May 13 2021, Fons Adriaensen has written:
  On Thu, May 13, 2021 at 09:14:47AM +0200, Jeanette C.
wrote:
 I get a 'smooth' waveform whch makes be believe the result is correct,
 but it certainly is not a sine wave. No fundamental F1, very strong
 4 * F1, 6 * F1, 11 * F1.
 How does it sound ? 
Many, many thanks, Fons! I can't exactly say how it sounds,
because I
don't have a listing of waveforms within wavetables. But there is a list
of all spectra, as images, I think this is it:
http://www.carbon111.com/300waves.pdf
What did you do to combine the nibbles into the final sample? I tried
something like:
char sysex_string[128];
signed char samples[64];
... // fill string
for (int item = 0;item<64;item++)
{
   sample[item] = (sysex_string[item /2])^0x80 + (sysex_string[(item / 2) +1]
     <<4);
}
I also tried by ^'ing the finished value with 0x80. Perhaps somewhere I
got the correct sample, but because I expected the sine, I didn't
believe my own code. :)
Best wishes,
Jeanette
 --
 FA
 
--
  * Website: 
http://juliencoder.de - for summer is a state of sound
  * Youtube: 
https://www.youtube.com/channel/UCMS4rfGrTwz8W7jhC1Jnv7g
  * Audiobombs: 
https://www.audiobombs.com/users/jeanette_c
  * GitHub: 
https://github.com/jeanette-c
And when you say those words
It's the sweetest thing I've ever heard <3
(Britney Spears)