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Re: [avr-gcc-list] Re: AVR byte swap optimization

From: Shaun Jackman
Subject: Re: [avr-gcc-list] Re: AVR byte swap optimization
Date: Mon, 18 Dec 2006 15:05:19 -0700

On 12/18/06, David VanHorn <address@hidden> wrote:
Am I missing something here?
Why not pop to assembler, push the high, push the low, pop the high, pop the

* Inline assembler cannot be used at compile time, for example to
initialize a static variable.

* If the swap function is called on a constant, the compiler cannot
remove the inline assembler. In general, any inline assembler tends to
handcuff the optimizer to some degree.

* Push and pop take two cycles since they access memory. Three mov
instructions are faster than one push and one pop.


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