diff --git a/library/IuUP_EncDec.cc b/library/IuUP_EncDec.cc
new file mode 100644
index 0000000..81742e8
--- /dev/null
+++ b/library/IuUP_EncDec.cc
@@ -0,0 +1,250 @@
+
+#include "Octetstring.hh"
+#include "Error.hh"
+#include "Logger.hh"
+
+#include "IuUP_Types.hh"
+
+#include <stdint.h>
+
+extern "C" {
+
+typedef uint8_t ubit_t;
+typedef uint8_t pbit_t;
+
+static int osmo_pbit2ubit(ubit_t *out, const pbit_t *in, unsigned int num_bits)
+{
+	unsigned int i;
+	ubit_t *cur = out;
+	ubit_t *limit = out + num_bits;
+
+	for (i = 0; i < (num_bits/8)+1; i++) {
+		pbit_t byte = in[i];
+		*cur++ = (byte >> 7) & 1;
+		if (cur >= limit)
+			break;
+		*cur++ = (byte >> 6) & 1;
+		if (cur >= limit)
+			break;
+		*cur++ = (byte >> 5) & 1;
+		if (cur >= limit)
+			break;
+		*cur++ = (byte >> 4) & 1;
+		if (cur >= limit)
+			break;
+		*cur++ = (byte >> 3) & 1;
+		if (cur >= limit)
+			break;
+		*cur++ = (byte >> 2) & 1;
+		if (cur >= limit)
+			break;
+		*cur++ = (byte >> 1) & 1;
+		if (cur >= limit)
+			break;
+		*cur++ = (byte >> 0) & 1;
+		if (cur >= limit)
+			break;
+	}
+	return cur - out;
+}
+
+
+struct osmo_crc8gen_code {
+	int bits;           /*!< Actual number of bits of the CRC */
+	uint8_t poly;      /*!< Polynom (normal representation, MSB omitted */
+	uint8_t init;      /*!< Initialization value of the CRC state */
+	uint8_t remainder; /*!< Remainder of the CRC (final XOR) */
+};
+
+static uint8_t
+osmo_crc8gen_compute_bits(const struct osmo_crc8gen_code *code,
+                           const ubit_t *in, int len)
+{
+	const uint8_t poly = code->poly;
+	uint8_t crc = code->init;
+	int i, n = code->bits-1;
+
+	for (i=0; i<len; i++) {
+		uint8_t bit = in[i] & 1;
+		crc ^= (bit << n);
+		if (crc & ((uint8_t)1 << n)) {
+			crc <<= 1;
+			crc ^= poly;
+		} else {
+			crc <<= 1;
+		}
+		crc &= ((uint8_t)1 << code->bits) - 1;
+	}
+
+	crc ^= code->remainder;
+
+	return crc;
+}
+
+struct osmo_crc16gen_code {
+	int bits;           /*!< Actual number of bits of the CRC */
+	uint16_t poly;      /*!< Polynom (normal representation, MSB omitted */
+	uint16_t init;      /*!< Initialization value of the CRC state */
+	uint16_t remainder; /*!< Remainder of the CRC (final XOR) */
+};
+
+static uint16_t
+osmo_crc16gen_compute_bits(const struct osmo_crc16gen_code *code,
+                           const ubit_t *in, int len)
+{
+	const uint16_t poly = code->poly;
+	uint16_t crc = code->init;
+	int i, n = code->bits-1;
+
+	for (i=0; i<len; i++) {
+		uint16_t bit = in[i] & 1;
+		crc ^= (bit << n);
+		if (crc & ((uint16_t)1 << n)) {
+			crc <<= 1;
+			crc ^= poly;
+		} else {
+			crc <<= 1;
+		}
+		crc &= ((uint16_t)1 << code->bits) - 1;
+	}
+
