Single-file cordic fixing most of the quirks of the previous implementation with testbench.

441147e0 · Nathan Pittet · d49f61cb · 441147e0 · 441147e0 · 441147e0
Commit 441147e0 authored Feb 17, 2023 by Nathan Pittet
6 changed files
--- a/modules/dsp/Manifest.py
+++ b/modules/dsp/Manifest.py
@@ -6,6 +6,7 @@ files = ["cordic_init.vhd",
         "gc_pipelined_fir_filter.vhd",
         "gc_cordic_pkg.vhd",
         "gc_cordic.vhd",
+         "gc_cordic_top.vhd",
         "gc_dsp_pkg.vhd",
         "gc_iq_demodulator.vhd",
         "gc_iq_modulator.vhd",

--- a/modules/dsp/gc_cordic_pkg.vhd
+++ b/modules/dsp/gc_cordic_pkg.vhd
@@ -29,6 +29,7 @@
 library ieee;
 use ieee.std_logic_1164.all;
 use ieee.numeric_std.all;
+use ieee.math_real.all;

 package gc_cordic_pkg is

@@ -108,6 +109,8 @@ package gc_cordic_pkg is
  constant c_FSDegMinus180HD : signed(31 downto 0) := X"80000000";
  constant c_FSDegZeroHD     : signed(31 downto 0) := X"00000000";

+  function f_compute_an(nbits : integer) return std_logic_vector;
+
 -- Cordic Sequencer Iteration Constants
  constant c_CirIter   : std_logic_vector(4 downto 0) := '0'&X"D";
  constant c_LinIter   : std_logic_vector(4 downto 0) := '0'&X"F";
@@ -157,6 +160,18 @@ end package;

 package body gc_cordic_pkg is

+  function f_compute_an(nbits : integer) return std_logic_vector is
+    variable v_an : real := 1.0;
+    variable v_ret : std_logic_vector(nbits-1 downto 0);
+  begin
+    for i in 0 to nbits-1 loop
+      v_an := v_an * sqrt(1.0+2.0**(-2*i));
+    end loop;
+    v_ret := std_logic_vector(to_signed(integer((1.0/v_an)*(2.0**(nbits-1))), nbits));
+    return v_ret;
+  end function f_compute_an;
+
+
  procedure f_limit_subtract
    (use_limiter :     boolean;
     a, b        : in  signed;
@@ -166,7 +181,7 @@ package body gc_cordic_pkg is
    constant c_min_val : signed(o'range)           := ('1', others => '0');
    variable l_sum     : signed(O'length downto 0) := (others      => '0');
  begin
-    l_sum := resize(a, o'length+1) - resize(b, o'length-1);
+    l_sum := a(a'left)&a - b;

    if not use_limiter then
      o   := l_sum(o'range);
@@ -193,9 +208,9 @@ package body gc_cordic_pkg is
      lim         : out std_logic) is
    constant c_max_val : signed(o'range)           := ('0', others => '1');
    constant c_min_val : signed(o'range)           := ('1', others => '0');
-    variable l_sum     : signed(O'length downto 0) := (others      => '0');
+    variable l_sum     : signed(o'length downto 0) := (others      => '0');
  begin
-    l_sum := resize(a, o'length+1) + resize(b, o'length-1);
+    l_sum := a(a'left)&a + b;

    if not use_limiter then
      o   := l_sum(o'range);
@@ -225,7 +240,7 @@ package body gc_cordic_pkg is
      if x = c_min_val and use_limiter then
        return c_max_val;
      else
-        return not x (x'length-1 downto 0) + 1;
+        return not x(x'length-1 downto 0)+1;
      end if;
    else
      return x;

--- a/modules/dsp/gc_cordic_top.vhd
+++ b/modules/dsp/gc_cordic_top.vhd
--- a/testbench/dsp/gc_cordic/Manifest.py
+++ b/testbench/dsp/gc_cordic/Manifest.py
@@ -21,4 +21,5 @@ modules = {

