1 files changed, 46 insertions, 0 deletions
diff --git a/src/osmo-bts-trx/gsm0503_interleaving.c b/src/osmo-bts-trx/gsm0503_interleaving.c
index 014b4c9c..ec47a6b3 100644
--- a/src/osmo-bts-trx/gsm0503_interleaving.c
+++ b/src/osmo-bts-trx/gsm0503_interleaving.c
@@ -96,3 +96,49 @@ void gsm0503_tch_fr_interleave(ubit_t *cB, ubit_t *iB)
 	}
 }
 
+/*
+ * GSM TCH HR/AHS interleaving and burst mapping
+ *
+ * Interleaving:
+ *
+ * Given 288 coded input bits, form 4 blocks of 114 bits,
+ * where even bits of the first 2 blocks and odd bits of the last 2 blocks
+ * are used:
+ *
+ *      i(B, j) = c(n, k)       k = 0, ..., 227
+ *                              n = 0, ..., N, N + 1, ...
+ *                              B = B_0 + 2n + b
+ *                              j, b = table[k];
+ *
+ * Mapping on Burst:
+ *
+ *      e(B, j) = i(B, j)
+ *      e(B, 59 + j) = i(B, 57 + j)     j = 0, ..., 56
+ *      e(B, 57) = h_l(B)
+ *      e(B, 58) = h_n(B)
+ *
+ * Where hl(B) and hn(B) are bits in burst B indicating flags.
+ */
+
+void gsm0503_tch_hr_deinterleave(sbit_t *cB, sbit_t *iB)
+{
+	int j, k, B;
+
+	for (k=0; k<228; k++) {
+		B = gsm0503_tch_hr_interleaving[k][1];
+		j = gsm0503_tch_hr_interleaving[k][0];
+		cB[k] = iB[B * 114 + j];
+	}
+}
+
+void gsm0503_tch_hr_interleave(ubit_t *cB, ubit_t *iB)
+{
+	int j, k, B;
+
+	for (k=0; k<228; k++) {
+		B = gsm0503_tch_hr_interleaving[k][1];
+		j = gsm0503_tch_hr_interleaving[k][0];
+		iB[B * 114 + j] = cB[k];
+	}
+}
+