port arfcn range encode support from osmo-bsc

As part of fixing issue OS#3075, we want to migrate support
for encoding system information from osmo-bsc to libosmocore.

This change ports one of the prerequisites for doing so:
osmo-bsc code for range-encoding ARFCNs, including tests.

An osmo_gsm48_ prefix has been prepended to public symbols in
order to avoid clashes with existing symbols in osmo-bsc code.

Change-Id: Ia220764fba451be5e975ae7c5eefb1a25ac2bf2c
Related: OS#3075

7 files changed, 760 insertions, 1 deletions

diff --git a/include/Makefile.am b/include/Makefile.am
index 86d8d157..6da5ab61 100644
--- a/include/Makefile.am
+++ b/include/Makefile.am
@@ -91,6 +91,7 @@ nobase_include_HEADERS = \
                        osmocom/gsm/gsm23003.h \
                        osmocom/gsm/gsm29118.h \
                        osmocom/gsm/gsm48.h \
+                       osmocom/gsm/gsm48_arfcn_range_encode.h \
                        osmocom/gsm/gsm48_ie.h \
                        osmocom/gsm/gsm_utils.h \
                        osmocom/gsm/gsup.h \
diff --git a/include/osmocom/gsm/gsm48_arfcn_range_encode.h b/include/osmocom/gsm/gsm48_arfcn_range_encode.h
new file mode 100644
index 00000000..146c8534
--- /dev/null
+++ b/include/osmocom/gsm/gsm48_arfcn_range_encode.h
@@ -0,0 +1,25 @@
+/*! \file gsm48_arfcn_range_encode.h */
+
+#pragma once
+
+#include <stdint.h>
+
+enum osmo_gsm48_range {
+	OSMO_GSM48_ARFCN_RANGE_INVALID	= -1,
+	OSMO_GSM48_ARFCN_RANGE_128		= 127,
+	OSMO_GSM48_ARFCN_RANGE_256		= 255,
+	OSMO_GSM48_ARFCN_RANGE_512		= 511,
+	OSMO_GSM48_ARFCN_RANGE_1024		= 1023,
+};
+
+#define OSMO_GSM48_RANGE_ENC_MAX_ARFCNS	29
+
+int osmo_gsm48_range_enc_determine_range(const int *arfcns, int size, int *f0_out);
+int osmo_gsm48_range_enc_arfcns(enum osmo_gsm48_range rng, const int *arfcns, int sze, int *out, int idx);
+int osmo_gsm48_range_enc_find_index(enum osmo_gsm48_range rng, const int *arfcns, int size);
+int osmo_gsm48_range_enc_filter_arfcns(int *arfcns, const int sze, const int f0, int *f0_included);
+
+int osmo_gsm48_range_enc_128(uint8_t *chan_list, int f0, int *w);
+int osmo_gsm48_range_enc_256(uint8_t *chan_list, int f0, int *w);
+int osmo_gsm48_range_enc_512(uint8_t *chan_list, int f0, int *w);
+int osmo_gsm48_range_enc_1024(uint8_t *chan_list, int f0, int f0_incl, int *w);
diff --git a/src/gsm/Makefile.am b/src/gsm/Makefile.am
index 3d2c5606..c4b5fce3 100644
--- a/src/gsm/Makefile.am
+++ b/src/gsm/Makefile.am
@@ -21,7 +21,8 @@ lib_LTLIBRARIES = libosmogsm.la
 BUILT_SOURCES = gsm0503_conv.c
 
 libgsmint_la_SOURCES =  a5.c rxlev_stat.c tlv_parser.c comp128.c comp128v23.c \
-			gsm_utils.c rsl.c gsm48.c gsm48_ie.c gsm0808.c sysinfo.c \
+			gsm_utils.c rsl.c gsm48.c gsm48_arfcn_range_encode.c \
+			gsm48_ie.c gsm0808.c sysinfo.c \
 			gprs_cipher_core.c gprs_rlc.c gsm0480.c abis_nm.c gsm0502.c \
 			gsm0411_utils.c gsm0411_smc.c gsm0411_smr.c gsm0414.c \
 			lapd_core.c lapdm.c kasumi.c gsm29205.c gsm_04_08_gprs.c \
diff --git a/src/gsm/gsm48_arfcn_range_encode.c b/src/gsm/gsm48_arfcn_range_encode.c
