ゲームボーイのノイズ音源の波形を表示するガバガバプログラム

gbnoise.py

import numpy as np
import matplotlib.pyplot as plt

def noize(shortFreq):
  reg = 0xffff
  output = 1
  fre = list()
  for i in range(300):
    if(reg == 0):
      reg = 1
    reg += reg + (((reg >> (6 if shortFreq else 14)) ^ (reg >> (5 if shortFreq else 13))) & 1)
    output = output ^ (reg & 1)
    fre.append((output-0.5)*-1)
  return fre

xmin = 0
xmax = 300
fig = plt.figure(figsize=(20, 3))

axes1 = fig.add_subplot(1, 2, 1)
x=np.arange(xmin, xmax, 1)
y=noize(False)
plt.xlim(0, 300)
plt.ylim(-1, 1)
plt.xticks(color="None")
plt.yticks(color="None")
plt.tick_params(length=0)
axes1.plot(x, y, label="Long period noise")
plt.legend(loc='upper left')

axes1 = fig.add_subplot(1, 2, 2)
x=np.arange(xmin, xmax, 1)
y=noize(True)
plt.xlim(0, 300)
plt.ylim(-1, 1)
plt.xticks(color="None")
plt.yticks(color="None")
plt.tick_params(length=0)
axes1.plot(x, y, label="Short period noise")
plt.legend(loc='upper left')

plt.show()