1 files changed, 71 insertions, 0 deletions

diff --git a/rsnix/src/cursor.rs b/rsnix/src/cursor.rs
new file mode 100644
index 0000000..18c9a1d
--- /dev/null
+++ b/rsnix/src/cursor.rs
@@ -0,0 +1,71 @@
+// ---------------------------------------------------------------------------
+// cursor — the mouse cursor task.
+//
+// One background task owns the PS/2 mouse: it polls the packet ring every
+// 10 ms, moves the on-screen cursor (gop's display overlay), tracks the
+// button state, and optionally *forwards* every event to another task's
+// message queue (`mouse <id>` sets the target) — the input-routing half
+// of the future window manager.
+//
+// The cursor itself never touches the text surface: `gop::push_rect`
+// composites it on top of every display write, so text scrolling and
+// cursor movement cannot corrupt each other (see gop.rs).
+// ---------------------------------------------------------------------------
+use core::sync::atomic::{AtomicUsize, Ordering};
+
+use crate::ps2::MouseEvent;
+use crate::sched::TaskMsg;
+
+/// Forward target task id, or `usize::MAX` = none.
+static FORWARD_TARGET: AtomicUsize = AtomicUsize::new(usize::MAX);
+
+/// Spawn the cursor task.  Call after `sched::init`; only makes sense
+/// when the PS/2 mouse came up at boot.  The cursor starts centred.
+pub fn spawn() -> Option<usize> {
+    let (w, h) = crate::gop::pixel_dims();
+    crate::gop::cursor_set(w / 2 - 6, h / 2 - 8);
+    // Draw it immediately: the vt diff only re-blits changed cells, so an
+    // idle centre cell would never push (and thus never composite) it.
+    crate::gop::cursor_redraw();
+    let id = crate::sched::spawn(task_main, "cursor")?;
+    crate::serial_println!(
+        "cursor: task {} — mouse poll + display overlay (forward target: none)",
+        id
+    );
+    Some(id)
+}
+
+/// Route decoded mouse events to a task's queue (the shell's `mouse
+/// <id>`).  `None` stops forwarding.
+pub fn set_forward(target: Option<usize>) {
+    FORWARD_TARGET.store(target.unwrap_or(usize::MAX), Ordering::Relaxed);
+}
+
+fn forward_target() -> Option<usize> {
+    match FORWARD_TARGET.load(Ordering::Relaxed) {
+        usize::MAX => None,
+        id => Some(id),
+    }
+}
+
+fn task_main() {
+    loop {
+        while let Some(ev) = crate::ps2::try_poll_mouse() {
+            crate::gop::cursor_move(ev.dx, ev.dy);
+            crate::gop::cursor_set_buttons(btn_bits(&ev));
+            if let Some(id) = forward_target()
+                && crate::sched::send(id, TaskMsg::Mouse(ev)).is_err()
+            {
+                // The listener died mid-stream: stop routing (the
+                // cursor keeps tracking) rather than spam errors.
+                set_forward(None);
+                crate::serial_println!("cursor: forward target task {} gone — stopped routing", id);
+            }
+        }
+        crate::sched::sleep_ms(10);
+    }
+}
+
+fn btn_bits(ev: &MouseEvent) -> u8 {
+    (ev.left as u8) | ((ev.right as u8) << 1) | ((ev.middle as u8) << 2)
+}