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1 66 robfinch
`timescale 1ns / 1ps
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// ============================================================================
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//        __
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//   \\__/ o\    (C) 2012-2022  Robert Finch, Waterloo
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//    \  __ /    All rights reserved.
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//     \/_//     robfinch@finitron.ca
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//       ||
8
//
9
//      BCDMath.sv
10
//
11
// BSD 3-Clause License
12
// Redistribution and use in source and binary forms, with or without
13
// modification, are permitted provided that the following conditions are met:
14
//
15
// 1. Redistributions of source code must retain the above copyright notice, this
16
//    list of conditions and the following disclaimer.
17
//
18
// 2. Redistributions in binary form must reproduce the above copyright notice,
19
//    this list of conditions and the following disclaimer in the documentation
20
//    and/or other materials provided with the distribution.
21
//
22
// 3. Neither the name of the copyright holder nor the names of its
23
//    contributors may be used to endorse or promote products derived from
24
//    this software without specific prior written permission.
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//
26
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
29
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
30
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
32
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
33
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
34
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
35
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36
//
37
// ============================================================================
38
//
39
// Could use the following approach for add/sub but it ends up being larger
40
// than using an adjustment lookup table.
41
 
42
module BCDAddNyb(ci,a,b,o,c);
43
input ci;               // carry input
44
input [3:0] a;
45
input [3:0] b;
46
output [3:0] o;
47
output c;
48
 
49
wire c0;
50
 
51
reg [4:0] hsN0;
52
always  @*
53
begin
54
        hsN0 = a[3:0] + b[3:0] + ci;
55
        if (hsN0 > 5'd9)
56
                hsN0 = hsN0 + 3'd6;
57
end
58
assign o = hsN0[3:0];
59
assign c = hsN0[4];
60
 
61
endmodule
62
 
63
module BCDAdd(ci,a,b,o,c);
64
input ci;               // carry input
65
input [7:0] a;
66
input [7:0] b;
67
output [7:0] o;
68
output c;
69
 
70
wire c0,c1;
71
 
72
wire [4:0] hsN0 = a[3:0] + b[3:0] + ci;
73
wire [4:0] hsN1 = a[7:4] + b[7:4] + c0;
74
 
75
BCDAddAdjust u1 (hsN0,o[3:0],c0);
76
BCDAddAdjust u2 (hsN1,o[7:4],c);
77
 
78
endmodule
79
 
80
module BCDAdd4(ci,a,b,o,c,c8);
81
input ci;               // carry input
82
input [15:0] a;
83
input [15:0] b;
84
output [15:0] o;
85
output c;
86
output c8;
87
 
88
wire c0,c1,c2;
89
assign c8 = c1;
90
 
91
wire [4:0] hsN0 = a[3:0] + b[3:0] + ci;
92
wire [4:0] hsN1 = a[7:4] + b[7:4] + c0;
93
wire [4:0] hsN2 = a[11:8] + b[11:8] + c1;
94
wire [4:0] hsN3 = a[15:12] + b[15:12] + c2;
95
 
96
BCDAddAdjust u1 (hsN0,o[3:0],c0);
97
BCDAddAdjust u2 (hsN1,o[7:4],c1);
98
BCDAddAdjust u3 (hsN2,o[11:8],c2);
99
BCDAddAdjust u4 (hsN3,o[15:12],c);
100
 
101
endmodule
102
 
103 80 robfinch
module BCDAddNClk(clk,ci,a,b,o,co);
104
parameter N=25;
105
input clk;
106
input ci;
107 66 robfinch
input [N*4-1:0] a;
108
input [N*4-1:0] b;
109 80 robfinch
output reg [N*4-1:0] o;
110
output reg co;
111 66 robfinch
 
112 80 robfinch
reg [N-1:0] cg;
113
wire [N*4-1:0] s;
114
reg [N*4-1:0] on [0:3];
115
reg [3:0] cn;
116
 
117 66 robfinch
genvar g;
118 80 robfinch
generate begin :gAdd
119
        for (g = 0; g < N; g = g + 1)
120
        BCDAddNyb u1 (
121
                .ci(g==0 ? ci : cg[g-1]),
122
                .a(a[g*4+3:g*4]),
123
                .b(b[g*4+3:g*4]),
124
                .o(s[g*4+3:g*4]),
125
                .c(cg[g])
126
        );
127 66 robfinch
end
128
endgenerate
129
 
