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From: kenton@abyss.zk3.dec.com (Jeff Kenton OSG/UEG)
Newsgroups: comp.sys.m88k
Subject: Re: Big Endian vs. Little Endian register pairs
Message-ID: <1991May1.124502.28414@decvax.dec.com>
Date: 1 May 91 12:45:02 GMT
References: <1991Apr30.185908.16474@eagle.lerc.nasa.gov> <1991Apr30.215621.25387@oakhill.sps.mot.com> <1991May1.120003.13827@eagle.lerc.nasa.gov>
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In article <1991May1.120003.13827@eagle.lerc.nasa.gov>,
fsset@bach.lerc.nasa.gov (Scott E. Townsend) writes:

|> 
|> Well, I was looking at some compiler output and found it often doing
|> something like this for a small double-precision constant:
|> 
|> 	or.u	r4,r0,hi16(constant upper half)
|> 	or	r5,r0,r0
|> 	fadd.ddd r6,r6,r4
|> 
|> This was to implement things like x += 3.0.  Now if the 'endianness' of 
|> register pairs was reversed, an equivalent scheme would be:
|> 
|> 	or.u	r1,r0,hi16(constant upper half)
|> 	fadd.ddd r7,r7,r1
|> 
|> Thus saving a cycle.

Or, you could put the upper word of the constant into r31 :-) :-) :-) and
use r31 and r0 for your double precision constant.

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==	jeff kenton		Consulting at kenton@decvax.dec.com        ==
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