gsm_04_12.h: Add beginning of structs for SMS CB

I am trying to understand the RSL and GSM 04.12
spec to implement CBS for OpenBSC...
diff --git a/include/osmocore/protocol/Makefile.am b/include/osmocore/protocol/Makefile.am
index 557950e..5df9fe7 100644
--- a/include/osmocore/protocol/Makefile.am
+++ b/include/osmocore/protocol/Makefile.am
@@ -1,3 +1,4 @@
-osmocore_proto_HEADERS = gsm_04_08.h gsm_04_11.h gsm_04_80.h gsm_08_58.h gsm_12_21.h gsm_08_08.h
+osmocore_proto_HEADERS = gsm_04_08.h gsm_04_11.h gsm_04_80.h gsm_08_58.h \
+			 gsm_12_21.h gsm_08_08.h gsm_04_12.h
 
 osmocore_protodir = $(includedir)/osmocore/protocol
diff --git a/include/osmocore/protocol/gsm_04_12.h b/include/osmocore/protocol/gsm_04_12.h
new file mode 100644
index 0000000..bd9e088
--- /dev/null
+++ b/include/osmocore/protocol/gsm_04_12.h
@@ -0,0 +1,31 @@
+#ifndef PROTO_GSM_04_12_H
+#define PROTO_GSM_04_12_H
+
+#include <stdint.h>
+
+/* GSM TS 04.12 definitions for Short Message Service Cell Broadcast */
+
+#define GSM412_SEQ_FST_BLOCK		0x0
+#define GSM412_SEQ_SND_BLOCK		0x1
+#define GSM412_SEQ_TRD_BLOCK		0x2
+#define GSM412_SEQ_FTH_BLOCK		0x3
+#define GSM412_SEQ_FST_SCHED_BLOCK	0x8
+#define GSM413_SEQ_NULL_MSG		0xf
+
+struct gsm412_block_type {
+	uint8_t	seq_nr : 4,
+		lb : 1,
+		lpd : 2,
+		spare : 1;
+} __attribute__((packed));
+
+struct gsm413_sched_msg {
+	uint8_t beg_slot_nr : 6,
+		type : 2;
+	uint8_t end_slot_nr : 6,
+		spare1 : 1, spare2: 1;
+	uint8_t cbsms_msg_map[6];
+	uint8_t data[0];
+} __attribute__((packed));
+
+#endif