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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
This commit is contained in:
Jacob Erlbeck 2014-01-14 10:42:58 +01:00
parent 131406c86d
commit 45014a0cad
4 changed files with 37 additions and 43 deletions
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2
openbsc/include/openbsc/arfcn_range_encode.h
View File

@ -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);

42
openbsc/src/libbsc/arfcn_range_encode.c
View File

@ -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);
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;

2
openbsc/src/libbsc/system_information.c
View File

@ -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));

34
openbsc/tests/gsm0408/gsm0408_test.c
View File

@ -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),
arfcns[0], &f0_included);
VERIFY(res, ==, ARRAY_SIZE(arfcns) - 1);
VERIFY(f0_included, ==, 0);
for (i = 0; i < res; ++i)
VERIFY(arfcns[i], ==, ((i+2) * 2) - (2+1));
/* check with range1024 */
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),
res = 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) - 1);
VERIFY(arfcns[i], ==, ((i+2) * 2) - (2+1));
/* check with range1024, not included */
/* check with range1024, ARFCN 0 is included */
for (i = 0; i < ARRAY_SIZE(arfcns); ++i)
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 + 1) * 2 - 1);
/* 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)