CE process watching WIP

kernel/device/ps2_kb.c

@@ -213,6 +213,33 @@ DEFINE_DEVICE_OP (ps2kb_read_key) {
   return ST_OK;
 }
 
+DEFINE_DEVICE_OP (ps2kb_read_key_nonblock) {
+  uint64_t frb, fsq;
+
+  uint8_t* chbuf = (uint8_t*)a1;
+
+  if (chbuf == NULL)
+    return -ST_BAD_ADDRESS_SPACE;
+
+  spin_lock (&ps2kb_ringbuffer_lock, &frb);
+
+  size_t prev_count = ps2kb_ringbuffer.count;
+
+  ringbuffer_pop (uint8_t, &ps2kb_ringbuffer, chbuf);
+
+  size_t new_count = ps2kb_ringbuffer.count;
+
+  /* didn't pop anything */
+  if (prev_count == new_count) {
+    spin_unlock (&ps2kb_ringbuffer_lock, frb);
+    return -ST_TRY_AGAIN;
+  }
+
+  spin_unlock (&ps2kb_ringbuffer_lock, frb);
+
+  return ST_OK;
+}
+
 static void ps2kb_set_typematic (uint8_t delay, uint8_t rate) {
   while (inb (KB_CTL_STATUS) & 0x02)
     ;