new file mode 100644
index 00000000..6423a9a8
--- /dev/null
+++ b/src/gsm/gsm48_arfcn_range_encode.c
@@ -0,0 +1,321 @@
+/* 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 <osmocom/gsm/protocol/gsm_04_08.h>
+#include <osmocom/gsm/gsm48_arfcn_range_encode.h>
+
+#include <osmocom/core/utils.h>
+
+#include <errno.h>
+
+static inline 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 osmo_gsm48_range_enc_find_index(enum osmo_gsm48_range 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;
+}
+
+/* Worker for range_enc_arfcns(), do not call directly. */
+static int _range_enc_arfcns(enum osmo_gsm48_range 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;
+
+	/* Now do the processing */
+	split_at = osmo_gsm48_range_enc_find_index(range, arfcns, size);
+	if (split_at < 0)
+		return -EINVAL;
+
+	/* 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.
+	 */
+	if (l_size)
+		osmo_gsm48_range_enc_arfcns(range / 2, arfcns_left, l_size,
+			out, index + greatest_power_of_2_lesser_or_equal_to(index + 1));
+	if (r_size)
+		osmo_gsm48_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;
+}
+
+/**
+ * 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 osmo_gsm48_range_enc_arfcns(enum osmo_gsm48_range range,
+		const int *arfcns, int size, int *out,
+		const int index)
+{
+	if (size <= 0)
+		return 0;
+
+	if (size == 1) {
+		out[index] = 1 + arfcns[0];
+		return 0;
+	}
+
+	return _range_enc_arfcns(range, arfcns, size, out, index);
+}
+
+/*
+ * 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. Note that for range
+ * 1024 encoding f0 always refers to ARFCN 0 even if it is not an element of
+ * the arfcns list.
+ *
+ * \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 osmo_gsm48_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 OSMO_GSM48_ARFCN_RANGE_128;
+	if (max < 256 && size <= 22)
+		return OSMO_GSM48_ARFCN_RANGE_256;
+	if (max < 512 && size <= 18)
+		return OSMO_GSM48_ARFCN_RANGE_512;
+	if (max < 1024 && size <= 17) {
+		*f0 = 0;
+		return OSMO_GSM48_ARFCN_RANGE_1024;
+	}
+
+	return OSMO_GSM48_ARFCN_RANGE_INVALID;
+}
+
+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;
+}
+
+static void write_all_wn(uint8_t *chan_list, int bit_offs,
+			 int *w, int w_size, int w1_len)
+{
+	int octet_offs = 0; /* offset into chan_list */
+	int wk_len = w1_len; /* encoding size in bits of w[k] */
+	int k; /* 1 based */
+	int level = 0; /* tree level, top level = 0 */
+	int lvl_left = 1; /* nodes per tree level */
+
+	/* W(2^i) to W(2^(i+1)-1) are on w1_len-i bits when present */
+
+	for (k = 1; k <= w_size; k++) {
+		int wk_left = wk_len;
+
+		while (wk_left > 0) {
+			int cur_bits = 8 - bit_offs;
+			int cur_mask;
+			int wk_slice;
+
+			if (cur_bits > wk_left)
+				cur_bits = wk_left;
+
+			cur_mask = ((1 << cur_bits) - 1);
+
+			/* advance */
+			wk_left -= cur_bits;
+			bit_offs += cur_bits;
+
+			/* right aligned wk data for current out octet */
+			wk_slice = (w[k-1] >> wk_left) & cur_mask;
+
+			/* cur_bits now contains the number of bits
+			 * that are to be copied from wk to the chan_list.
