gprs: fix T3186 encoding in Sysinfo 13
The timer T3186, which is described in 3GPP TS 44.060, is using 3
bits of the si13 mac block. This requires special encoding. In the
case of T3186, the value is encoded by the formula: bits = t/500-1.
Our implementation uses the formula bits=t/500, which is incorrect.
Change-Id: Ifd340c536cff2d1c4b1b3677a358ea95438801eb
diff --git a/openbsc/src/libbsc/rest_octets.c b/openbsc/src/libbsc/rest_octets.c
index 6fae9cd..ed6c573 100644
--- a/openbsc/src/libbsc/rest_octets.c
+++ b/openbsc/src/libbsc/rest_octets.c
@@ -566,6 +566,8 @@
static int encode_t3192(unsigned int t3192)
{
+ /* See also 3GPP TS 44.060
+ Table 12.24.2: GPRS Cell Options information element details */
if (t3192 == 0)
return 3;
else if (t3192 <= 80)
@@ -645,7 +647,11 @@
return drx_timer_max;
bitvec_set_uint(bv, gco->nmo, 2);
- bitvec_set_uint(bv, gco->t3168 / 500, 3);
+
+ /* See also 3GPP TS 44.060
+ Table 12.24.2: GPRS Cell Options information element details */
+ bitvec_set_uint(bv, gco->t3168 / 500 - 1, 3);
+
bitvec_set_uint(bv, t3192, 3);
bitvec_set_uint(bv, drx_timer_max, 3);
/* ACCESS_BURST_TYPE: Hard-code 8bit */