Rên4_0b

Sound create use FM synthesis use C program. Use 0.5 - 0.5*cos(time*π •2/3 ) envelop.

Algorithm 7 of YM2515 chip (not use chip, only follow its algorithm in C program)
• no feedback
• ampl_m1 = 335
• ampl_m2 = 258
• ampl_c1 = 452
• ampl_c2 = 304

• freq_m1 = 3512320
• freq_m2 = 1582080
• freq_c1 = 13424640
• freq_c2 = 1118720

Random change frequency every 8 sample
 (random number range ±1, use same random number for all 4 oscillator)
• new_freq = base_freq_ + range_xx*randomNumber
• base frequency for new frequency change

range_m1 = 220000

range_m2 = 320000

range_c1 = 220000

range_c2 = 22000