pcu: Introduce as_ms_rx_ignore_empty helper

It will be further used in follow-up patches.

Change-Id: I3c80ba4b8d229fa4a75dfd04abb7c5aae26e221c
diff --git a/pcu/GPRS_Components.ttcn b/pcu/GPRS_Components.ttcn
index 1014498..d6749d7 100644
--- a/pcu/GPRS_Components.ttcn
+++ b/pcu/GPRS_Components.ttcn
@@ -559,6 +559,21 @@
 	}
 }
 
+altstep as_pcuif_rx_ignore_empty(template (value) TsTrxBtsNum nr := ts_TsTrxBtsNum)
+runs on MS_BTS_IFACE_CT {
+	var BTS_PDTCH_Block data_msg;
+	[] BTS.receive(tr_PCUIF_DATA_PDTCH(nr.bts_nr,
+					   tr_PCUIF_DATA(nr.trx_nr, nr.ts_nr, sapi := PCU_IF_SAPI_PDTCH),
+					   omit)) -> value data_msg {
+
+		BTS.send(ts_PCUIF_RTS_REQ(nr.bts_nr, nr.trx_nr, nr.ts_nr,
+					  sapi := PCU_IF_SAPI_PDTCH, fn := 0,
+					  arfcn := f_trxnr2arfcn(valueof(nr.trx_nr)),
+					  block_nr := nr.blk_nr));
+		repeat;
+	}
+}
+
 altstep as_rx_fail_dummy(template (value) TsTrxBtsNum nr := ts_TsTrxBtsNum)
 runs on MS_BTS_IFACE_CT {
 	var BTS_PDTCH_Block data_msg;