130 80 robfinch
always_ff @(posedge clk)
131
        on[0] <= s;
132
always_ff @(posedge clk)
133
        on[1] <= on[0];
134
always_ff @(posedge clk)
135
        on[2] <= on[1];
136
always_ff @(posedge clk)
137
        o <= on[2];
138
always_ff @(posedge clk)
139
        cn[0] <= cg[N-1];
140
always_ff @(posedge clk)
141
        cn[1] <= cn[0];
142
always_ff @(posedge clk)
143
        cn[2] <= cn[1];
144
always_ff @(posedge clk)
145
        co <= cn[2];
146 66 robfinch
 
147
endmodule
148
 
149 80 robfinch
module BCDAddN(ci,a,b,o,co);
150
parameter N=25;
151
input ci;
152
input [N*4-1:0] a;
153
input [N*4-1:0] b;
154
output [N*4-1:0] o;
155
output co;
156 66 robfinch
 
157 80 robfinch
reg [N-1:0] cg;
158
wire [N*4-1:0] s;
159 66 robfinch
 
160 80 robfinch
genvar g;
161
generate begin :gAdd
162
        for (g = 0; g < N; g = g + 1)
163
        BCDAddNyb u1 (
164
                .ci(g==0 ? ci : cg[g-1]),
165
                .a(a[g*4+3:g*4]),
166
                .b(b[g*4+3:g*4]),
167
                .o(s[g*4+3:g*4]),
168
                .c(cg[g])
169
        );
170
end
171
endgenerate
172 66 robfinch
 
173 80 robfinch
assign o = s;
174
assign co = cg[N-1];
175 66 robfinch
 
176
endmodule
177
 
178 80 robfinch
/*
179
module BCDAddN(ci,a,b,o,co);
180 66 robfinch
parameter N=24;
181
input ci;               // carry input
182
input [N*4-1:0] a;
183
input [N*4-1:0] b;
184
output [N*4-1:0] o;
185
output co;
186
 
187
genvar g;
188 80 robfinch
generate begin : gBCDAddN
189
reg [4:0] hsN [0:N-1];
190 66 robfinch
wire [N:0] c;
191
 
192
assign c[0] = ci;
193
assign co = c[N];
194
 
195
for (g = 0; g < N; g = g + 1)
196
        always @*
197 80 robfinch
                hsN[g] = a[g*4+3:g*4] + b[g*4+3:g*4] + c[g];
198 66 robfinch
 
199
for (g = 0; g < N; g = g + 1)
200 80 robfinch
        BCDAddAdjust u1 (hsN[g],o[g*4+3:g*4],c[g+1]);
201 66 robfinch
end
202
endgenerate
203
 
204
endmodule
205 80 robfinch
*/
206 66 robfinch
module BCDAddAdjust(i,o,c);
207
input [4:0] i;
208
output [3:0] o;
209
reg [3:0] o;
210
output c;
211
reg c;
212
always @(i)
213
case(i)
214
5'h0: begin o = 4'h0; c = 1'b0; end
215
5'h1: begin o = 4'h1; c = 1'b0; end
216
5'h2: begin o = 4'h2; c = 1'b0; end
217
5'h3: begin o = 4'h3; c = 1'b0; end
218
5'h4: begin o = 4'h4; c = 1'b0; end
219
5'h5: begin o = 4'h5; c = 1'b0; end
220
5'h6: begin o = 4'h6; c = 1'b0; end
221
5'h7: begin o = 4'h7; c = 1'b0; end
222
5'h8: begin o = 4'h8; c = 1'b0; end
223
5'h9: begin o = 4'h9; c = 1'b0; end
224
5'hA: begin o = 4'h0; c = 1'b1; end
225
5'hB: begin o = 4'h1; c = 1'b1; end
226
5'hC: begin o = 4'h2; c = 1'b1; end
227
5'hD: begin o = 4'h3; c = 1'b1; end
228
5'hE: begin o = 4'h4; c = 1'b1; end
229
5'hF: begin o = 4'h5; c = 1'b1; end
230
5'h10:  begin o = 4'h6; c = 1'b1; end
231
5'h11:  begin o = 4'h7; c = 1'b1; end
232
5'h12:  begin o = 4'h8; c = 1'b1; end
233
5'h13:  begin o = 4'h9; c = 1'b1; end
234
default:        begin o = 4'h9; c = 1'b1; end
235
endcase
236
endmodule
237
 
