Using abs and sign in code

1

Hi guys

Im gonna try a bit of multipication and division on samples so Im gonna need to use the abs/sign trick. Ie only done that in JSFX and ahve no idea how do implement it in iPlug2-

So is a there any bit of code I can check to see how its supposed to look? Tips appreciated :slight_smile:

Sincerely /Bo

2

what is the abs sign trick?

3

Hi Oli

Its the process of making all sample values positive and then do the math. Then revert back the negative values via the sig/sign. In JSFX it would look like this:

s0 = abs(spl0);
//Do math
spl0 = s0 * sign(spl0);

Also. How does iPlug2 handle divide by zero? Any best practice?

Sincerely /Bo

4

These are more C++ questions than iPlug2. the C++ standard library has std::abs() and std::copysign() which I think are the equivalents

5

Hi

I see. Thanks for clarifying :slight_smile:

Sincerely /Bo

6

My practice is simple:

int sign;
if (inputs[c][s] < 0.) sign = -1;
else sign = 1;
outputs[c][s] = inputs[c][s] * sign;
// Do the Math …
outputs[c][s] *= sign;

and slightly faster than:

outputs[c][s] = std::abs(inputs[c][s]);
// Do the Math …
outputs[c][s] = std::copysign(outputs[c][s] , inputs[c][s]);

:sunglasses:

1 Like
7

Thanks John

Thats exactly what I what looking for :slight_smile:

Sincerely /Bo

1 Like