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From: al davis <ad252 AT freeelectron DOT net>
To: geda-user AT delorie DOT com
Subject: Re: [geda-user] Wav to C array ~ 16 bit to 12 bit
Date: Sat, 29 Mar 2014 16:48:16 -0400
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On Saturday 29 March 2014, Stephen R. Besch wrote:
> On 03/29/2014 04:03 PM, al davis wrote:
> > On Saturday 29 March 2014, Stephen R. Besch wrote:
> >> realizing that I had forgotten
> >> about the sign bit it became clear that you cannot just
> >> toss the high  bits - you need to toss the low bits
> >> (essentially an integer divide by 16).
> > 
> > Usually if numbers are small enough, you can toss the high
> > bits.
> > 
> > "Usually" means the usual two's complement representation.
> 
> True enough as long as they are all positive. With signed
> data, you  really have no choice but division of some kind

True even with negative numbers, assuming the usual "two's 
complement" representation.  Even with other representations the 
conversion is usually simple.

If the number is "small enough" and positive, the high bits are 
all zero.  If negative, the high bits are all 1, and after 
tossing the high bits are still all 1.