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[avr-gcc-list] movw and asm


From: James Dabbs
Subject: [avr-gcc-list] movw and asm
Date: Tue, 5 Aug 2003 16:14:08 -0400

I am interested in using the movw instruction in inline assembler.  I am
working on several 32-bit values as "r" parameters, but right now I have no
way of knowing whether %a0,%b0,%c0,%d0 is aligned in any way on register
boundaries or whether they are organized sequentially or what.  Using movw
could save me about 10% performance and I am down to counting cycles on a
16-mhz part.

Any "assemble time" or "compile time" test to figure out whether the
compiler has placed these values on lucky boundaries would work.  Also, if
the compiler has conventions about where these things are located, that
could work too.  I have found nothing on the net.

Any help would be greatly appreciated!


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