Question

我编写了以下代码，使用Cordic算法生成正弦角。以下是为给定角度生成x，y，z坐标的代码的一部分。

genvar i;
generate
  for (i=0; i < (width-1); i=i+1) begin 
    wire z_sign;
    wire signed [width-1:0] x_shr, y_shr;
    assign x_shr = x[i] >>> i; // signed shift right
    assign y_shr = y[i] >>> i;

    initial begin
      #20 $display("x_shr = %b, y_shr = %b ",x_shr,y_shr);
    end

    //the sign of the current rotation angle

    assign z_sign = z[i][31];
    always @(posedge clock) begin
      // add/subtract shifted data
      x[i+1] <= z_sign ? x[i] + y_shr : x[i] - y_shr;
      y[i+1] <= z_sign ? y[i] - x_shr : y[i] + x_shr;
      z[i+1] <= z_sign ? z[i] + atan_table[i] : z[i] - atan_table[i];

      #25 $display("x[%d] = %b",i,x[i]);

    end
  end
endgenerate

给出的输入是：

x_shr = 'b0000000000000100;
y_shr = 'b0000000000000000;

z_sign是z [i]：

的符号

z[0] = 'b00100000000000000000000000000000;
width = 16;
x[0] <= 'b0000000000000100;
y[0] <= 'b0;

所有声明如下

parameter width = 16;
// Inputs
input clock;
input signed [width-1:0] x_start,y_start;
reg signed [width-1:0] x [0:width-1];
reg signed [width-1:0] y [0:width-1];
reg signed [31:0] z [0:width-1];

但我得到的输出是

x_shr = 0000000000000100, y_shr = 0000000000000000 
x_shr = xxxxxxxxxxxxxxxx, y_shr = xxxxxxxxxxxxxxxx 
x_shr = xxxxxxxxxxxxxxxx, y_shr = xxxxxxxxxxxxxxxx 
x_shr = xxxxxxxxxxxxxxxx, y_shr = xxxxxxxxxxxxxxxx 
x_shr = xxxxxxxxxxxxxxxx, y_shr = xxxxxxxxxxxxxxxx 
x_shr = xxxxxxxxxxxxxxxx, y_shr = xxxxxxxxxxxxxxxx 
x_shr = xxxxxxxxxxxxxxxx, y_shr = xxxxxxxxxxxxxxxx 
x_shr = xxxxxxxxxxxxxxxx, y_shr = xxxxxxxxxxxxxxxx 
x_shr = xxxxxxxxxxxxxxxx, y_shr = xxxxxxxxxxxxxxxx 
x_shr = xxxxxxxxxxxxxxxx, y_shr = xxxxxxxxxxxxxxxx 
x_shr = xxxxxxxxxxxxxxxx, y_shr = xxxxxxxxxxxxxxxx 
x_shr = xxxxxxxxxxxxxxxx, y_shr = xxxxxxxxxxxxxxxx 
x_shr = xxxxxxxxxxxxxxxx, y_shr = xxxxxxxxxxxxxxxx 
x_shr = xxxxxxxxxxxxxxxx, y_shr = xxxxxxxxxxxxxxxx 
x_shr = xxxxxxxxxxxxxxxx, y_shr = xxxxxxxxxxxxxxxx 
x[ 14] = xxxxxxxxxxxxxxxx
x[ 13] = xxxxxxxxxxxxxxxx
x[ 12] = xxxxxxxxxxxxxxxx
x[ 11] = xxxxxxxxxxxxxxxx
x[ 10] = xxxxxxxxxxxxxxxx
x[  9] = xxxxxxxxxxxxxxxx
x[  8] = xxxxxxxxxxxxxxxx
x[ 7] = xxxxxxxxxxxxxxxx
x[ 6] = xxxxxxxxxxxxxxxx
x[ 5] = xxxxxxxxxxxxxxxx
x[ 4] = xxxxxxxxxxxxxxxx
x[ 3] = xxxxxxxxxxxxxxxx
x[ 2] = xxxxxxxxxxxxxxxx
x[ 1] = xxxxxxxxxxxxxxxx
x[ 0] = 0000000000000100

为什么我在单次迭代后得到x？

Answer 1

如果显示Z的值，则会看到Z未提供初始值。这最终会将X和Y驱动到'x'。所以，也为Z提供初始值。

Verilog代码生成“不关心”迭代

1 个答案: