adaptive sync

i3/scripts/guide-freeze

@@ -0,0 +1,50 @@
+#!/usr/bin/env python3
+# Freeze/resume the focused window on the controller's Home/guide button (BTN_MODE).
+# Stdlib only: reads raw evdev events. Gamepads are readable by the seat user.
+import glob, os, select, signal, struct, subprocess, time
+
+EV_KEY, BTN_MODE = 1, 0x13c
+EVENT = struct.Struct('llHHi')  # struct input_event
+LONG_BITS = struct.calcsize('l') * 8
+CMD = [os.path.expanduser('~/.config/i3/scripts/freeze-toggle')]
+
+signal.signal(signal.SIGCHLD, signal.SIG_IGN)  # auto-reap child processes
+
+def has_btn_mode(path):
+    try:
+        with open(f'/sys/class/input/{os.path.basename(path)}/device/capabilities/key') as f:
+            words = f.read().split()
+    except OSError:
+        return False
+    bits = 0
+    for w in words:
+        bits = bits << LONG_BITS | int(w, 16)
+    return bits >> BTN_MODE & 1
+
+fds = {}  # fd -> device path
+last = 0.0
+rescan = 0.0
+while True:
+    if time.monotonic() >= rescan:  # pick up hotplugged controllers
+        for path in glob.glob('/dev/input/event*'):
+            if path not in fds.values() and has_btn_mode(path):
+                try:
+                    fds[os.open(path, os.O_RDONLY)] = path
+                except OSError:
+                    pass
+        rescan = time.monotonic() + 2
+    ready, _, _ = select.select(list(fds), [], [], 2)
+    for fd in ready:
+        try:
+            data = os.read(fd, EVENT.size * 64)
+        except OSError:  # controller unplugged
+            os.close(fd)
+            del fds[fd]
+            continue
+        for sec, usec, type_, code, value in EVENT.iter_unpack(data):
+            if type_ == EV_KEY and code == BTN_MODE and value == 1:
+                now = sec + usec / 1e6
+                if now - last < 0.4:  # GuliKit's Home button double-fires ~10ms apart
+                    continue
+                last = now
+                subprocess.Popen(CMD, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)