Fix Channel Coding Command for MCS

Previously result of ".to_num() - 1" was used without any checks which
means that in case of to_num() returning zero we would effectively try
to encode (uint8_t)(-1).

Let's fix this by using proper mcs_chan_code() function which returns
Channel Coding Command for MCS without the need to further correct it
and adjust expected tests output accordingly.

Change-Id: I868062a81fffe6714a811c032215f25a79259905

4 files changed, 12 insertions, 12 deletions

diff --git a/src/encoding.cpp b/src/encoding.cpp
index 9920b461..b0d04679 100644
--- a/src/encoding.cpp
+++ b/src/encoding.cpp
@@ -268,7 +268,7 @@ static int write_ia_rest_uplink_mba(const gprs_rlcmac_ul_tbf *tbf, bitvec *dest,
 	bitvec_write_field(dest, &wp, usf, 3);    // USF
 	bitvec_write_field(dest, &wp, 0, 1);    // USF_GRANULARITY
 	bitvec_write_field(dest, &wp, 0, 1);   // "0" power control: Not Present
-	bitvec_write_field(dest, &wp, tbf->current_cs().to_num() - 1, 2);    // CHANNEL_CODING_COMMAND
+	bitvec_write_field(dest, &wp, mcs_chan_code(tbf->current_cs()), 2);    // CHANNEL_CODING_COMMAND
 	bitvec_write_field(dest, &wp, 1, 1);    // TLLI_BLOCK_CHANNEL_CODING
 	if (alpha) {
 		bitvec_write_field(dest, &wp, 0x1, 1);   // ALPHA = present
@@ -315,7 +315,7 @@ static int write_ia_rest_egprs_uplink_sba(const gprs_rlcmac_ul_tbf *tbf, bitvec
 	CHECK(rc);
 
 	/* 3GPP TS 44.060 §12.10d EGPRS Modulation and coding Scheme description: */
-	rc = bitvec_set_u64(dest, tbf->current_cs().to_num() - 1, 4, false); /* EGPRS CHANNEL_CODING_COMMAND */
+	rc = bitvec_set_u64(dest, mcs_chan_code(tbf->current_cs()), 4, false); /* EGPRS CHANNEL_CODING_COMMAND */
 	CHECK(rc);
 
 	/* TLLI_BLOCK_CHANNEL_CODING */
@@ -571,7 +571,7 @@ void Encoding::write_packet_uplink_assignment(
 
 	if (!use_egprs) {
 		bitvec_write_field(dest, &wp,0x0,1); // Message escape
-		bitvec_write_field(dest, &wp,tbf->current_cs().to_num()-1, 2); // CHANNEL_CODING_COMMAND
+		bitvec_write_field(dest, &wp, mcs_chan_code(tbf->current_cs()), 2); // CHANNEL_CODING_COMMAND
 		bitvec_write_field(dest, &wp,0x1,1); // TLLI_BLOCK_CHANNEL_CODING
 		write_ta_ie(dest, wp,tbf->ta(), ta_idx, ta_ts);
 	} else { /* EPGRS */
@@ -579,7 +579,7 @@ void Encoding::write_packet_uplink_assignment(
 		bitvec_write_field(dest, &wp,0x0,2); // EGPRS message contents
 		bitvec_write_field(dest, &wp,0x0,1); // No CONTENTION_RESOLUTION_TLLI
 		bitvec_write_field(dest, &wp,0x0,1); // No COMPACT reduced MA
-		bitvec_write_field(dest, &wp,tbf->current_cs().to_num()-1, 4); // EGPRS Modulation and Coding IE
+		bitvec_write_field(dest, &wp, mcs_chan_code(tbf->current_cs()), 4); // EGPRS Modulation and Coding IE
 		/* 0: no RESEGMENT, 1: Segmentation*/
 		bitvec_write_field(dest, &wp, 0x1, 1);
 		write_ws(dest, &wp, tbf->window_size()); // EGPRS Window Size
@@ -809,7 +809,7 @@ static void write_packet_uplink_ack_gprs(
 	struct gprs_rlcmac_ul_tbf *tbf, bool is_final)
 {
 
-	bitvec_write_field(dest, &wp, tbf->current_cs().to_num() - 1, 2); // CHANNEL_CODING_COMMAND
+	bitvec_write_field(dest, &wp, mcs_chan_code(tbf->current_cs()), 2); // CHANNEL_CODING_COMMAND
 	write_packet_ack_nack_desc_gprs(bts, dest, wp, tbf->window(), is_final);
 
 	bitvec_write_field(dest, &wp, 1, 1); // 1: have CONTENTION_RESOLUTION_TLLI
@@ -991,7 +991,7 @@ static void write_packet_uplink_ack_egprs(
 	bitvec_write_field(dest, &wp, 0, 2); // fixed 00
 	/* CHANNEL_CODING_COMMAND */
 	bitvec_write_field(dest, &wp,
-		tbf->current_cs().to_num() - 1, 4);
+		mcs_chan_code(tbf->current_cs()), 4);
 	/* 0: no RESEGMENT, 1: Segmentation*/
 	bitvec_write_field(dest, &wp, 1, 1);
 	bitvec_write_field(dest, &wp, 1, 1); // PRE_EMPTIVE_TRANSMISSION, TODO: This resembles GPRS, change it?
diff --git a/tests/tbf/TbfTest.cpp b/tests/tbf/TbfTest.cpp
index 6dc802cf..151e7fac 100644
--- a/tests/tbf/TbfTest.cpp
+++ b/tests/tbf/TbfTest.cpp
@@ -739,7 +739,7 @@ static gprs_rlcmac_ul_tbf *puan_urbb_len_issue(BTS *the_bts,
 
 	struct msgb *msg1 = ul_tbf->create_ul_ack(*fn, ts_no);
 
