RE: Assign an array to an ESB Payload ?

Steve Jordi — Tue, 13 Feb 2024 06:15:10 GMT

Hi Mike

Thanks for this reminder and solution. It's exactly what I need.
And guess what, I already used that in a C++ app back in... 1999. I was a bit rusted (no pun intended with Rust).

I knew it was something like that but was struggling with the data[4] offset for the 2nd value. I worked around using a string but avoid unless conversions back and forth is always slimmer, faster and nicer.

Perfect, you made my day.

Steve

RE: Assign an array to an ESB Payload ?

Mike Thompson — Tue, 13 Feb 2024 02:26:11 GMT

Hi Steve, the payload data is itself an array of unsigned 8-bit values (uint8_t). There are many ways to do what you describe, but one way would be to dereference the array elements as pointers to 32-bit values and assign them directly.

It might look something as follows (putty the values into variables is optional).

uint32_t num1 = 301;
uint32_t num2 = 257;
*((uint32_t *) &tx_payload.data[0]) = num1;
*((uint32_t *) &tx_payload.data[4]) = num2;
tx_payload.length = sizeof(uint32_t) * 2;

Then on the receiving side, do the opposite dereference the values from the received payload data.

uint32_t num1, num2;
num1 = *((uint32_t *) &rx_payload.data[0]);
num2 = *((uint32_t *) &rx_payload.data[4]);

You will probably want to familiarize yourself with how C handles pointers into arrays and type conversion. It's quite a bit different than other languages that you may be more familiar with.

Mike