diff --git a/src/Makefile.am b/src/Makefile.am
index 25fdab2..fedc96f 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -73,7 +73,7 @@
 	encoding.cpp \
 	sba.c \
 	decoding.cpp \
-	llc.cpp \
+	llc.c \
 	rlc.cpp \
 	osmobts_sock.c \
 	gprs_codel.c \
diff --git a/src/llc.cpp b/src/llc.c
similarity index 69%
rename from src/llc.cpp
rename to src/llc.c
index 5cf2213..700585a 100644
--- a/src/llc.cpp
+++ b/src/llc.c
@@ -15,32 +15,36 @@
  * GNU General Public License for more details.
  */
 
-#include <bts.h>
 
 #include <stdio.h>
 
-extern "C" {
 #include <osmocom/core/msgb.h>
-}
 
+#include "bts.h"
 #include "pcu_utils.h"
+#include "llc.h"
+
+void llc_init(struct gprs_llc *llc)
+{
+	llc_reset(llc);
+}
 
 /* reset LLC frame */
-void gprs_llc::reset()
+void llc_reset(struct gprs_llc *llc)
 {
-	index = 0;
-	length = 0;
+	llc->index = 0;
+	llc->length = 0;
 
-	memset(frame, 0x42, sizeof(frame));
+	memset(llc->frame, 0x42, sizeof(llc->frame));
 }
 
-void gprs_llc::reset_frame_space()
+void llc_reset_frame_space(struct gprs_llc *llc)
 {
-	index = 0;
+	llc->index = 0;
 }
 
 /* Put an Unconfirmed Information (UI) Dummy command, see GSM 44.064, 6.4.2.2 */
-void gprs_llc::put_dummy_frame(size_t req_len)
+void llc_put_dummy_frame(struct gprs_llc *llc, size_t req_len)
 {
 	/* The shortest dummy command (the spec requests at least 6 octets) */
 	static const uint8_t llc_dummy_command[] = {
@@ -48,39 +52,34 @@
 	};
 	static const size_t max_dummy_command_len = 79;
 
-	put_frame(llc_dummy_command, sizeof(llc_dummy_command));
+	llc_put_frame(llc, llc_dummy_command, sizeof(llc_dummy_command));
 
 	if (req_len > max_dummy_command_len)
 		req_len = max_dummy_command_len;
 
 	/* Add further stuffing, if the requested length exceeds the minimum
 	 * dummy command length */
-	if (length < req_len) {
-		memset(&frame[length], 0x2b, req_len - length);
-		length = req_len;
+	if (llc->length < req_len) {
+		memset(&llc->frame[llc->length], 0x2b, req_len - llc->length);
+		llc->length = req_len;
 	}
 }
 
-void gprs_llc::put_frame(const uint8_t *data, size_t len)
+void llc_put_frame(struct gprs_llc *llc, const uint8_t *data, size_t len)
 {
 	/* only put frames when we are empty */
-	OSMO_ASSERT(index == 0 && length == 0);
-	append_frame(data, len);
+	OSMO_ASSERT(llc->index == 0 && llc->length == 0);
+	llc_append_frame(llc, data, len);
 }
 
-void gprs_llc::append_frame(const uint8_t *data, size_t len)
+void llc_append_frame(struct gprs_llc *llc, const uint8_t *data, size_t len)
 {
 	/* TODO: bounds check */
-	memcpy(frame + length, data, len);
-	length += len;
+	memcpy(llc->frame + llc->length, data, len);
+	llc->length += len;
 }
 
-void gprs_llc::init()
-{
-	reset();
-}
-
-bool gprs_llc::is_user_data_frame(uint8_t *data, size_t len)
+bool llc_is_user_data_frame(const uint8_t *data, size_t len)
 {
 	if (len < 2)
 		return false;
@@ -104,20 +103,20 @@
 }
 
 
-void gprs_llc_queue::enqueue(struct msgb *llc_msg, const struct timespec *expire_time)
+void llc_queue_enqueue(struct gprs_llc_queue *q, struct msgb *llc_msg, const struct timespec *expire_time)
 {
-	MetaInfo *meta_storage;
+	struct MetaInfo *meta_storage;
 
 	osmo_static_assert(sizeof(*meta_storage) <= sizeof(llc_msg->cb), info_does_not_fit);
 
-	queue_size += 1;
-	queue_octets += msgb_length(llc_msg);
+	q->queue_size += 1;
+	q->queue_octets += msgb_length(llc_msg);
 
