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[/] [thor/] [trunk/] [rtl/] [verilog/] [Thor_multiplier.v] - Blame information for rev 45

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// ============================================================================
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//        __
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//   \\__/ o\    (C) 2013-2016  Robert Finch, Stratford
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//    \  __ /    All rights reserved.
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//     \/_//     robfinch<remove>@finitron.ca
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//       ||
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//
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// This source file is free software: you can redistribute it and/or modify 
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// it under the terms of the GNU Lesser General Public License as published 
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// by the Free Software Foundation, either version 3 of the License, or     
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// (at your option) any later version.                                      
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//                                                                          
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// This source file is distributed in the hope that it will be useful,      
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// but WITHOUT ANY WARRANTY; without even the implied warranty of           
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the            
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// GNU General Public License for more details.                             
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//                                                                          
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// You should have received a copy of the GNU General Public License        
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// along with this program.  If not, see <http://www.gnu.org/licenses/>.    
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//
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//
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// Thor Superscaler
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// Thor_multiplier.v
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//  - 64 bit multiplier
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//
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// ============================================================================
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//
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module Thor_multiplier(rst, clk, ld, abort, sgn, isMuli, a, b, imm, o, done, idle);
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parameter WID=64;
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parameter SGNADJO=3'd2;
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parameter MULT=3'd3;
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parameter IDLE=3'd4;
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parameter DONE=3'd5;
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input clk;
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input rst;
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input ld;
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input abort;
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input sgn;
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input isMuli;
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input [WID-1:0] a;
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input [WID-1:0] b;
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input [WID-1:0] imm;
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output [WID*2-1:0] o;
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reg [WID*2-1:0] o;
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output done;
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output idle;
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reg [WID-1:0] aa,bb;
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reg so;
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reg [2:0] state;
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reg [7:0] cnt;
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wire cnt_done = cnt==8'd0;
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assign done = state==DONE || (state==IDLE && !ld); // State == DONE
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assign idle = state==IDLE;
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reg [WID*2-1:0] prod;
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//wire [64:0] p1 = aa[0] ? prod[127:64] + b : prod[127:64];
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//wire [65:0] p2 = aa[1] ? p1 + {b,1'b0} : p1;
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wire [WID+WID/4-1:0] p1 = bb * aa[WID/4-1:0] + prod[WID*2-1:WID];
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initial begin
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    prod = 64'd0;
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    o = 64'd0;
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end
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always @(posedge clk)
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if (rst) begin
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        aa <= {WID{1'b0}};
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        bb <= {WID{1'b0}};
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        prod <= {WID*2{1'b0}};
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        o <= {WID*2{1'b0}};
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        state <= IDLE;
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end
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else
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begin
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if (abort)
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    cnt <= 8'd00;
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else if (!cnt_done)
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        cnt <= cnt - 8'd1;
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case(state)
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IDLE:
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        if (ld) begin
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                if (sgn) begin
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                        aa <= a[WID-1] ? -a : a;
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                        bb <= isMuli ? (imm[WID-1] ? -imm : imm) :(b[WID-1] ? -b : b);
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                        so <= isMuli ? a[WID-1] ^ imm[WID-1] : a[WID-1] ^ b[WID-1];
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                end
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                else begin
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                        aa <= a;
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                        bb <= isMuli ? imm : b;
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                        so <= 1'b0;
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                end
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                prod <= {WID*2{1'b0}};
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                cnt <= 8'd4;
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                state <= MULT;
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        end
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MULT:
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        if (!cnt_done) begin
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                aa <= {16'b0,aa[WID-1:WID/4]};
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                prod <= {16'b0,prod[WID*2-1:WID/4]};
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                prod[WID*2-1:WID*3/4] <= p1;
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        end
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        else begin
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                if (sgn) begin
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                        if (so)
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                                o <= -prod;
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                        else
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                                o <= prod;
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                end
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                else
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                        o <= prod;
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                state <= DONE;
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        end
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default:
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        state <= IDLE;
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endcase
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end
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endmodule
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module Thor_multiplier_tb();
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reg rst;
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reg clk;
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reg ld;
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wire [127:0] o;
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initial begin
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        clk = 1;
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        rst = 0;
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        #100 rst = 1;
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        #100 rst = 0;
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        #100 ld = 1;
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        #150 ld = 0;
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end
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always #10 clk = ~clk;  //  50 MHz
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Thor_multiplier u1
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(
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        .rst(rst),
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        .clk(clk),
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        .ld(ld),
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        .sgn(1'b0),
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        .isMuli(1'b1),
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        .a(64'd56),
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        .b(64'd0),
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        .imm(64'd27),
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        .o(o)
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);
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endmodule
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