rtio: add timestamp function

artiq/devices/rtio_core.py

@@ -137,3 +137,13 @@ class RTIOIn(_RTIOBase):
         while syscall("rtio_get", self.channel) >= 0:
             count += 1
         return count
+
+    @kernel
+    def timestamp(self):
+        """Poll the RTIO input and returns an event timestamp, according to
+        the gating.
+
+        If the gate is permanently closed, returns a negative value.
+
+        """
+        return cycles_to_time(syscall("rtio_get", self.channel))

soc/runtime/rtio.c

@@ -60,7 +60,7 @@ long long int rtio_get(int channel)
     rtio_chan_sel_write(channel);
     while(rtio_i_readable_read() || (rtio_o_level_read() != 0)) {
         if(rtio_i_readable_read()) {
-            r = rtio_i_value_read();
+            r = rtio_i_timestamp_read();
             rtio_i_re_write(1);
             return r;
         }