-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathmath_log2.v
More file actions
270 lines (240 loc) · 10.7 KB
/
Copy pathmath_log2.v
File metadata and controls
270 lines (240 loc) · 10.7 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
////////////////////////////////////////////////////////////////////////////////
// Company: 奥新智能
// Engineer: 耿慧慧
//
// Description: A fast base-2 logarithm function
//
// Revision: N/A
// Additional Comments:
//
////////////////////////////////////////////////////////////////////////////////
module math_log2 #(
parameter DIN_WIDTH = 64,
parameter DIN_DECI_WIDTH = 0,
parameter DOUT_WIDTH = 10,
parameter DOUT_DECI_WIDTH = 4,
// derived parameters
localparam DIN_INT_WIDTH = DIN_WIDTH-DIN_DECI_WIDTH,
localparam DOUT_INT_WIDTH = DOUT_WIDTH-DOUT_DECI_WIDTH,
// bit width parameters
localparam W1 = DIN_WIDTH-1,
localparam W2 = DOUT_WIDTH-1,
localparam W3 = DOUT_INT_WIDTH-1,
localparam W4 = DOUT_DECI_WIDTH-1,
localparam W5 = DIN_INT_WIDTH-1,
localparam W6 = W1-4
) (
input [W1:0] DIN,
input clk,
output [W2:0] DOUT
);
// Comprises 3 main blocks: priority encoder, barrel shifter, and LUT
reg [W3:0] priencout1;
(*dont_touch="true"*)reg [W4:0] LUTout;
reg [W3:0] priencout2;
(*dont_touch="true"*)reg [W3:0] priencout3;
reg [W6:0] barrelin ;
reg [ 4:0] barrelout ;
assign DOUT = {priencout3, LUTout}; // Basic top-level connectivity
// Barrel shifter - OMG, it's a primitive in Verilog!
wire [W5:0] priencin = DIN[W1:DIN_DECI_WIDTH];
wire [W6:0] tmp1 = (barrelin << ~priencout1);
always @(posedge clk) begin
barrelout <= tmp1[W1-4:W1-8];
end
// Priority encoder
always @(posedge clk) begin
priencout2 <= priencout1;
priencout3 <= priencout2;
barrelin <= DIN[W1-1:3];
end
always @(posedge clk)
casex (priencin)
64'b1xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 63;
64'b01xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 62;
64'b001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 61;
64'b0001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 60;
64'b00001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 59;
64'b000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 58;
64'b0000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 57;
64'b00000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 56;
64'b000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 55;
64'b0000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 54;
64'b00000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 53;
64'b000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 52;
64'b0000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 51;
64'b00000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 50;
64'b000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 49;
64'b0000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 48;
64'b00000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 47;
64'b000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 46;
64'b0000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 45;
64'b00000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 44;
64'b000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 43;
64'b0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 42;
64'b00000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 41;
64'b000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 40;
64'b0000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 39;
64'b00000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 38;
64'b000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 37;
64'b0000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 36;
64'b00000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 35;
64'b000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 34;
64'b0000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 33;
64'b00000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 32;
64'b000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 31;
64'b0000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 30;
64'b00000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 29;
64'b000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 28;
64'b0000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 27;
64'b00000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 26;
64'b000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 25;
64'b0000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 24;
64'b00000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 23;
64'b000000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxx: priencout1 <= 22;
64'b0000000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxx: priencout1 <= 21;
64'b00000000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxx: priencout1 <= 20;
64'b000000000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxx: priencout1 <= 19;
64'b0000000000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxx: priencout1 <= 18;
64'b00000000000000000000000000000000000000000000001xxxxxxxxxxxxxxxxx: priencout1 <= 17;
64'b000000000000000000000000000000000000000000000001xxxxxxxxxxxxxxxx: priencout1 <= 16;
64'b0000000000000000000000000000000000000000000000001xxxxxxxxxxxxxxx: priencout1 <= 15;
64'b00000000000000000000000000000000000000000000000001xxxxxxxxxxxxxx: priencout1 <= 14;
64'b000000000000000000000000000000000000000000000000001xxxxxxxxxxxxx: priencout1 <= 13;
64'b0000000000000000000000000000000000000000000000000001xxxxxxxxxxxx: priencout1 <= 12;
64'b00000000000000000000000000000000000000000000000000001xxxxxxxxxxx: priencout1 <= 11;
64'b000000000000000000000000000000000000000000000000000001xxxxxxxxxx: priencout1 <= 10;
64'b0000000000000000000000000000000000000000000000000000001xxxxxxxxx: priencout1 <= 9;
64'b00000000000000000000000000000000000000000000000000000001xxxxxxxx: priencout1 <= 8;
64'b000000000000000000000000000000000000000000000000000000001xxxxxxx: priencout1 <= 7;
64'b0000000000000000000000000000000000000000000000000000000001xxxxxx: priencout1 <= 6;
64'b00000000000000000000000000000000000000000000000000000000001xxxxx: priencout1 <= 5;
64'b000000000000000000000000000000000000000000000000000000000001xxxx: priencout1 <= 4;
64'b0000000000000000000000000000000000000000000000000000000000001xxx: priencout1 <= 3;
64'b00000000000000000000000000000000000000000000000000000000000001xx: priencout1 <= 2;
64'b000000000000000000000000000000000000000000000000000000000000001x: priencout1 <= 1;
64'b000000000000000000000000000000000000000000000000000000000000000x: priencout1 <= 0;
endcase
/*
LUT for log fraction lookup
- can be done with array or case:
case (addr)
0:out=0;
.
