Verify Duktape/C code [question]

[noomio]

Hi,

I'm trying to validate that my approach is correct. It seems to work, but whenever I dump the stack I cant see the function "read". What I want to achieve is the following:

function DigitalIn(pin,mode) { 
  return { pin: pin,
               mode: mode, 
               read: function(){ 
                  return true;
               } 
          } 
};

Main C code:

void main(void){

duk_push_c_function(ctx, native_digital_in, 2 /*nargs*/);
duk_put_global_string(ctx, "DigitalIn");

duk_eval_string_noresult(ctx, "
var din = DigitalIn(23,0); 
var din2 = DigitalIn(2,1); 
print(din.read()); 
print(din2.read());
");


static duk_ret_t read(duk_context *ctx) {
    duk_push_this(ctx);

    (void) duk_get_prop_string(ctx,0, "pin");
    printf("obj.propertyName = %s\r\n", duk_to_string(ctx, -1));
    (void) duk_get_prop_string(ctx, 0, "mode");
    printf("obj.propertyName = %s\r\n", duk_to_string(ctx, -1));

    duk_push_true(ctx);
    return 1;
}

duk_ret_t native_digital_in(duk_context *ctx) {
   
    uint32_t pin = duk_require_uint(ctx, 0);
    uint32_t mode = duk_require_uint(ctx, 1);

    duk_set_top(ctx, 0); // clear stack args
    
    duk_idx_t obj_idx = duk_push_object(ctx);   /* -> [ ... global obj ] */
    duk_push_number(ctx, pin);
    duk_put_prop_string(ctx, obj_idx, "pin");

    duk_push_number(ctx, mode);
    duk_put_prop_string(ctx, obj_idx, "mode");

    duk_push_c_function(ctx, read, 0  /*nargs*/);
    duk_put_prop_string(ctx, obj_idx, "read");


    return 1;
}

[svaarala]

What does the test print, and what stack dump do you get?

Quick observation (unrelated to the issue):

• The duk_set_top(ctx, 0) in native_digital_in is not necessary. You can just push an object and return 1, Duktape will take care of the stack unwind.

[noomio]

Here is the output:

[svaarala]

That output seems like it is working?

• Each call prints the expected property values
• Each call returns true, because of the duk_push_true() + return 1 combination

What is missing?

[noomio]

Yes it's working but I'm wondering why I can't see the function in the stack dump.

On Tue., 25 Jun. 2019, 8:06 pm Sami Vaarala, [email protected] wrote:

That output seems like it is working?

• Each call prints the expected property values
• Each call returns true, because of the duk_push_true() + return 1 combination

What is missing?

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/svaarala/duktape/issues/2124?email_source=notifications&email_token=AMMJ33DZFHSQFLXMUDZA7UTP4HUZXA5CNFSM4H3EZV62YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGODYPXI6A#issuecomment-505377912, or mute the thread https://github.com/notifications/unsubscribe-auth/AMMJ33EUYLOCSRSOGOEQCITP4HUZXANCNFSM4H3EZV6Q .

[svaarala]

Can you try what happens if you Duktape.enc('jx', obj); for the same object?

[noomio]

Hi,

It didn't print anything so I enabled it with: DUK_USE_JX: true

Now it's visible!

[svaarala]

Good to hear :)

[noomio]

Hi,

So far it's working well but when I integrate it to my setTimeout losing "scope" it calls the object constructor again. What's the best approach to stop this from happening? Singleton?

var count = 0;
var intervalId;


var dout = DigitalOut(4,0); 
var val = false;

setTimeout(function cb() {
   print('one shot timer, called after 10 seconds');
}, 10000);


intervalId = setInterval(function () {

    print('interval', ++count);
    
    val = !val;
    dout.write(val);

    if (count >= 25) {
    	clearInterval(intervalId);
    }

}, 1000);

print("Hello from Javascript!");

[noomio]

I removed var from dout :)