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`timescale 1ns / 1ps
// ============================================================================
//        __
//   \\__/ o\    (C) 2010-2020  Robert Finch, Waterloo
//    \  __ /    All rights reserved.
//     \/_//     robfinch<remove>@finitron.ca
//       ||
//
//      dfisqrt.v
//      - integer square root
//  - uses the standard long form calc.
//      - geared towards use in an decimal floating point unit
//      - calculates to WID fractional precision (double width output)
//
//
// BSD 3-Clause License
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
//    list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice,
//    this list of conditions and the following disclaimer in the documentation
//    and/or other materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its
//    contributors may be used to endorse or promote products derived from
//    this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//                                                                          
// ============================================================================
 
module dfisqrt(rst, clk, ce, ld, a, o, done);
parameter N=34;
parameter WID = N*4;
localparam MSB = WID-1;
input rst;
input clk;
input ce;
input ld;
input [MSB:0] a;
output reg [WID*2-1:0] o;
output reg done;
 
reg [3:0] state;
parameter SKIPLZ = 4'd1;
parameter A0 = 4'd2;
parameter S3 = 4'd3;
parameter INCJ = 4'd4;
parameter DONE = 4'd5;
parameter S1 = 4'd6;
parameter S4 = 4'd7;
parameter S2 = 4'd8;
 
reg [3:0] tbl [0:255];
reg [7:0] tbl5 [0:9];
reg [7:0] sqra [0:9];
 
initial begin
        sqra[0] = 8'h00;
        sqra[1] = 8'h01;
        sqra[2] = 8'h04;
        sqra[3] = 8'h09;
        sqra[4] = 8'h16;
        sqra[5] = 8'h25;
        sqra[6] = 8'h36;
        sqra[7] = 8'h49;
        sqra[8] = 8'h64;
        sqra[9] = 8'h81;
end
 
genvar g;
generate begin
        for (g = 0; g < 256; g = g + 1)
                initial begin
                        if (g >= 8'h81)
                                tbl[g] = 4'h9;
                        else if (g >= 8'h64)
                                tbl[g] = 4'h8;
                        else if (g >= 8'h49)
                                tbl[g] = 4'h7;
                        else if (g >= 8'h36)
                                tbl[g] = 4'h6;
                        else if (g >= 8'h25)
                                tbl[g] = 4'h5;
                        else if (g >= 8'h16)
                                tbl[g] = 4'h4;
                        else if (g >= 8'h09)
                                tbl[g] = 4'd3;
                        else if (g >= 8'h04)
                                tbl[g] = 4'h2;
                        else if (g >= 8'h01)
                                tbl[g] = 4'h1;
                        else
                                tbl[g] = 4'h0;
                end
end
endgenerate
 
initial begin
        tbl5[0] = 8'h05;
        tbl5[1] = 8'h15;
        tbl5[2] = 8'h25;
        tbl5[3] = 8'h35;
        tbl5[4] = 8'h45;
        tbl5[5] = 8'h55;
        tbl5[6] = 8'h65;
        tbl5[7] = 8'h75;
        tbl5[8] = 8'h85;
        tbl5[9] = 8'h95;
end
 
 
reg [7:0] dcnt;
reg [7:0] j;
reg [N*2*4-1:0] b;
reg [N*4*2-1:0] ii;
wire [N*4*2-1:0] firstRa;
reg [N*4*2-1+4:0] ai, Rbx5;
wire [(N*2+1)*4-1:0] Rax2, Rax4, Rax5i, newRax5a;
reg [(N*2+1)*4-1:0] Rax5, pRax5, newRax5;
wire tooBig;
 
BCDAddN #(.N(N*2+1)) ua1 (.ci(1'b0), .a({4'h0,firstRa}), .b({4'h0,firstRa}), .o(Rax2), .co());
BCDAddN #(.N(N*2+1)) ua2 (.ci(1'b0), .a(Rax2), .b(Rax2), .o(Rax4), .co());
BCDAddN #(.N(N*2+1)) ua3 (.ci(1'b0), .a({4'h0,firstRa}), .b(Rax4), .o(Rax5i), .co());
 
BCDSubN #(.N(N*2+1)) ua4 (.ci(1'b0), .a(Rax5), .b(Rbx5), .o(newRax5a), .co(tooBig));
 
 
wire [3:0] a0 = tbl[ii[N*4*2-1:N*4*2-8]];
wire [7:0] sqra00 = sqra[a0];
wire [N*2*4+3:0] srqa0 = {4'h0,sqra00,{N*2*4-8{1'b0}}};
 
