si: Fix range1024 encoding
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
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 @@
*/
/**
* 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 @@
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 @@
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);
+ 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;
}
- } 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);
- }
+ arfcns[j++] = mod(arfcns[i] - (f0 + 1), 1024);
}
return j;