+			 * wk_left is set to the number of bits that must
+			 * not yet be copied.
+			 * bit_offs points after the bit area that is going to
+			 * be overwritten:
+			 *
+			 *          wk_left
+			 *             |
+			 *             v
+			 * wk: WWWWWWWWWWW
+			 *        |||||<-- wk_slice, cur_bits=5
+			 *      --WWWWW-
+			 *             ^
+			 *             |
+			 *           bit_offs
+			 */
+
+			chan_list[octet_offs] &= ~(cur_mask << (8 - bit_offs));
+			chan_list[octet_offs] |= wk_slice << (8 - bit_offs);
+
+			/* adjust output */
+			if (bit_offs == 8) {
+				bit_offs = 0;
+				octet_offs += 1;
+			}
+		}
+
+		/* adjust bit sizes */
+		lvl_left -= 1;
+		if (!lvl_left) {
+			/* completed tree level, advance to next */
+			level += 1;
+			lvl_left = 1 << level;
+			wk_len -= 1;
+		}
+	}
+}
+
+int osmo_gsm48_range_enc_128(uint8_t *chan_list, int f0, int *w)
+{
+	chan_list[0] = 0x8C;
+	write_orig_arfcn(chan_list, f0);
+
+	write_all_wn(&chan_list[2], 1, w, 28, 7);
+	return 0;
+}
+
+int osmo_gsm48_range_enc_256(uint8_t *chan_list, int f0, int *w)
+{
+	chan_list[0] = 0x8A;
+	write_orig_arfcn(chan_list, f0);
+
+	write_all_wn(&chan_list[2], 1, w, 21, 8);
+	return 0;
+}
+
+int osmo_gsm48_range_enc_512(uint8_t *chan_list, int f0, int *w)
+{
+	chan_list[0] = 0x88;
+	write_orig_arfcn(chan_list, f0);
+
+	write_all_wn(&chan_list[2], 1, w, 17, 9);
+	return 0;
+}
+
+int osmo_gsm48_range_enc_1024(uint8_t *chan_list, int f0, int f0_included, int *w)
+{
+	chan_list[0] = 0x80 | (f0_included << 2);
+
+	write_all_wn(&chan_list[0], 6, w, 16, 10);
+	return 0;
+}
+
+int osmo_gsm48_range_enc_filter_arfcns(int *arfcns, const int size, const int f0, int *f0_included)
+{
+	int i, j = 0;
+	*f0_included = 0;
+
+	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) {
+			*f0_included = 1;
+			continue;
+		}
+
+		arfcns[j++] = mod(arfcns[i] - (f0 + 1), 1024);
+	}
+
+	return j;
+}
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index cdcbcc98..922ac01f 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -518,6 +518,15 @@ osmo_apn_qualify_from_imsi;
 osmo_apn_to_str;
 osmo_apn_from_str;
 
+osmo_gsm48_range_enc_determine_range;
+osmo_gsm48_range_enc_arfcns;
+osmo_gsm48_range_enc_find_index;
+osmo_gsm48_range_enc_filter_arfcns;
+osmo_gsm48_range_enc_128;
+osmo_gsm48_range_enc_256;
