"integer operation result is out of range" warning? Can someone explain why?

I'm working on an embedded project for an ARM based microcontroller. In one function, I'm casting six 1-byte integers into two words with 0xFFFF to make up the empty space. The lines are below:

Code:

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report_addr[0] = (0xFFFF)<<16 | p_adv_report->peer_addr.addr[0]<<8 | p_adv_report->peer_addr.addr[1];

report_addr[1] = p_adv_report->peer_addr.addr[2]<<24 | p_adv_report->peer_addr.addr[3]<<16 | p_adv_report->peer_addr.addr[4]<<8 | p_adv_report->peer_addr.addr[5];

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report_addr is an array of uint32.
peer_addr.addr is an array of uint8.

My compilers is giving me this warning:
#61-D: integer operation result is out of range.

Seems like there's exactly two bytes of data fitting into a 2-byte word. Why is this spitting out a warning? I'd like the project to build without the warning, if possible.

What 'type' is 0xffff?? Therein lies he issue. Surprised you didn't work that out yourself.

Quote:

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Originally Posted by Hobbit

What 'type' is 0xffff?? Therein lies he issue. Surprised you didn't work that out yourself.

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I declared a uint16 variable with the hex value, then used that in the casting operation. Now, no warning.

Still learning... Thought I could simply provide the hex value rather than have to make a variable for it.

You simply needed to change 0xffff to 0xffffU.

The U tells the compiler that 0xffff is unsigned.

That worked, too. Thank you.