buffer it, aww yeah that's real nice and good

[Sam (Deleted User)]

I don't know what the heck that is, but I buffer it anyway.

tl;dr how to use buffer functions with GM extensions?

C++ func be liek:
double buffer_me_nice_and_good(char *** buffer, int *size)

How to buffs?

I want to get to get the buffer copied to char pointer and the size integer pointer as well, it's a vector of char *.

Is too how buffs?

If you can read past the weirdness, this is a real and serious question I just am too lazy to explain more intelligently.
Thank

 

[rwkay]

OK for an extension then all strings are passed as char*,so if you declare the extension in GM as taking a string then a pointer is passed instead

if you take a look at https://github.com/YoYoGames/GameMakerStudio_ExtensionExample then you will see that in the https://github.com/YoYoGames/GameMakerStudio_ExtensionExample/blob/master/ExampleExtension.cpp file the function MyExtension_BufferPointer declaration is the correct way to do it, on the GM side the first param would be a string.

EXPORTED_FN  char*  MyExtension_BufferPointer( void* _pBuffer, double _size)
{
    if( !g_Initialised ) return NULL;

    unsigned char* pBuffer = (unsigned char*)_pBuffer;
    int i,total = 0;
    for(i=0;i<_size;i++){
        total+=pBuffer[i];                    // buffer read example
        pBuffer[i] = (unsigned char)i;        // buffer write example
    }


    char s[1024];
    snprintf(&s[0], 1023, "Total = %d", total);
    char* pString = strdup(s);
    return pString;
}

the _pBuffer parameter is declared as a void pointer but is then cast to be an unsigned char*

In the GML code use buffer_get_address() to get the base of the buffer and pass that pointer to the C++

Any probs let me know

Russell

 

[Sam (Deleted User)]

OK for an extension then all strings are passed as char*,so if you declare the extension in GM as taking a string then a pointer is passed instead

if you take a look at https://github.com/YoYoGames/GameMakerStudio_ExtensionExample then you will see that in the https://github.com/YoYoGames/GameMakerStudio_ExtensionExample/blob/master/ExampleExtension.cpp file the function MyExtension_BufferPointer declaration is the correct way to do it, on the GM side the first param would be a string.

EXPORTED_FN  char*  MyExtension_BufferPointer( void* _pBuffer, double _size)
{
    if( !g_Initialised ) return NULL;

    unsigned char* pBuffer = (unsigned char*)_pBuffer;
    int i,total = 0;
    for(i=0;i<_size;i++){
        total+=pBuffer[i];                    // buffer read example
        pBuffer[i] = (unsigned char)i;        // buffer write example
    }


    char s[1024];
    snprintf(&s[0], 1023, "Total = %d", total);
    char* pString = strdup(s);
    return pString;
}

the _pBuffer parameter is declared as a void pointer but is then cast to be an unsigned char*

In the GML code use buffer_get_address() to get the base of the buffer and pass that pointer to the C++

Any probs let me know

Russell

I'm not 100% sure if I understand correctly, but I'll try your example and throw together a small project that calls that and see how it responds to it. (I think?) Seems like I'm supposed to pass buffer_get_size(buffer) to the second argument, and of course because of the strdup I need to free the buffer from memory on the gml as well. Let's hope I know what I'm doing enough my computer doesn't esplode.

Will ask more questions here if needed. Thank you!!!

 

[rwkay]

If you are looking to pass back any more than a string from the C++ then you would be better to use the buffer to pass back any other types of data.

Russell

 

[JeffJ]

OK for an extension then all strings are passed as char*,so if you declare the extension in GM as taking a string then a pointer is passed instead

if you take a look at https://github.com/YoYoGames/GameMakerStudio_ExtensionExample then you will see that in the https://github.com/YoYoGames/GameMakerStudio_ExtensionExample/blob/master/ExampleExtension.cpp file the function MyExtension_BufferPointer declaration is the correct way to do it, on the GM side the first param would be a string.

the _pBuffer parameter is declared as a void pointer but is then cast to be an unsigned char*

In the GML code use buffer_get_address() to get the base of the buffer and pass that pointer to the C++

Slightly off topic, but I feel like this type of stuff should be officially documented - from time to time I stumble upon what seems to be internal stuff that is good to know but not documented anywhere, and this is a good example of this. Question is, where in the docs would be fitting?

 

[Sam (Deleted User)]

Slightly off topic, but I feel like this type of stuff should be officially documented - from time to time I stumble upon what seems to be internal stuff that is good to know but not documented anywhere, and this is a good example of this. Question is, where in the docs would be fitting?

I could give matharoo a little help with extension-related documentation, but the only stuff that isn't already covered I don't actually know how to do either. I'm still a little confused by what Russell told me to do, but i often have that problem in other communities when people explain stuff to me c++-related anyway it usually takes for me to do a bit of debugging before i have one of those "oh, gotcha!" moments. Perhaps I could help him with it after I figure it out myself. We'll see what happens. I've been working on other stuff alongside this.