+osmo_gsm48_range_enc_512;
+osmo_gsm48_range_enc_1024;
+
 osmo_gsup_encode;
 osmo_gsup_decode;
 osmo_gsup_message_type_names;
diff --git a/tests/gsm0408/gsm0408_test.c b/tests/gsm0408/gsm0408_test.c
index 37ef3f15..6902e8e2 100644
--- a/tests/gsm0408/gsm0408_test.c
+++ b/tests/gsm0408/gsm0408_test.c
@@ -25,6 +25,7 @@
 #include <osmocom/gsm/protocol/gsm_04_08.h>
 #include <osmocom/gsm/gsm48_ie.h>
 #include <osmocom/gsm/gsm48.h>
+#include <osmocom/gsm/gsm48_arfcn_range_encode.h>
 #include <osmocom/gsm/mncc.h>
 #include <osmocom/core/backtrace.h>
 #include <osmocom/core/utils.h>
@@ -609,6 +610,338 @@ static void test_mid_decode_zero_length(void)
 	printf("\n");
 }
 
+struct {
+	int range;
+	int arfcns_num;
+	int arfcns[OSMO_GSM48_RANGE_ENC_MAX_ARFCNS];
+} arfcn_test_ranges[] = {
+	{OSMO_GSM48_ARFCN_RANGE_512, 12,
+		{ 1, 12, 31, 51, 57, 91, 97, 98, 113, 117, 120, 125 }},
+	{OSMO_GSM48_ARFCN_RANGE_512, 17,
+		{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 }},
+	{OSMO_GSM48_ARFCN_RANGE_512, 18,
+		{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 }},
+	{OSMO_GSM48_ARFCN_RANGE_512, 18,
+		{ 1, 17, 31, 45, 58, 79, 81, 97,
+		  113, 127, 213, 277, 287, 311, 331, 391,
+		  417, 511 }},
+	{OSMO_GSM48_ARFCN_RANGE_512, 6,
+		{ 1, 17, 31, 45, 58, 79 }},
+	{OSMO_GSM48_ARFCN_RANGE_512, 6,
+		{ 10, 17, 31, 45, 58, 79 }},
+	{OSMO_GSM48_ARFCN_RANGE_1024, 17,
+		{ 0, 17, 31, 45, 58, 79, 81, 97,
+		  113, 127, 213, 277, 287, 311, 331, 391,
+		  1023 }},
+	{OSMO_GSM48_ARFCN_RANGE_1024, 16,
+		{ 17, 31, 45, 58, 79, 81, 97, 113,
+		  127, 213, 277, 287, 311, 331, 391, 1023 }},
+	{-1}
+};
+
+static int test_single_range_encoding(int range, const int *orig_arfcns, int arfcns_num, int silent)
+{
+	int arfcns[OSMO_GSM48_RANGE_ENC_MAX_ARFCNS];
+	int w[OSMO_GSM48_RANGE_ENC_MAX_ARFCNS];
+	int f0_included = 0;
+	int rc, f0;
+	uint8_t chan_list[16] = {0};
+	struct gsm_sysinfo_freq dec_freq[1024] = {{0}};
+	int dec_arfcns[OSMO_GSM48_RANGE_ENC_MAX_ARFCNS] = {0};
+	int dec_arfcns_count = 0;
+	int arfcns_used = 0;
+	int i;
+
+	arfcns_used = arfcns_num;
+	memmove(arfcns, orig_arfcns, sizeof(arfcns));
+
+	f0 = range == OSMO_GSM48_ARFCN_RANGE_1024 ? 0 : arfcns[0];
+	/*
+	 * Manipulate the ARFCN list according to the rules in J4 depending
+	 * on the selected range.
