From 7351d68814d20442b11953737883aa9f2ef05b4b Mon Sep 17 00:00:00 2001
From: Jeremy Soller <jackpot51@gmail.com>
Date: Wed, 7 Dec 2022 11:27:36 -0700
Subject: [PATCH] Add Redox/Orbital support

---
 Cargo.toml     |   3 ++
 README.md      |   2 +-
 src/lib.rs     |   4 ++
 src/orbital.rs | 108 +++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 116 insertions(+), 1 deletion(-)
 create mode 100644 src/orbital.rs

diff --git a/Cargo.toml b/Cargo.toml
index 954d934..f0557fe 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -37,6 +37,9 @@ wasm-bindgen = "0.2.78"
 version = "0.3.55"
 features = ["CanvasRenderingContext2d", "Document", "Element", "HtmlCanvasElement", "ImageData", "Window"]
 
+[target.'cfg(target_os = "redox")'.dependencies]
+redox_syscall = "0.3"
+
 [dev-dependencies]
 instant = "0.1.12"
 winit = "0.27.2"
diff --git a/README.md b/README.md
index 7c91089..8c4b006 100644
--- a/README.md
+++ b/README.md
@@ -43,7 +43,7 @@ For now, the priority for new platforms is:
 ✅: Present | ❌: Absent
  - AndroidNdk ❌
  - AppKit ✅ (Thanks to [Seo Sanghyeon](https://github.com/sanxiyn) and [lunixbochs](https://github.com/lunixbochs)!)
- - Orbital ❌
+ - Orbital ✅
  - UiKit ❌
  - Wayland ✅ (Wayland support in winit is immature at the moment, so it might be wise to force X11 if you're using winit)
  - Web ✅ (Thanks to [Liamolucko](https://github.com/Liamolucko)!)
diff --git a/src/lib.rs b/src/lib.rs
index 8730629..f597386 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -15,6 +15,8 @@ mod x11;
 mod wayland;
 #[cfg(target_arch = "wasm32")]
 mod web;
+#[cfg(target_os = "redox")]
+mod orbital;
 
 mod error;
 
@@ -52,6 +54,8 @@ impl<W: HasRawWindowHandle + HasRawDisplayHandle> GraphicsContext<W> {
             (RawWindowHandle::AppKit(appkit_handle), _) => Box::new(cg::CGImpl::new(appkit_handle)?),
             #[cfg(target_arch = "wasm32")]
             (RawWindowHandle::Web(web_handle), _) => Box::new(web::WebImpl::new(web_handle)?),
+            #[cfg(target_os = "redox")]
+            (RawWindowHandle::Orbital(orbital_handle), _) => Box::new(orbital::OrbitalImpl::new(orbital_handle)?),
             (unimplemented_window_handle, unimplemented_display_handle) => return Err(SoftBufferError::UnsupportedPlatform {
                 window,
                 human_readable_window_platform_name: window_handle_type_name(&unimplemented_window_handle),
diff --git a/src/orbital.rs b/src/orbital.rs
new file mode 100644
index 0000000..76cbdb6
--- /dev/null
+++ b/src/orbital.rs
@@ -0,0 +1,108 @@
+use raw_window_handle::HasRawWindowHandle;
+use raw_window_handle::OrbitalWindowHandle;
+use std::{
+    cmp,
+    slice,
+    str,
+};
+
+use crate::GraphicsContextImpl;
+use crate::SoftBufferError;
+
+struct OrbitalMap {
+    address: usize,
+    size: usize,
+}
+
+impl OrbitalMap {
+    unsafe fn new(fd: usize, size_unaligned: usize) -> syscall::Result<Self> {
+        // Page align size
+        let pages = (size_unaligned + syscall::PAGE_SIZE - 1) / syscall::PAGE_SIZE;
+        let size = pages * syscall::PAGE_SIZE;
+
+        // Map window buffer
+        let address = syscall::fmap(fd, &syscall::Map {
+            offset: 0,
+            size,
+            flags: syscall::PROT_READ | syscall::PROT_WRITE,
+            address: 0,
+        })?;
+
+        Ok(Self { address, size })
+    }
+}
+
+impl Drop for OrbitalMap {
+    fn drop(&mut self) {
+        unsafe {
+            // Unmap window buffer on drop
+            syscall::funmap(self.address, self.size)
+                .expect("failed to unmap orbital window");
+        }
+    }
+}
+
+pub struct OrbitalImpl {
+    handle: OrbitalWindowHandle,
+}
+
+impl OrbitalImpl {
+    pub fn new<W: HasRawWindowHandle>(handle: OrbitalWindowHandle) -> Result<Self, SoftBufferError<W>> {
+        Ok(Self { handle })
+    }
+}
+
+impl GraphicsContextImpl for OrbitalImpl {
+    unsafe fn set_buffer(&mut self, buffer: &[u32], width_u16: u16, height_u16: u16) {
+        let window_fd = self.handle.window as usize;
+
+        // Read the current width and size
+        let mut window_width = 0;
+        let mut window_height = 0;
+        {
+            let mut buf: [u8; 4096] = [0; 4096];
+            let count = syscall::fpath(window_fd, &mut buf).unwrap();
+            let path = str::from_utf8(&buf[..count]).unwrap();
+            // orbital:/x/y/w/h/t
+            let mut parts = path.split('/').skip(3);
+            if let Some(w) = parts.next() {
+                window_width = w.parse::<usize>().unwrap_or(0);
+            }
+            if let Some(h) = parts.next() {
+                window_height = h.parse::<usize>().unwrap_or(0);
+            }
+        }
+
+        {
+            // Map window buffer
+            let window_map = OrbitalMap::new(
+                window_fd,
+                window_width * window_height * 4
+            ).expect("failed to map orbital window");
+
+            // Window buffer is u32 color data in 0xAABBGGRR format
+            let window_data = slice::from_raw_parts_mut(
+                window_map.address as *mut u32,
+                window_width * window_height
+            );
+
+            // Copy each line, cropping to fit
+            let width = width_u16 as usize;
+            let height = height_u16 as usize;
+            let min_width = cmp::min(width, window_width);
+            let min_height = cmp::min(height, window_height);
+            for y in 0..min_height {
+                let offset_buffer = y * width;
+                let offset_data = y * window_width;
+                window_data[offset_data..offset_data + min_width].copy_from_slice(
+                    &buffer[offset_buffer..offset_buffer + min_width]
+                );
+            }
+
+            // Window buffer map is dropped here
+        }
+
+        // Tell orbital to show the latest window data
+        syscall::fsync(window_fd).expect("failed to sync orbital window");
+    }
+}