decode.v

M序列。。。。。。。。。。。。。。。。。。。

//接收端的解码模块（可综合）
//在信号接收的刚开始发送端发送的是10个1信号，
//即10个+M序列，所以我们在开始时每接收到一个信号做一次累加运算
//当出现正的高峰时则认为达到同步，进入同步解调过程（mainbody）。
//也就是从此每进入一个信号就进行相应的相乘相加，
//在解接收到31个信号后进行一次判断，大于0认为接收到1，小于0认为接收到0。

`timescale	1ns/1ns
module	decoder(	clk_31,		//输入时钟
			indata,		//接收到的m序列
			outdata,	//解码以后的序列
			rst,
			en,
			sum);
			
input			clk_31,en,rst;
input	[2:0]	indata;
output	[8:0]	sum;
output			outdata;
reg		[8:0]	i,j,i1,i2,i3,i4,i5,i6,i7,i8,i9,i10,
                        i11,i12,i13,i14,i15,i16,i17,i18,i19,
                        i20,i21,i22,i23,i24,i25,i26,i27,i28,i29,i30;

reg		enable;
reg	[30:0]	flag;		//叠加使能控制信号
reg	[2:0]	indata_buf;	
reg	[1:0]	state;
reg		outdata;
reg	[8:0]	sum;
wire	[30:0]	m;
parameter	find_head	=2'b01,	 //找发送头信号111111110
		main_body	=2'b10;	 //找到头信号之后的同步解码过程
		
assign	m = 31'b 1010011000001110010001010111101;	
                        //与发射端协调好的解调M序列
		
reg	[8:0]	sum0,	//加法结果寄存器
		sum1,	//理论上我们是在每进入一个信号后就立即对已有的31个信号进行乘加运算，
		sum2,	//这是一个31位的加法，即使采用流水线算法也需要5个并行加法器。
		sum3,	//所以在实际实现的时候，我们为了提高处理速度，将这个运算转化为
		sum4,	//31个加法寄存器，将每次进来的信号与不同的31位M序列进行叠加，
		sum5,	//再存入不同的原有寄存器中，不同存器在寄进行了31次加法后进行一次判断，
		sum6,	//如果大于阈值则认为达到同步，进入同步判断状态（state<=main_body）
		sum7,
		sum8,	//这组加法寄存器的初始值为50，进行31次乘法加法运算之后，选取的阈值为75
		sum9,
		sum10,
		sum11,
		sum12,
		sum13,
		sum14,
		sum15,
		sum16,
		sum17,
		sum18,
		sum19,
		sum20,
		sum21,
		sum22,
		sum23,
		sum24,
		sum25,
		sum26,
		sum27,
		sum28,
		sum29,
		sum30;	

always@(posedge	clk_31)
begin
	if(!rst)
		flag		<=31'd1;
	if(en)
	begin
		indata_buf	<=indata;
		case(i)
		1:	flag[1]	<=1'b1;
		2:	flag[2]	<=1'b1;
		3:	flag[3]	<=1'b1;
		4:	flag[4]	<=1'b1;
		5:	flag[5]	<=1'b1;
		6:	flag[6]	<=1'b1;
		7:	flag[7]	<=1'b1;
		8:	flag[8]	<=1'b1;
		9:	flag[9]	<=1'b1;
		10:	flag[10]<=1'b1;
		11:	flag[11]<=1'b1;
		12:	flag[12]<=1'b1;
		13:	flag[13]<=1'b1;
		14:	flag[14]<=1'b1;
		15:	flag[15]<=1'b1;
		16:	flag[16]<=1'b1;
		17:	flag[17]<=1'b1;
		18:	flag[18]<=1'b1;
		19:	flag[19]<=1'b1;
		20:	flag[20]<=1'b1;
		21:	flag[21]<=1'b1;
		22:	flag[22]<=1'b1;
		23:	flag[23]<=1'b1;
		24:	flag[24]<=1'b1;
		25:	flag[25]<=1'b1;
		26:	flag[26]<=1'b1;
		27:	flag[27]<=1'b1;
		28:	flag[28]<=1'b1;
		29:	flag[29]<=1'b1;
		30:	flag[30]<=1'b1;		
		