+	crc ^= code->remainder;
+
+	return crc;
+}
+
+}
+
+
+static const struct osmo_crc8gen_code iuup_hdr_crc_code = {
+	.bits = 6,
+	.poly = 47,
+	.init = 0,
+	.remainder = 0,
+};
+
+static const struct osmo_crc16gen_code iuup_data_crc_code = {
+	.bits = 10,
+	.poly = 563,
+	.init = 0,
+	.remainder = 0,
+};
+
+static int iuup_get_payload_offset(const uint8_t *iuup_pdu)
+{
+	uint8_t pdu_type = iuup_pdu[0] >> 4;
+	switch (pdu_type) {
+	case 0:
+	case 14:
+		return 4;
+	case 1:
+		return 3;
+	default:
+		return -1;
+	}
+}
+
+int osmo_iuup_compute_payload_crc(const uint8_t *iuup_pdu, unsigned int pdu_len)
+{
+	ubit_t buf[1024*8];
+	uint8_t pdu_type;
+	int offset, payload_len_bytes;
+
+	if (pdu_len < 1)
+		return -1;
+
+	pdu_type = iuup_pdu[0] >> 4;
+
+	/* Type 1 has no CRC */
+	if (pdu_type == 1)
+		return 0;
+
+	offset = iuup_get_payload_offset(iuup_pdu);
+	if (offset < 0)
+		return offset;
+
+	if (pdu_len < (unsigned int)offset)
+		return -1;
+
+	payload_len_bytes = pdu_len - offset;
+	osmo_pbit2ubit(buf, iuup_pdu+offset, payload_len_bytes*8);
+	return osmo_crc16gen_compute_bits(&iuup_data_crc_code, buf, payload_len_bytes*8);
+}
+
+int osmo_iuup_compute_header_crc(const uint8_t *iuup_pdu, unsigned int pdu_len)
+{
+	ubit_t buf[2*8];
+
+	if (pdu_len < 2)
+		return -1;
+
+	osmo_pbit2ubit(buf, iuup_pdu, 2*8);
+	return osmo_crc8gen_compute_bits(&iuup_hdr_crc_code, buf, 2*8);
+}
+/* IuUP CRC Implementation */
+
+/* (C) 2017 by Harald Welte <laforge@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace IuUP__Types {
+
+
+INTEGER f__IuUP__compute__crc__payload(OCTETSTRING const &in)
+{
+	int crc_calc;
+	const unsigned char *data = (const unsigned char *)in;
+	int len = in.lengthof();
+
+	crc_calc = osmo_iuup_compute_payload_crc(data, len);
+
+	return INTEGER(crc_calc);
+}
+
+INTEGER f__IuUP__compute__crc__header(OCTETSTRING const &in)
+{
+	int crc_calc;
+	const unsigned char *data = (const unsigned char *)in;
+	int len = in.lengthof();
+
+	crc_calc = osmo_iuup_compute_header_crc(data, len);
+
+	return INTEGER(crc_calc);
+}
+
+OCTETSTRING f__enc__IuUP__PDU(const IuUP__PDU& pdu)
+{
+	TTCN_Buffer buf;
+	int crc_hdr, crc_payload;
+	uint8_t in[2];
+	pdu.encode(IuUP__PDU_descr_, buf, TTCN_EncDec::CT_RAW);
+	OCTETSTRING ret_val(buf.get_len(), buf.get_data());
+
+	crc_hdr = osmo_iuup_compute_header_crc(buf.get_data(), buf.get_len());
+	crc_payload = osmo_iuup_compute_payload_crc(buf.get_data(), buf.get_len());
+	in[0] = (crc_hdr & 0x3f) << 2;
+	in[0] |= (crc_payload & 0x3ff) >> 8;
+	in[1] = crc_payload & 0xff;
+	OCTETSTRING CHECKSUM(2, in);
+
+	ret_val = substr(ret_val, 0, 2) + CHECKSUM + substr(ret_val, 4, ret_val.lengthof()-4);
+
+	return ret_val;
+}
+
+}