On Feb 2, 2011, at 08:15:40, Michael Hennebry wrote:
> 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.
So, it looks like this?
foo = (int) ((long) 1 << v)
BTW, love the .sig!
--
Rick
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