diff --git a/openbsc/src/libbsc/arfcn_range_encode.c b/openbsc/src/libbsc/arfcn_range_encode.c
new file mode 100644
index 0000000..02a75a5
--- /dev/null
+++ b/openbsc/src/libbsc/arfcn_range_encode.c
@@ -0,0 +1,305 @@
+/* gsm 04.08 system information (si) encoding and decoding
+ * 3gpp ts 04.08 version 7.21.0 release 1998 / etsi ts 100 940 v7.21.0 */
+
+/*
+ * (C) 2012 Holger Hans Peter Freyther
+ * (C) 2012 by On-Waves
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 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/>.
+ */
+
+#include <openbsc/arfcn_range_encode.h>
+#include <openbsc/debug.h>
+
+#include <osmocom/gsm/protocol/gsm_04_08.h>
+
+#include <osmocom/core/utils.h>
+
+int greatest_power_of_2_lesser_or_equal_to(int index)
+{
+	int power_of_2 = 1;
+
+	do {
+		power_of_2 *= 2;
+	} while (power_of_2 <= index);
+
+	/* now go back one step */
+	return power_of_2 / 2;
+}
+
+static inline int mod(int data, int range)
+{
+	int res = data % range;
+	while (res < 0)
+		res += range;
+	return res;
+}
+
+/**
+ * Determine at which index to split the ARFCNs to create an
+ * equally size partition for the given range. Return -1 if
+ * no such partition exists.
+ */
+int range_enc_find_index(const int range, const int *freqs, const int size)
+{
+	int i, j, n;
+
+	const int RANGE_DELTA = (range - 1) / 2;
+
+	for (i = 0; i < size; ++i) {
+		n = 0;
+		for (j = 0; j < size; ++j) {
+			if (mod(freqs[j] - freqs[i], range) <= RANGE_DELTA)
+				n += 1;
+		}
+
+		if (n - 1 == (size - 1) / 2)
+			return i;
+	}
+
+	return -1;
+}
+
+/**
+ * Range encode the ARFCN list.
+ * \param range The range to use.
+ * \param arfcns The list of ARFCNs
+ * \param size The size of the list of ARFCNs
+ * \param out Place to store the W(i) output.
+ */
+int range_enc_arfcns(const int range,
+		const int *arfcns, int size, int *out,
+		const int index)
+{
+	int split_at;
+	int i;
+
+	/*
+	 * The below is a GNU extension and we can remove it when
+	 * we move to a quicksort like in-situ swap with the pivot.
+	 */
+	int arfcns_left[size / 2];
+	int arfcns_right[size / 2];
+	int l_size;
+	int r_size;
+	int l_origin;
+	int r_origin;
+
+
+	/* Test the two recursion anchors and stop processing */
+	if (size == 0)
+		return 0;
+
+	if (size == 1) {
+		out[index] = 1 + arfcns[0];
+		return 0;
+	}
+
+	/* Now do the processing */
+	split_at = range_enc_find_index(range, arfcns, size);
+
+	/* we now know where to split */
+	out[index] = 1 + arfcns[split_at];
+
+	/* calculate the work that needs to be done for the leafs */
+	l_origin = mod(arfcns[split_at] + ((range - 1) / 2) + 1, range);
+	r_origin = mod(arfcns[split_at] + 1, range);
+	for (i = 0, l_size = 0, r_size = 0; i < size; ++i) {
+		if (mod(arfcns[i] - l_origin, range) < range / 2)
+			arfcns_left[l_size++] = mod(arfcns[i] - l_origin, range);
+		if (mod(arfcns[i] - r_origin, range) < range / 2)
+			arfcns_right[r_size++] = mod(arfcns[i] - r_origin, range);
+	}
+
+	/*
+	 * Now recurse and we need to make this iterative... but as the
+	 * tree is balanced the stack will not be too deep.
+	 */
+	range_enc_arfcns(range / 2, arfcns_left, l_size,
+			out, index + greatest_power_of_2_lesser_or_equal_to(index + 1));
+	range_enc_arfcns((range -1 ) / 2, arfcns_right, r_size,
+			 out, index + (2 * greatest_power_of_2_lesser_or_equal_to(index + 1)));
+	return 0;
+}
+
+/*
+ * The easiest is to use f0 == arfcns[0]. This means that under certain
+ * circumstances we can encode less ARFCNs than possible with an optimal f0.
+ *
+ * TODO: Solve the optimisation problem and pick f0 so that the max distance
+ * is the smallest. Taking into account the modulo operation. I think picking
+ * size/2 will be the optimal arfcn.
+ */
+/**
+ * This implements the range determination as described in GSM 04.08 J4. The
+ * result will be a base frequency f0 and the range to use.
+ *
+ * \param[in] arfcns The input frequencies, they must be sorted, lowest number first
+ * \param[in] size The length of the array
+ * \param[out] f0 The selected F0 base frequency. It might not be inside the list
+ */
+int range_enc_determine_range(const int *arfcns, const int size, int *f0)
+{
+	int max = 0;
+
+	/*
+	 * Go for the easiest. And pick arfcns[0] == f0.
+	 */
+	max = arfcns[size - 1] - arfcns[0];
+	*f0 = arfcns[0];
+
+	if (max < 128 && size <= 29)
+		return ARFCN_RANGE_128;
+	if (max < 256 && size <= 22)
+		return ARFCN_RANGE_256;
+	if (max < 512 && size <= 18)
+		return ARFCN_RANGE_512;
+	if (max < 1024 && size <= 17)
+		return ARFCN_RANGE_1024;
+
+	return ARFCN_RANGE_INVALID;
+}
+
+/*
+ * The below is easier is to write in four methods than
+ * to use the max_bits. The encoding is so screwed.. as
+ * the bits need to be put in place in the wrong order..