BCDSubN #(.N(N*2)) ua5 (.ci(1'b0), .a(ii), .b(srqa0), .o(firstRa), .co());
 
wire [WID*2-1:0] tbl5x = {tbl5[b[3:0]],{(N*2-3)*4{1'b0}}};
wire [WID*2-1:0] tbl5s = tbl5x >> {j,2'h0};
 
wire [N*2*4-1:0] sum_ai;
BCDAddN #(.N(N*2)) ua6 (.ci(1'b0), .a(ai), .b(tbl5s), .o(sum_ai), .co());
 
always @(posedge clk)
begin
case(state)
SKIPLZ:
        begin
                Rax5 <= {N*2*4+4{1'd0}};
                Rbx5 <= {N*2*4+4{1'd0}};
                if (ii[N*4*2-1:N*4*2-8]==8'h00) begin
                        ii <= {ii[N*4*2-9:0],8'h00};
                        dcnt <= dcnt - 8'd2;
                        if (dcnt==8'h00) begin
                                o <= {WID*2{1'b0}};
                                state <= DONE;
                        end
                end
                else
                        state <= A0;
        end
        // Get the first digit of the square root.
A0:
        begin
                b <= 4'd0;
                ai <= {4'd0,a0,{(N*2-2)*4{1'b0}}};
                state <= S1;
        end
        // Set initial Ra5
S1:
        begin
                Rax5 <= Rax5i;
                Rbx5 <= {4'h0,sum_ai};
                pRax5 <= Rax5i;
                state <= S2;
        end
S2:
        begin
                newRax5 <= newRax5a;
                if (tooBig) begin
                        Rax5 <= {Rax5,4'h0};
                        ai <= ai | (b << (N*2-j)*4-8);
                        state <= INCJ;
                end
                else begin
                        b <= b + 1'd1;
                        state <= S3;
                end
        end
S3:
        begin
                pRax5 <= Rax5;
                Rax5 <= newRax5;
                Rbx5 <= {4'h0,sum_ai};
                state <= S2;
        end
INCJ:
        begin
                b <= 4'd0;
                j <= j + 1'd1;
                dcnt <= dcnt - 1'd1;
                if (dcnt==0) begin
                        state <= DONE;
                        o <= ai;
                end
                else
                        state <= S4;
        end
S4:
        begin
                Rbx5 <= {4'h0,sum_ai};
                state <= S2;
        end
DONE:
        begin
                done <= 1'b1;
        end
endcase
if (ld) begin
        state <= SKIPLZ;
        dcnt <= N*2;
        j <= 8'd1;
        b <= 4'd0;
        ii <= {a,{N*4{1'b0}}};
        done <= 1'b0;
end
end
 
endmodule
 
 
module dfisqrt_tb();
parameter N=34;
 
reg clk;
reg rst;
reg [N*4-1:0] a;
wire [N*4*2-1:0] o;
reg ld;
wire done;
reg [7:0] state;
 
initial begin
        clk = 1;
        rst = 0;
        #100 rst = 1;
        #100 rst = 0;
end
 
always #10 clk = ~clk;  //  50 MHz
 
always @(posedge clk)
if (rst) begin
        state <= 8'd0;
        a <= 64'h987654321;
end
else
begin
ld <= 1'b0;
case(state)
8'd0:
        begin
                a <= 64'h987654321;
                ld <= 1'b1;
                state <= 8'd1;
        end
8'd1:
        if (done) begin
                $display("i=%h o=%h", a, o);
        end
endcase
end
 
dfisqrt #(.N(N)) u1 (.rst(rst), .clk(clk), .ce(1'b1), .ld(ld), .a(a), .o(o), .done(done));
 
endmodule
 
 

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[/] [ft816float/] [trunk/] [rtl/] [verilog2/] [dfisqrt.v] - Blame information for rev 79

