LibrariesinsideAPI reference

Updated Mar 2025

FreeRTOS_GetUDPPayloadBuffer()

[FreeRTOS-Plus-TCP API Reference]

FreeRTOS_sockets.h

1void *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().