Add an example to show how to read bytes from wasm memory

[AntsyLich]

No description provided.

[CharlieTap]

Hey, I'll be adding docs as part of the 1.0 coming up in the couple of months but maybe I can answer your question in interim. You'll need to get a reference to the memory itself first, this is done by calling:

val exports = exports(instance)

Provided your module is in fact exporting the memory, the you can call:

val memory = exports.filterIsInstance<Memory>().first()
val buffer = ByteArray()
readBytes(store, memory, buffer, pointer, bytesToRead)

Theres also a way to create a memory and import it into your module at instantiation time, but its probably easier to just export what you already have.

[AntsyLich]

Unrelated but does K/Wasm support exporting memory? There's seems to be a very recent issue which mentions importing/exporting memory (https://youtrack.jetbrains.com/issue/KT-73234)

[CharlieTap]

Yes, it exports the memory (theres only one at present) with the name "memory". You can check for yourself by turning your .wasm file into a .wat file using a cli tool like wasm-tools:

wasm-tools parse ./module.wasm

You should see an export entry like this:

(export "memory" (memory 0))

[mipastgt]

I'd very much appreciate it if you could provide a complete but simple example of how to call a wasm function which takes a ByteArray as input and returns another ByteArray as output. That would open the door for testing chasm with non-trivial code examples.