Line No.	Rev	Author	Line
1	56	robfinch	`timescale 1ns / 1ps
2			`// ============================================================================`
3			`// __`
4			`// \\__/ o\ (C) 2010-2020 Robert Finch, Waterloo`
5			`// \ __ / All rights reserved.`
6			`// \/_// robfinch<remove>@finitron.ca`
7			`// \|\|`
8			`//`
9			`// dfisqrt.v`
10			`// - integer square root`
11			`// - uses the standard long form calc.`
12			`// - geared towards use in an decimal floating point unit`
13			`// - calculates to WID fractional precision (double width output)`
14			`//`
15			`//`
16			`// BSD 3-Clause License`
17			`// Redistribution and use in source and binary forms, with or without`
18			`// modification, are permitted provided that the following conditions are met:`
19			`//`
20			`// 1. Redistributions of source code must retain the above copyright notice, this`
21			`// list of conditions and the following disclaimer.`
22			`//`
23			`// 2. Redistributions in binary form must reproduce the above copyright notice,`
24			`// this list of conditions and the following disclaimer in the documentation`
25			`// and/or other materials provided with the distribution.`
26			`//`
27			`// 3. Neither the name of the copyright holder nor the names of its`
28			`// contributors may be used to endorse or promote products derived from`
29			`// this software without specific prior written permission.`
30			`//`
31			`// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"`
32			`// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE`
33			`// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE`
34			`// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE`
35			`// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL`
36			`// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR`
37			`// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER`
38			`// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,`
39			`// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE`
40			`// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.`
41			`//`
42			`// ============================================================================`
43
44			`module dfisqrt(rst, clk, ce, ld, a, o, done);`
45			`parameter N=34;`
46			`parameter WID = N*4;`
47			`localparam MSB = WID-1;`
48			`input rst;`
49			`input clk;`
50			`input ce;`
51			`input ld;`
52			`input [MSB:0] a;`
53			`output reg [WID*2-1:0] o;`
54			`output reg done;`
55
56			`reg [3:0] state;`
57			`parameter SKIPLZ = 4'd1;`
58			`parameter A0 = 4'd2;`
59			`parameter S3 = 4'd3;`
60			`parameter INCJ = 4'd4;`
61			`parameter DONE = 4'd5;`
62			`parameter S1 = 4'd6;`
63			`parameter S4 = 4'd7;`
64			`parameter S2 = 4'd8;`
65
66			`reg [3:0] tbl [0:255];`
67			`reg [7:0] tbl5 [0:9];`
68			`reg [7:0] sqra [0:9];`
69
70			`initial begin`
71			`sqra[0] = 8'h00;`
72			`sqra[1] = 8'h01;`
73			`sqra[2] = 8'h04;`
74			`sqra[3] = 8'h09;`
75			`sqra[4] = 8'h16;`
76			`sqra[5] = 8'h25;`
77			`sqra[6] = 8'h36;`
78			`sqra[7] = 8'h49;`
79			`sqra[8] = 8'h64;`
80			`sqra[9] = 8'h81;`
81			`end`
82
83			`genvar g;`
84			`generate begin`
85			`for (g = 0; g < 256; g = g + 1)`
86			`initial begin`
87			`if (g >= 8'h81)`
88			`tbl[g] = 4'h9;`
89			`else if (g >= 8'h64)`
90			`tbl[g] = 4'h8;`
91			`else if (g >= 8'h49)`
92			`tbl[g] = 4'h7;`
93			`else if (g >= 8'h36)`
94			`tbl[g] = 4'h6;`
95			`else if (g >= 8'h25)`
96			`tbl[g] = 4'h5;`
97			`else if (g >= 8'h16)`
98			`tbl[g] = 4'h4;`
99			`else if (g >= 8'h09)`
100			`tbl[g] = 4'd3;`
101			`else if (g >= 8'h04)`
102			`tbl[g] = 4'h2;`
103			`else if (g >= 8'h01)`
104			`tbl[g] = 4'h1;`
105			`else`
106			`tbl[g] = 4'h0;`
107			`end`
108			`end`
109			`endgenerate`
110
111			`initial begin`
112			`tbl5[0] = 8'h05;`
113			`tbl5[1] = 8'h15;`
114			`tbl5[2] = 8'h25;`
115			`tbl5[3] = 8'h35;`
116			`tbl5[4] = 8'h45;`
117			`tbl5[5] = 8'h55;`
118			`tbl5[6] = 8'h65;`