-	static uint8_t exp1[] = { 0x40, 0x24, 0x01, 0x3f, 0x3e, 0x24, 0x46, 0x68, 0x90, 0x87, 0xb0, 0x06,
+	static uint8_t exp1[] = { 0x40, 0x24, 0x01, 0x03, 0x3e, 0x24, 0x46, 0x68, 0x90, 0x87, 0xb0, 0x06,
 				  0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b
 	};
 
@@ -766,7 +766,7 @@ static gprs_rlcmac_ul_tbf *puan_urbb_len_issue(BTS *the_bts,
 
 	msg1 = ul_tbf->create_ul_ack(*fn, ts_no);
 
-	static uint8_t exp2[] = { 0x40, 0x24, 0x01, 0x3f, 0x3e, 0x24, 0x46, 0x68, 0x90, 0x88, 0xb0, 0x06, 0x8b,
+	static uint8_t exp2[] = { 0x40, 0x24, 0x01, 0x03, 0x3e, 0x24, 0x46, 0x68, 0x90, 0x88, 0xb0, 0x06, 0x8b,
 				  0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b
 	};
 
diff --git a/tests/types/TypesTest.cpp b/tests/types/TypesTest.cpp
index 9c24ffe6..48794243 100644
--- a/tests/types/TypesTest.cpp
+++ b/tests/types/TypesTest.cpp
@@ -497,7 +497,7 @@ void test_immediate_assign_ul0m()
 				 0x23, /* TA */
 				 0x00, /* 0-length §10.5.2.21 Mobile Allocation */
 				 /* ETSI TS 44.018 §10.5.2.16 IA Rest Octets */
-				 0xc8, 0x02, 0x7b, 0xa0, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, };
+				 0xc8, 0x02, 0x1b, 0xa0, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, };
 
 	check_imm_ass(tbf, false, GSM_L1_BURST_TYPE_ACCESS_0, res, sizeof(res), "ia_rest_uplink(MBA)");
 }
@@ -537,7 +537,7 @@ void test_immediate_assign_ul1s()
 				 0x23, /* TA */
 				 0x00, /* 0-length §10.5.2.21 Mobile Allocation */
 				 /* ETSI TS 44.018 §10.5.2.16 IA Rest Octets */
-				 0x46, 0xa0, 0x09, 0xe0, 0x17, 0x40, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, };
+				 0x46, 0xa0, 0x08, 0x00, 0x17, 0x40, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, };
 
 	check_imm_ass(tbf, false, GSM_L1_BURST_TYPE_ACCESS_1, res, sizeof(res), "ia_rest_egprs_uplink(SBA)");
 }
diff --git a/tests/types/TypesTest.ok b/tests/types/TypesTest.ok
index d4cc2550..dd7dc4c7 100644
--- a/tests/types/TypesTest.ok
+++ b/tests/types/TypesTest.ok
@@ -9,13 +9,13 @@ show_rbb: IIRRIIIR
 [11] DL Immediate Assignment <ia_rest_downlink>:
 	06 3f 30 0d 23 6d 7f 03 18 23 00 d0 00 00 00 08 17 47 08 0b 5b 2b 2b 
 [11] UL Immediate Assignment <ia_rest_uplink(MBA)>:
-	06 3f 10 0d 23 6d 0d 03 18 23 00 c8 02 7b a0 2b 2b 2b 2b 2b 2b 2b 2b 
+	06 3f 10 0d 23 6d 0d 03 18 23 00 c8 02 1b a0 2b 2b 2b 2b 2b 2b 2b 2b 
 [11] UL Immediate Assignment <ia_rest_uplink(SBA)>:
 	06 3f 10 0d 23 6d 0d 03 18 23 00 c5 d1 08 0b 5b 2b 2b 2b 2b 2b 2b 2b 
 [11] UL Immediate Assignment <ia_rest_egprs_uplink(MBA)>:
 	06 3f 10 0d 23 6d 7f 03 18 23 00 46 97 40 0b 58 2b 2b 2b 2b 2b 2b 2b 
 [11] UL Immediate Assignment <ia_rest_egprs_uplink(SBA)>:
-	06 3f 10 0d 23 6d 7f 03 18 23 00 46 a0 09 e0 17 40 2b 2b 2b 2b 2b 2b 
+	06 3f 10 0d 23 6d 7f 03 18 23 00 46 a0 08 00 17 40 2b 2b 2b 2b 2b 2b 
 assignment reject: 06 3a 10 7f 06 36 14 7f 06 36 14 7f 06 36 14 7f 06 36 14 c0 2b 2b 
 assignment reject: 06 3a 10 70 06 36 14 70 06 36 14 70 06 36 14 70 06 36 14 0b 2b 2b 
 Testing LBS utility...