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SI2q: cleanup UARFCN addition 

* fix comment typo
* constify parameter
* move try-add-adjust routine into separate function to facilitate
  further modifications
* remove excessive checks and unnecessary return values

Change-Id: Ia72f848dec40723510ca56868e08081804227d47
Related: OS#2357
This commit is contained in:
Max 2017-09-29 14:10:24 +02:00
parent 918cfeb787
commit 78f532992a
2 changed files with 44 additions and 55 deletions
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97
src/libbsc/rest_octets.c
View File

@ -232,7 +232,7 @@ static inline int f0_helper(int *sc, size_t length, uint8_t *chan_list)
}
/* Estimate how many bits it'll take to append single FDD UARFCN */
static inline int append_utran_fdd_length(uint16_t u, int *sc, size_t sc_len, size_t length)
static inline int append_utran_fdd_length(uint16_t u, const int *sc, size_t sc_len, size_t length)
{
uint8_t chan_list[16] = { 0 };
int tmp[sc_len], f0;
@ -274,18 +274,42 @@ static inline int append_utran_fdd(struct bitvec *bv, uint16_t u, int *sc, size_
return 21 + range1024_p(length);
}
/* Append multiple FDD UARFCNs */
static inline int append_uarfcns(struct bitvec *bv, struct gsm_bts *bts, uint8_t budget)
static inline int try_adding_uarfcn(struct bitvec *bv, struct gsm_bts *bts, uint16_t uarfcn,
uint8_t num_sc, uint8_t start_pos, uint8_t budget)
{
const uint16_t *u = bts->si_common.data.uarfcn_list, *sc = bts->si_common.data.scramble_list;
int i, j, k, rc, st = 0, a[bts->si_common.uarfcn_length];
int i, k, rc, a[bts->si_common.uarfcn_length];
if (budget < 23)
return -ENOMEM;
/* copy corresponding Scrambling Codes: range encoder make in-place modifications */
for (i = start_pos, k = 0; i < num_sc; a[k++] = bts->si_common.data.scramble_list[i++]);
/* estimate bit length requirements */
rc = append_utran_fdd_length(uarfcn, a, bts->si_common.uarfcn_length, k);
if (rc < 0)
return rc; /* range encoder failure */
if (budget - rc <= 0)
return -ENOMEM; /* we have ran out of budget in current SI2q */
/* compute next offset */
bts->u_offset += k;
return budget - append_utran_fdd(bv, uarfcn, a, k);
}
/* Append multiple FDD UARFCNs */
static inline void append_uarfcns(struct bitvec *bv, struct gsm_bts *bts, uint8_t budget)
{
const uint16_t *u = bts->si_common.data.uarfcn_list;
int i, rem = budget - 7, st = 0; /* account for constant bits right away */
uint16_t cu = u[bts->u_offset]; /* caller ensures that length is positive */
uint8_t rem = budget - 7, offset_diff; /* account for constant bits right away */
OSMO_ASSERT(budget <= SI2Q_MAX_LEN);
if (budget <= 7)
return -ENOMEM;
return;
/* 3G Neighbour Cell Description */
bitvec_set_bit(bv, 1);
@ -299,53 +323,24 @@ static inline int append_uarfcns(struct bitvec *bv, struct gsm_bts *bts, uint8_t
/* No Bandwidth_FDD */
bitvec_set_bit(bv, 0);
for (i = bts->u_offset; i < bts->si_common.uarfcn_length; i++) {
offset_diff = 0;
for (j = st, k = 0; j < i; j++) {
a[k++] = sc[j]; /* copy corresponding SCs */
offset_diff++; /* compute proper offset step */
}
for (i = bts->u_offset; i <= bts->si_common.uarfcn_length; i++)
if (u[i] != cu) { /* we've reached new UARFCN */
rc = append_utran_fdd_length(cu, a, bts->si_common.uarfcn_length, k);
if (rc < 0) { /* estimate bit length requirements */
return rc;
}
rem = try_adding_uarfcn(bv, bts, cu, i, st, rem);
if (rem < 0)
break;
if (rem - rc <= 0)
break; /* we have ran out of budget in current SI2q */
else {
rem -= append_utran_fdd(bv, cu, a, k);
bts->u_offset += offset_diff;
}
cu = u[i];
st = i; /* update start position */
if (i < bts->si_common.uarfcn_length) {
cu = u[i];
st = i;
} else
break;
}
}
if (rem > 22) { /* add last UARFCN not covered by previous cycle if it could possibly fit into budget */
offset_diff = 0;
for (i = st, k = 0; i < bts->si_common.uarfcn_length; i++) {
a[k++] = sc[i];
offset_diff++;
}
rc = append_utran_fdd_length(cu, a, bts->si_common.uarfcn_length, k);
if (rc < 0) {
return rc;
}
if (rem - rc >= 0) {
rem -= append_utran_fdd(bv, cu, a, k);
bts->u_offset += offset_diff;
}
}
/* stop bit - end of Repeated UTRAN FDD Neighbour Cells */
bitvec_set_bit(bv, 0);
/* UTRAN TDD Description */
bitvec_set_bit(bv, 0);
return 0;
}
/* generate SI2quater rest octets: 3GPP TS 44.018 § 10.5.2.33b */
@ -393,15 +388,9 @@ int rest_octets_si2quater(uint8_t *data, struct gsm_bts *bts)
bitvec_set_bit(&bv, 0);
rc = SI2Q_MAX_LEN - (bv.cur_bit + 3);
if (rc > 0 && bts->si_common.uarfcn_length - bts->u_offset > 0) {
rc = append_uarfcns(&bv, bts, rc);
if (rc < 0) {
LOGP(DRR, LOGL_ERROR, "SI2quater [%u/%u]: failed to append %zu UARFCNs due to range encoding "
"failure: %s\n",
bts->si2q_index, bts->si2q_count, bts->si_common.uarfcn_length, strerror(-rc));
return rc;
}
} else /* No 3G Neighbour Cell Description */
if (rc > 0 && bts->si_common.uarfcn_length - bts->u_offset > 0)
append_uarfcns(&bv, bts, rc);
else /* No 3G Neighbour Cell Description */
bitvec_set_bit(&bv, 0);
/* No 3G Measurement Parameters Description */

2
src/libbsc/system_information.c
View File

@ -182,7 +182,7 @@ uint8_t si2q_num(struct gsm_bts *bts)
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;