fir.v

11 阶FIR 数字滤波器,verolog描述

//11 阶FIR 数字滤波器
module fir(clk,x,y);
input[7:0] x;
input clk;
output[15:0] y;
reg[15:0] y;
reg[7:0] tap0,tap1,tap2,tap3,tap4,tap5,tap6,tap7,tap8,tap9,tap10;
reg[7:0] t0,t1,t2,t3,t4,t5;
reg[15:0] sum;
always@(posedge clk)
begin
t0<=tap5;
t1<=tap4+tap6;
t2<=tap3+tap7;
t3<=tap2+tap8;
t4<=tap1+tap9;
t5<=tap0+tap10; //利用对称性
sum<=(t1<<4)+{t1[7],t1[7:1]}+{t1[7],t1[7],t1[7:2]}+
{t1[7],t1[7],t1[7],
t1[7:3]}-(t2<<3)-(t2<<2)+t2-{t2[7],t2[7],t2[7:2]}
+(t3<<2)+t3+{t3[7],t3[7],t3[7:2]}+{t3[7],t3[7],t3[7],t3[7],t3[7:4]}
+{t3[7],t3[7],t3[7],t3[7],t3[7],t3[7:5]}
-t4-{t4[7],t4[7:1]}-{t4[7],t4[7],t4[7],t4[7:3]}
+{t5[7],t5[7:1]}-{t5[7],t5[7],t5[7],t5[7],t5[7],t5[7:5]}
+(t0<<7)-((t0<<2)<<2)-(t0<<2)+{t0[7],t0[7:1]}
+{t0[7],t0[7],t0[7:2]}+{t0[7],t0[7],t0[7],t0[7],t0[7:4]};
//16+0.5+0.25+0.125=16.875
//8+4-1+0.25=11.25
//4+1+0.25+0.0625+0.03125=5.34375
//1+0.5+0.125=1.625
//0.5-0.03125=0.46875
//128-4*4-4+0.5+0.25+0.0625=108.8125
/* 0.0036，-0.0127，0.0417，-0.0878，0.1318，0.8500，0.1318，-0.0878，
0.0417，-0.0127，0.0036，0.4608，-1.6256，5.3376，-11.2384，16.8704，
108.800，16.8704，-11.238，5.3376，-1.6256，0.4608 */
tap10<=tap9;
tap9<=tap8;
tap8<=tap7;
tap7<=tap6;
tap6<=tap5;
tap5<=tap4;
tap4<=tap3;
tap3<=tap2;
tap2<=tap1;
tap1<=tap0;
tap0<=x;
y<={sum[15],sum[15],sum[15],sum[15],sum[15],sum[15],sum[15],sum[15:7]}
;
end
endmodule