238
module BCDSubAdjust(i,o,c);
239
input [4:0] i;
240
output [3:0] o;
241
reg [3:0] o;
242
output c;
243
reg c;
244
always @(i)
245
case(i)
246
5'h0: begin o = 4'h0; c = 1'b0; end
247
5'h1: begin o = 4'h1; c = 1'b0; end
248
5'h2: begin o = 4'h2; c = 1'b0; end
249
5'h3: begin o = 4'h3; c = 1'b0; end
250
5'h4: begin o = 4'h4; c = 1'b0; end
251
5'h5: begin o = 4'h5; c = 1'b0; end
252
5'h6: begin o = 4'h6; c = 1'b0; end
253
5'h7: begin o = 4'h7; c = 1'b0; end
254
5'h8: begin o = 4'h8; c = 1'b0; end
255
5'h9: begin o = 4'h9; c = 1'b0; end
256
5'h16: begin o = 4'h0; c = 1'b1; end
257
5'h17: begin o = 4'h1; c = 1'b1; end
258
5'h18: begin o = 4'h2; c = 1'b1; end
259
5'h19: begin o = 4'h3; c = 1'b1; end
260
5'h1A: begin o = 4'h4; c = 1'b1; end
261
5'h1B: begin o = 4'h5; c = 1'b1; end
262
5'h1C: begin o = 4'h6; c = 1'b1; end
263
5'h1D: begin o = 4'h7; c = 1'b1; end
264
5'h1E: begin o = 4'h8; c = 1'b1; end
265
5'h1F: begin o = 4'h9; c = 1'b1; end
266
default: begin o = 4'h9; c = 1'b1; end
267
endcase
268
endmodule
269
 
270
// Multiply two BCD digits
271
// Method used is table lookup
272
module BCDMul1(a,b,o);
273
input [3:0] a;
274
input [3:0] b;
275
output [7:0] o;
276
reg [7:0] o;
277
 