+	 */
+	arfcns_used = osmo_gsm48_range_enc_filter_arfcns(arfcns, arfcns_used, f0, &f0_included);
+
+	memset(w, 0, sizeof(w));
+	osmo_gsm48_range_enc_arfcns(range, arfcns, arfcns_used, w, 0);
+
+	if (!silent)
+		printf("range=%d, arfcns_used=%d, f0=%d, f0_included=%d\n", range, arfcns_used, f0, f0_included);
+
+	/* Select the range and the amount of bits needed */
+	switch (range) {
+	case OSMO_GSM48_ARFCN_RANGE_128:
+		osmo_gsm48_range_enc_128(chan_list, f0, w);
+		break;
+	case OSMO_GSM48_ARFCN_RANGE_256:
+		osmo_gsm48_range_enc_256(chan_list, f0, w);
+		break;
+	case OSMO_GSM48_ARFCN_RANGE_512:
+		osmo_gsm48_range_enc_512(chan_list, f0, w);
+		break;
+	case OSMO_GSM48_ARFCN_RANGE_1024:
+		osmo_gsm48_range_enc_1024(chan_list, f0, f0_included, w);
+		break;
+	default:
+		return 1;
+	};
+
+	if (!silent)
+		printf("chan_list = %s\n",
+		       osmo_hexdump(chan_list, sizeof(chan_list)));
+
+	rc = gsm48_decode_freq_list(dec_freq, chan_list, sizeof(chan_list),
+				    0xfe, 1);
+	if (rc != 0) {
+		printf("Cannot decode freq list, rc = %d\n", rc);
+		return 1;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(dec_freq); i++) {
+		if (dec_freq[i].mask &&
+		    dec_arfcns_count < ARRAY_SIZE(dec_arfcns))
+			dec_arfcns[dec_arfcns_count++] = i;
+	}
+
+	if (!silent) {
+		printf("Decoded freqs %d (expected %d)\n",
+		       dec_arfcns_count, arfcns_num);
+		printf("Decoded: ");
+		for (i = 0; i < dec_arfcns_count; i++) {
+			printf("%d ", dec_arfcns[i]);
+			if (dec_arfcns[i] != orig_arfcns[i])
+				printf("(!= %d) ", orig_arfcns[i]);
+		}
+		printf("\n");
+	}
+
+	if (dec_arfcns_count != arfcns_num) {
+		printf("Wrong number of arfcns\n");
+		return 1;
+	}
+
+	if (memcmp(dec_arfcns, orig_arfcns, sizeof(dec_arfcns)) != 0) {
+		printf("Decoding error, got wrong freqs\n");
+		printf(" w = ");
+		for (i = 0; i < ARRAY_SIZE(w); i++)
+			printf("%d ", w[i]);
+		printf("\n");
+		return 1;
+	}
+
+	return 0;
+}
+
+static void test_random_range_encoding(int range, int max_arfcn_num)
+{
+	int arfcns_num = 0;
+	int test_idx;
+	int rc, max_count;
+	int num_tests = 1024;
+
+	printf("Random range test: range %d, max num ARFCNs %d\n",
+	       range, max_arfcn_num);
+
+	srandom(1);
+
+	for (max_count = 1; max_count < max_arfcn_num; max_count++) {
+		for (test_idx = 0; test_idx < num_tests; test_idx++) {
+			int count;
+			int i;
+			int min_freq = 0;
+
+			int rnd_arfcns[OSMO_GSM48_RANGE_ENC_MAX_ARFCNS] = {0};
+			char rnd_arfcns_set[1024] = {0};
+
+			if (range < OSMO_GSM48_ARFCN_RANGE_1024)
+				min_freq = random() % (1023 - range);
+
+			for (count = max_count; count; ) {
+				int arfcn = min_freq + random() % (range + 1);
