image processing on fpga problem

[hodahussein]

dear all



i do some processing on image stored in fpga block ram virtex2pro30.

i want to do this equation x= A+2*i*k where A and K are constant and i is counter





i wait your reply for very importance



regards

 

[Dave_PL]

When A,K are constants and i is counter so why not use LUT ?

 

[hodahussein]

could you tell me how i can use LUT?plz

 

[Dave_PL]

Its simple ROM. You have to store "X" values in e.g. BRAM and read from it depending on "I" value. Lets say A = 1, K = 2 so considering your equation: x(i) = A + 2*i*K you will get:

x(0) = 1 + 2*0*2 = 1
x(1) = 1 + 2*1*2 = 5
x(2) = 1 + 2*2*2 = 9
etc.

So you fill ROM with values 1,5,9 etc and to the input address of ROM you connect your counter.

Hope this helps.

 

[TrickyDicky]

x= A+2*i*k only needs 1 multiplier and an adder. No need for a rom.

 

[Dave_PL]

Yes, thats true. I gave just one solution.

But which will be faster?

 

[hodahussein]

hi tricky

how can i do multiplier and is it cost (tack resouce form fpga)

wait your reply

 

[TrickyDicky]

multiplier should use less resources. Virtex 2 have embedded multipliers so you can use them.

Are you trying to use VHDL or Verilog?

 

[hodahussein]

dear tricky
are you mean it should use ip [multiplier] ? or what?
plz explaine

regards

 

[mrflibble]

If "i" is a linearly incrementing counter, then all you would need is an adder I'd say.

Anticipating the next question, let me pre-emptively answer it with a question:
What are typical values of "i" you run through on say an example that runs for 100 cycles? From 0 to 99? Cool! What are A and K? Got values? excellent. Now calculate "x", and see if you see a pattern emerging here? ;-)

As already suggested, you can use a lookup table, or a multiplier, or an adder. All these can give you a solution. Which is best depends on the values of A, K and the sequence of your "i" counter. Not to mention clock speed, what parts, etc.