Simplify TS alloc: split off RX mask computation

Move computation of RX mask into separate function and document it. This
allows to significantly shrink find_multi_slot() function and overall
improve code readability.

Since the test output requires cosmetic adjustment anyway due to change
in the sequence of log messages, use this opportunity to better group
and format log message.

Change-Id: I731726a096bba7ee97499e5cbe3e7401869d7392
Related: OS#2282

1 files changed, 42 insertions, 0 deletions

diff --git a/src/mslot_class.c b/src/mslot_class.c
index 12d6d9e2..1c79a214 100644
--- a/src/mslot_class.c
+++ b/src/mslot_class.c
@@ -21,6 +21,7 @@
  */
 
 #include <mslot_class.h>
+#include <gprs_debug.h>
 
 #include <osmocom/core/utils.h>
 #include <osmocom/core/logging.h>
@@ -170,3 +171,44 @@ uint8_t mslot_class_get_type(uint8_t ms_cl)
 {
 	return get_mslot_table(ms_cl)->type;
 }
+
+/*! Fill in RX mask table for a given MS Class
+ *
+ *  \param[in] ms_cl MS Class pointer
+ *  \param[in] num_tx Number of TX slots to consider
+ *  \param[out] rx_mask RX mask table
+ */
+void mslot_fill_rx_mask(uint8_t mslot_class, uint8_t num_tx, uint8_t *rx_mask)
+{
+	static const char *digit[10] = { "0","1","2","3","4","5","6","7","8","9" };
+	uint8_t Tx = mslot_class_get_tx(mslot_class),     /* Max number of Tx slots */
+		Sum = mslot_class_get_sum(mslot_class),	  /* Max number of Tx + Rx slots */
+		Type = mslot_class_get_type(mslot_class), /* Type of Mobile */
+		Tta = mslot_class_get_ta(mslot_class),    /* Minimum number of slots */
+		Ttb = mslot_class_get_tb(mslot_class),
+		/* FIXME: use actual TA offset for computation - make sure to adjust "1 + MS_TO" accordingly
+		   see also "Offset required" bit in 3GPP TS 24.008 §10.5.1.7 */
+		Tra = mslot_class_get_ra(mslot_class, 0),
+		Trb = mslot_class_get_rb(mslot_class, 0);
+
+	if (num_tx == 1) /* it's enough to log this once per TX slot set iteration */
+		LOGP(DRLCMAC, LOGL_DEBUG,
+		     "Rx=%d Tx=%d Sum Rx+Tx=%s, Tta=%s Ttb=%d, Tra=%d Trb=%d, Type=%d\n",
+		     mslot_class_get_rx(mslot_class), Tx,
+		     (Sum == MS_NA) ? "N/A" : digit[Sum],
+		     (Tta == MS_NA) ? "N/A" : digit[Tta], Ttb, Tra, Trb, Type);
+
+	if (Type == 1) {
+		rx_mask[MASK_TT] = (0x100 >> OSMO_MAX(Ttb, Tta)) - 1;
+		rx_mask[MASK_TT] &= ~((1 << (Trb + num_tx)) - 1);
+		rx_mask[MASK_TR] = (0x100 >> Ttb) - 1;
+		rx_mask[MASK_TR] &= ~((1 << (OSMO_MAX(Trb, Tra) + num_tx)) - 1);
+	} else {
+		/* Class type 2 MS have independant RX and TX */
+		rx_mask[MASK_TT] = 0xff;
+		rx_mask[MASK_TR] = 0xff;
+	}
+
+	rx_mask[MASK_TT] = (rx_mask[MASK_TT] << 3) | (rx_mask[MASK_TT] >> 5);
+	rx_mask[MASK_TR] = (rx_mask[MASK_TR] << 3) | (rx_mask[MASK_TR] >> 5);
+}