[sdiy] help understanding circular buffers for delay line

[dan snazelle]

lately i have been spending a lot of time in XCODE trying to understand programming for audio.
 I am trying hard to understand how to make a delay line or echo, flanger, etc.

I even found some example code but usually, the code doesnt show how to get your ADC input into the code and your  DAC output out



can anyone here help me understand the basics of writing a circular buffer delay line?

I have heard that this is an application where pointers can be very useful


thanks for any help






example code below:



	float vdelay_tick(VDELAY* vdelay, float input, double vlength)
{

unsigned long readpos, vlength_samps; 
float output;
 float* buf = vdelay->buffer; 
/* calculate delay length from stored sample rate */
 vlength_samps = (unsigned long)(vlength * vdelay->srate);
 /* find required readpos from supplied vlength */
readpos = vdelay->writepos + vlength_samps; 
/* wrap around buffer as usual */
 if(readpos >= vdelay->maxlenth)
readpos -= vdelay->maxlength; 
output = buf[readpos]; 
/* add in new input with the usual wrap-around */
 buf[vdelay->writepos++] = input; 
if(vdelay->writepos == vdelay->maxlength)
vdelay->writepos = 0; 
return output;

}