		endcase
	end
end

always@(posedge	clk_31)
begin
	if(!rst)
	begin  
		i		<=9'd0;  
		j		<=9'd0;       	
		sum0		<=9'd50;
		sum1		<=9'd50;
		sum2		<=9'd50;
		sum3		<=9'd50;
		sum4		<=9'd50;
		sum5		<=9'd50;
		sum6		<=9'd50;
		sum7		<=9'd50;
		sum8		<=9'd50;
		sum9		<=9'd50;
		sum10		<=9'd50;
		sum11		<=9'd50;
		sum12		<=9'd50;
		sum13		<=9'd50;
		sum14		<=9'd50;
		sum15		<=9'd50;
		sum16		<=9'd50;
		sum17		<=9'd50;
		sum18		<=9'd50;
		sum19		<=9'd50;
		sum20		<=9'd50;
		sum21		<=9'd50;
		sum22		<=9'd50;
		sum23		<=9'd50;
		sum24		<=9'd50;
		sum25		<=9'd50;
		sum26		<=9'd50;
		sum27		<=9'd50;
		sum28		<=9'd50;
		sum29		<=9'd50;
		sum30		<=9'd50;
		sum		<=9'd50;
		enable		<=1'b0;
		state		<=find_head;
	end
	else
	if(en)
	begin
		case(state)
		find_head:
		begin
		if(!enable)
			enable	<=1'b1;
		else
		begin
			if(flag[0])
			begin
				i1	<=i;
				if(indata[2]==m[i])
				sum0	<=sum0+{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				else
				sum0	<=sum0-{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				if(i==30)
				begin
					i	<=9'd0;
					if(sum0>=75)
					begin
						outdata	<=1'b1;
						state	<=main_body;
					end
					else
					state	<=find_head;
				end
				else
					i	<=i+1;
			end
			if(flag[1])
			begin
				i2	<=i1;
				if(indata[2]==m[i1])
				sum1	<=sum1+{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				else
				sum1	<=sum1-{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				if(i1==30)
				begin
					i1	<=9'd0;
					if(sum1>=75)
					begin
						outdata	<=1'b1;
						state	<=main_body;
					end
					else
					state	<=find_head;
				end
			end
			if(flag[2])
			begin
				i3	<=i2;
				if(indata[2]==m[i2])
				sum2	<=sum2+{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				else
				sum2	<=sum2-{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				if(i2==30)
				begin
					i2	<=9'd0;
					if(sum2>=75)
					begin
						outdata	<=1'b1;
						state	<=main_body;
					end
					else
					state	<=find_head;
				end
			end
			if(flag[3])
			begin
				i4	<=i3;
				if(indata[2]==m[i3])
				sum3	<=sum3+{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				else
				sum3	<=sum3-{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				if(i3==30)
				begin
					i3	<=9'd0;
					if(sum3>=75)
					begin
						outdata	<=1'b1;
						state	<=main_body;
					end
					else
					state	<=find_head;
				end
			end
			if(flag[4])
			begin
				i5	<=i4;
				if(indata[2]==m[i4])
				sum4	<=sum4+{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				else
				sum4	<=sum4-{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				if(i1==30)
				begin
					i4	<=9'd0;
					if(sum2>=75)
					begin
						outdata	<=1'b1;
						state	<=main_body;
					end
					else
					state	<=find_head;
				end
			end
			if(flag[5])
			begin
				i6	<=i5;
				if(indata[2]==m[i5])
				sum5	<=sum5+{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				else
				sum5	<=sum5-{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				if(i5==30)
				begin
					i5	<=9'd0;
					if(sum5>=75)
					begin
						outdata	<=1'b1;
						state	<=main_body;
					end
					else
					state	<=find_head;
				end
			end
			if(flag[6])
			begin
				i7	<=i6;
				if(indata[2]==m[i6])
				sum6	<=sum6+{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				else
				sum6	<=sum6-{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				if(i6==30)
				begin
					i6	<=9'd0;
					if(sum6>=75)
					begin
						outdata	<=1'b1;
						state	<=main_body;
					end
					else
					state	<=find_head;
				end
			end
			if(flag[7])
			begin
				i8	<=i7;
				if(indata[2]==m[i7])
				sum7	<=sum7+{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				else
				sum7	<=sum7-{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				if(i7==30)
				begin
					i7	<=9'd0;
					if(sum7>=75)
					begin
						outdata	<=1'b1;
						state	<=main_body;
					end
					else
					state	<=find_head;
				end
			end
			if(flag[8])
			begin
				i9	<=i8;
				if(indata[2]==m[i8])
				sum8	<=sum8+{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				else
				sum8	<=sum8-{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				if(i8==30)
				begin
					i8	<=9'd0;
					if(sum8>=75)
					begin
						outdata	<=1'b1;
						state	<=main_body;
					end
					else
					state	<=find_head;
				end
			end
			if(flag[9])
			begin
				i10	<=i9;
				if(indata[2]==m[i9])
				sum9	<=sum9+{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				else
				sum9	<=sum9-{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				if(i9==30)
				begin
					i9	<=9'd0;
					if(sum9>=75)
					begin
						outdata	<=1'b1;
						state	<=main_body;
					end
					else
					state	<=find_head;
				end
			end
			if(flag[10])
			begin
				i11	<=i10;
				if(indata[2]==m[i10])
				sum10	<=sum10+{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				else
				sum10	<=sum10-{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				if(i10==30)
				begin
					i10	<=9'd0;
					if(sum10>=75)
					begin
						outdata	<=1'b1;
						state	<=main_body;
					end
					else
					state	<=find_head;
				end
			end
			if(flag[11])
			begin
				i12	<=i11;
				if(indata[2]==m[i11])
				sum11	<=sum11+{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				else
				sum11	<=sum11-{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				if(i11==30)
				begin
					i11	<=9'd0;
					if(sum11>=75)
					begin
						outdata	<=1'b1;
						state	<=main_body;
					end
					else
					state	<=find_head;
				end
			end
			if(flag[12])
			begin
				i13	<=i12;
				if(indata[2]==m[i12])
				sum12	<=sum12+{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				else
				sum12	<=sum12-{((indata[2]^indata[1])||((indata[2]
					&&indata[1])&&(!indata[0]))),indata[0]};
				if(i12==30)
				begin