+ */
+#define HIGH_BITS(w, index, bits, offset) \
+		(w[index - 1] >> (bits - offset))
+#define LOW_BITS(w, index, bits, offset) \
+		(w[index - 1])
+
+static void write_orig_arfcn(uint8_t *chan_list, int f0)
+{
+	chan_list[0] |= (f0 >> 9) & 1;
+	chan_list[1] = (f0 >> 1);
+	chan_list[2] = (f0 & 1) << 7;
+}
+
+int range_enc_range128(uint8_t *chan_list, int f0, int *w)
+{
+	chan_list[0] = 0x8C;
+	write_orig_arfcn(chan_list, f0);
+
+	LOGP(DRR, LOGL_ERROR, "Range128 encoding is not implemented.\n");
+	return -1;
+}
+
+int range_enc_range256(uint8_t *chan_list, int f0, int *w)
+{
+	chan_list[0] = 0x8A;
+	write_orig_arfcn(chan_list, f0);
+
+	LOGP(DRR, LOGL_ERROR, "Range256 encoding is not implemented.\n");
+	return -1;
+}
+
+int range_enc_range512(uint8_t *chan_list, int f0, int *w)
+{
+	struct gsm48_range_512 *range512;
+	write_orig_arfcn(chan_list, f0);
+
+	range512 = (struct gsm48_range_512 *) &chan_list[0];
+	range512->form_id = chan_list[0] = 0x44;
+
+	/* W(1) */
+	range512->w1_hi = HIGH_BITS(w, 1, 9, 7);
+	range512->w1_lo = LOW_BITS (w, 1, 9, 2);
+	/* W(2) */
+	range512->w2_hi = HIGH_BITS(w, 2, 8, 6);
+	range512->w2_lo = LOW_BITS (w, 2, 8, 2);
+	/* W(3) */
+	range512->w3_hi = HIGH_BITS(w, 3, 8, 6);
+	range512->w3_lo = LOW_BITS (w, 3, 8, 2);
+	/* W(4) */
+	range512->w4_hi = HIGH_BITS(w, 4, 7, 6);
+	range512->w4_lo = LOW_BITS (w, 4, 7, 1);
+	/* W(5) */
+	range512->w5 = HIGH_BITS(w, 5, 7, 7);
+	/* W(6) */
+	range512->w6 = HIGH_BITS(w, 6, 7, 7);
+	/* W(7) */
+	range512->w7_hi = HIGH_BITS(w, 7, 7, 1);
+	range512->w7_lo = LOW_BITS (w, 7, 7, 6);
+	/* W(8) */
+	range512->w8_hi = HIGH_BITS(w, 8, 6, 2);
+	range512->w8_lo = LOW_BITS (w, 8, 6, 4);
+	/* W(9) */
+	range512->w9_hi = HIGH_BITS(w, 9, 6, 4);
+	range512->w9_lo = LOW_BITS(w, 9, 6, 2);
+	/* W(10) */
+	range512->w10 = HIGH_BITS(w, 10, 6, 6);
+	/* W(11) */
+	range512->w11 = HIGH_BITS(w, 11, 6, 6);
+	/* W(12) */
+	range512->w12_hi = HIGH_BITS(w, 12, 6, 2);
+	range512->w12_lo = LOW_BITS (w, 12, 6, 4);
+	/* W(13) */
+	range512->w13_hi = HIGH_BITS(w, 13, 6, 4);
+	range512->w13_lo = LOW_BITS(w, 13, 6, 2);
+	/* W(14) */
+	range512->w14 = HIGH_BITS(w, 14, 6, 6);
+	/* W(15) */
+	range512->w15 = HIGH_BITS(w, 15, 6, 6);
+	/* W(16) */
+	range512->w16_hi = HIGH_BITS(w, 16, 5, 2);
+	range512->w16_lo = HIGH_BITS(w, 16, 5, 3);
+	/* W(17) */
+	range512->w17 = HIGH_BITS(w, 17, 5, 5);
+
+	return 0;
+}
+
+int range_enc_range1024(uint8_t *chan_list, int f0, int f0_included, int *w)
+{
+	chan_list[0] = 0x80 | (f0_included << 2);
+
+	LOGP(DRR, LOGL_ERROR, "Range1024 encoding is not implemented.\n");
+	return -1;
+}
+
+int range_enc_filter_arfcns(const int range, int *arfcns,
+			const int size, const int f0, int *f0_included)
+{
+	int i, j = 0;
+	*f0_included = 0;
+
+	if (range == ARFCN_RANGE_1024) {
+		for (i = 0; i < size; ++i) {
+			if (arfcns[i] == f0) {
+				*f0_included = 1;
+				continue;
+			}
+
+			/* copy and subtract */
+			arfcns[j++] = mod(arfcns[i] - 1, 1024);
+		}
+	} else {
+		for (i = 0; i < size; ++i) {
+			/*
+			 * Appendix J.4 says the following:
+			 * All frequencies except F(0), minus F(0) + 1.
+			 * I assume we need to exclude it here.
+			 */
+			if (arfcns[i] == f0)
+				continue;
+
+			arfcns[j++] = mod(arfcns[i] - (f0 + 1), 1024);
+		}
+	}
+
+	return j;
+}