WasmSequencer

[Kronos3]

Related Issue(s)
Has Unit Tests (y/n)
Documentation Included (y/n)
Generative AI was used in this contribution (y/n)

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Change Description

This component is still under active development. I'm creating a draft PR to work in tandem with @zimri-leisher Fpy development and capture review items.

Rationale

Testing/Review Recommendations

Future Work

AI Usage (see policy)

[zimri-leisher]

Documenting the host environment assumptions:

• exit host func for user-triggered early end of sequence. should have an i32 code
• fault host func for non-user-triggered early end of sequence, should have an i32 code
  • this is used for things like arithmetic overflow and other implicit termination points in the code
• write_tlm host func (id, time ptr, time size, value ptr, value size)
• write_prm host func (id, value ptr, value size)
• dispatch_cmd host func ((opcode+args) buf ptr, (opcode+args) buf size)
  • TODO should the buf be a fully constructed fprime cmd? or should the component build the cmd from opcode+args
• emit_event host func (severity, message size, message bytes)
  • TODO consider how we want to provide string formatting in events
• sleep_relative (timeinterval) and sleep_absolute (fw.time)
• output_serial (value ptr, value size) (see current FpySequencer POP_SERIALIZABLE)
  • also TODO, we may want to consider having this able to return a value back into the sequence? it would be a step towards allowing users to define their own host environment behavior
• write_time host func (time ptr, time size)

Math functions (use libm implementation, trap if undefined behavior or out of domain)

• sin, cos, tan, inverse of those, hyperbolic of those, atan2
• ln, exp

[Kronos3]

String formatting in events should be done one of two ways.

1. Inside the Wasm code: We have shown this done using the Rust core crate so presumably something to that end.
2. The other way to do it is something like https://github.com/knurling-rs/defmt which basically detects string formatting in the frontend and generates a ground-side lookup (dictionary). Then all we need to do is encode format arguments into a buffer and downlink it in the event.
   a. This can be used if the formatted string is not needed on-board and reduces downlink and on-board processing.

[zimri-leisher]

if you want to follow the idioms of the fpy sequencer, you could split all the sm guard/action impls out into a separate file. just helps to keep the length of any one file down

[zimri-leisher]

typo in completion

[zimri-leisher]

consider more descriptive name? WAIT_FOR_SEQUENCE?

[zimri-leisher]

this is a very interesting capability and i wonder if we can make use of it more

[zimri-leisher]

do we need a fuel param or arg?

[Kronos3]

Good idea, I was going to make it a config but parameter makes more sense.

[Kronos3]

That parameter essentially controls how responsive the interpreter is to PAUSE if it's doing computationally heavy tasks.

[zimri-leisher]

briefly, would it be more clear if you called it "RUNNING"? spin is a bit jargony

[zimri-leisher]

Some non substantive review. I think I will wait to deeply review this component until you can go over it with me together.