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FreeRTOS+TCP V2 is now included in the main FreeRTOS kernel download under the MIT license.

FreeRTOS_GetUDPPayloadBuffer()

[FreeRTOS+TCP API Reference]

FreeRTOS_sockets.h
void *FreeRTOS_GetUDPPayloadBuffer( size_t xRequestedSizeBytes, TickType_t xBlockTimeTicks );
		

Obtains a buffer from the TCP/IP stack for use with the zero copy interface.

The zero copy interface for transmitting data is described on the FreeRTOS_sendto() documentation page.

Parameters:

xRequestedSizeBytes   The size of the buffer being requested. The size is specified in bytes.

xBlockTimeTicks   The maximum time the calling RTOS task is prepared to wait for a buffer if one is not immediately available.

If a buffer is not available then the calling RTOS task will be held in the Blocked state (so other tasks can execute) until either a buffer becomes available or the block time expires.

The block time is specified in ticks. Milliseconds can be converted to ticks by dividing the time in milliseconds by portTICK_PERIOD_MS.

To prevent deadlocks the maximum block time is capped to ipconfigMAX_SEND_BLOCK_TIME_TICKS. ipconfigMAX_SEND_BLOCK_TIME_TICKS is defined in FreeRTOSIPConfig.h

Returns:

If a buffer was obtained then a pointer to the obtained buffer is returned.

If a buffer could not be obtained then NULL is returned.

Example usage:

The FreeRTOS_sendto() documentation page contains an example zero copy send operation that includes a call to FreeRTOS_GetUDPPayloadBuffer().


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