f0 is currently set to arfcns[0] in range_enc_determine_range(),
while GSM 04.08 requires f0 to be ARFCN 0 in range1024 encoding.
This patch modifies range_enc_determine_range() to force f0 to be 0
if this encoding is used. This way the case distinction in
range_enc_filter_arfcns() is not longer necessary.
Sponsored-by: On-Waves ehf
---
openbsc/include/openbsc/arfcn_range_encode.h | 2 +-
openbsc/src/libbsc/arfcn_range_encode.c | 44 +++++++++++---------------
openbsc/src/libbsc/system_information.c | 2 +-
openbsc/tests/gsm0408/gsm0408_test.c | 24 +++++++-------
4 files changed, 33 insertions(+), 39 deletions(-)
diff --git a/openbsc/include/openbsc/arfcn_range_encode.h
b/openbsc/include/openbsc/arfcn_range_encode.h
index 7a6fff0..bd85d6a 100644
--- a/openbsc/include/openbsc/arfcn_range_encode.h
+++ b/openbsc/include/openbsc/arfcn_range_encode.h
@@ -16,7 +16,7 @@ enum {
int range_enc_determine_range(const int *arfcns, int size, int *f0_out);
int range_enc_arfcns(const int rng, const int *arfcns, int sze, int *out, int
idx);
int range_enc_find_index(const int rng, const int *arfcns, int size);
-int range_enc_filter_arfcns(const int rng, int *arfcns, const int sze, const
int f0, int *f0_included);
+int range_enc_filter_arfcns(int *arfcns, const int sze, const int f0, int
*f0_included);
int range_enc_range128(uint8_t *chan_list, int f0, int *w);
int range_enc_range256(uint8_t *chan_list, int f0, int *w);
diff --git a/openbsc/src/libbsc/arfcn_range_encode.c
b/openbsc/src/libbsc/arfcn_range_encode.c
index 9177546..a047a06 100644
--- a/openbsc/src/libbsc/arfcn_range_encode.c
+++ b/openbsc/src/libbsc/arfcn_range_encode.c
@@ -144,7 +144,9 @@ int range_enc_arfcns(const int range,
*/
/**
* 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.
+ * 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
@@ -166,8 +168,10 @@ int range_enc_determine_range(const int *arfcns, const int
size, int *f0)
return ARFCN_RANGE_256;
if (max < 512 && size <= 18)
return ARFCN_RANGE_512;
- if (max < 1024 && size <= 17)
+ if (max < 1024 && size <= 17) {
+ *f0 = 0;
return ARFCN_RANGE_1024;
+ }
return ARFCN_RANGE_INVALID;
}
@@ -271,34 +275,24 @@ int range_enc_range1024(uint8_t *chan_list, int f0, int
f0_included, int *w)
return -1;
}
-int range_enc_filter_arfcns(const int range, int *arfcns,
- const int size, const int f0, int *f0_included)
+int range_enc_filter_arfcns(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);
+ 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/openbsc/src/libbsc/system_information.c
b/openbsc/src/libbsc/system_information.c
index 5f46bf9..95ac736 100644
--- a/openbsc/src/libbsc/system_information.c
+++ b/openbsc/src/libbsc/system_information.c
@@ -197,7 +197,7 @@ static int enc_freq_lst_range(uint8_t *chan_list,
* Manipulate the ARFCN list according to the rules in J4 depending
* on the selected range.
*/
- arfcns_used = range_enc_filter_arfcns(range, arfcns, arfcns_used,
+ arfcns_used = range_enc_filter_arfcns(arfcns, arfcns_used,
f0, &f0_included);
memset(w, 0, sizeof(w));
diff --git a/openbsc/tests/gsm0408/gsm0408_test.c
b/openbsc/tests/gsm0408/gsm0408_test.c
index 3a6bbdd..894eb0f 100644
--- a/openbsc/tests/gsm0408/gsm0408_test.c
+++ b/openbsc/tests/gsm0408/gsm0408_test.c
@@ -152,12 +152,12 @@ static int test_single_range_encoding(int range, const
int *orig_arfcns,
arfcns_used = arfcns_num;
memmove(arfcns, orig_arfcns, sizeof(arfcns));
- f0 = arfcns[0];
+ f0 = range == ARFCN_RANGE_1024 ? 0 : arfcns[0];
/*
* Manipulate the ARFCN list according to the rules in J4 depending
* on the selected range.
*/
- arfcns_used = range_enc_filter_arfcns(range, arfcns, arfcns_used,
+ arfcns_used = range_enc_filter_arfcns(arfcns, arfcns_used,
f0, &f0_included);
memset(w, 0, sizeof(w));
@@ -354,28 +354,28 @@ static void test_arfcn_filter()
/* check that the arfcn is taken out. f0_included is only set for
Range1024 */
f0_included = 24;
- res = range_enc_filter_arfcns(ARFCN_RANGE_512, arfcns,
ARRAY_SIZE(arfcns),
+ res = range_enc_filter_arfcns(arfcns, ARRAY_SIZE(arfcns),
arfcns[0], &f0_included);
VERIFY(res, ==, ARRAY_SIZE(arfcns) - 1);
- VERIFY(f0_included, ==, 0);
+ VERIFY(f0_included, ==, 1);
for (i = 0; i < res; ++i)
VERIFY(arfcns[i], ==, ((i+2) * 2) - (2+1));
- /* check with range1024 */
+ /* check with range1024, ARFCN 0 is included */
for (i = 0; i < ARRAY_SIZE(arfcns); ++i)
- arfcns[i] = (i + 1) * 2;
- res = range_enc_filter_arfcns(ARFCN_RANGE_1024, arfcns,
ARRAY_SIZE(arfcns),
- arfcns[0], &f0_included);
+ arfcns[i] = i * 2;
+ res = 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 + 2) * 2) - 1);
+ VERIFY(arfcns[i], ==, (i + 1) * 2 - 1);
- /* check with range1024, not included */
+ /* check with range1024, ARFCN 0 not included */
for (i = 0; i < ARRAY_SIZE(arfcns); ++i)
arfcns[i] = (i + 1) * 2;
- res = range_enc_filter_arfcns(ARFCN_RANGE_1024, arfcns,
ARRAY_SIZE(arfcns),
- 11, &f0_included);
+ res = 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)
--
1.7.9.5
