`timescale 1ns / 1ps
|
`timescale 1ns / 1ps
|
// ============================================================================
|
// ============================================================================
|
// __
|
// __
|
// \\__/ o\ (C) 2017-2018 Robert Finch, Waterloo
|
// \\__/ o\ (C) 2017-2018 Robert Finch, Waterloo
|
// \ __ / All rights reserved.
|
// \ __ / All rights reserved.
|
// \/_// robfinch<remove>@finitron.ca
|
// \/_// robfinch<remove>@finitron.ca
|
// ||
|
// ||
|
//
|
//
|
// DivGoldschmidt.v
|
// DivGoldschmidt.v
|
//
|
//
|
//
|
//
|
// This source file is free software: you can redistribute it and/or modify
|
// This source file is free software: you can redistribute it and/or modify
|
// it under the terms of the GNU Lesser General Public License as published
|
// it under the terms of the GNU Lesser General Public License as published
|
// by the Free Software Foundation, either version 3 of the License, or
|
// by the Free Software Foundation, either version 3 of the License, or
|
// (at your option) any later version.
|
// (at your option) any later version.
|
//
|
//
|
// This source file is distributed in the hope that it will be useful,
|
// This source file is distributed in the hope that it will be useful,
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
// GNU General Public License for more details.
|
// GNU General Public License for more details.
|
//
|
//
|
// You should have received a copy of the GNU General Public License
|
// You should have received a copy of the GNU General Public License
|
// along with this program. If not, see <http://www.gnu.org/licenses/>.
|
// along with this program. If not, see <http://www.gnu.org/licenses/>.
|
//
|
//
|
//
|
//
|
// ============================================================================
|
// ============================================================================
|
//
|
//
|
module DivGoldschmidt(rst, clk, ld, a, b, q, f0, done, lzcnt);
|
module DivGoldschmidt(rst, clk, ld, a, b, q, done, lzcnt);
|
parameter WID=32;
|
parameter WID=32;
|
parameter WHOLE=16;
|
parameter WHOLE=16;
|
parameter POINTS=16;
|
parameter POINTS=16;
|
parameter LEFT=1'b1;
|
parameter LEFT=1'b1;
|
localparam SIZE=WID+WHOLE;
|
localparam SIZE=WID+WHOLE;
|
localparam POINTS2 = POINTS+WHOLE;
|
localparam POINTS2 = POINTS+WHOLE;
|
input rst;
|
input rst;
|
input clk;
|
input clk;
|
input ld;
|
input ld;
|
input [WID-1:0] a;
|
input [WID-1:0] a;
|
input [WID-1:0] b;
|
input [WID-1:0] b;
|
output reg [WID*2-1:0] q;
|
output reg [WID*2-1:0] q;
|
output reg [SIZE-1:0] f0;
|
|
output reg done;
|
output reg done;
|
output reg [7:0] lzcnt;
|
output reg [7:0] lzcnt;
|
parameter IDLE = 2'd0;
|
parameter IDLE = 2'd0;
|
parameter DIV = 2'd1;
|
parameter DIV = 2'd1;
|
parameter DONE = 2'd2;
|
parameter DONE = 2'd2;
|
parameter DIV2 = 2'd3;
|
parameter DIV2 = 2'd3;
|
|
|
integer n;
|
integer n;
|
// Scale D so it is between 0 < D < 1 (shift)
|
// Scale D so it is between 0 < D < 1 (shift)
|
reg [SIZE-1:0] F;
|
reg [SIZE-1:0] F;
|
reg [SIZE*3-1:0] N, D;
|
reg [SIZE*3-1:0] N, D;
|
wire [SIZE*3-1:0] N1, D1;
|
wire [SIZE*3-1:0] N1, D1;
|
assign N1 = N * F;
|
assign N1 = N * F;
|
assign D1 = D * F;
|
assign D1 = D * F;
|
reg [1:0] state = IDLE;
|
reg [1:0] state = IDLE;
|
reg [7:0] count = 0;
|
reg [7:0] count = 0;
|
reg [7:0] lzcnt2;
|
reg [7:0] lzcnt2;
|
wire [7:0] shft;
|
wire [7:0] shft;
|
|
|
// Count the leading zeros on the b side input. Determines how much
|
// Count the leading zeros on the b side input. Determines how much
|
// shifting is required.
|
// shifting is required.
|
always @*
|
always @*
|
begin
|
begin
|
lzcnt2 = 8'd0;
|
lzcnt2 = 8'd0;
|
if (b[WID-1]==1'b0)
|
if (b[WID-1]==1'b0)
|
for (n = WID-2; n >= 0; n = n - 1)
|
for (n = WID-2; n >= 0; n = n - 1)
|
if(b[n] && lzcnt2==8'd0)
|
if(b[n] && lzcnt2==8'd0)
|
lzcnt2 = (WID-1)-n;
|
lzcnt2 = (WID-1)-n;
|
end
|
end
|
|
|
|
|
// Count the leading zeros in the output. the float divider uses this.
|
// Count the leading zeros in the output. the float divider uses this.