+				OSMO_ASSERT(arfcn < ARRAY_SIZE(rnd_arfcns_set));
+
+				if (!rnd_arfcns_set[arfcn]) {
+					rnd_arfcns_set[arfcn] = 1;
+					count -= 1;
+				}
+			}
+
+			arfcns_num = 0;
+			for (i = 0; i < ARRAY_SIZE(rnd_arfcns_set); i++)
+				if (rnd_arfcns_set[i])
+					rnd_arfcns[arfcns_num++] = i;
+
+			rc = test_single_range_encoding(range, rnd_arfcns,
+							arfcns_num, 1);
+			if (rc != 0) {
+				printf("Failed on test %d, range %d, num ARFCNs %d\n",
+				       test_idx, range, max_count);
+				test_single_range_encoding(range, rnd_arfcns,
+							   arfcns_num, 0);
+				return;
+			}
+		}
+	}
+}
+
+static void test_range_encoding()
+{
+	int *arfcns;
+	int arfcns_num = 0;
+	int test_idx;
+	int range;
+
+	for (test_idx = 0; arfcn_test_ranges[test_idx].arfcns_num > 0; test_idx++)
+	{
+		arfcns_num = arfcn_test_ranges[test_idx].arfcns_num;
+		arfcns = &arfcn_test_ranges[test_idx].arfcns[0];
+		range = arfcn_test_ranges[test_idx].range;
+
+		printf("Range test %d: range %d, num ARFCNs %d\n",
+		       test_idx, range, arfcns_num);
+
+		test_single_range_encoding(range, arfcns, arfcns_num, 0);
+	}
+
+	test_random_range_encoding(OSMO_GSM48_ARFCN_RANGE_128, 29);
+	test_random_range_encoding(OSMO_GSM48_ARFCN_RANGE_256, 22);
+	test_random_range_encoding(OSMO_GSM48_ARFCN_RANGE_512, 18);
+	test_random_range_encoding(OSMO_GSM48_ARFCN_RANGE_1024, 16);
+}
+
+static int freqs1[] = {
+	12, 70, 121, 190, 250, 320, 401, 475, 520, 574, 634, 700, 764, 830, 905, 980
+};
+
+static int freqs2[] = {
+	402, 460, 1, 67, 131, 197, 272, 347,
+};
+
+static int freqs3[] = {
+	68, 128, 198, 279, 353, 398, 452,
+
+};
+
+static int w_out[] = {
+	122, 2, 69, 204, 75, 66, 60, 70, 83, 3, 24, 67, 54, 64, 70, 9,
+};
+
+static int range128[] = {
+	1, 1 + 127,
+};
+
+static int range256[] = {
+	1, 1 + 128,
+};
+
+static int range512[] = {
+	1, 1+ 511,
+};
+
+
+#define VERIFY(res, cmp, wanted)					\
+	if (!(res cmp wanted)) {					\
+		printf("ASSERT failed: %s:%d Wanted: %d %s %d\n",	\
+			__FILE__, __LINE__, (int) res, # cmp, (int) wanted);	\
+	}
+
+static void test_arfcn_filter()
+{
+	int arfcns[50], i, res, f0_included;
+	for (i = 0; i < ARRAY_SIZE(arfcns); ++i)
+		arfcns[i] = (i + 1) * 2;
+
+	/* check that the arfcn is taken out. f0_included is only set for Range1024 */
+	f0_included = 24;
+	res = osmo_gsm48_range_enc_filter_arfcns(arfcns, ARRAY_SIZE(arfcns), arfcns[0], &f0_included);
+	VERIFY(res, ==, ARRAY_SIZE(arfcns) - 1);
+	VERIFY(f0_included, ==, 1);
+	for (i = 0; i < res; ++i)
+		VERIFY(arfcns[i], ==, ((i+2) * 2) - (2+1));
+
+	/* check with range1024, ARFCN 0 is included */
+	for (i = 0; i < ARRAY_SIZE(arfcns); ++i)
+		arfcns[i] = i * 2;
