Fixes #164

lib/src/phy/phch/pbch.c

@@ -399,35 +399,41 @@ uint32_t srslte_pbch_crc_check(srslte_pbch_t *q, uint8_t *bits, uint32_t nof_por
 int decode_frame(srslte_pbch_t *q, uint32_t src, uint32_t dst, uint32_t n,
     uint32_t nof_bits, uint32_t nof_ports) {
   int j;
-  
-  memcpy(&q->temp[dst * nof_bits], &q->llr[src * nof_bits],
-      n * nof_bits * sizeof(float));
 
-  /* descramble */
-  srslte_scrambling_f_offset(&q->seq, &q->temp[dst * nof_bits], dst * nof_bits,
-      n * nof_bits);
+  if (dst + n <= 4 && src + n <= 4) {
+    memcpy(&q->temp[dst * nof_bits], &q->llr[src * nof_bits],
+           n * nof_bits * sizeof(float));
 
-  for (j = 0; j < dst * nof_bits; j++) {
-    q->temp[j] = SRSLTE_RX_NULL;
-  }
-  for (j = (dst + n) * nof_bits; j < 4 * nof_bits; j++) {
-    q->temp[j] = SRSLTE_RX_NULL;
-  }
+    /* descramble */
+    srslte_scrambling_f_offset(&q->seq, &q->temp[dst * nof_bits], dst * nof_bits,
+                               n * nof_bits);
 
-  /* unrate matching */
-  srslte_rm_conv_rx(q->temp, 4 * nof_bits, q->rm_f, SRSLTE_BCH_ENCODED_LEN);
-  
-  /* Normalize LLR */
-  srslte_vec_sc_prod_fff(q->rm_f, 1.0/((float) 2*n), q->rm_f, SRSLTE_BCH_ENCODED_LEN);
-  
-  /* decode */
-  srslte_viterbi_decode_f(&q->decoder, q->rm_f, q->data, SRSLTE_BCH_PAYLOADCRC_LEN);
+    for (j = 0; j < dst * nof_bits; j++) {
+      q->temp[j] = SRSLTE_RX_NULL;
+    }
+    for (j = (dst + n) * nof_bits; j < 4 * nof_bits; j++) {
+      q->temp[j] = SRSLTE_RX_NULL;
+    }
+
+    /* unrate matching */
+    srslte_rm_conv_rx(q->temp, 4 * nof_bits, q->rm_f, SRSLTE_BCH_ENCODED_LEN);
 
- if (!srslte_pbch_crc_check(q, q->data, nof_ports)) {
-    return 1;
+    /* Normalize LLR */
+    srslte_vec_sc_prod_fff(q->rm_f, 1.0/((float) 2*n), q->rm_f, SRSLTE_BCH_ENCODED_LEN);
+
+    /* decode */
+    srslte_viterbi_decode_f(&q->decoder, q->rm_f, q->data, SRSLTE_BCH_PAYLOADCRC_LEN);
+
+    if (!srslte_pbch_crc_check(q, q->data, nof_ports)) {
+      return 1;
+    } else {
+      return SRSLTE_SUCCESS;
+    }
   } else {
-    return SRSLTE_SUCCESS;
+    fprintf(stderr, "Error in PBCH decoder: Invalid frame pointers dst=%d, src=%d, n=%d\n", src, dst, n);
+    return -1;
   }
+
 }
 
 /* Decodes the PBCH channel
@@ -514,7 +520,7 @@ int srslte_pbch_decode(srslte_pbch_t *q, cf_t *slot1_symbols, cf_t *ce_slot1[SRS
         for (nb = 0; nb < q->frame_idx; nb++) {
           for (dst = 0; (dst < 4 - nb); dst++) {
             for (src = 0; src < q->frame_idx - nb; src++) {
-              ret = decode_frame(q, src, dst, nb + 1, nof_bits, nant);     
+              ret = decode_frame(q, src, dst, nb + 1, nof_bits, nant);
               if (ret == 1) {
                 if (sfn_offset) {
                   *sfn_offset = (int) dst - src + q->frame_idx - 1;
@@ -526,15 +532,16 @@ int srslte_pbch_decode(srslte_pbch_t *q, cf_t *slot1_symbols, cf_t *ce_slot1[SRS
                   memcpy(bch_payload, q->data, sizeof(uint8_t) * SRSLTE_BCH_PAYLOAD_LEN);      
                 }
                 INFO("Decoded PBCH: src=%d, dst=%d, nb=%d, sfn_offset=%d\n", src, dst, nb+1, (int) dst - src + q->frame_idx - 1);
-                return 1; 
+                srslte_pbch_decode_reset(q);
+                return 1;
               }
             }
           }
         }
       }
       nant++;
-    } while(nant <= q->cell.nof_ports); 
-    
+    } while(nant <= q->cell.nof_ports);
+
     /* If not found, make room for the next packet of radio frame symbols */
     if (q->frame_idx == 4) {
       memmove(q->llr, &q->llr[nof_bits], nof_bits * 3 * sizeof(float));