|
always @*
|
always @*
|
begin
|
begin
|
lzcnt = 8'd0;
|
lzcnt = 8'd0;
|
if (q[WID*2-1]==1'b0)
|
if (q[WID*2-1]==1'b0)
|
for (n = WID*2-2; n >= 0; n = n - 1)
|
for (n = WID*2-2; n >= 0; n = n - 1)
|
if(q[n] && lzcnt==8'd0)
|
if(q[n] && lzcnt==8'd0)
|
lzcnt = (WID*2-1)-n;
|
lzcnt = (WID*2-1)-n;
|
end
|
end
|
|
|
wire shift_left = lzcnt2 > WHOLE;
|
wire shift_left = lzcnt2 > WHOLE;
|
assign shft = shift_left ? lzcnt2-WHOLE : WHOLE-lzcnt2;
|
assign shft = shift_left ? lzcnt2-WHOLE : WHOLE-lzcnt2;
|
//assign done = (state==IDLE && !ld)||state==DONE;
|
//assign done = (state==IDLE && !ld)||state==DONE;
|
|
|
always @(posedge clk)
|
always @(posedge clk)
|
if (rst) begin
|
if (rst) begin
|
done <= 1'b0;
|
done <= 1'b0;
|
count <= 6'd0;
|
count <= 6'd0;
|
state <= IDLE;
|
state <= IDLE;
|
end
|
end
|
else begin
|
else begin
|
done <= 1'b0;
|
done <= 1'b0;
|
case(state)
|
case(state)
|
IDLE:
|
IDLE:
|
begin
|
begin
|
if (ld) begin
|
if (ld) begin
|
// Shifting the numerator and denomintor right or left using a barrel
|
// Shifting the numerator and denomintor right or left using a barrel
|
// or funnel shifter is what gives Goldschmidt a lot of it's performance.
|
// or funnel shifter is what gives Goldschmidt a lot of it's performance.
|
// Most of the divide is being performed by shifting.
|
// Most of the divide is being performed by shifting.
|
// For most floating point numbers shifting left isn't required as the
|
// For most floating point numbers shifting left isn't required as the
|
// number is always between 1.0 and 2.0. Instead typically only a single
|
// number is always between 1.0 and 2.0. Instead typically only a single
|
// shift to the right is required. For fixed point numbers however, we
|
// shift to the right is required. For fixed point numbers however, we
|
// probably want to be able to shift left, hence the LEFT parameter.
|
// probably want to be able to shift left, hence the LEFT parameter.
|
// With no left shifting the only impact is for denormal numbers which
|
// With no left shifting the only impact is for denormal numbers which
|
// take longer for the divide to converge.
|
// take longer for the divide to converge.
|
if (shift_left) begin
|
if (shift_left) begin
|
if (LEFT) begin
|
if (LEFT) begin
|
N <= {16'd0,a,{WHOLE{1'b0}}} << shft;
|
N <= {16'd0,a,{WHOLE{1'b0}}} << shft;
|
D <= {16'd0,b,{WHOLE{1'd0}}} << shft;
|
D <= {16'd0,b,{WHOLE{1'd0}}} << shft;
|
F <= {16'd2,{POINTS2{1'b0}}} - ({b,{WHOLE{1'd0}}} << shft);
|
F <= {16'd2,{POINTS2{1'b0}}} - ({b,{WHOLE{1'd0}}} << shft);
|
f0 <= {16'd2,{POINTS2{1'b0}}} - ({b,{WHOLE{1'd0}}} << shft);
|
|
end
|
end
|
else begin
|
else begin
|
N <= {16'd0,a,{WHOLE{1'b0}}};
|
N <= {16'd0,a,{WHOLE{1'b0}}};
|
D <= {16'd0,b,{WHOLE{1'd0}}};
|
D <= {16'd0,b,{WHOLE{1'd0}}};
|
F <= {16'd2,{POINTS2{1'b0}}} - ({b,{WHOLE{1'd0}}});
|
F <= {16'd2,{POINTS2{1'b0}}} - ({b,{WHOLE{1'd0}}});
|
f0 <= {16'd2,{POINTS2{1'b0}}} - ({b,{WHOLE{1'd0}}});
|
|
end
|
end
|
end
|
end
|
else begin
|
else begin
|
N <= {16'd0,a,{WHOLE{1'b0}}} >> shft;
|
N <= {16'd0,a,{WHOLE{1'b0}}} >> shft;
|
D <= {16'd0,b,{WHOLE{1'd0}}} >> shft;
|
D <= {16'd0,b,{WHOLE{1'd0}}} >> shft;
