parity: add amr crc14 definition
AMR not only specifies a 6 bit CRC for regular voice information. It also
specifies a 14 bit CRC to protect the comfort noise updates contained in
the SID_UPDATE frames.
Change-Id: I5cfd8ca806aba8d42cb9787f69605cea7de6e900
Related: OS#2978
diff --git a/include/osmocom/coding/gsm0503_parity.h b/include/osmocom/coding/gsm0503_parity.h
index 28a5444..c35477f 100644
--- a/include/osmocom/coding/gsm0503_parity.h
+++ b/include/osmocom/coding/gsm0503_parity.h
@@ -19,5 +19,6 @@
const struct osmo_crc8gen_code gsm0503_tch_fr_crc3;
const struct osmo_crc8gen_code gsm0503_tch_efr_crc8;
const struct osmo_crc8gen_code gsm0503_amr_crc6;
+const struct osmo_crc16gen_code gsm0503_amr_crc14;
/*! @} */
diff --git a/src/coding/gsm0503_parity.c b/src/coding/gsm0503_parity.c
index 874114f..a8daacc 100644
--- a/src/coding/gsm0503_parity.c
+++ b/src/coding/gsm0503_parity.c
@@ -134,4 +134,15 @@
.remainder = 0x3f,
};
+/*! GSM AMR parity (SID_UPDATE)
+ *
+ * g(x) = x^14 + x^13 + x^5 + x^3 + x^2 + 1
+ */
+const struct osmo_crc16gen_code gsm0503_amr_crc14 = {
+ .bits = 14,
+ .poly = 0x202d,
+ .init = 0x0000,
+ .remainder = 0x3fff,
+};
+
/*! @} */
diff --git a/src/coding/libosmocoding.map b/src/coding/libosmocoding.map
index 87b3886..7f88111 100644
--- a/src/coding/libosmocoding.map
+++ b/src/coding/libosmocoding.map
@@ -56,6 +56,7 @@
gsm0503_tch_fr_crc3;
gsm0503_tch_efr_crc8;
gsm0503_amr_crc6;
+gsm0503_amr_crc14;
gsm0503_xcch_burst_unmap;
gsm0503_xcch_burst_map;