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+++ b/src/server.rs
@@ -0,0 +1,142 @@
+// Tablet emulator, for people who don’t own one
+// Copyright © 2020 Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+use std::net::UdpSocket;
+use std::io::{self, ErrorKind};
+use crate::state::State;
+use bitflags::bitflags;
+use input_linux::Key;
+
+bitflags! {
+    /// This is the memory layout of the buttons on the 3DS.
+    #[derive(Default)]
+    struct Buttons: u32 {
+        const A = 0x00000001;
+        const B = 0x00000002;
+        const SELECT = 0x00000004;
+        const START = 0x00000008;
+        const RIGHT = 0x00000010;
+        const LEFT = 0x00000020;
+        const UP = 0x00000040;
+        const DOWN = 0x00000080;
+        const R = 0x00000100;
+        const L = 0x00000200;
+        const X = 0x00000400;
+        const Y = 0x00000800;
+        // Nothing
+        // Nothing
+        const ZL = 0x00004000;
+        const ZR = 0x00008000;
+        // Nothing
+        // Nothing
+        // Nothing
+        // Nothing
+        const TOUCH = 0x00100000;
+        // Nothing
+        // Nothing
+        // Nothing
+        const C_RIGHT = 0x01000000;
+        const C_LEFT = 0x02000000;
+        const C_UP = 0x04000000;
+        const C_DOWN = 0x08000000;
+        const CIRCLE_RIGHT = 0x10000000;
+        const CIRCLE_LEFT = 0x20000000;
+        const CIRCLE_UP = 0x40000000;
+        const CIRCLE_DOWN = 0x80000000;
+    }
+}
+
+#[derive(Debug, Default)]
+struct Event {
+    buttons: Buttons,
+    pad: (i16, i16),
+    c_pad: (i16, i16),
+    touch: (u16, u16),
+}
+
+pub fn run_server(address: &str) -> io::Result<()> {
+    let mut state = match State::new() {
+        Ok(state) => state,
+        Err(err) => {
+            match err.kind() {
+                ErrorKind::NotFound => {
+                    eprintln!("Couldn’t find /dev/uinput: {}", err);
+                    eprintln!("Maybe you forgot to `modprobe uinput`?");
+                }
+                ErrorKind::PermissionDenied => {
+                    eprintln!("Couldn’t open /dev/uinput for writing: {}", err);
+                    eprintln!("Maybe you aren’t allowed to create input devices?");
+                }
+                _ => eprintln!("Couldn’t open /dev/uinput for writing: {}", err),
+            }
+            std::process::exit(1);
+        }
+    };
+
+    let socket = UdpSocket::bind(address)?;
+    println!("Listening on {:?}", socket);
+    println!("Here is an example client: https://hg.linkmauve.fr/remote-gamepad");
+
+    let mut event: Event = Default::default();
+    let mut last = Some((0., 0.));
+    state.set_size((320, 240));
+    loop {
+        // TODO: Yolo-alignment.
+        let buf: &mut [u8; 16] = unsafe { std::mem::transmute(&mut event) };
+        let (amount, source) = socket.recv_from(buf)?;
+        if amount != std::mem::size_of::<Event>() {
+            eprintln!("Invalid data length: {}", amount);
+            continue;
+        }
+        println!("{:?} from {:?}", event, source);
+        if event.buttons.contains(Buttons::A) {
+            state.select_tool(Key::ButtonToolPen);
+        } else if event.buttons.contains(Buttons::B) {
+            state.select_tool(Key::ButtonToolRubber);
+        } else if event.buttons.contains(Buttons::X) {
+            state.select_tool(Key::ButtonToolBrush);
+        } else if event.buttons.contains(Buttons::Y) {
+            state.select_tool(Key::ButtonToolPencil);
+        } else if event.buttons.contains(Buttons::SELECT) {
+            state.select_tool(Key::ButtonToolAirbrush);
+        }
+        let (x, y) = event.touch;
+        if event.buttons.contains(Buttons::TOUCH) {
+            if let None = last {
+                state.press(x as f64, y as f64)?;
+                last = Some((x as f64, y as f64));
+                continue;
+            }
+        } else {
+            if let Some((x, y)) = last {
+                state.release(x, y)?;
+                last = None;
+                continue;
+            }
+        }
+        state.motion(x as f64, y as f64)?;
+        last = Some((x as f64, y as f64));
+    }
+}
+
+pub fn main(args: &[String]) {
+    let address = if args.len() > 1 {
+        args[1].clone()
+    } else {
+        String::from("0.0.0.0:16150")
+    };
+    run_server(&address).unwrap();
+}