pp::VarArrayBuffer to transfer data from JavaScript to NaCl, but not vice versa

[DevelopDaily]

It seems to me that it is easy to use pp::VarArrayBuffer to transfer binary data from the Chrome/JavaScript to the NaCl, but not vice versa.

I have a chunk of bytes produced in the NaCl, but I cannot find a way to construct a pp::VarArrayBuffer object to transfer the bytes to the JavaScript. Did I miss something?

Thanks.

[David Michael]

You can just create one of the size you need:
https://developers.google.com/native-client/peppercpp/classpp_1_1_var_array_buffer#a7fd29347661fc1539dd474cc3f0e2a72
then write to it, probably using memcpy.

E.g.:

pp::VarArrayBuffer buffer(num_bytes);

memcpy(buffer.Map(), data, num_bytes);

instance->PostMessage(buffer);

Let me know if this doesn't work for you.

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[taimoo...@gorillabox.net]

Hello David

I am using your code template to transfer a simple uint8* array from PNaCl to javascript.

            uint8_t array[] = {120,120,120,120};

            struct PP_Var data = PSInterfaceVarArrayBuffer()->Create(num_bytes);

            memcpy(PSInterfaceVarArrayBuffer()->Map(data), array, sizeof(array));

            PSInterfaceMessaging()->PostMessage(PSGetInstanceId(), data);

But on the javascript side I am getting an empty ArrayBuffer. Can you please tell me what the problem might be?

On Thursday, 21 February 2013 02:00:11 UTC+5, David Michael wrote:

You can just create one of the size you need:
https://developers.google.com/native-client/peppercpp/classpp_1_1_var_array_buffer#a7fd29347661fc1539dd474cc3f0e2a72
then write to it, probably using memcpy.

E.g.:

pp::VarArrayBuffer buffer(num_bytes);

memcpy(buffer.Map(), data, num_bytes);

instance->PostMessage(buffer);

Let me know if this doesn't work for you.

On Tue, Feb 19, 2013 at 10:23 PM, DevelopDaily <c...@datacivilization.com> wrote:

It seems to me that it is easy to use pp::VarArrayBuffer to transfer binary data from the Chrome/JavaScript to the NaCl, but not vice versa.

I have a chunk of bytes produced in the NaCl, but I cannot find a way to construct a pp::VarArrayBuffer object to transfer the bytes to the JavaScript. Did I miss something?

Thanks.

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[David Michael]

Where does "num_bytes" come from? If I remember correctly, the ArrayBuffer has fixed size for its lifetime, so make sure that number is correct. If it's zero, you'll get an empty buffer sent to JavaScript.

HTH

On Wed, Feb 3, 2016 at 2:12 AM, <taimoo...@gorillabox.net> wrote:

Hello David

I am using your code template to transfer a simple uint8* array from PNaCl to javascript.

            uint8_t array[] = {120,120,120,120};

            struct PP_Var data = PSInterfaceVarArrayBuffer()->Create(num_bytes);

            memcpy(PSInterfaceVarArrayBuffer()->Map(data), array, sizeof(array));

            PSInterfaceMessaging()->PostMessage(PSGetInstanceId(), data);

But on the javascript side I am getting an empty ArrayBuffer. Can you please tell me what the problem might be?

On Thursday, 21 February 2013 02:00:11 UTC+5, David Michael wrote:

You can just create one of the size you need:
https://developers.google.com/native-client/peppercpp/classpp_1_1_var_array_buffer#a7fd29347661fc1539dd474cc3f0e2a72
then write to it, probably using memcpy.

E.g.:

pp::VarArrayBuffer buffer(num_bytes);

memcpy(buffer.Map(), data, num_bytes);

instance->PostMessage(buffer);

Let me know if this doesn't work for you.

On Tue, Feb 19, 2013 at 10:23 PM, DevelopDaily <c...@datacivilization.com> wrote:

It seems to me that it is easy to use pp::VarArrayBuffer to transfer binary data from the Chrome/JavaScript to the NaCl, but not vice versa.

I have a chunk of bytes produced in the NaCl, but I cannot find a way to construct a pp::VarArrayBuffer object to transfer the bytes to the JavaScript. Did I miss something?

Thanks.

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