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Programmable WASM Activities

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COMING SOON: This API is currently in development and will be released soon.

Boppo provides a WASM API to program new activities, interactive content, and games that run directly on Boppo.

To get started developing your own activities quickly its best to read the documentation for your language of choice:

  • Rust: boppofun/rust_boppo_wasm
  • AssemblyScript: coming soon
  • If your preferred langauge does not exist and it has the ability to compile to WASM modules suitable for an ESP32 let us know your interested in a language binding or feel free to build your own using the WASM API below.

WASM API for Language Bindings​

The following APIs are meant to be used by language binding libraries. For activity developers please read the API documentation for your language which will wrap the following in a more friendly API.

The Boppo tablet WASM runtime is WASIp1 compatible but not all WASI features are supported (e.g. filesystem APIs are not yet available).

Host Functions​

boppo_poll_events(timeout_millis: i32) -> i64​

If timeout_millis is less than 0, the function will block indefinitely until an event occurs. If timeout_millis is greather than 0 the function will return after the timeout if no host event occurred first. If timeout_millis is 0, the function will check for events and return immediately if none are available.

Returns a HostEvent represented as an i64. The least significant byte is the event type, and the remaining bytes are event-specific data.

Event types:

  • 0: Exit

    The WASM activity should exit gracefully (i.e. return from the _start/main() function).

    Payload: None

  • 1: Button

    A top button has been pressed or released.

    Payload: The two most signficiant bytes are a 2 byte payload. Of those 2 bytes, the least significant 4 bits are the button index of the event. The next 10 bits are the current pressed state (1 is pressed) of all ten 10 buttons (in index order). The 15th bit is if the current event is a press event (1) or a release event (0).

  • 2: Audio

    TBD

  • 3: Timeout

    The timeout_millis has elapsed without another event occuring.

    Payload: None

boppo_set_and_flush_lights(framebuffer_colors: *void)​

Sets all 40 of the device lights and flushes the lights to the hardware.

The passed in pointer must point to a buffer of 120 bytes. Each light is represented by a 3 byte color value (RGB).

The ordering of the lights is the same as defined in the Rust Lights struct

Module Exports​

_start() (required)​

As defined by WASIp1 this is the function the runtime will call to start the WASM activity. When this function returns the runtime will return to the active menu.