Merge remote-tracking branch 'origin/fix_0_tbs' into integration_2025_w41 (!3688)

Fixes to prevent assertion due to 0 PRB allocation

Assertion (NPRB>0 && (NPRB + RBstart <= BWPsize)) failed!
In PRBalloc_to_locationandbandwidth0() /home/user/openairinterface5g/common/utils/nr/nr_common.c:506
Illegal NPRB/RBstart Configuration (0,51) for BWPsize 51

Probably caused by missing safeguards to prevent computing TBS with 0 PRB
as input.

openair2/LAYER2/NR_MAC_COMMON/nr_compute_tbs_common.c

@@ -59,6 +59,11 @@ uint32_t nr_compute_tbs(uint16_t Qm,
         tb_scaling,
         Nl);
 
+  if (Qm == 0 || R == 0 || nb_rb == 0 || Nl == 0) {
+    LOG_E(NR_MAC, "Error in compute TBS with a NULL input, returning NULL TBS\n");
+    return 0;
+  }
+
   const int nb_subcarrier_per_rb = 12;
   const uint32_t nbp_re =  nb_subcarrier_per_rb * nb_symb_sch - nb_dmrs_prb - nb_rb_oh;
   const uint32_t nb_re = min(156, nbp_re) * nb_rb;

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_primitives.c

@@ -673,8 +673,7 @@ bool nr_find_nb_rb(uint16_t Qm,
                    uint16_t *nb_rb)
 {
   // for transform precoding only RB = 2^a_2 * 3^a_3 * 5^a_5 is allowed with a non-negative
-  while(transform_precoding == NR_PUSCH_Config__transformPrecoder_enabled &&
-        !multiple_2_3_5(nb_rb_max))
+  while (transform_precoding == NR_PUSCH_Config__transformPrecoder_enabled && !multiple_2_3_5(nb_rb_max))
     nb_rb_max--;
 
   /* is the maximum (not even) enough? */