-	meta_storage = (MetaInfo *)&llc_msg->cb[0];
+	meta_storage = (struct MetaInfo *)&llc_msg->cb[0];
 	osmo_clock_gettime(CLOCK_MONOTONIC, &meta_storage->recv_time);
 	meta_storage->expire_time = *expire_time;
 
-	msgb_enqueue(&queue, llc_msg);
+	msgb_enqueue(&q->queue, llc_msg);
 }
 
 void llc_queue_clear(struct gprs_llc_queue *q, struct gprs_rlcmac_bts *bts)
@@ -159,8 +158,8 @@
 			msg = msg1;
 			msg1 = NULL;
 		} else {
-			const MetaInfo *mi1 = (MetaInfo *)&msg1->cb[0];
-			const MetaInfo *mi2 = (MetaInfo *)&msg2->cb[0];
+			const struct MetaInfo *mi1 = (struct MetaInfo *)&msg1->cb[0];
+			const struct MetaInfo *mi2 = (struct MetaInfo *)&msg2->cb[0];
 
 			if (timespeccmp(&mi2->recv_time, &mi1->recv_time, >)) {
 				msg = msg1;
@@ -189,24 +188,24 @@
 
 #define ALPHA 0.5f
 
-struct msgb *gprs_llc_queue::dequeue(const MetaInfo **info)
+struct msgb *llc_queue_dequeue(struct gprs_llc_queue *q, const struct MetaInfo **info)
 {
 	struct msgb *msg;
 	struct timespec *tv, tv_now, tv_result;
 	uint32_t lifetime;
-	const MetaInfo *meta_storage;
+	const struct MetaInfo *meta_storage;
 
-	msg = msgb_dequeue(&queue);
+	msg = msgb_dequeue(&q->queue);
 	if (!msg)
 		return NULL;
 
-	meta_storage = (MetaInfo *)&msg->cb[0];
+	meta_storage = (struct MetaInfo *)&msg->cb[0];
 
 	if (info)
 		*info = meta_storage;
 
-	queue_size -= 1;
-	queue_octets -= msgb_length(msg);
+	q->queue_size -= 1;
+	q->queue_octets -= msgb_length(msg);
 
 	/* take the second time */
 	osmo_clock_gettime(CLOCK_MONOTONIC, &tv_now);
@@ -214,12 +213,12 @@
 	timespecsub(&tv_now, &meta_storage->recv_time, &tv_result);
 
 	lifetime = tv_result.tv_sec*1000 + tv_result.tv_nsec/1000000;
-	avg_queue_delay = avg_queue_delay * ALPHA + lifetime * (1-ALPHA);
+	q->avg_queue_delay = q->avg_queue_delay * ALPHA + lifetime * (1-ALPHA);
 
 	return msg;
 }
 
-void gprs_llc_queue::calc_pdu_lifetime(struct gprs_rlcmac_bts *bts, const uint16_t pdu_delay_csec, struct timespec *tv)
+void llc_queue_calc_pdu_lifetime(struct gprs_rlcmac_bts *bts, const uint16_t pdu_delay_csec, struct timespec *tv)
 {
 	uint16_t delay_csec;
 	if (bts->pcu->vty.force_llc_lifetime)
@@ -241,8 +240,7 @@
 	timespecadd(&now, &csec, tv);
 }
 
-bool gprs_llc_queue::is_frame_expired(const struct timespec *tv_now,
-	const struct timespec *tv)
+bool llc_queue_is_frame_expired(const struct timespec *tv_now, const struct timespec *tv)
 {
 	/* Timeout is infinite */
 	if (tv->tv_sec == 0 && tv->tv_nsec == 0)
diff --git a/src/llc.h b/src/llc.h
index e7548d4..a371b68 100644
--- a/src/llc.h
+++ b/src/llc.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2013 by Holger Hans Peter Freyther
+ * Copyright (C) 2022 by by Sysmocom s.f.m.c. GmbH
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -17,15 +18,14 @@
 #ifdef __cplusplus
 extern "C" {
 #endif
-	#include <osmocom/core/linuxlist.h>
-#ifdef __cplusplus
-}
-#endif
 
