SI2q: cleanup UARFCN addition
* expand comments, fix typos
* constify parameter
* move try-add-adjust routine into separate function to facilitate
further modifications
* remove excessive checks and unnecessary return values
* move (UARFCN, Scrambling Code) tuple uniqueness check into separate
function and use it early
Change-Id: Ia72f848dec40723510ca56868e08081804227d47
Related: OS#2357
diff --git a/src/libbsc/system_information.c b/src/libbsc/system_information.c
index 7bdb80a..761e848 100644
--- a/src/libbsc/system_information.c
+++ b/src/libbsc/system_information.c
@@ -182,7 +182,7 @@
int rc = make_si2quaters(bts, true);
uint8_t num = bts->si2q_index + 1; /* number of SI2quater messages */
- /* N. B: si2q_num() should NEVER be called during actualSI2q rest octets generation
+ /* N. B: si2q_num() should NEVER be called during actual SI2q rest octets generation
we're not re-entrant because of the following code: */
bts->u_offset = 0;
bts->e_offset = 0;
@@ -239,27 +239,41 @@
return r;
}
+/* Scrambling Code as defined in 3GPP TS 25.213 is 9 bit long so number below is unreacheable upper bound */
+#define SC_BOUND 600
+
+/* Find position for a given UARFCN (take SC into consideration if it's available) in a sorted list
+ N. B: we rely on the assumption that (uarfcn, scramble) tuple is unique in the lists */
+static int uarfcn_sc_pos(const struct gsm_bts *bts, uint16_t uarfcn, uint16_t scramble)
+{
+ const uint16_t *sc = bts->si_common.data.scramble_list;
+ uint16_t i, scramble0 = encode_fdd(scramble, false), scramble1 = encode_fdd(scramble, true);
+ for (i = 0; i < bts->si_common.uarfcn_length; i++)
+ if (uarfcn == bts->si_common.data.uarfcn_list[i]) {
+ if (scramble < SC_BOUND) {
+ if (scramble0 == sc[i] || scramble1 == sc[i])
+ return i;
+ } else
+ return i;
+ }
+
+ return -1;
+}
+
int bts_uarfcn_del(struct gsm_bts *bts, uint16_t arfcn, uint16_t scramble)
{
- uint16_t sc0 = encode_fdd(scramble, false), sc1 = encode_fdd(scramble, true),
- *ual = bts->si_common.data.uarfcn_list,
- *scl = bts->si_common.data.scramble_list;
- size_t len = bts->si_common.uarfcn_length, i;
- for (i = 0; i < len; i++) {
- if (arfcn == ual[i] && (sc0 == scl[i] || sc1 == scl[i])) {
- /* we rely on the assumption that (uarfcn, scramble)
- tuple is unique in the lists */
- if (i != len - 1) { /* move the tail if necessary */
- memmove(ual + i, ual + i + 1, 2 * (len - i + 1));
- memmove(scl + i, scl + i + 1, 2 * (len - i + 1));
- }
- break;
- }
- }
+ uint16_t *ual = bts->si_common.data.uarfcn_list, *scl = bts->si_common.data.scramble_list;
+ size_t len = bts->si_common.uarfcn_length;
+ int pos = uarfcn_sc_pos(bts, arfcn, scramble);
- if (i == len)
+ if (pos < 0)
return -EINVAL;
+ if (pos != len - 1) { /* move the tail if necessary */
+ memmove(ual + pos, ual + pos + 1, 2 * (len - pos + 1));
+ memmove(scl + pos, scl + pos + 1, 2 * (len - pos + 1));
+ }
+
bts->si_common.uarfcn_length--;
return 0;
}
@@ -267,29 +281,27 @@
int bts_uarfcn_add(struct gsm_bts *bts, uint16_t arfcn, uint16_t scramble, bool diversity)
{
size_t len = bts->si_common.uarfcn_length, i, k = 0;
- uint16_t scr, chk,
+ uint8_t si2q;
+ int pos = uarfcn_sc_pos(bts, arfcn, scramble);
+ uint16_t scr = diversity ? encode_fdd(scramble, true) : encode_fdd(scramble, false),
*ual = bts->si_common.data.uarfcn_list,
- *scl = bts->si_common.data.scramble_list,
- scramble1 = encode_fdd(scramble, true),
- scramble0 = encode_fdd(scramble, false);
-
- scr = diversity ? scramble1 : scramble0;
- chk = diversity ? scramble0 : scramble1;
+ *scl = bts->si_common.data.scramble_list;
if (len == MAX_EARFCN_LIST)
return -ENOMEM;
- for (i = 0; i < len; i++) /* find the position of arfcn if any */
- if (arfcn == ual[i])
- break;
+ if (pos >= 0)
+ return -EADDRINUSE;
- for (k = 0; i < len; i++) {
- if (arfcn == ual[i] && (scr == scl[i] || chk == scl[i]))
- return -EADDRINUSE;
+ /* find the suitable position for arfcn if any */
+ pos = uarfcn_sc_pos(bts, arfcn, SC_BOUND);
+ i = (pos < 0) ? len : pos;
+
+ for (k = 0; i < len; i++)
if (scr > scl[i])
k = i + 1;
- }
- /* we keep lists sorted by scramble code:
+
+ /* we keep lists sorted by scramble code of a given UARFCN:
insert into appropriate position and move the tail */
if (len - k) {
memmove(ual + k + 1, ual + k, (len - k) * 2);
@@ -299,9 +311,10 @@
ual[k] = arfcn;
scl[k] = scr;
bts->si_common.uarfcn_length++;
+ si2q = si2q_num(bts);
- if (si2q_num(bts) <= SI2Q_MAX_NUM) {
- bts->si2q_count = si2q_num(bts) - 1;
+ if (si2q <= SI2Q_MAX_NUM) {
+ bts->si2q_count = si2q - 1;
return 0;
}