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[avr-chat] Type promotion and shift operators

From: Rick Mann
Subject: [avr-chat] Type promotion and shift operators
Date: Wed, 2 Feb 2011 03:26:59 -0800

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?


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