| Author |
Message |
Woody Brison
Guest
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 Posted:
Thu Dec 01, 2005 1:35 am Post subject:
Re: How to count zeros in registers? |
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Jim Thompson wrote:
| Quote: | On 29 Nov 2005 06:12:56 -0800, "Davy" <zhushenli@gmail.com> wrote:
Hi all,
reg[7:0] register;
The register contains data like
[0 0 0 1 0 1 0 1]
And I want to know the number of the zeros before the first 1
(in this example is 3 zeros).
How to do this in a combinational logic?
Best regards,
Davy
See...
http://www.analog-innovations.com/SED/HowManyOnes.pdf
You'll need to modify it for "zeroes" and to stop at the first
occurrence of a "one"
|
Holy Mole, that seems like a contest winner how to do the job
with the most gates possible (altho a modern compiler will
optimize it down some)
Just draw the K-map and loop the functions.
The problem tells us there are 8 bits, people
One thing, the problem doesn't specify: what is wanted when
the register contains 0 0 0 0 0 0 0 0
Wood
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Jim Thompson
Guest
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| Posted:
Thu Dec 01, 2005 1:35 am Post subject:
Re: How to count zeros in registers? |
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On 30 Nov 2005 15:58:57 -0800, "Woody Brison" <woody_brison@yahoo.com>
wrote:
| Quote: | Jim Thompson wrote:
On 29 Nov 2005 06:12:56 -0800, "Davy" <zhushenli@gmail.com> wrote:
Hi all,
reg[7:0] register;
The register contains data like
[0 0 0 1 0 1 0 1]
And I want to know the number of the zeros before the first 1
(in this example is 3 zeros).
How to do this in a combinational logic?
Best regards,
Davy
See...
http://www.analog-innovations.com/SED/HowManyOnes.pdf
You'll need to modify it for "zeroes" and to stop at the first
occurrence of a "one"
Holy Mole, that seems like a contest winner how to do the job
with the most gates possible (altho a modern compiler will
optimize it down some)
|
Just half-adders.
| Quote: |
Just draw the K-map and loop the functions.
|
If you have that luxury.
| Quote: |
The problem tells us there are 8 bits, people
One thing, the problem doesn't specify: what is wanted when
the register contains 0 0 0 0 0 0 0 0
Wood
|
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food. |
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Jim Thompson
Guest
|
| Posted:
Thu Dec 01, 2005 1:35 am Post subject:
Re: How to count zeros in registers? |
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On 30 Nov 2005 15:58:57 -0800, "Woody Brison" <woody_brison@yahoo.com>
wrote:
| Quote: | Jim Thompson wrote:
On 29 Nov 2005 06:12:56 -0800, "Davy" <zhushenli@gmail.com> wrote:
Hi all,
reg[7:0] register;
The register contains data like
[0 0 0 1 0 1 0 1]
And I want to know the number of the zeros before the first 1
(in this example is 3 zeros).
How to do this in a combinational logic?
Best regards,
Davy
See...
http://www.analog-innovations.com/SED/HowManyOnes.pdf
You'll need to modify it for "zeroes" and to stop at the first
occurrence of a "one"
Holy Mole, that seems like a contest winner how to do the job
with the most gates possible (altho a modern compiler will
optimize it down some)
[snip] |
The OP (for HowManyOnes) wanted to count ALL 1's, not just leading.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
|
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Rich Grise
Guest
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| Posted:
Thu Dec 01, 2005 9:35 am Post subject:
Re: How to count zeros in registers? |
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On Wed, 30 Nov 2005 17:35:47 -0700, Jim Thompson wrote:
| Quote: | On 30 Nov 2005 15:58:57 -0800, "Woody Brison" <woody_brison@yahoo.com
wrote:
Jim Thompson wrote:
On 29 Nov 2005 06:12:56 -0800, "Davy" <zhushenli@gmail.com> wrote:
Hi all,
reg[7:0] register;
The register contains data like
[0 0 0 1 0 1 0 1]
And I want to know the number of the zeros before the first 1
(in this example is 3 zeros).
How to do this in a combinational logic?
Best regards,
Davy
See...
http://www.analog-innovations.com/SED/HowManyOnes.pdf
You'll need to modify it for "zeroes" and to stop at the first
occurrence of a "one"
Holy Mole, that seems like a contest winner how to do the job
with the most gates possible (altho a modern compiler will
optimize it down some)
[snip]
The OP (for HowManyOnes) wanted to count ALL 1's, not just leading.
|
I thought "before the first 1" meant "leading". ;-)
Here's the part:
http://pdf.alldatasheet.co.kr/datasheet-pdf/view/53747/FAIRCHILD/74HC148.html
Might have to invert the bits - this chip actually counts '1's.
Or you could do it in Xilinx schematic mode. ;-)
Cheers!
Rich |
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Jasen Betts
Guest
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| Posted:
Thu Dec 01, 2005 4:59 pm Post subject:
Re: How to count zeros in registers? |
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["Followup-To:" header set to sci.electronics.basics.]
On 2005-11-29, Davy <zhushenli@gmail.com> wrote:
| Quote: | Hi all,
reg[7:0] register;
The register contains data like
[0 0 0 1 0 1 0 1]
And I want to know the number of the zeros before the first 1
(in this example is 3 zeros).
How to do this in a combinational logic?
|
what output do you want?
--
Bye.
Jasen |
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Jim Thompson
Guest
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| Posted:
Fri Dec 02, 2005 1:35 am Post subject:
Re: How to count zeros in registers? |
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On 1 Dec 2005 13:48:52 -0800, "Woody Brison" <woody_brison@yahoo.com>
wrote:
| Quote: |
Jim Thompson wrote:
On 30 Nov 2005 15:58:57 -0800, "Woody Brison" <woody_brison@yahoo.com
wrote:
Just draw the K-map and loop the functions.
If you have that luxury.
Yes... and I think the original poster has that luxury, I concur
that this looks a lot like homework. So what he's needing to
do is draw a K-map. I just wanted to steer him in the right
direction without doing it for him
By the way, code to draw K-maps is not too hard to write.
Collecting minterms isn't too far beyond that.
Reducing 'em isn't too far beyond that.
Having tools like that cuts the time down, bringing such luxuries
into reach of even the humble compiler user
Wood
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I can still do 'em by hand but, now-a-days, I use KarnaughMap v4.4.5,
by Russell Sasamori... http://www.puz.com/sw/karnaugh/index.htm
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food. |
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Woody Brison
Guest
|
| Posted:
Fri Dec 02, 2005 1:35 am Post subject:
Re: How to count zeros in registers? |
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Jim Thompson wrote:
| Quote: | On 30 Nov 2005 15:58:57 -0800, "Woody Brison" <woody_brison@yahoo.com
wrote:
Just draw the K-map and loop the functions.
If you have that luxury.
|
Yes... and I think the original poster has that luxury, I concur
that this looks a lot like homework. So what he's needing to
do is draw a K-map. I just wanted to steer him in the right
direction without doing it for him
By the way, code to draw K-maps is not too hard to write.
Collecting minterms isn't too far beyond that.
Reducing 'em isn't too far beyond that.
Having tools like that cuts the time down, bringing such luxuries
into reach of even the humble compiler user
Wood |
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