pcu_l1_if: move direct phy l1if functions to dedicated header file

The function headers for the direct phy related functions (l1if_...) are
currently directly listed in pcu_l1_if.cpp and osmobts_sock.c. Those
functions are basically the API interface definition between the
platform independed PCU code and the platform dependant direct phy code.
Lets put them into a dedicated header file.

Change-Id: Id54b96a4cd498a9860f3f209498132455e2aa6f8
Related: OS#5198
diff --git a/src/Makefile.am b/src/Makefile.am
index e020ffa..e747d74 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -100,6 +100,7 @@
 	gprs_ms_storage.h \
 	gprs_pcu.h \
 	pcu_l1_if.h \
+	pcu_l1_if_phy.h \
 	pcu_vty.h \
 	pcu_vty_functions.h \
 	mslot_class.h \
diff --git a/src/osmobts_sock.c b/src/osmobts_sock.c
index 1cbd1a0..282e33f 100644
--- a/src/osmobts_sock.c
+++ b/src/osmobts_sock.c
@@ -30,6 +30,7 @@
 
 
 #include <pcu_l1_if.h>
+#include <pcu_l1_if_phy.h>
 #include <gprs_debug.h>
 #include <gprs_bssgp_pcu.h>
 #include <osmocom/pcu/pcuif_proto.h>
@@ -37,8 +38,6 @@
 #include <tbf.h>
 #include <pdch.h>
 
-int l1if_close_pdch(void *obj);
-
 /*
  * osmo-bts PCU socket functions
  */
diff --git a/src/pcu_l1_if.cpp b/src/pcu_l1_if.cpp
index 02f56ac..62f02d9 100644
--- a/src/pcu_l1_if.cpp
+++ b/src/pcu_l1_if.cpp
@@ -43,6 +43,7 @@
 #include <osmocom/gsm/gsm0502.h>
 
 #include <nacc_fsm.h>
+#include <pcu_l1_if_phy.h>
 }
 
 #include <gprs_rlcmac.h>
@@ -56,15 +57,6 @@
 #include <tbf_dl.h>
 #include <gprs_ms_storage.h>
 
-// FIXME: move this, when changed from c++ to c.
-extern "C" {
-void *l1if_open_pdch(uint8_t trx_no, uint32_t hlayer1,
-		     struct gsmtap_inst *gsmtap);
-int l1if_connect_pdch(void *obj, uint8_t ts);
-int l1if_pdch_req(void *obj, uint8_t ts, int is_ptcch, uint32_t fn,
-        uint16_t arfcn, uint8_t block_nr, uint8_t *data, uint8_t len);
-}
-
 extern void *tall_pcu_ctx;
 
 #define PAGING_GROUP_LEN 3
diff --git a/src/pcu_l1_if_phy.h b/src/pcu_l1_if_phy.h
new file mode 100644
index 0000000..f25bf7b
--- /dev/null
+++ b/src/pcu_l1_if_phy.h
@@ -0,0 +1,9 @@
+#pragma once
+
+#include <stdint.h>
+
+void *l1if_open_pdch(uint8_t trx_no, uint32_t hlayer1, struct gsmtap_inst *gsmtap);
+int l1if_connect_pdch(void *obj, uint8_t ts);
+int l1if_pdch_req(void *obj, uint8_t ts, int is_ptcch, uint32_t fn, uint16_t arfcn, uint8_t block_nr, uint8_t *data,
+		  uint8_t len);
+int l1if_close_pdch(void *obj);