Hi there,
I was diving in the Faust mailing lists when I stumbled upon an example
using the enable() function:
gen(N) =
par(i, N, os.osc(200*(i+1)) : enable(hslider("oscillators",0,0,N,1) : int :
>(i))) :> _ <: _,_;
process = gen(5);
I wasn't able to find the documentation of enable() and I'm not entirely
sure of what it does but I took a look at the C++ code produced.
virtual void compute(int count, FAUSTFLOAT** RESTRICT inputs, FAUSTFLOAT**
RESTRICT outputs) {
FAUSTFLOAT* output0 = outputs[0];
FAUSTFLOAT* output1 = outputs[1];
int iSlow0 = int(float(fHslider0));
float fSlow1 = float((iSlow0 > 0));
int iSlow2 = (fSlow1 != 0.0f); This test seems to be the enable condition
in the 1st branch of the par iteration
float fTemp0 = fTempPerm0;
float fSlow3 = float((iSlow0 > 1)); This test seems to be the enable
condition in the 2nd branch of the par
int iSlow4 = (fSlow3 != 0.0f);
float fTemp1 = fTempPerm1;
for (int i0 = 0; (i0 < count); i0 = (i0 + 1)) {
if (iSlow2) {
This code isn't executed when iSlow2 is false avoiding unnecessary
computation relative to the oscillator
fRec1[0] = (fConst1 + (fRec1[1] - std::floor((fConst1 + fRec1[1]))));
fConst1 equals 200 which is the frequency of the first oscillator
fTemp0 = (fSlow1 * ftbl0mydspSIG0[int((65536.0f * fRec1[0]))]);
}
if (iSlow4) {
And here the same for the second enable condition
fRec2[0] = (fConst2 + (fRec2[1] - std::floor((fConst2 + fRec2[1]))));
fConst2 equals 400
fTemp1 = (fSlow3 * ftbl0mydspSIG0[int((65536.0f * fRec2[0]))]);
}
float fTemp2 = (fTemp0 + fTemp1);
output0[i0] = FAUSTFLOAT(fTemp2);
output1[i0] = FAUSTFLOAT(fTemp2);
Not sure what the 2 following ifs do (buffer swapping?)
if (iSlow2) {
fRec1[1] = fRec1[0];
}
if (iSlow4) {
fRec2[1] = fRec2[0];
}
}
fTempPerm0 = fTemp0;
fTempPerm1 = fTemp1;
}
So the enable() function (I should say primitive btw) seems to avoid
unnecessary computation when it is disabled.
Am I right?
Best regards,
jlp
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