278
always @(a or b)
279
casex({a,b})
280
8'h00: o = 8'h00;
281
8'h01: o = 8'h00;
282
8'h02: o = 8'h00;
283
8'h03: o = 8'h00;
284
8'h04: o = 8'h00;
285
8'h05: o = 8'h00;
286
8'h06: o = 8'h00;
287
8'h07: o = 8'h00;
288
8'h08: o = 8'h00;
289
8'h09: o = 8'h00;
290
8'h10: o = 8'h00;
291
8'h11: o = 8'h01;
292
8'h12: o = 8'h02;
293
8'h13: o = 8'h03;
294
8'h14: o = 8'h04;
295
8'h15: o = 8'h05;
296
8'h16: o = 8'h06;
297
8'h17: o = 8'h07;
298
8'h18: o = 8'h08;
299
8'h19: o = 8'h09;
300
8'h20: o = 8'h00;
301
8'h21: o = 8'h02;
302
8'h22: o = 8'h04;
303
8'h23: o = 8'h06;
304
8'h24: o = 8'h08;
305
8'h25: o = 8'h10;
306
8'h26: o = 8'h12;
307
8'h27: o = 8'h14;
308
8'h28: o = 8'h16;
309
8'h29: o = 8'h18;
310
8'h30: o = 8'h00;
311
8'h31: o = 8'h03;
312
8'h32: o = 8'h06;
313
8'h33: o = 8'h09;
314
8'h34: o = 8'h12;
315
8'h35: o = 8'h15;
316
8'h36: o = 8'h18;
317
8'h37: o = 8'h21;
318
8'h38: o = 8'h24;
319
8'h39: o = 8'h27;
320
8'h40: o = 8'h00;
321
8'h41: o = 8'h04;
322
8'h42: o = 8'h08;
323
8'h43: o = 8'h12;
324
8'h44: o = 8'h16;
325
8'h45: o = 8'h20;
326
8'h46: o = 8'h24;
327
8'h47: o = 8'h28;
328
8'h48: o = 8'h32;
329
8'h49: o = 8'h36;
330
8'h50: o = 8'h00;
331
8'h51: o = 8'h05;
332
8'h52: o = 8'h10;
333
8'h53: o = 8'h15;
334
8'h54: o = 8'h20;
335
8'h55: o = 8'h25;
336
8'h56: o = 8'h30;
337
8'h57: o = 8'h35;
338
8'h58: o = 8'h40;
339
8'h59: o = 8'h45;
340
8'h60: o = 8'h00;
341
8'h61: o = 8'h06;
342
8'h62: o = 8'h12;
343
8'h63: o = 8'h18;
344
8'h64: o = 8'h24;
345
8'h65: o = 8'h30;
346
8'h66: o = 8'h36;
347
8'h67: o = 8'h42;
348
8'h68: o = 8'h48;
349
8'h69: o = 8'h54;
350
8'h70: o = 8'h00;
351
8'h71: o = 8'h07;
352
8'h72: o = 8'h14;
353
8'h73: o = 8'h21;
354
8'h74: o = 8'h28;
355
8'h75: o = 8'h35;
356
8'h76: o = 8'h42;
357
8'h77: o = 8'h49;
358
8'h78: o = 8'h56;
359
8'h79: o = 8'h63;
360
8'h80: o = 8'h00;
361
8'h81: o = 8'h08;
362
8'h82: o = 8'h16;
363
8'h83: o = 8'h24;
364
8'h84: o = 8'h32;
365
8'h85: o = 8'h40;
366
8'h86: o = 8'h48;
367
8'h87: o = 8'h56;
368
8'h88: o = 8'h64;
369
8'h89: o = 8'h72;
370
8'h90: o = 8'h00;
371
8'h91: o = 8'h09;
372
8'h92: o = 8'h18;
373
8'h93: o = 8'h27;
374
8'h94: o = 8'h36;
375
8'h95: o = 8'h45;
376
8'h96: o = 8'h54;
377
8'h97: o = 8'h63;
378
8'h98: o = 8'h72;
379
8'h99: o = 8'h81;
380
default:        o = 8'h00;
381
endcase
382
endmodule
383
 
384
 
385
// Multiply two pairs of BCD digits
386
// handles from 0x0 to 99x99
387
module BCDMul2(a,b,o);
388
input [7:0] a;
389
input [7:0] b;
390
output [15:0] o;
391
 
392
wire [7:0] p1,p2,p3,p4;
393
wire [15:0] s1;
394
 
395
BCDMul1 u1 (a[3:0],b[3:0],p1);
396
BCDMul1 u2 (a[7:4],b[3:0],p2);
397
BCDMul1 u3 (a[3:0],b[7:4],p3);
398
BCDMul1 u4 (a[7:4],b[7:4],p4);
399
 
400
BCDAdd4 u5 (1'b0,{p4,p1},{4'h0,p2,4'h0},s1);
401
BCDAdd4 u6 (1'b0,s1,{4'h0,p3,4'h0},o);
402
 
403
endmodule
404
 
405
module BCDMul4(a,b,o);
406
input [15:0] a;
407
input [15:0] b;
408
output [31:0] o;
409
 
410
wire [15:0] p1,p2,p3,p4;
411
wire [31:0] s1;
412
 
413
BCDMul2 u1 (a[7:0],b[7:0],p1);
414
BCDMul2 u2 (a[15:8],b[7:0],p2);
415
BCDMul2 u3 (a[7:0],b[15:8],p3);
416
BCDMul2 u4 (a[15:8],b[15:8],p4);
417
 
418
BCDAddN #(.N(8)) u5 (1'b0,{p4,p1},{8'h0,p2,8'h0},s1);
419
BCDAddN #(.N(8)) u6 (1'b0,s1,{8'h0,p3,8'h0},o);
420
 
421
endmodule
422
 
423
module BCDMul8(a,b,o);
424
input [31:0] a;
425
input [31:0] b;
426
output [63:0] o;
427
 
428
wire [31:0] p1,p2,p3,p4;
429
wire [63:0] s1;
430
 
431
BCDMul4 u1 (a[15:0],b[15:0],p1);
432
BCDMul4 u2 (a[31:16],b[15:0],p2);
433
BCDMul4 u3 (a[15:0],b[31:16],p3);
434
BCDMul4 u4 (a[31:16],b[31:16],p4);
435
 