+	res = osmo_gsm48_range_enc_filter_arfcns(arfcns, ARRAY_SIZE(arfcns), 0, &f0_included);
+	VERIFY(res, ==, ARRAY_SIZE(arfcns) - 1);
+	VERIFY(f0_included, ==, 1);
+	for (i = 0; i < res; ++i)
+		VERIFY(arfcns[i], ==, (i + 1) * 2 - 1);
+
+	/* check with range1024, ARFCN 0 not included */
+	for (i = 0; i < ARRAY_SIZE(arfcns); ++i)
+		arfcns[i] = (i + 1) * 2;
+	res = osmo_gsm48_range_enc_filter_arfcns(arfcns, ARRAY_SIZE(arfcns), 0, &f0_included);
+	VERIFY(res, ==, ARRAY_SIZE(arfcns));
+	VERIFY(f0_included, ==, 0);
+	for (i = 0; i < res; ++i)
+		VERIFY(arfcns[i], ==, ((i + 1) * 2) - 1);
+}
+
+static void test_print_encoding()
+{
+	int rc;
+	int w[17];
+	uint8_t chan_list[16];
+	memset(chan_list, 0x23, sizeof(chan_list));
+
+	for (rc = 0; rc < ARRAY_SIZE(w); ++rc)
+		switch (rc % 3) {
+		case 0:
+			w[rc] = 0xAAAA;
+			break;
+		case 1:
+			w[rc] = 0x5555;
+			break;
+		case 2:
+			w[rc] = 0x9696;
+			break;
+		}
+
+	osmo_gsm48_range_enc_512(chan_list, (1 << 9) | 0x96, w);
+
+	printf("Range512: %s\n", osmo_hexdump(chan_list, ARRAY_SIZE(chan_list)));
+}
+
+static void test_si_range_helpers()
+{
+	int ws[(sizeof(freqs1)/sizeof(freqs1[0]))];
+	int i, f0 = 0xFFFFFF;
+
+	memset(&ws[0], 0x23, sizeof(ws));
+
+	i = osmo_gsm48_range_enc_find_index(1023, freqs1, ARRAY_SIZE(freqs1));
+	printf("Element is: %d => freqs[i] = %d\n", i, i >= 0 ? freqs1[i] : -1);
+	VERIFY(i, ==, 2);
+
+	i = osmo_gsm48_range_enc_find_index(511, freqs2, ARRAY_SIZE(freqs2));
+	printf("Element is: %d => freqs[i] = %d\n", i,  i >= 0 ? freqs2[i] : -1);
+	VERIFY(i, ==, 2);
+
+	i = osmo_gsm48_range_enc_find_index(511, freqs3, ARRAY_SIZE(freqs3));
+	printf("Element is: %d => freqs[i] = %d\n", i,  i >= 0 ? freqs3[i] : -1);
+	VERIFY(i, ==, 0);
+
+	osmo_gsm48_range_enc_arfcns(1023, freqs1, ARRAY_SIZE(freqs1), ws, 0);
+
+	for (i = 0; i < sizeof(freqs1)/sizeof(freqs1[0]); ++i) {
+		printf("w[%d]=%d\n", i, ws[i]);
+		VERIFY(ws[i], ==, w_out[i]);
+	}
+
+	i = osmo_gsm48_range_enc_determine_range(range128, ARRAY_SIZE(range128), &f0);
+	VERIFY(i, ==, OSMO_GSM48_ARFCN_RANGE_128);
+	VERIFY(f0, ==, 1);
+
+	i = osmo_gsm48_range_enc_determine_range(range256, ARRAY_SIZE(range256), &f0);
+	VERIFY(i, ==, OSMO_GSM48_ARFCN_RANGE_256);
+	VERIFY(f0, ==, 1);
+
+	i = osmo_gsm48_range_enc_determine_range(range512, ARRAY_SIZE(range512), &f0);
+	VERIFY(i, ==, OSMO_GSM48_ARFCN_RANGE_512);
+	VERIFY(f0, ==, 1);
+}
+
 int main(int argc, char **argv)
 {
 	test_bearer_cap();
@@ -619,5 +952,10 @@ int main(int argc, char **argv)
 	test_ra_cap();
 	test_lai_encode_decode();
 
+	test_si_range_helpers();
+	test_arfcn_filter();
+	test_print_encoding();
+	test_range_encoding();
+
 	return EXIT_SUCCESS;
 }
diff --git a/tests/gsm0408/gsm0408_test.ok b/tests/gsm0408/gsm0408_test.ok
