alloc: Move the collision handling to a new method
The naming of RX/TX still looks fishy and it should use DL/UL instead.
Work on pointers right now. We could introduce a struct with the window
min and max and pass this struct. The usage of 'D' appears wrong in the
ul_usage..
diff --git a/src/gprs_rlcmac_ts_alloc.cpp b/src/gprs_rlcmac_ts_alloc.cpp
index eb7f0ec..f270874 100644
--- a/src/gprs_rlcmac_ts_alloc.cpp
+++ b/src/gprs_rlcmac_ts_alloc.cpp
@@ -252,6 +252,89 @@
return rx_window;
}
+static int reduce_rx_window(const int ms_type, const struct gprs_rlcmac_tbf *old_tbf,
+ const int Tt, const int Tr,
+ int *rx_window,
+ uint8_t *rx_win_min, uint8_t *rx_win_max)
+{
+ if (ms_type != 1)
+ return 0;
+ if (!old_tbf)
+ return 0;
+ if (old_tbf->direction != GPRS_RLCMAC_UL_TBF)
+ return 0;
+
+ uint8_t collide = 0, ul_usage = 0;
+
+ /* calculate mask of colliding slots */
+ for (uint8_t ts_no = 0; ts_no < 8; ts_no++) {
+ int j;
+ if (!old_tbf->pdch[ts_no])
+ continue;
+
+ ul_usage |= (1 << ts_no);
+ /* mark bits from TS-t .. TS+r */
+ for (j = ts_no - Tt; j != ((ts_no + Tr + 1) & 7); j = (j + 1) & 7)
+ collide |= (1 << j);
+ }
+
+ LOGP(DRLCMAC, LOGL_DEBUG, "- Not allowed slots due to existing "
+ "UL allocation: (TS=0)\"%c%c%c%c%c%c%c%c\"(TS=7) "
+ " D=downlink x=not usable\n",
+ ((ul_usage & 0x01)) ? 'D' : ((collide & 0x01))?'x':'.',
+ ((ul_usage & 0x02)) ? 'D' : ((collide & 0x02))?'x':'.',
+ ((ul_usage & 0x04)) ? 'D' : ((collide & 0x04))?'x':'.',
+ ((ul_usage & 0x08)) ? 'D' : ((collide & 0x08))?'x':'.',
+ ((ul_usage & 0x10)) ? 'D' : ((collide & 0x10))?'x':'.',
+ ((ul_usage & 0x20)) ? 'D' : ((collide & 0x20))?'x':'.',
+ ((ul_usage & 0x40)) ? 'D' : ((collide & 0x40))?'x':'.',
+ ((ul_usage & 0x80)) ? 'D' : ((collide & 0x80))?'x':'.');
+
+ /*
+ * Uplink/Downlink in GSM is shifted by three timeslots. Make
+ * sure they don't collide.
+ */
+ *rx_window &= ~(collide << 3);
+ *rx_window &= ~(collide >> 5);
+ LOGP(DRLCMAC, LOGL_DEBUG, "- Remaining slots for RX: "
+ "(TS=0)\"%c%c%c%c%c%c%c%c\"(TS=7)\n",
+ ((*rx_window & 0x01)) ? 'D' : '.',
+ ((*rx_window & 0x02)) ? 'D' : '.',
+ ((*rx_window & 0x04)) ? 'D' : '.',
+ ((*rx_window & 0x08)) ? 'D' : '.',
+ ((*rx_window & 0x10)) ? 'D' : '.',
+ ((*rx_window & 0x20)) ? 'D' : '.',
+ ((*rx_window & 0x40)) ? 'D' : '.',
+ ((*rx_window & 0x80)) ? 'D' : '.');
+
+ if (!*rx_window) {
+ LOGP(DRLCMAC, LOGL_NOTICE, "No suitable downlink slots "
+ "available with current uplink assignment\n");
+ return -EBUSY;
+ }
+
+ /* calculate new min/max */
+ for (uint8_t ts_no = *rx_win_min; ts_no <= *rx_win_max; ts_no++) {
+ if ((*rx_window & (1 << ts_no)))
+ break;
+ *rx_win_min = ts_no + 1;
+ LOGP(DRLCMAC, LOGL_DEBUG, "- TS has been deleted, so "
+ "raising start of DL window to %d\n",
+ *rx_win_min);
+ }
+ for (uint8_t ts_no = *rx_win_max; ts_no >= *rx_win_min; ts_no--) {
+ if ((*rx_window & (1 << ts_no)))
+ break;
+ *rx_win_max = ts_no - 1;
+ LOGP(DRLCMAC, LOGL_DEBUG, "- TS has been deleted, so "
+ "lowering end of DL window to %d\n",
+ *rx_win_max);
+ }
+
+ return 0;
+}
+
+
/* Slot Allocation: Algorithm B
*
* Assign as many downlink slots as possible.
