Re: Transforming vector position to binary value

Peter Alfke <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>...
> As I had posted a while ago, the Virtex-II BlockRAM is surprisingly
> efficient as a priority encoder.
> Use one BlockRAM as a dual-ported 4K x 4 ROM.
> Feed 12 inputs as address to one port, and the next 12 bits as address
> to the other port. That gives you two sets of 4 outputs defining the
> priority-encoded position in the two 12-bit inputs separately.No problem
> with multiple 1s!  Should work at 200+ MHz, but note that the BlockROM
> is a synchronous device, it operates on a clock edge!
> The remaining 8 inputs and the combining of the eight BlockROM outputs
> can be done the conventional way, but might also be done in another
> BlockROM (generating a second clock latency!)
> Peter Alfke, Xilinx Applications

Dear Mr Alfke,

thank you for your proposal.
Do you have some application note in which the connection of the ROMs is explained?
How many ROMs are used at all? As I understand you there are used four ROMs?
Do you mean with "to one port" the write address port and with "to other port"
the read address port?

Thank you for your help.

Best regards
A. Vazquez
G&D System Development