generating the square wave with pulses - ios

Question

I am trying to modify the method of generating the square wave that
it can generate eight pulses with different pulse width with 0.3ms delay each per a period. I have seen that
sampleBuffer is responsible for generating the pulse signals but i am not sure how to create a function of the pulse for such specific pattern. Would you please tell me whether there is a library function at AudioTrack.h for generating the pulse ?
The below is my code for
generating the square wave
void generateSquare(SInt16 *sampleBuffer, int numFrames, float sampleRate, float frequency, float amp) {
if(amp>1) amp=1;
if(amp<0) amp=0;
amp = amp*SHRT_MAX;
float samplesPerCycle = sampleRate/frequency;
for(int i = 0; i < numFrames; i++) {
if(fmodf(squareIndex, samplesPerCycle)/samplesPerCycle > 0.5) {
sampleBuffer[i] = amp;
} else {
sampleBuffer[i] = -1*amp;
}
squareIndex = squareIndex+1;
if(squareIndex >= samplesPerCycle) squareIndex-=samplesPerCycle;
}
}

Answer 1

Here is my solution for nearly the same problem.
In my case I create pulse with 1ms width, which I modify with the fill value by +/-0.5ms.
So according to fillValue I generate a square wave with 0.5-1.5ms pulse width.
int squareIndex = 0;
void generateSquare(SInt16 *sampleBuffer, int numFrames, float sampleRate, float fillValue, float amp) {
// Fill value = pulse width value in frames
// fillValue = [-20, 20];
if(amp>1) amp=1;
if(amp<0) amp=0;
if(fillValue > 20) fillValue = 20;
if(fillValue < -20) fillValue = -20;
amp = amp*SHRT_MAX;
float samplesPerCycle = sampleRate/50;
//Sample / Cycle = 882
//1ms = 41 frame -> 0.5ms = 20(.5)frame
//In your case 0.3ms = 12(.3) frame
#pragma mark - PWM
for(int i = 0; i < numFrames; i++) {
//if(fmodf(squareIndex, samplesPerCycle)/samplesPerCycle < 0.05) {
if(squareIndex < 41 + fillValue) {
sampleBuffer[i] = 1*SHRT_MAX;
} else {
sampleBuffer[i] = 0;
}
squareIndex = squareIndex+1;
if(squareIndex >= samplesPerCycle) squareIndex-=samplesPerCycle;
}
}