 files = [
    "main.sv",
+    "gc_cordic_tb.vhd"
 ]
--- a/testbench/dsp/gc_cordic/cordic_error_measurement.py
+++ b/testbench/dsp/gc_cordic/cordic_error_measurement.py
+import matplotlib.pyplot as plt
+import pandas as pd
+
+def main():
+    filename = "res.txt"
+    data = pd.read_csv(filename, header=None, names=["ix", "iy", "iz","ox", "oy", "oz", "ex", "ey", "ez", "mode", "submode"])
+    
+    data["mode"][data["mode"] == 0] = "vector"
+    data["mode"][data["mode"] == 1] = "rotate"
+
+    data["submode"][data["submode"] == 0] = "circular"
+    data["submode"][data["submode"] == 1] = "linear"
+
+    data.insert(len(data.columns), "err_x",abs(data["ox"]-data["ex"]))
+    data.insert(len(data.columns), "err_y",abs(data["oy"]-data["ey"]))
+    data.insert(len(data.columns), "err_z",abs(data["oz"]-data["ez"]))
+
+    print(data)
+    
+    rotcirc      = data[data["mode"] == "rotate"]
+    rotcirc      = rotcirc[rotcirc["submode"] == "circular"]
+
+    rotlinear      = data[data["mode"] == "rotate"]
+    rotlinear      = rotlinear[rotlinear["submode"] == "linear"]
+    
+    vectcirc      = data[data["mode"] == "vector"]
+    vectcirc      = vectcirc[vectcirc["submode"] == "circular"]
+
+    vectlinear      = data[data["mode"] == "vector"]
+    vectlinear      = vectlinear[vectlinear["submode"] == "linear"]
+    
+    print(rotcirc      )
+    print(rotlinear    )
+    print(vectcirc   )
+    print(vectlinear )
+
+    # How is error defined ?
+    # rotate/Circular -> 2 errors, xo and yo
+    # rotate/linear -> 2 errors, x and y
+    # vector/circular -> 2 errors, x and z
+    # vector/linear -> 2 errors, x and z
+    
+    
+    import numpy as np
+     
+    fig = plt.figure()
+     
+    # syntax for 3-D projection
+    ax = plt.axes(projection ='3d')
+     
+    # defining axes
+    x = vectcirc["ix"]
+    y = vectcirc["iy"]
+    z = vectcirc["iz"]
+    err_x = vectcirc["err_x"]
+    err_y = vectcirc["err_y"]
+    err_z = vectcirc["err_z"]
+
+    
+    plt.subplot(4,3,1)
+    plt.plot(x, err_x, 'x')
+    plt.plot(y, err_x, 'x')
+    plt.plot(z, err_x, 'x')
+    #plt.legend(["errx = f(x)", "errx = f(y)", "errx = f(z)"])
+    plt.title("vect/circle : magnitude error")
+
+    plt.subplot(4,3,2)
+    plt.plot(x, err_y, 'x')
+    plt.plot(y, err_y, 'x')
+    plt.plot(z, err_y, 'x')
+    #plt.legend(["erry = f(x)", "erry = f(y)", "erry = f(z)"])
+    plt.title("vector/circle")
+
+    plt.subplot(4,3,3)
+    plt.plot(x, err_z, 'x')
+    plt.plot(y, err_z, 'x')
+    plt.plot(z, err_z, 'x')
+    #plt.legend(["errz = f(x)", "errz = f(y)", "errz = f(z)"])
+    plt.title("vector/circle : angle error")
+
+    x = rotcirc["ix"]
+    y = rotcirc["iy"]
+    z = rotcirc["iz"]
+    err_x = rotcirc["err_x"]
+    err_y = rotcirc["err_y"]
+    err_z = rotcirc["err_z"]
+
+    
+    plt.subplot(4,3,4)
+    plt.plot(x, err_x, 'x')
+    plt.plot(y, err_x, 'x')
+    plt.plot(z, err_x, 'x')
+    #plt.legend(["errx = f(x)", "errx = f(y)", "errx = f(z)"])
+    plt.title("rotate/circle")
+
+    plt.subplot(4,3,5)
+    plt.plot(x, err_y, 'x')
+    plt.plot(y, err_y, 'x')
+    plt.plot(z, err_y, 'x')
+    #plt.legend(["erry = f(x)", "erry = f(y)", "erry = f(z)"])
+    plt.title("rotate/circle")
+
+    plt.subplot(4,3,6)
+    plt.plot(x, err_z, 'x')
+    plt.plot(y, err_z, 'x')
+    plt.plot(z, err_z, 'x')
+    #plt.legend(["errz = f(x)", "errz = f(y)", "errz = f(z)"])
+    plt.title("rotate/circle")
+
+    x = rotlinear["ix"]
+    y = rotlinear["iy"]
+    z = rotlinear["iz"]
+    err_x = rotlinear["err_x"]
+    err_y = rotlinear["err_y"]
+    err_z = rotlinear["err_z"]
+    
+    plt.subplot(4,3,7)
+    plt.plot(x, err_x, 'x')
+    plt.plot(y, err_x, 'x')
+    plt.plot(z, err_x, 'x')
+    #plt.legend(["errx = f(x)", "errx = f(y)", "errx = f(z)"])
+    plt.title("rotate/linear")
+
+    plt.subplot(4,3,8)
+    plt.plot(x, err_y, 'x')
+    plt.plot(y, err_y, 'x')
+    plt.plot(z, err_y, 'x')
+    #plt.legend(["erry = f(x)", "erry = f(y)", "erry = f(z)"])
+    plt.title("rotate/linear")
+
+    plt.subplot(4,3,9)
+    plt.plot(x, err_z, 'x')
+    plt.plot(y, err_z, 'x')
+    plt.plot(z, err_z, 'x')
+    #plt.legend(["errz = f(x)", "errz = f(y)", "errz = f(z)"])
+    plt.title("rotate/linear")
+
+    x = vectlinear["ix"]
+    y = vectlinear["iy"]
+    z = vectlinear["iz"]
+    xy = vectlinear["iy"]/vectlinear["ix"]
+    err_x = vectlinear["err_x"]
+    err_y = vectlinear["err_y"]
+    err_z = vectlinear["err_z"]
+
+    
+    plt.subplot(4,3,10)
+    plt.plot(xy, err_x, 'x')
+    plt.plot(xy, err_y, 'x')
+    plt.plot(xy, err_z, 'x')
+    #plt.legend(["errx = f(y/x)", "erry = f(y/x)", "errz = f(y/x)"])
+    plt.title("vector/linear: ratio error = f(ratio)")
+
+    plt.subplot(4,3,11)
+    plt.plot(x, err_y, 'x')
+    plt.plot(y, err_y, 'x')
+    plt.plot(z, err_y, 'x')
+    #plt.legend(["erry = f(x)", "erry = f(y)", "erry = f(z)"])
+    plt.title("vector/linear")
+
+    plt.subplot(4,3,12)
+    plt.plot(x, err_z, 'x')
+    plt.plot(y, err_z, 'x')
+    plt.plot(z, err_z, 'x')
+    #plt.legend(["errz = f(x)", "errz = f(y)", "errz = f(z)"])
+    plt.title("vector/linear: ratio error")
+
+     
+     
+    plt.show()
+    
+
+if __name__ == "__main__":
+    main()
\ No newline at end of file
--- a/testbench/dsp/gc_cordic/gc_cordic_tb.vhd
+++ b/testbench/dsp/gc_cordic/gc_cordic_tb.vhd