 #include <stdint.h>
 #include <string.h>
 #include <time.h>
 
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/msgb.h>
+
 #define LLC_MAX_LEN 1543
 
 struct gprs_rlcmac_bts;
@@ -34,23 +34,19 @@
  * I represent the LLC data to a MS
  */
 struct gprs_llc {
-
-#ifdef __cplusplus
-	static bool is_user_data_frame(uint8_t *data, size_t len);
-
-	void init();
-	void reset();
-	void reset_frame_space();
-
-	void put_frame(const uint8_t *data, size_t len);
-	void put_dummy_frame(size_t req_len);
-	void append_frame(const uint8_t *data, size_t len);
-#endif
-
 	uint8_t frame[LLC_MAX_LEN]; /* current DL or UL frame */
 	uint16_t index; /* current write/read position of frame */
 	uint16_t length; /* len of current DL LLC_frame, 0 == no frame */
 };
+bool llc_is_user_data_frame(const uint8_t *data, size_t len);
+
+void llc_init(struct gprs_llc *llc);
+void llc_reset(struct gprs_llc *llc);
+void llc_reset_frame_space(struct gprs_llc *llc);
+
+void llc_put_frame(struct gprs_llc *llc, const uint8_t *data, size_t len);
+void llc_put_dummy_frame(struct gprs_llc *llc, size_t req_len);
+void llc_append_frame(struct gprs_llc *llc, const uint8_t *data, size_t len);
 
 struct MetaInfo {
 	struct timespec recv_time;
@@ -60,28 +56,21 @@
  * I store the LLC frames that come from the SGSN.
  */
 struct gprs_llc_queue {
-#ifdef __cplusplus
-	static void calc_pdu_lifetime(struct gprs_rlcmac_bts *bts, const uint16_t pdu_delay_csec,
-		struct timespec *tv);
-	static bool is_frame_expired(const struct timespec *now,
-		const struct timespec *tv);
-	static bool is_user_data_frame(uint8_t *data, size_t len);
-
-	void enqueue(struct msgb *llc_msg, const struct timespec *expire_time);
-	struct msgb *dequeue(const MetaInfo **info = 0);
-#endif
 	uint32_t avg_queue_delay; /* Average delay of data going through the queue */
 	size_t queue_size;
 	size_t queue_octets;
 	struct llist_head queue; /* queued LLC DL data */
 };
 
-#ifdef __cplusplus
-extern "C" {
-#endif
+void llc_queue_calc_pdu_lifetime(struct gprs_rlcmac_bts *bts, const uint16_t pdu_delay_csec,
+		struct timespec *tv);
+bool llc_queue_is_frame_expired(const struct timespec *tv_now, const struct timespec *tv);
+
 void llc_queue_init(struct gprs_llc_queue *q);
 void llc_queue_clear(struct gprs_llc_queue *q, struct gprs_rlcmac_bts *bts);
 void llc_queue_move_and_merge(struct gprs_llc_queue *q, struct gprs_llc_queue *o);
+void llc_queue_enqueue(struct gprs_llc_queue *q, struct msgb *llc_msg, const struct timespec *expire_time);
+struct msgb *llc_queue_dequeue(struct gprs_llc_queue *q, const struct MetaInfo **info);
 
 static inline uint16_t llc_chunk_size(const struct gprs_llc *llc)
 {
diff --git a/src/tbf.cpp b/src/tbf.cpp
index c2eeb89..2c68ede 100644
--- a/src/tbf.cpp
+++ b/src/tbf.cpp
@@ -130,7 +130,7 @@
 	OSMO_ASSERT(dl_ass_fsm.fi);
 
 	m_rlc.init();
-	m_llc.init();
+	llc_init(&m_llc);
 
 	m_name_buf[0] = '\0';
 
diff --git a/src/tbf_dl.cpp b/src/tbf_dl.cpp
index ec455c1..01b8f68 100644
--- a/src/tbf_dl.cpp
+++ b/src/tbf_dl.cpp
@@ -217,9 +217,9 @@
 	if (!llc_msg)
 		return -ENOMEM;
 
-	gprs_llc_queue::calc_pdu_lifetime(bts, pdu_delay_csec, &expire_time);
+	llc_queue_calc_pdu_lifetime(bts, pdu_delay_csec, &expire_time);
 	memcpy(msgb_put(llc_msg, len), data, len);
-	llc_queue()->enqueue(llc_msg, &expire_time);
+	llc_queue_enqueue(llc_queue(), llc_msg, &expire_time);
 	start_llc_timer();
 
 	if (state_is(TBF_ST_WAIT_RELEASE)) {
@@ -358,7 +358,7 @@
 	osmo_clock_gettime(CLOCK_MONOTONIC, &tv_now);
 	timespecadd(&tv_now, &hyst_delta, &tv_now2);
 
