52 lines
1.7 KiB
Verilog
52 lines
1.7 KiB
Verilog
/// @Author: Alexandre Felipe (o.alexandre.felipe@gmail.com)
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/// @Date: 2018-Jan-25
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///
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class fft_definition_checker #(
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parameter LOG2_NS = 3,
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parameter NS = 1<<LOG2_NS,
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parameter NB = 10);
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rand logic [NB:0] x_bits[0:NS-1][1:0];
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static real TWO_PI = 2.0*math_pkg::atan2(0.0, -1.0);
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real w[0:NS-1][1:0];
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function new;
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foreach(w[i]) begin
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w[i][0] = math_pkg::cos(TWO_PI * i / real'(NS));
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w[i][1] =-math_pkg::sin(TWO_PI * i / real'(NS));
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end
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endfunction
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function void post_randomize;
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real x[0:NS-1][1:0];
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real X[0:NS-1][1:0];
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real X_ref[0:NS-1][1:0];
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real errorEnergy;
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begin
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// Convert randomized binary numbers to real (floating point)
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foreach(x_bits[i]) begin
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x[i][0] = x_bits[i][0];
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x[i][1] = x_bits[i][1];
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end
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//// START THE MAGIC HERE ////
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fft_fp #(.LOG2_NS(LOG2_NS), .NS(NS))::transform(x, X);
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//// END OF THE MAGIC ////
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/// Calculate X_ref, the discrete Fourier transform by the definition ///
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foreach(X_ref[k]) begin
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X_ref[k] = '{0.0, 0.0};
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foreach(x[i]) begin
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X_ref[k][0] = X_ref[k][0] + x[i][0] * w[(i*k) % NS][0] - x[i][1] * w[(i*k) % NS][1];
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X_ref[k][1] = X_ref[k][1] + x[i][0] * w[(i*k) % NS][1] + x[i][1] * w[(i*k) % NS][0];
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end
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end
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// Measure the error
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errorEnergy = 0.0;
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foreach(X[k]) begin
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errorEnergy = errorEnergy + (X_ref[k][0] - X[k][0]) * (X_ref[k][0] - X[k][0]);
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errorEnergy = errorEnergy + (X_ref[k][1] - X[k][1]) * (X_ref[k][1] - X[k][1]);
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end
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$display("FFT of %d integers %d bits (error @ %g)", NS, NB, errorEnergy / real'(NS));
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end
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endfunction
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endclass
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