index 0c135558..8f6630be 100644
--- a/tests/gsm0408/gsm0408_test.ok
+++ b/tests/gsm0408/gsm0408_test.ok
@@ -282,3 +282,67 @@ RA test...passed
   Encoded 21 63 54 00 17 
   gsm48_decode_lai2() gives  123-456-23 (3-digit MNC)
   passed
+Element is: 2 => freqs[i] = 121
+Element is: 2 => freqs[i] = 1
+Element is: 0 => freqs[i] = 68
+w[0]=122
+w[1]=2
+w[2]=69
+w[3]=204
+w[4]=75
+w[5]=66
+w[6]=60
+w[7]=70
+w[8]=83
+w[9]=3
+w[10]=24
+w[11]=67
+w[12]=54
+w[13]=64
+w[14]=70
+w[15]=9
+Range512: 89 4b 2a 95 65 95 55 2c a9 55 aa 55 6a 95 59 55 
+Range test 0: range 511, num ARFCNs 12
+range=511, arfcns_used=11, f0=1, f0_included=1
+chan_list = 88 00 98 34 85 36 7c 50 22 dc 5e ec 00 00 00 00 
+Decoded freqs 12 (expected 12)
+Decoded: 1 12 31 51 57 91 97 98 113 117 120 125 
+Range test 1: range 511, num ARFCNs 17
+range=511, arfcns_used=16, f0=1, f0_included=1
+chan_list = 88 00 82 7f 01 3f 7e 04 0b ff ff fc 10 41 07 e0 
+Decoded freqs 17 (expected 17)
+Decoded: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 
+Range test 2: range 511, num ARFCNs 18
+range=511, arfcns_used=17, f0=1, f0_included=1
+chan_list = 88 00 82 7f 01 7f 7e 04 0b ff ff fc 10 41 07 ff 
+Decoded freqs 18 (expected 18)
+Decoded: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 
+Range test 3: range 511, num ARFCNs 18
+range=511, arfcns_used=17, f0=1, f0_included=1
+chan_list = 88 00 94 3a 44 32 d7 2a 43 2a 13 94 e5 38 39 f6 
+Decoded freqs 18 (expected 18)
+Decoded: 1 17 31 45 58 79 81 97 113 127 213 277 287 311 331 391 417 511 
+Range test 4: range 511, num ARFCNs 6
+range=511, arfcns_used=5, f0=1, f0_included=1
+chan_list = 88 00 8b 3c 88 b9 6b 00 00 00 00 00 00 00 00 00 
+Decoded freqs 6 (expected 6)
+Decoded: 1 17 31 45 58 79 
+Range test 5: range 511, num ARFCNs 6
+range=511, arfcns_used=5, f0=10, f0_included=1
+chan_list = 88 05 08 fc 88 b9 6b 00 00 00 00 00 00 00 00 00 
+Decoded freqs 6 (expected 6)
+Decoded: 10 17 31 45 58 79 
+Range test 6: range 1023, num ARFCNs 17
+range=1023, arfcns_used=16, f0=0, f0_included=1
+chan_list = 84 71 e4 ab b9 58 05 cb 39 17 fd b0 75 62 0f 2f 
+Decoded freqs 17 (expected 17)
+Decoded: 0 17 31 45 58 79 81 97 113 127 213 277 287 311 331 391 1023 
+Range test 7: range 1023, num ARFCNs 16
+range=1023, arfcns_used=16, f0=0, f0_included=0
+chan_list = 80 71 e4 ab b9 58 05 cb 39 17 fd b0 75 62 0f 2f 
+Decoded freqs 16 (expected 16)
+Decoded: 17 31 45 58 79 81 97 113 127 213 277 287 311 331 391 1023 
+Random range test: range 127, max num ARFCNs 29
+Random range test: range 255, max num ARFCNs 22
+Random range test: range 511, max num ARFCNs 18
+Random range test: range 1023, max num ARFCNs 16