31:out=15;
endcase
OR
wire [3:0] lut [0:31];
assign lut[0] = 0;
.
assign lut[31] = 15;
Are there any better ways?
*/
// Let's try "case".
// The equation is: output = log2(1+input/32)*16
// For larger tables, better to generate a separate data file using a program!
/* always @*
case (barrelout)
0 : LUTout = 0;
1 : LUTout = 0;
2 : LUTout = 1;
3 : LUTout = 2;
4 : LUTout = 2;
5 : LUTout = 3;
6 : LUTout = 4;
7 : LUTout = 4;
8 : LUTout = 5;
9 : LUTout = 6;
10: LUTout = 6;
11: LUTout = 7;
12: LUTout = 7;
13: LUTout = 8;
14: LUTout = 9;
15: LUTout = 9;
16: LUTout = 10;
17: LUTout = 10;
18: LUTout = 11;
19: LUTout = 12;
20: LUTout = 12;
21: LUTout = 13;
22: LUTout = 13;
23: LUTout = 14;
24: LUTout = 14;
25: LUTout = 15;
26: LUTout = 15;
27: LUTout = 16;
28: LUTout = 16; // calculated value is *slightly* closer to 15, but 14 makes for a smoother curve!
29: LUTout = 17;
30: LUTout = 17;
31: LUTout = 18;
32: LUTout = 18;
33: LUTout = 19;
34: LUTout = 19;
35: LUTout = 20;
36: LUTout = 20;
37: LUTout = 21;
38: LUTout = 21;
39: LUTout = 21;
40: LUTout = 22;
41: LUTout = 22;
42: LUTout = 23;
43: LUTout = 23;
44: LUTout = 24;
45: LUTout = 24;
46: LUTout = 25;
47: LUTout = 25;
48: LUTout = 25;
49: LUTout = 26;
50: LUTout = 26;
51: LUTout = 27;
52: LUTout = 27;
53: LUTout = 27;
54: LUTout = 28;
55: LUTout = 28;
56: LUTout = 29;
57: LUTout = 29;
58: LUTout = 29;
59: LUTout = 30;
60: LUTout = 30; // calculated value is *slightly* closer to 15, but 14 makes for a smoother curve!
61: LUTout = 30;
62: LUTout = 31;
63: LUTout = 31;
endcase */
always @(posedge clk)
case (barrelout)
0 : LUTout <= 0;
1 : LUTout <= 1;
2 : LUTout <= 1;
3 : LUTout <= 2;
4 : LUTout <= 3;
5 : LUTout <= 3;
6 : LUTout <= 4;
7 : LUTout <= 5;
8 : LUTout <= 5;
9 : LUTout <= 6;
10: LUTout <= 6;
11: LUTout <= 7;
12: LUTout <= 7;
13: LUTout <= 8;
14: LUTout <= 8;
15: LUTout <= 9;
16: LUTout <= 9;
17: LUTout <= 10;
18: LUTout <= 10;
19: LUTout <= 11;
20: LUTout <= 11;
21: LUTout <= 12;
22: LUTout <= 12;
23: LUTout <= 13;
24: LUTout <= 13;
25: LUTout <= 13;
26: LUTout <= 14;
27: LUTout <= 14;
28: LUTout <= 14;
29: LUTout <= 15;
30: LUTout <= 15;
31: LUTout <= 15;
endcase
endmodule
////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////