than copied into, the FreeRTOS_sendto()
function.
First obtain a buffer of adequate length from the TCP/IP stack into which
the string will be written. */
pucBuffer = FreeRTOS_GetUDPPayloadBuffer_Multi( xStringLength,
portMAX_DELAY,
ipTYPE_IPv6);
/* Check a buffer was obtained. */
configASSERT( pucBuffer );
/* Create the string that is sent. */
memset( pucBuffer, 0x00, xStringLength );
sprintf( pucBuffer, "%s%lurn", ucStringToSend, ulCount );
/* Pass the buffer into the send function. ulFlags has the
FREERTOS_ZERO_COPY bit set so the TCP/IP stack will take control of the
buffer rather than copy data out of the buffer. */
lReturned = FreeRTOS_sendto( xSocket,
( void * ) pucBuffer,
strlen( ( const char * ) pucBuffer ) + 1,
FREERTOS_ZERO_COPY,
&xDestinationAddress,
sizeof( xDestinationAddress ) );
if( lReturned == 0 )
{ /* The send operation failed, so this RTOS task is still responsible
for the buffer obtained from the TCP/IP stack. To ensure the buffer
is not lost it must either be used again, or, as in this case,
returned to the TCP/IP stack using FreeRTOS_ReleaseUDPPayloadBuffer().
pucBuffer can be safely re-used after this call. */
FreeRTOS_ReleaseUDPPayloadBuffer( ( void * ) pucBuffer );
}
else
{ /* The send was successful so the TCP/IP stack is now managing the
buffer pointed to by pucBuffer, and the TCP/IP stack will
return the buffer once it has been sent. pucBuffer can
be safely re-used. */
}
ulCount++;
/* Wait until it is time to send again. */
vTaskDelay( x1000ms );
}
}
}
