• split out model ptr into a ModelRef struct for easier reuse
• split model into separate pins and evaluator structs so it can be split

todo:

• re-add >64bit ports
• dynamic ports

The port structs interface directly with state in the verilator model

Async runtime implementation made possible with this api: https://codeberg.org/icewind/marlin_async/src/branch/pin-structs

The main api different for users not doing anything fancy is doing model.input_port.set(1) instead of model.input_port = 1 and let val = model.output_port.get() instead of let val = model.output_port.

In exchange we get the port direction enforced by the type system and the ability to split the model into separate parts and move individual pins into higher level constructs.

An example of a higher level construct this makes possible is:

pub struct UartRx<'ctx> {
    pub has_out: OutputPort<'ctx, u8>,
    pub out_val: OutputPort<'ctx, u8>,
    pub clear: InputPort<'ctx, u8>,
    pub waiter: Waiter, // from https://codeberg.org/icewind/marlin_async
}

impl UartRx<'_> {
    pub async fn recv(&mut self) -> u8 {
        ...
    }
}

that can then be used as a high level api for reading serial output from a model while being free to touch the other ports independently.