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AR# 17710

LeonardoSpectrum - How do I turn off the dedicated Virtex-II multiplier for a given operator?

Description

Keywords: Multiplier, Virtex-II, Virtex, II, dedicated, Leonardo, Spectrum

Urgency: Standard

General Description:
In LeonardoSpectrum there is the global attribute "virtex2_multipliers" which turns on/off the dedicated multiplier for the entire project. Is there an attribute which can turn off the dedicated multiplier for a specific multiplier operator?

Solution

The "dedicated_mult" attribute can turn off the multiplier for a specific operator by either embedding the attribute inside of the TCL script for the signal receiving the operation or embedding the attribute in the HDL code. Below are examples for HDL code:

VHDL

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

entity test is
port (a,b,c,d : integer range -256 to 255;
f,g : out integer range -512 to 511);
end;
architecture rtl of test is
attribute dedicated_mult : string;
attribute dedicated_mult of f : signal is "OFF";
begin
f <= a * b; -- will use LUTs and MULT_ANDs, etc
g <= c * d; -- will use MULT18X18
end;


Verilog

module test (a,b,c,d,f,g);
input [9:0] a,b,c,d;
output [10:0] f,g;

assign f = a * b; //exemplar attribute f dedicated_mult off
assign g = c * d; //exemplar attribute g dedicated_mult on

endmodule
AR# 17710
Date Created 07/30/2003
Last Updated 04/25/2007
Status Archive
Type General Article