|
F <= {16'd2,{POINTS2{1'b0}}} - ({b,{WHOLE{1'd0}}} >> shft);
|
F <= {16'd2,{POINTS2{1'b0}}} - ({b,{WHOLE{1'd0}}} >> shft);
|
f0 <= {16'd2,{POINTS2{1'b0}}} - ({b,{WHOLE{1'd0}}} >> shft);
|
|
end
|
end
|
count <= 0;
|
count <= 0;
|
state <= DIV;
|
state <= DIV;
|
end
|
end
|
end
|
end
|
DIV:
|
DIV:
|
begin
|
begin
|
$display("C: %d N: %x D: %x F: %x", count, N,D,F);
|
$display("C: %d N: %x D: %x F: %x", count, N,D,F);
|
N <= N1[SIZE*3-1:POINTS2] + N1[POINTS2-1];
|
N <= N1[SIZE*3-1:POINTS2] + N1[POINTS2-1];
|
D <= D1[SIZE*3-1:POINTS2] + D1[POINTS2-1];
|
D <= D1[SIZE*3-1:POINTS2] + D1[POINTS2-1];
|
F <= {16'd2,{POINTS2{1'd0}}} - (D1[SIZE*3-1:POINTS2] + D1[POINTS2-1]);
|
F <= {16'd2,{POINTS2{1'd0}}} - (D1[SIZE*3-1:POINTS2] + D1[POINTS2-1]);
|
// q <= N1[SIZE*2-1:POINTS2] + N1[POINTS2-1];
|
// q <= N1[SIZE*2-1:POINTS2] + N1[POINTS2-1];
|
if (D[SIZE*3-1:0]=={2'h1,{POINTS2{1'd0}}})
|
if (D[SIZE*3-1:0]=={2'h1,{POINTS2{1'd0}}})
|
state <= DONE;
|
state <= DONE;
|
count <= count + 1;
|
count <= count + 1;
|
end
|
end
|
DONE:
|
DONE:
|
begin
|
begin
|
done <= 1'b1;
|
done <= 1'b1;
|
q <= N[SIZE*3-1:0];
|
q <= N[SIZE*3-1:0];
|
state <= IDLE;
|
state <= IDLE;
|
end
|
end
|
endcase
|
endcase
|
end
|
end
|
|
|
endmodule
|
endmodule
|
|
|
module G_divider_tb();
|
module G_divider_tb();
|
parameter WID=4;
|
parameter WID=4;
|
reg rst;
|
reg rst;
|
reg clk;
|
reg clk;
|
reg ld;
|
reg ld;
|
wire done;
|
wire done;
|
wire [WID*2-1:0] qo;
|
wire [WID*2-1:0] qo;
|
wire [7:0] f0;
|
|
reg [3:0] state;
|
reg [3:0] state;
|
reg [3:0] a, b;
|
reg [3:0] a, b;
|
reg [7:0] count;
|
reg [7:0] count;
|
|
|
initial begin
|
initial begin
|
clk = 1;
|
clk = 1;
|
rst = 0;
|
rst = 0;
|
#100 rst = 1;
|
#100 rst = 1;
|
#100 rst = 0;
|
#100 rst = 0;
|
#100 ld = 1;
|
#100 ld = 1;
|
#150 ld = 0;
|
#150 ld = 0;
|
end
|
end
|
|
|
always #10 clk = ~clk; // 50 MHz
|
always #10 clk = ~clk; // 50 MHz
|
|
|
always @(posedge clk)
|
always @(posedge clk)
|
if (rst) begin
|
if (rst) begin
|
state <= 3'd0;
|
state <= 3'd0;
|
count = 0;
|
count = 0;
|
end
|
end
|
else begin
|
else begin
|
case(state)
|
case(state)
|
3'd0:
|
3'd0:
|
begin
|
begin
|
ld <= 1;
|
ld <= 1;
|
a <= count[7:4];
|
a <= count[7:4];
|
b <= count[3:0];
|
b <= count[3:0];
|
end
|
end
|
3'd1:
|
3'd1:
|
if (done) begin
|
if (done) begin
|
$display("C: %x Q: %x f: %x", count, qo, f0);
|
$display("C: %x Q: %x f: %x", count, qo, f0);
|
state <= 3'd2;
|
state <= 3'd2;
|
end
|
end
|
3'd2:
|
3'd2:
|
begin
|
begin
|
count <= count + 8'd1;
|
count <= count + 8'd1;
|
state <= 3'd0;
|
state <= 3'd0;
|
end
|
end
|
endcase
|
endcase
|
end
|
end
|
|
|
DivGoldschmidt #(.WID(WID),.WHOLE(1),.POINTS(3)) u00
|
DivGoldschmidt #(.WID(WID),.WHOLE(1),.POINTS(3)) u00
|
(
|
(
|
.rst(rst),
|
.rst(rst),
|
.clk(clk),
|
.clk(clk),
|
.ld(ld),
|
.ld(ld),
|
// .sgn(1'b1),
|
// .sgn(1'b1),
|
// .isDivi(1'b0),
|
// .isDivi(1'b0),
|
.a(a),
|
.a(a),
|
.b(b),
|
.b(b),
|
// .imm(64'd123),
|
// .imm(64'd123),
|
.q(qo),
|
.q(qo),
|
.f0(f0),
|
|
// .ro(ro),
|
// .ro(ro),
|
// .dvByZr(),
|
// .dvByZr(),
|
.left_right(),
|
.done(done),
|
.shift(),
|
.lzcnt()
|
.done(done)
|
|
);
|
);
|
|
|
endmodule
|
endmodule
|
|
|
|
|
