69 lines
1.5 KiB
Python
Executable file
69 lines
1.5 KiB
Python
Executable file
#!/usr/bin/env python3
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import sys
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from math import *
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preamble = """// This file was auto-generated using gen_lut.py
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#include "lut.h"
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"""
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postamble = """
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value_type lookup_sin(int layer, int element) {
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return sin_lut[layer][element];
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}
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value_type lookup_cos(int layer, int element) {
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return cos_lut[layer][element];
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}
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"""
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if len(sys.argv) < 2:
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print("Argument required: FFT_EXPONENT")
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exit(1)
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fft_exponent = int(sys.argv[1])
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with open("lut.c", "w") as ofile:
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ofile.write(preamble)
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# generate the sin() lookup table
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for layer in range(0, fft_exponent):
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num_elements = (1 << layer)
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ofile.write("value_type sin_lut%i[%i] = {" % (layer, num_elements))
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ofile.write("0")
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for element in range(1, num_elements):
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ofile.write(", %.10f" % sin(-pi * element / num_elements));
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ofile.write("};\n\n")
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ofile.write("value_type *sin_lut[%i] = {sin_lut0" % fft_exponent);
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for i in range(1, fft_exponent):
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ofile.write(", sin_lut" + str(i));
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ofile.write("};\n");
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# generate the cos() lookup table
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for layer in range(0, fft_exponent):
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num_elements = (1 << layer)
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ofile.write("value_type cos_lut%i[%i] = {" % (layer, num_elements))
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ofile.write("1")
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for element in range(1, num_elements):
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ofile.write(", %.10f" % cos(-pi * element / num_elements));
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ofile.write("};\n\n")
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ofile.write("value_type *cos_lut[%i] = {cos_lut0" % fft_exponent);
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for i in range(1, fft_exponent):
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ofile.write(", cos_lut" + str(i));
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ofile.write("};\n");
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ofile.write(postamble)
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