-	while ((msg = llc_queue()->dequeue(&info))) {
+	while ((msg = llc_queue_dequeue(llc_queue(), &info))) {
 		const struct timespec *tv_disc = &info->expire_time;
 		const struct timespec *tv_recv = &info->recv_time;
 
@@ -372,11 +372,11 @@
 		}
 
 		/* Is the age below the low water mark? */
-		if (!gprs_llc_queue::is_frame_expired(&tv_now2, tv_disc))
+		if (!llc_queue_is_frame_expired(&tv_now2, tv_disc))
 			break;
 
 		/* Is the age below the high water mark */
-		if (!gprs_llc_queue::is_frame_expired(&tv_now, tv_disc)) {
+		if (!llc_queue_is_frame_expired(&tv_now, tv_disc)) {
 			/* Has the previous message not been dropped? */
 			if (frames == 0)
 				break;
@@ -391,7 +391,7 @@
 				break;
 
 			/* Is it a GMM message? */
-			if (!gprs_llc::is_user_data_frame(msg->data, msg->len))
+			if (!llc_is_user_data_frame(msg->data, msg->len))
 				break;
 		}
 
@@ -634,7 +634,7 @@
 
 	LOGPTBFDL(this, LOGL_DEBUG, "Dequeue next LLC (len=%d)\n", msg->len);
 
-	m_llc.put_frame(msg->data, msg->len);
+	llc_put_frame(&m_llc, msg->data, msg->len);
 	bts_do_rate_ctr_inc(bts, CTR_LLC_FRAME_SCHED);
 	msgb_free(msg);
 	m_last_dl_drained_fn = -1;
@@ -726,7 +726,7 @@
 			 * "Delayed release of downlink Temporary Block Flow" */
 			/* A header will need to by added, so we just need
 			 * space-1 octets */
-			m_llc.put_dummy_frame(space - 1);
+			llc_put_dummy_frame(&m_llc, space - 1);
 
 			LOGPTBFDL(this, LOGL_DEBUG,
 				  "Empty chunk, added LLC dummy command of size %d, drained_since=%d\n",
@@ -747,7 +747,7 @@
 		LOGPTBFDL(this, LOGL_DEBUG, "Complete DL frame, len=%d\n", llc_frame_length(&m_llc));
 		gprs_rlcmac_dl_bw(this, llc_frame_length(&m_llc));
 		bts_do_rate_ctr_add(bts, CTR_LLC_DL_BYTES, llc_frame_length(&m_llc));
-		m_llc.reset();
+		llc_reset(&m_llc);
 
 		if (is_final) {
 			request_dl_ack();
diff --git a/src/tbf_ul.cpp b/src/tbf_ul.cpp
index 305daaa..21a7a76 100644
--- a/src/tbf_ul.cpp
+++ b/src/tbf_ul.cpp
@@ -283,7 +283,7 @@
 				i + 1, frame->offset, frame->length,
 				frame->is_complete);
 
-			m_llc.append_frame(data + frame->offset, frame->length);
+			llc_append_frame(&m_llc, data + frame->offset, frame->length);
 			llc_consume(&m_llc, frame->length);
 		}
 
@@ -292,7 +292,7 @@
 			LOGPTBFUL(this, LOGL_DEBUG, "complete UL frame len=%d\n", llc_frame_length(&m_llc));
 			snd_ul_ud();
 			bts_do_rate_ctr_add(bts, CTR_LLC_UL_BYTES, llc_frame_length(&m_llc));
-			m_llc.reset();
+			llc_reset(&m_llc);
 		}
 	}
 
@@ -544,7 +544,7 @@
 	LOGP(DBSSGP, LOGL_INFO, "LLC [PCU -> SGSN] %s len=%d\n", tbf_name(this), llc_frame_length(&m_llc));
 	if (!bctx) {
 		LOGP(DBSSGP, LOGL_ERROR, "No bctx\n");
-		m_llc.reset_frame_space();
+		llc_reset_frame_space(&m_llc);
 		return -EIO;
 	}
 
@@ -556,7 +556,7 @@
 	qos_profile[2] = QOS_PROFILE;
 	bssgp_tx_ul_ud(bctx, tlli(), qos_profile, llc_pdu);
 
-	m_llc.reset_frame_space();
+	llc_reset_frame_space(&m_llc);
 	return 0;
 }