119			`tbl5[7] = 8'h75;`
120			`tbl5[8] = 8'h85;`
121			`tbl5[9] = 8'h95;`
122			`end`
123
124
125			`reg [7:0] dcnt;`
126			`reg [7:0] j;`
127			`reg [N24-1:0] b;`
128			`reg [N42-1:0] ii;`
129			`wire [N42-1:0] firstRa;`
130			`reg [N42-1+4:0] ai, Rbx5;`
131			`wire [(N2+1)4-1:0] Rax2, Rax4, Rax5i, newRax5a;`
132			`reg [(N2+1)4-1:0] Rax5, pRax5, newRax5;`
133			`wire tooBig;`
134
135			`BCDAddN #(.N(N*2+1)) ua1 (.ci(1'b0), .a({4'h0,firstRa}), .b({4'h0,firstRa}), .o(Rax2), .co());`
136			`BCDAddN #(.N(N*2+1)) ua2 (.ci(1'b0), .a(Rax2), .b(Rax2), .o(Rax4), .co());`
137			`BCDAddN #(.N(N*2+1)) ua3 (.ci(1'b0), .a({4'h0,firstRa}), .b(Rax4), .o(Rax5i), .co());`
138
139			`BCDSubN #(.N(N*2+1)) ua4 (.ci(1'b0), .a(Rax5), .b(Rbx5), .o(newRax5a), .co(tooBig));`
140
141
142			`wire [3:0] a0 = tbl[ii[N42-1:N42-8]];`
143			`wire [7:0] sqra00 = sqra[a0];`
144			`wire [N24+3:0] srqa0 = {4'h0,sqra00,{N24-8{1'b0}}};`
145
146			`BCDSubN #(.N(N*2)) ua5 (.ci(1'b0), .a(ii), .b(srqa0), .o(firstRa), .co());`
147
148			`wire [WID2-1:0] tbl5x = {tbl5[b[3:0]],{(N2-3)*4{1'b0}}};`
149			`wire [WID*2-1:0] tbl5s = tbl5x >> {j,2'h0};`
150
151			`wire [N24-1:0] sum_ai;`
152			`BCDAddN #(.N(N*2)) ua6 (.ci(1'b0), .a(ai), .b(tbl5s), .o(sum_ai), .co());`
153
154			`always @(posedge clk)`
155			`begin`
156			`case(state)`
157			`SKIPLZ:`
158			`begin`
159			`Rax5 <= {N24+4{1'd0}};`
160			`Rbx5 <= {N24+4{1'd0}};`
161			`if (ii[N42-1:N42-8]==8'h00) begin`
162			`ii <= {ii[N42-9:0],8'h00};`
163			`dcnt <= dcnt - 8'd2;`
164			`if (dcnt==8'h00) begin`
165			`o <= {WID*2{1'b0}};`
166			`state <= DONE;`
167			`end`
168			`end`
169			`else`
170			`state <= A0;`
171			`end`
172			`// Get the first digit of the square root.`
173			`A0:`
174			`begin`
175			`b <= 4'd0;`
176			`ai <= {4'd0,a0,{(N2-2)4{1'b0}}};`
177			`state <= S1;`
178			`end`
179			`// Set initial Ra5`
180			`S1:`
181			`begin`
182			`Rax5 <= Rax5i;`
183			`Rbx5 <= {4'h0,sum_ai};`
184			`pRax5 <= Rax5i;`
185			`state <= S2;`
186			`end`
187			`S2:`
188			`begin`
189			`newRax5 <= newRax5a;`
190			`if (tooBig) begin`
191			`Rax5 <= {Rax5,4'h0};`
192			`ai <= ai \| (b << (N2-j)4-8);`
193			`state <= INCJ;`
194			`end`
195			`else begin`
196			`b <= b + 1'd1;`
197			`state <= S3;`
198			`end`
199			`end`
200			`S3:`
201			`begin`
202			`pRax5 <= Rax5;`
203			`Rax5 <= newRax5;`
204			`Rbx5 <= {4'h0,sum_ai};`
205			`state <= S2;`
206			`end`
207			`INCJ:`
208			`begin`
209			`b <= 4'd0;`
210			`j <= j + 1'd1;`
211			`dcnt <= dcnt - 1'd1;`
212			`if (dcnt==0) begin`
213			`state <= DONE;`
214			`o <= ai;`
215			`end`
216			`else`
217			`state <= S4;`
218			`end`
219			`S4:`
220			`begin`
221			`Rbx5 <= {4'h0,sum_ai};`
222			`state <= S2;`
223			`end`
224			`DONE:`
225			`begin`
226			`done <= 1'b1;`
227			`end`
228			`endcase`
229			`if (ld) begin`
230			`state <= SKIPLZ;`
231			`dcnt <= N*2;`
232			`j <= 8'd1;`
233			`b <= 4'd0;`
234			`ii <= {a,{N*4{1'b0}}};`
235			`done <= 1'b0;`
236			`end`
237			`end`
238
239			`endmodule`
240
241
242			`module dfisqrt_tb();`
243			`parameter N=34;`
244
245			`reg clk;`
246			`reg rst;`
247			`reg [N*4-1:0] a;`
248			`wire [N42-1:0] o;`
249			`reg ld;`
250			`wire done;`
251			`reg [7:0] state;`
252
253			`initial begin`
254			`clk = 1;`
255			`rst = 0;`
256			`#100 rst = 1;`
257			`#100 rst = 0;`
258			`end`
259
260			`always #10 clk = ~clk; // 50 MHz`
261
262			`always @(posedge clk)`
263			`if (rst) begin`
264			`state <= 8'd0;`
265			`a <= 64'h987654321;`
266			`end`
267			`else`
268			`begin`
269			`ld <= 1'b0;`
270			`case(state)`
271			`8'd0:`
272			`begin`
273			`a <= 64'h987654321;`
274			`ld <= 1'b1;`
275			`state <= 8'd1;`
276			`end`
277			`8'd1:`
278			`if (done) begin`
279			`$display("i=%h o=%h", a, o);`
280			`end`
281			`endcase`
282			`end`
283
284			`dfisqrt #(.N(N)) u1 (.rst(rst), .clk(clk), .ce(1'b1), .ld(ld), .a(a), .o(o), .done(done));`
285
286			`endmodule`
287
288