Do you have a math library of some sort to do 10.6 arithmetic?

For example, a 1/2 scale left justified A/D reading would be

1000 0000 00.00 0000
and 1/16 would be
0000 0000 00.00 0100
The desired result is 0000 1000 00.00 0000
Doing a binary multiply would result in a value of 0.
On the other hand, a 1/2 scale right justified A/D reading would be
0000 0010 00.00 0000
And doing a binary multiply by 1/16 would result in a value of
0000 1000 00.00 0000
which is correct.

Please pardon my ignorance, I'm here to learn.  Is 10.6 arithmetic=20
something that everybody but me uses?  Is it an assembly language=20
thing?  I use a C compiler almost exclusively.

Kerry


Olin Lathrop wrote:
> Kerry Wentworth wrote:
>  =20
>> My Filt is the Total (or your Filt) right justified and truncated (or
>> rounded) to 10 bits, to give a filtered A/D between 0 and 1023.
>>    =20
>
> Yes.
>
>  =20
>> This step is optional, if one wanted the 14 bit number, one could
>> skip the conversion.
>>    =20
>
> No, not with your algorithm, since it requires your FILT in a previous st=
ep.
>
> It is optional in the normal method that I described.  You can convert to
> the original integer scale when you want, but are not forced to do so eac=
h
> iteration.  More likely, you adjust the scale factors in the rest of the
> system so no conversion is ever required.  Usually the A/D values are in
> some arbitrary scale, so having values in that scale times 2**N is no
> different in that it's just as arbitrary.
>
>  =20
>> And your FF(NEW - FILT) is really (NEW - FILT) / FF.
>> Is this correct?
>>    =20
>
> Clearly not if FF can take on values other than 1, which of course it can=
..
> As I said before, useful values for FF are between 0 and 1.  For easy
> implementation on small systems, FF =3D 2**-N since the multiply by FF th=
en
> becomes a right shift by N.
>
>
> ********************************************************************
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> (978) 742-9014.  Gold level PIC consultants since 2000.
>  =20



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