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Hello group,

Does anybody know about an online resource that I can find some
samples on how to implement a full adder using LUT? either using
Flex10k or any other classical methods?

I've started learning FPGA and have done something but need to compare
it.

Regards,
Amit

On Dec 9, 9:34 pm, Amit <amit.ko...@gmail.com> wrote:
> Hello group,
>
> Does anybody know about an online resource that I can find some
> samples on how to implement a full adder using LUT?

Google lists about 19000

http://www.google.com/search?hl=en&q=VHDL+full+adder

KJ

Amit schrieb:

> Does anybody know about an online resource that I can find some
> samples on how to implement a full adder using LUT? either using
> Flex10k or any other classical methods?

Usually you don't need to think about every single fulladder. Just use
result<=a+b; -- all signals are vectors of type signed or unsigned

For a single fulladder you could use:

signal result : unsigned(1 downto 0);
signal a,b,c_in : std_ulogic;
signal sum,c_out : std_ulogic;

result<=unsigned('0' & a) + unsigned('0' & b) + unsigned('0' & c_in);
sum<=result(0);
c_out<=result(1);


Ralf

On Dec 11, 9:01 am, Ralf Hildebrandt <Ralf-Hildebra...@gmx.de> wrote:
> Amit schrieb:
>
> > Does anybody know about an online resource that I can find some
> > samples on how to implement a full adder using LUT? either using
> > Flex10k or any other classical methods?
>
> Usually you don't need to think about every single fulladder. Just use
> result<=a+b; -- all signals are vectors of type signed or unsigned
>
> For a single fulladder you could use:
>
> signal result : unsigned(1 downto 0);
> signal a,b,c_in : std_ulogic;
> signal sum,c_out : std_ulogic;
>
> result<=unsigned('0' & a) + unsigned('0' & b) + unsigned('0' & c_in);
> sum<=result(0);
> c_out<=result(1);
>
> Ralf

It's even easier with integers:

signal a,b,sum,c_in,c_out : integer range 0 to 1;

sum <= (a + b + c_in) mod 2;
c_out <= (a + b + c_in) / 2;

Andy

Andy wrote:

> It's even easier with integers:


Easier still, if I let synthesis wire up the carries

-- Mike Treseler

On Dec 12, 9:44 am, Mike Treseler <mike_trese...@comcast.net> wrote:
> Andy wrote:
> > It's even easier with integers:
>
> Easier still, if I let synthesis wire up the carries
>
> -- Mike Treseler

Thanks to all,

But maybe I didn't ask the question properly or I had to post in a
different group (I'm sure doesn't exist). My concern is not regarding
VHDL sytnax but trying to understand how to tacking the flow on a
Flex10K diagram.

I apologize all for this.

However, if somebody knows this I will be more than happy to have your
help.

Regards,
Amit