sqrt? 1

[edje66]

Hello,
somebody know how to realized a fonction sqrt in VHDL?
Thank you!

 

[VHDLguy]

ieee.math_real package has a function sqrt.

It may only be behavioural, if it is and you need a working function that you can synthesize, you will probably have the most luck looking for a function from your vendor (fpga, asic, whatever)

--

http://www.lateralsands.com/

 

[VHDLguy]

just a note. I am guessing that it will be really hard to implement in hardware unless you have a DSP embedded in your device.

A quick google search finds this paper:

http://venus.elfak.ni.ac.yu/IMPEG/DigitalSystem.pdf

which looks like it could be implemented, but its going to take a lot of work and logic resources. The DSP would be much better if you have it.

--

http://www.lateralsands.com/

 

[senjed]

There are not-so-hard algorithms for implementation. the best is the non-storing recursive algorithm. have a look at this:

http://www.cp.eng.chula.ac.th/~krerk/publication/iscit-sqrt.pdf

 

[senjed]

And I should say that this doesn't use too much logic, although not little either:
Length= 32 bit : Number of SLICES : 81; Clock Frequency : 131.70 MHz
Length=16 bit : Number of SLICES : 43; Clock Frequency :143.37 MHz

(On a Spartan II)

 

[senjed]

And I should say that this doesn't use too much logic, although not little either:
Length= 32 bit : Number of SLICES : 81; Clock Frequency : 131.70 MHz
Length=16 bit : Number of SLICES : 43; Clock Frequency :143.37 MHz
(I think the algorithm iterates the number of bits of each input.)

(On a Spartan II)

 

[edje66]

I need to calculate the magnitude of a complex number: sqrt(X²+Y²). Now I think the best is the CORDIC algorithm. But I don't know yet how to implement that in VHDL. I expect find that nearly!

 

[yangth]

only + - * and logic operations can be synthesized;and the
others maybe can be synthesized,but you don't know the result