436
BCDAddN #(.N(16)) u5 (1'b0,{p4,p1},{16'h0,p2,16'h0},s1);
437
BCDAddN #(.N(16)) u6 (1'b0,s1,{16'h0,p3,16'h0},o);
438
 
439
endmodule
440
 
441
module BCDMul16(a,b,o);
442
input [63:0] a;
443
input [63:0] b;
444
output [127:0] o;
445
 
446
wire [63:0] p1,p2,p3,p4;
447
wire [127:0] s1;
448
 
449
BCDMul8 u1 (a[31:0],b[31:0],p1);
450
BCDMul8 u2 (a[63:32],b[31:0],p2);
451
BCDMul8 u3 (a[31:0],b[63:32],p3);
452
BCDMul8 u4 (a[63:32],b[63:32],p4);
453
 
454
BCDAddN #(.N(32)) u5 (1'b0,{p4,p1},{32'h0,p2,32'h0},s1);
455
BCDAddN #(.N(32)) u6 (1'b0,s1,{32'h0,p3,32'h0},o);
456
 
457
endmodule
458
 
459
module BCDMul32(a,b,o);
460
input [127:0] a;
461
input [127:0] b;
462
output [255:0] o;
463
 
464
wire [127:0] p1,p2,p3,p4;
465
wire [255:0] s1;
466
 
467
BCDMul16 u1 (a[63:0],b[63:0],p1);
468
BCDMul16 u2 (a[127:64],b[63:0],p2);
469
BCDMul16 u3 (a[63:0],b[127:64],p3);
470
BCDMul16 u4 (a[127:64],b[127:64],p4);
471
 
472
BCDAddN #(.N(64)) u5 (1'b0,{p4,p1},{64'h0,p2,64'h0},s1);
473
BCDAddN #(.N(64)) u6 (1'b0,s1,{64'h0,p3,64'h0},o);
474
 
475
endmodule
476
 
477
module BCDMul_tb();
478
 
479
wire [15:0] o1,o2,o3,o4;
480
 
481
BCDMul2 u1 (8'h00,8'h00,o1);
482
BCDMul2 u2 (8'h99,8'h99,o2);
483
BCDMul2 u3 (8'h25,8'h18,o3);
484
BCDMul2 u4 (8'h37,8'h21,o4);
485
 
486
endmodule
487
 
488
module BinToBCD(i, o);
489
input [7:0] i;
490
output [11:0] o;
491
 
492
reg [11:0] tbl [0:255];
493
 
494
genvar g;
495
generate begin : gTbl
496
reg [3:0] n0 [0:255];
497
reg [3:0] n1 [0:255];
498
reg [3:0] n2 [0:255];
499
 
500
for (g = 0; g < 256; g = g + 1) begin
501
        initial begin
502
                n0[g] = g % 10;
503
                n1[g] = g / 10;
504
                n2[g] = g / 100;
505
                tbl[g] <= {n2[g],n1[g],n0[g]};
506
        end
507
end
508
 
509
assign o = tbl[i];
510
 
511
end
512
endgenerate
513
 
514
endmodule
515
 
516
// Perform a logical shift to the right.
517
module BCDSRL(ci, i, o, co);
518
parameter N=4;
519
input ci;
520
input [N*4-1:0] i;
521
output reg [N*4-1:0] o;
522
output co;
523
 
524
reg [N:0] c;
525
 
526
genvar g;
527
generate begin
528
always @*
529
        c[N] = ci;
530
for (g = N - 1; g >= 0; g = g - 1)
531
always @*
532
        c[g] = i[g*4];
533
for (g = N - 1; g >= 0; g = g - 1)
534
always @*
535
begin
536
        o[g*4+3:g*4] = {1'b0,i[g*4+3:g*4+1]};
537
        // Because there is a divide by two, the value will range between 0 and 4.
538
        // Adding 5 keeps it within deicmal boundaries of 0 to 9. No carry can be
539
        // generated
540
        if (c[N+1])
541
                o[g*4+3:g*4] = o[g*4+3:g*4] + 4'd5;
542
end
543
        assign co = c[0];
544
end
545
endgenerate
546
 
547
endmodule

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