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64 lines
2.7 KiB
Markdown
64 lines
2.7 KiB
Markdown
# REPL
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A simple demo application that provides a bare-bones REPL framework.
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## Copying This Demo to a New App
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1. Copy this demo application, and rename the relevant structures in its `Cargo.toml` and `main.rs`.
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2. Add it to the Workspace `default-members` and `members` arrays by editing `./Cargo.toml`
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3. Edit the `manifest.json` file as documented in its [README](../README.md)
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4. Build using `cargo xtask app-image you_new_app` to create a flashable Xous image with your app in it.
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## Details
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`repl` is a baseline demo application for Xous. It uses a chat-client
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style interface (stacking bubbles of text, with user input right-aligned
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and shell feedback left-aligned) to facilitate interactions.
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It implements the basic envisioned structure of a Xous application, namely:
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- Text input comes via the `ime-frontend`
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- Graphical output is rendered via the `gam`
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[Push Events and Listeners](https://github.com/betrusted-io/xous-core/wiki/Push-Events-and-Listeners) provides an overview of the flow of
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messages between an Xous application and the Xous Services.
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The one demo command provisioned in the `repl` app plays a tone via
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the `codec` service. This was chosen because it is about one of the most complicated
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and comprehensive things you can do in the `repl` environment, as it requires
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real-time callbacks to fill the audio buffer with new samples. If you have
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specific questions about how the callbacks work, we encourage you to open
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an issue in this repo and ask your question. Your questions will help us
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direct effort toward building the documentation base.
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To make your own command, copy the `audio.rs` template
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in the `apps/repl/src/cmds/` directory, or use this very basic `echo`
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template:
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```Rust
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use crate::{ShellCmdApi, CommonEnv};
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use String;
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#[derive(Debug)]
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pub struct Echo {
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}
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impl<'a> ShellCmdApi<'a> for Echo {
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cmd_api!(echo); // inserts boilerplate for command API
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fn process(&mut self, args: String, _env: &mut CommonEnv) -> Result<Option<String>, xous::Error> {
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Ok(Some(rest))
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}
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}
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```
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The "verb" is the name of your command, and it is the argument to the `cmd_api!()` macro.
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`process()` is your "main" function, and `args` is a string which contains the
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rest of the line that was typed into the chat, minus the verb used to identify
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your command (e.g. the arguments, but not tokenized or parsed in
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any way). `env` contains some items in a common environment, for example, connections
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to the GAM, LLIO server or other resources required by your implementation.
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Once you've added your command to the directory, go to the `cmds.rs` file, and follow
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the four-step instructions embedded within the file, starting around line 40.
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