Re: [sc-dev] Impulse UGen Fix: was Re: [sc-users] is this really phase offset?

[James McCartney <asynth@xxxxxx>]

> void Impulse_next_aa(Impulse *unit, int inNumSamples)
> {
> 	float *out = ZOUT(0);
> 	float *freq = ZIN(0);
> 	float *phaseOffset =  ZIN(1);
> 	
> 	float freqmul = unit->mFreqMul;
> 	double phase = unit->mPhase;
> 	double rate_acum = unit->mPhase;
> 	//	double phaseSlope = CALCSLOPE(phaseOffset, prev_phaseOffset);
> 	phase += unit->mPhaseOffset;
> 	
> 	LOOP(inNumSamples,
> 		float z;
> 	
> 		if (phase >= 1.f) {
> 			rate_acum -= 1.f;
> 			z = 1.f;
> 		} else if (phase < 0.f) {
> 		  rate_acum += 1.f;
> 		  z = 1.f;
>                 }
>                 else {
> 			z = 0.f;
> 		}
> 		rate_acum += (ZXP(freq) * freqmul);
>                 phase = rate_acum + ZXP(phaseOffset);
> 		ZXP(out) = z;
> 	);
>
> 	unit->mPhase = rate_acum;
> 	unit->mPhaseOffset = phase - rate_acum;
> }

This is not correct. The phase modulation should not be accumulated 
into the phase. Phase modulation always comes after the phase 
accumulator. If phase modulation is audio rate, I don't see a reason to 
store mPhaseOffset. The phase offset is updated every sample, so 
storing it should be unecessary. All you need to store is phase.