Re: [avr-chat] Type promotion and shift operators

[Michael Hennebry]

On Wed, 2 Feb 2011, Rick Mann wrote:

> I was working with some uint32_t variables, using shifts, like this:
>
> uint32_t foo = 0;
>
> for (...)
> {
>    uint32_t v = // some value between [0, 31)
>
>    foo |= 1 << v;
> }
>
> This didn't work correctly for values of v greater than 15 until I changed the 
> line to:
>
>    foo |= 1UL << v;
>
> From what I understand of C, it should've promoted 1 to long, but maybe it's a 
> signed-vs-unsigned issue? What's happening on an ATmega644A with this code?

'Twas a quiet change.
the type of x<<y is now the type of x after the usual integer promotions.

--
Michael   address@hidden
"Pessimist: The glass is half empty.
Optimist:   The glass is half full.
Engineer:   The glass is twice as big as it needs to be."