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Re: [avr-chat] Missed Optimisation ?

From: Graham Davies
Subject: Re: [avr-chat] Missed Optimisation ?
Date: Tue, 01 Mar 2011 06:56:53 -0500 
bob wrote:



... The code is very simple (runs in Port Change interrupt):

   if ((PINA & _BV(A2DDATA)) != 0)
result |= 0x80000000;

   result >>= 1;
How is result declared? Are you using the volatile qualifier? If so, that would explain why the compiler feels obliged to load and store the entire 32 bits. 

Graham.
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