@@ -266,7 +349,7 @@
uint8_t Tx, Sum; /* Maximum Number of Slots: RX, Tx, Sum Rx+Tx */
uint8_t Tta, Ttb, Tra, Trb, Tt, Tr; /* Minimum Number of Slots */
uint8_t Type; /* Type of Mobile */
- uint8_t rx_window;
+ int rx_window;
uint8_t tx_win_min, tx_win_max, tx_range;
uint8_t tx_window = 0;
static const char *digit[10] = { "0","1","2","3","4","5","6","7","8","9" };
@@ -328,69 +411,10 @@
/* reduce window, if existing uplink slots collide RX window */
- if (Type == 1 && old_tbf && old_tbf->direction == GPRS_RLCMAC_UL_TBF) {
- uint8_t collide = 0, ul_usage = 0;
- int j;
-
- /* calculate mask of colliding slots */
- for (ts = 0; ts < 8; ts++) {
- if (old_tbf->pdch[ts]) {
- ul_usage |= (1 << ts);
- /* mark bits from TS-t .. TS+r */
- for (j = ts - Tt; j != ((ts + Tr + 1) & 7);
- j = (j + 1) & 7)
- collide |= (1 << j);
- }
- }
- LOGP(DRLCMAC, LOGL_DEBUG, "- Not allowed slots due to existing "
- "UL allocation: (TS=0)\"%c%c%c%c%c%c%c%c\"(TS=7) "
- " D=downlink x=not usable\n",
- ((ul_usage & 0x01)) ? 'D' : ((collide & 0x01))?'x':'.',
- ((ul_usage & 0x02)) ? 'D' : ((collide & 0x02))?'x':'.',
- ((ul_usage & 0x04)) ? 'D' : ((collide & 0x04))?'x':'.',
- ((ul_usage & 0x08)) ? 'D' : ((collide & 0x08))?'x':'.',
- ((ul_usage & 0x10)) ? 'D' : ((collide & 0x10))?'x':'.',
- ((ul_usage & 0x20)) ? 'D' : ((collide & 0x20))?'x':'.',
- ((ul_usage & 0x40)) ? 'D' : ((collide & 0x40))?'x':'.',
- ((ul_usage & 0x80)) ? 'D' : ((collide & 0x80))?'x':'.');
-
- /* apply mask to reduce tx_window (shifted by 3 slots) */
- rx_window &= ~(collide << 3);
- rx_window &= ~(collide >> 5);
- LOGP(DRLCMAC, LOGL_DEBUG, "- Remaining slots for RX: "
- "(TS=0)\"%c%c%c%c%c%c%c%c\"(TS=7)\n",
- ((rx_window & 0x01)) ? 'D' : '.',
- ((rx_window & 0x02)) ? 'D' : '.',
- ((rx_window & 0x04)) ? 'D' : '.',
- ((rx_window & 0x08)) ? 'D' : '.',
- ((rx_window & 0x10)) ? 'D' : '.',
- ((rx_window & 0x20)) ? 'D' : '.',
- ((rx_window & 0x40)) ? 'D' : '.',
- ((rx_window & 0x80)) ? 'D' : '.');
- if (!rx_window) {
- LOGP(DRLCMAC, LOGL_NOTICE, "No suitable downlink slots "
- "available with current uplink assignment\n");
- return -EBUSY;
- }
-
- /* calculate new min/max */
- for (ts = rx_win_min; ts <= rx_win_max; ts++) {
- if ((rx_window & (1 << ts)))
- break;
- rx_win_min = ts + 1;
- LOGP(DRLCMAC, LOGL_DEBUG, "- TS has been deleted, so "
- "raising start of DL window to %d\n",
- rx_win_min);
- }
- for (ts = rx_win_max; ts >= rx_win_min; ts--) {
- if ((rx_window & (1 << ts)))
- break;
- rx_win_max = ts - 1;
- LOGP(DRLCMAC, LOGL_DEBUG, "- TS has been deleted, so "
- "lowering end of DL window to %d\n",
- rx_win_max);
- }
- }
+ int rc = reduce_rx_window(ms_class->type, old_tbf, Tt, Tr,
+ &rx_window, &rx_win_min, &rx_win_max);
+ if (rc < 0)
+ return rc;
/* reduce window, to allow at least one uplink TX slot
* this is only required for Type 1 */