[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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

From: Michael Hennebry
Subject: Re: [avr-chat] Type promotion and shift operators
Date: Wed, 2 Feb 2011 10:15:40 -0600 (CST)
User-agent: Alpine 1.00 (DEB 882 2007-12-20)

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."

reply via email to

[Prev in Thread] Current Thread [Next in Thread]