Csound opcode with arbitrary number of input arguments

Developers
#1

Hello dear Csounders!

Is it possible to register a csound opcode with an arbitrary number of input arguments?

So that an opcode can be called with one, two or more e.g. a-values:

  • my_cool_opcode(av1)
  • my_cool_opcode(av1, av2)
  • my_cool_opcode(av1, av2 …. av10)

I guess one way would be something like

void csnd::on_load(Csound *csound) {
  csnd::plugin<MyCoolOpcode>(csound, "my_cool_opcode.a", , "a", csnd::thread::a);
  csnd::plugin<MyCoolOpcode>(csound, "my_cool_opcode.aa", , "aa", csnd::thread::a);
  csnd::plugin<MyCoolOpcode>(csound, "my_cool_opcode.aaa", , "aaa", csnd::thread::a);
  ...  
  csnd::plugin<MyCoolOpcode>(csound, "my_cool_opcode.aaaaaaaaaa", , "aaaaaaaaaa", csnd::thread::a);
}

but this would then mean that I also need to make x-different constructors, something like:

struct MyCoolOpcode : csnd::Plugin<0, 1> {}
struct MyCoolOpcode : csnd::Plugin<0, 2> {}
struct MyCoolOpcode : csnd::Plugin<0, 3> {}
...
struct MyCoolOpcode : csnd::Plugin<0, 10> {}

Is there a more elegant way to do this?

#2

I can’t really help you. But maybe check the code of the linseg opcode out, which can take an arbitrary number of input arguments.

#3

Yes you can use m I think:

You can check the num of args using in_count().

#4

Hi @Philipp and @rory! That is exactly what I was looking for! I think that N is the best type for me since I’m interested in any count/rate i,k,a,S.

But check this out…

If I make following plugin:

struct MyCoolOpcode : csnd::Plugin<1, 'N'> {

    int kperf() {
        int numInputs = in_count();
        for(int i = 0; i < numInputs; i++) {
            std::string input_value ="kperf: input:" + std::to_string(inargs[i]);
            csound->message(input_value);
        }
        return OK;
    }

};

#include <modload.h>

void csnd::on_load(Csound *csound) {
    csnd::plugin<MyCoolOpcode>(csound, "cooling.N", "k", "N", csnd::thread::k);
}

I can use it as expected in an instrument:

instr 1
    k1 = 1
    k2 = 2
    k3 = cooling(k1, k2)
endin

but when I make plugin without outputs:

struct MyCoolOpcode : csnd::Plugin<0, 'N'> {

    int kperf() {
        int numInputs = in_count();
        for(int i = 0; i < numInputs; i++) {
            std::string input_value ="kperf: input:" + std::to_string(inargs[i]);
            csound->message(input_value);
        }
        return OK;
    }

};

#include <modload.h>

void csnd::on_load(Csound *csound) {
    csnd::plugin<MyCoolOpcode>(csound, "cooling.N", "", "N", csnd::thread::k);
}

And use it in similar way:

instr 1
    k1 = 1
    k2 = 2
    cooling(k1, k2)
endin

I get → csound command: Segmentation violation when accessing second input argument.

Any ideas what is wrong here? I am using Csound 6.18 on Windows 11.

#5

No, in this case you must define the max number of inputs you need, even if you have no intention of ever using that many. Something like:

struct MyCoolOpcode : csnd::Plugin<0,64> {

Also, if you are building an opcode with no outputs there is a special csnd::InPlug struct you should use.

struct MyCoolOpcode : csnd::InPlug<64> {

And in this case inargs becomes args. :+1:

1 Like
#6

Cool! many thanks @rory ! I will give it a try :crossed_fingers: