If I understand correctly you are clocking in all bit 7's followed by all bit
6's down to all bit 0's

Try the following:

        acc = 0

        for (int j=0; j<8; j++)
        {        acc = (acc << 1) + count_one_bits(read_port())
        }

count_one_bits() could be implemented as a lookup table

Sorry I don't have time to convert this to assembler.

Regards
Sergio Masci


----- Original Message -----
From: Ishaan Dalal <izx@XIZX.NET>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Thursday, June 26, 2003 4:23 AM
Subject: Re: [PIC]: 8-byte vertical adder?


> > I have no idea what you mean by "vertically stacked data".  Data is in
> > RAM.  Left, right, up, and down orientations are rather meaningless.
>
> For example, for bytes A...H
>
> 0x0020    LSB_A    LSB_B    LSB_C    LSB_D    .....    LSB_H
> 0x0021    ..
> 0x0022    ..
> 0x0023    ..
> 0x0024    ...
> 0x0025    ..
> 0x0026    ..
> 0x0027    MSB_A    MSB_B    MSB_C    MSB_D    ....    MSB_H
>
> > You have 8 bytes of data you want to add, so just add them.  The PIC can
> > do an 8 bit add in one instruction.  What's the problem?
>
>     Scott suggested the standard store vertically and then rotate each into
> 8 different registers (thanks for the complete workthrough!). There wouldn't
> be enough time on the "momma PIC" end to process these before the next round
> of bitstreams started pouring in. I'll probably look at lowering my sample
> rate -- then this might work.
>
> Cheers,
> Ishaan
>
> --
> http://www.piclist.com hint: To leave the PICList
> mailto:piclist-unsubscribe-request@mitvma.mit.edu

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