MCS: add Channel Coding Command encoder

Add function to encode MCS value as proper EDGE or GPRS Channel Coding
value according to 3GPP TS 44.060 and corresponding helpers.

Use it for everything except IA Rest Octet encoding which is done in a
follow-up patches to make sure that we distinguish between
encoding-related changes to test output and unrelated changes.

Change-Id: I127fb29f5aaf77a7f6c4c565dfeb3b711af9845d

1 files changed, 13 insertions, 0 deletions

diff --git a/src/coding_scheme.c b/src/coding_scheme.c
index 4a5d0d4d..a4ae8827 100644
--- a/src/coding_scheme.c
+++ b/src/coding_scheme.c
@@ -64,6 +64,19 @@ bool mcs_is_edge_gmsk(enum CodingScheme cs)
 	return false;
 }
 
+/* Return 3GPP TS 44.060 §12.10d (EDGE) or Table 11.2.28.2 (GPRS) Channel Coding Command value */
+uint8_t mcs_chan_code(enum CodingScheme cs)
+{
+	if (mcs_is_gprs(cs))
+		return cs - CS1;
+
+	if (mcs_is_edge(cs))
+		return cs - MCS1;
+
+	/* Defaults to (M)CS1 */
+	return 0;
+}
+
 static struct {
 	struct {
 		uint8_t data_header_bits;