Reading Data with MacOs

[babasler]

Hey,
your functions worked fine, but when I try to implement read from the SimpleBLE, all the data I read is unusable. Do you have any idea how to implement the function?

boolean simpleble_peripheral_read(Pointer handle, uuid_t service, uuid_t characteristic, Pointer data, Pointer data_length);

Thanks!

[4lml4]

Hey @babasler
Thanks for trying out this repo!

For my specific use case I haven't had to read data using SimpleBLE (I mainly use the writeCommand function), but I imagine it should be similar to how the other functions have been implemented.

During development, I discovered (after many many hours of pulling my hair) that I actually needed to mix around the function parameter order when translating the simpleBLE native function definitions to the java ones. The best example of this is as follows:

SimpleBLE writeCommand:

simpleble_err_t simpleble_peripheral_write_request(simpleble_peripheral_t handle, simpleble_uuid_t service,
                                                   simpleble_uuid_t characteristic, const uint8_t* data,
                                                   size_t data_length)

simpleBLEJava writeCommand:
boolean simpleble_peripheral_write_command(Pointer handle, byte[] data, size_t length, uuid_t.ByValue service, uuid_t.ByValue characteristic);

As you can see, in order for this function to work, I had to pass my parameters in a completely different order... but it works. It must be something to do with the way that JNA translates java functions to native function calls but I still have not found a good explanation for this.

So my suggestion would be for you to first try and move around the order in which you are defining and passing your parameters in your read function, probably starting with this order: handle, data, data_length, service, characteristic

If that doesn't work, you'll unfortunately need to go down the rabbit hole of dynamically debugging your java code, and printing out the values of what is returned and also breaking on your function call and having a look at what is being passed on to the simpleBLE dll

Let me know how you go and best of luck

[leobert-lan]

in SimpleBLE, the function defined as follow: be attention with version and be attention with paramter data, the pointer of one pointer,

SIMPLEBLE_EXPORT simpleble_err_t simpleble_peripheral_read(simpleble_peripheral_t handle, simpleble_uuid_t service,
                                                           simpleble_uuid_t characteristic, uint8_t** data,
                                                           size_t* data_length);

the JNA (also JNI) bridge Java runtime and native runtime by function name 、parameter type、parameter counts，you should keep the order of each paramter as same with original function definition.

the JNAerator may simplify the work.

The most complex job is building a stable facade layer and proxy classes for handles (the Pointer).