Extracting digits [0-9] from an number/integer
--mms
I would like to know if there is any function/method, in VHDL, to
extract the digits of an integer.
What I wish to do is take, for example, an integer like 2043, and
extract first the number '3', then '4', '0', and '2'.
Each digit will then be converted to a std_logic_vector(3 downto 0).
Thank you!,
m m s
Jonathan Bromley
wrote:
So you're trying to convert decimal to BCD ("binary coded decimal").
There's a neat shift-and-subtract trick that has been mentioned here
many times before, and maps easily to hardware - google for
"binary to BCD fpga" should do it.
How is your integer represented? Is it a binary number (an
integer signal or variable, or a std_logic_vector or numeric_std
signal or variable?
A non-synthesisable version might look like this - note it will do
hex, binary and octal conversion as well...
subtype BCD_digit is std_logic_vector(3 downto 0);
type BCD_number is array (natural range <>) of BCD_digit;
...
function to_BCD(N: natural; radix: integer := 10)
return BCD_number
is
variable digits: BCD_number (0 to 31); -- big enough for 2^31
variable more_digits: integer := N;
begin
assert (radix >= 2) and (radix <= 16)
report "Bad radix, must be between 2 and 16"
severity ERROR;
for i in digits'range loop
digits(i) := std_logic_vector(
to_unsigned(more_digits rem radix, BCD_digit'length) );
more_digits := more_digits / radix;
if (more_digits = 0) then
return digits(0 to i);
end if;
end loop;
report "Overflow in to_BCD" severity ERROR;
return (0 => "----");
end function to_BCD;
enjoy :-)
--
Jonathan Bromley, Consultant
DOULOS - Developing Design Know-how
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jonathan...@MYCOMPANY.com
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The contents of this message may contain personal views which
are not the views of Doulos Ltd., unless specifically stated.
m__ m___s
It is an integer signal that holds the "i" of a counter. The counter
goes from 0 to 2046. I needed each digit separately to display it on
the LCD screen that has the Spartan-3A board.
--m m _s
-----------------
On Jul 13, 8:07 am, Jonathan Bromley <jonathan.brom...@MYCOMPANY.com>
wrote:
rickman
> Thank you. It seems that is what I was looking for. :-)
>
> It is an integer signal that holds the "i" of a counter. The counter
> goes from 0 to 2046. I needed each digit separately to display it on
> the LCD screen that has the Spartan-3A board.
There is more than one way to skin a cat. If you are incrementing the
counter, then you can just form a BCD counter and increment that.
That is likely going to use fewer resources than the conversion
code.
Rick
Victor
you can have 4 counters for each integer.
each can advanced 1 when the before one reached 10.
m m
http://www.mikrocontroller.net/attachment/19220/D3.1_Binary2BCD.ppt.pdf
On Jul 12, 11:31 pm, --mms <msmeer...@gmail.com> wrote:
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