clifft

#!/usr/bin/env python

import sys
import numpy as np
import math
import subprocess

def main():
    bins = 128

    signal = np.frombuffer(sys.stdin.read(), dtype=np.complex64)

    window = 0.5 * (1.0 - np.cos((2 * math.pi * np.arange(bins)) / bins))
    window /= np.sqrt(np.sum(window**2))
    segment = int(bins / 2)
    nsegments = int(len(signal) / segment)
    m = np.repeat(np.reshape(signal[0:segment * nsegments], (nsegments, segment)), 2, axis=0)
    t = np.reshape(m[1:len(m) - 1], (nsegments - 1, bins))
    psd = np.sum(np.abs(np.fft.fft(np.multiply(t, window)))**2, axis=0) / nsegments
    psd = np.concatenate((psd[len(psd)//2:len(psd)], psd[0:len(psd)//2]))
    y_axis = np.log10(psd)*10
    x_axis = np.arange(len(y_axis), dtype=np.float32)/len(y_axis) - 0.5
    gnuplot_cmds = "set terminal dumb 120 36; set xrange [-0.5:0.5];" \
                   "set yrange [-80:0]; plot \"-\" using 1:2 with lines notitle;"
    cmdline = ["gnuplot", "-e", gnuplot_cmds]
    process = subprocess.Popen(cmdline, stdin=subprocess.PIPE)

    for x, y in zip(x_axis, y_axis):
        process.stdin.write(b"%f\t%f\n" % (x, y))
    process.stdin.close()
    process.wait()

if __name__ == "__main__":
    main()