• Andrej Mitrovic (37/37) Apr 28 2011 Here's a little 100-line thingy that generates a wavetable of some

Andrej Mitrovic <andrej.mitrovich gmail.com> writes:

Here's a little 100-line thingy that generates a wavetable of some
shape (sine, saw, square - although only sine is implemented at the
moment), of any length, and of either float or double element type. It
stores this inside a struct which can also keep a number of different
phases, which do bounds checking themselves and wrap around themselves
when the phase reaches a limit.

https://gist.github.com/947429

The cool thing about this is that it's all done at compile time. And,
yes it does actually work! I have tested it with ASIO realtime
playback and I can hear the sounds of sines.

You can even have some fun and generate pitch changes using
randomization by controlling the phase stepping. Here's a little
snippet from my other code which generates some random melodic tones
with sinewaves:

// generate a new phase half-way through the buffer.
// If the buffer is filled with 22050 samples per second,
// the phase stepping will change every half of a second.
int step = inputBuffer.length / 2;
int index;
foreach (ref sample; inputBuffer)
{
    if (index == step)  // generate new stepping
    {
        index = 0;
        leftPhase = uniform(1, 7);
        rigthPhase = uniform(1, 7);
    }
    index++;

    if (channel.channel == 0)  // left channel
    {
        sample = audioTable.table[audioTable.phase[0] += step];
    }
    else if (channel.channel == 1)  // right channel
    {
        sample = audioTable.table[audioTable.phase[1] += step+2];
    }
}