How to send through rapidIO ?

Hello,

I am trying to understand how to transmit with RapdIO.

I am using a reference design & document from here:

https://www.altera.co.jp/content/dam/altera-www/global/ja_jp/pdfs/literature/an/an568.pdf

https://www.altera.com/products/reference-designs/all-reference-designs/interface/ref-serial-rapidio-to-ti-6488-dsp.html

I don't understand how to send through RapidIO.

I see in reference code that the sending is done as following :

target_address = (pkt_id & 0x0000ffff) * (payload);

IOWR_32DIRECT(DMA_WRITE_BASE, 4, (int)tx_data);

IOWR_32DIRECT(DMA_WRITE_BASE, 8, (int)target_address);

IOWR_32DIRECT(DMA_WRITE_BASE, 12, payload); // page size length register in dma

IOWR_32DIRECT(DMA_WRITE_BASE, 24, 0x8); // go_bit=1, enable_soft_burst=0, continous mode=0

But I don't understand how these lines code should result in sending data through RapidIO to the other endpoint.

Thank you for any hint.

Ran