[SOLVED] lookup table in xlinx using verilog

[manasasn]

hi
iam not getting how to write verilog code for 4 bit multiplier using lookup table
actualy my project is to find square of a n number so please help us

 

[gck]

hi,

Please check the syntax for User Defined Primitives (UDP)
Here is some sample code from IEEE Spec of Verilog

primitive multiplexer (mux, control, dataA, dataB);
output mux;
input control, dataA, dataB;
table
// control dataA dataB mux
0 1 ? : 1 ; // ? = 0 1 x
0 0 ? : 0 ;
1 ? 1 : 1 ;
1 ? 0 : 0 ;
x 0 0 : 0 ;
x 1 1 : 1 ;
endtable
endprimitive

hope this helps

 

[jimwu88]

If you are using Xilinx device, below is a coding example for a lookup table or ROM from page 193 of XST User Guide (by the way, download Xilinx Document Navigator to manage all Xilinx documents)

module v_rams_21a (clk, en, addr, data);
input clk;
input en;
input [5:0] addr;
output reg [19:0] data;
always @(posedge clk) begin
if (en)
case(addr)
6’b000000: data <= 20’h0200A; 6’b100000: data <= 20’h02222;
6’b000001: data <= 20’h00300; 6’b100001: data <= 20’h04001;
6’b000010: data <= 20’h08101; 6’b100010: data <= 20’h00342;
6’b000011: data <= 20’h04000; 6’b100011: data <= 20’h0232B;
6’b000100: data <= 20’h08601; 6’b100100: data <= 20’h00900;
6’b000101: data <= 20’h0233A; 6’b100101: data <= 20’h00302;
6’b000110: data <= 20’h00300; 6’b100110: data <= 20’h00102;
6’b000111: data <= 20’h08602; 6’b100111: data <= 20’h04002;
6’b001000: data <= 20’h02310; 6’b101000: data <= 20’h00900;
6’b001001: data <= 20’h0203B; 6’b101001: data <= 20’h08201;
6’b001010: data <= 20’h08300; 6’b101010: data <= 20’h02023;
6’b001011: data <= 20’h04002; 6’b101011: data <= 20’h00303;
6’b001100: data <= 20’h08201; 6’b101100: data <= 20’h02433;
6’b001101: data <= 20’h00500; 6’b101101: data <= 20’h00301;
6’b001110: data <= 20’h04001; 6’b101110: data <= 20’h04004;
6’b001111: data <= 20’h02500; 6’b101111: data <= 20’h00301;
6’b010000: data <= 20’h00340; 6’b110000: data <= 20’h00102;
6’b010001: data <= 20’h00241; 6’b110001: data <= 20’h02137;
6’b010010: data <= 20’h04002; 6’b110010: data <= 20’h02036;
6’b010011: data <= 20’h08300; 6’b110011: data <= 20’h00301;
6’b010100: data <= 20’h08201; 6’b110100: data <= 20’h00102;
6’b010101: data <= 20’h00500; 6’b110101: data <= 20’h02237;
6’b010110: data <= 20’h08101; 6’b110110: data <= 20’h04004;
6’b010111: data <= 20’h00602; 6’b110111: data <= 20’h00304;
6’b011000: data <= 20’h04003; 6’b111000: data <= 20’h04040;
6’b011001: data <= 20’h0241E; 6’b111001: data <= 20’h02500;
6’b011010: data <= 20’h00301; 6’b111010: data <= 20’h02500;
6’b011011: data <= 20’h00102; 6’b111011: data <= 20’h02500;
6’b011100: data <= 20’h02122; 6’b111100: data <= 20’h0030D;
6’b011101: data <= 20’h02021; 6’b111101: data <= 20’h02341;
6’b011110: data <= 20’h00301; 6’b111110: data <= 20’h08201;
6’b011111: data <= 20’h00102; 6’b111111: data <= 20’h0400D;
endcase
end
endmodule