Add header type 1 support for EGPRS uplink

Function is added to parse the EGPRS header type 1 in uplink tbf path.
along with configuration parameter updation to reflect max mcs in UL

Change-Id: I13c250e2e07377982ac3f29745f3cffd4088552a
Reviewed-on: https://gerrit.osmocom.org/270
Reviewed-by: Harald Welte <laforge@gnumonks.org>
Tested-by: Jenkins Builder

src/bts.h

@@ -41,6 +41,8 @@ extern "C" {
 
 #define LLC_CODEL_DISABLE 0
 #define LLC_CODEL_USE_DEFAULT (-1)
+#define MAX_GPRS_CS 9
+
 
 struct BTS;
 struct GprsMs;
@@ -188,7 +190,7 @@ struct gprs_rlcmac_bts {
 	uint8_t cs_adj_enabled;
 	uint8_t cs_adj_upper_limit;
 	uint8_t cs_adj_lower_limit;
-	struct {int16_t low; int16_t high;} cs_lqual_ranges[4];
+	struct {int16_t low; int16_t high; } cs_lqual_ranges[MAX_GPRS_CS];
 	uint16_t cs_downgrade_threshold; /* downgrade if less packets left (DL) */
 	uint16_t ws_base;
 	uint16_t ws_pdch; /* increase WS by this value per PDCH */

src/decoding.cpp

@@ -357,8 +357,8 @@ int Decoding::rlc_parse_ul_data_header(struct gprs_rlc_data_info *rlc,
 		cur_bit = rlc_parse_ul_data_header_egprs_type_2(rlc, data, cs);
 		break;
 	case GprsCodingScheme::HEADER_EGPRS_DATA_TYPE_1 :
-		/* TODO: Support both header type 1 */
-		/* fall through */
+		cur_bit = rlc_parse_ul_data_header_egprs_type_1(rlc, data, cs);
+		break;
 	default:
 		LOGP(DRLCMACDL, LOGL_ERROR,
 			"Decoding of uplink %s data blocks not yet supported.\n",
@@ -455,6 +455,65 @@ int Decoding::rlc_parse_ul_data_header_egprs_type_2(
 	return cur_bit;
 }
 
+int Decoding::rlc_parse_ul_data_header_egprs_type_1(
+	struct gprs_rlc_data_info *rlc,
+	const uint8_t *data, const GprsCodingScheme &cs)
+{
+	struct gprs_rlc_ul_header_egprs_1 *egprs1;
+	unsigned int e_ti_header, cur_bit = 0, offs;
+	int punct, punct2, with_padding;
+
+	egprs1 = static_cast < struct gprs_rlc_ul_header_egprs_1 * >
+		((void *)data);
+	gprs_rlc_mcs_cps_decode(egprs1->cps, cs, &punct, &punct2,
+		&with_padding);
+	gprs_rlc_data_info_init_ul(rlc, cs, with_padding);
+
+	rlc->r      = egprs1->r;
+	rlc->si     = egprs1->si;
+	rlc->tfi    = (egprs1->tfi_a << 0)  | (egprs1->tfi_b << 2);
+	rlc->cps    = egprs1->cps;
+	rlc->rsb    = egprs1->rsb;
+	rlc->num_data_blocks = 2;
+	rlc->block_info[0].cv  = egprs1->cv;
+	rlc->block_info[0].pi  = egprs1->pi;
+	rlc->block_info[0].bsn =
+			(egprs1->bsn1_a << 0) | (egprs1->bsn1_b << 5);
+
+	cur_bit += rlc->data_offs_bits[0] - 2;
+	offs = rlc->data_offs_bits[0] / 8;
+	OSMO_ASSERT(rlc->data_offs_bits[0] % 8 == 0);
+
+	e_ti_header = data[offs - 1] >> 6;
+	rlc->block_info[0].e   = (e_ti_header & 0x01);
+	rlc->block_info[0].ti  = !!(e_ti_header & 0x02);
+	cur_bit += 2;
+
+	rlc->block_info[1].cv  = egprs1->cv;
+	rlc->block_info[1].pi  = egprs1->pi;
+	rlc->block_info[1].bsn = rlc->block_info[0].bsn +
+		((egprs1->bsn2_a << 0) | (egprs1->bsn2_b << 2));
+	rlc->block_info[1].bsn = rlc->block_info[1].bsn &  (RLC_EGPRS_SNS - 1);
+
+	if ((rlc->block_info[1].bsn != rlc->block_info[0].bsn) &&
+			(rlc->block_info[0].cv == 0))
+		rlc->block_info[0].cv = 1;
+
+	cur_bit = rlc->data_offs_bits[1] - 2;
+
+	offs = rlc->data_offs_bits[1] / 8;
+	OSMO_ASSERT(rlc->data_offs_bits[1] % 8 == 2);
+
+	e_ti_header = (data[offs] & (0x03));
+	rlc->block_info[1].e   = (e_ti_header & 0x01);
+	rlc->block_info[1].ti  = !!(e_ti_header & 0x02);
+	cur_bit += 2;
+	/* skip data area */
+	cur_bit += cs.maxDataBlockBytes() * 8;
+
+	return cur_bit;
+}
+
 int Decoding::rlc_parse_ul_data_header_gprs(struct gprs_rlc_data_info *rlc,
 	const uint8_t *data, const GprsCodingScheme &cs)
 {

src/decoding.h

@@ -52,6 +52,10 @@ public:
 		struct gprs_rlc_data_info *rlc,
 		const uint8_t *data,
 		const GprsCodingScheme &cs);
+	static int rlc_parse_ul_data_header_egprs_type_1(
+		struct gprs_rlc_data_info *rlc,
+		const uint8_t *data,
+		const GprsCodingScheme &cs);
 	static int rlc_parse_ul_data_header_gprs(
 		struct gprs_rlc_data_info *rlc,
 		const uint8_t *data,

src/encoding.cpp

@@ -610,8 +610,9 @@ static void write_packet_uplink_ack_egprs(
 	struct gprs_rlcmac_ul_tbf *tbf, bool is_final)
 {
 	bitvec_write_field(dest, wp, 0, 2); // fixed 00
-	bitvec_write_field(dest, wp, 2, 4); // CHANNEL_CODING_COMMAND: MCS-3
-	// bitvec_write_field(dest, wp, tbf->current_cs() - 1, 4); // CHANNEL_CODING_COMMAND
+	/* CHANNEL_CODING_COMMAND */
+	bitvec_write_field(dest, wp,
+		tbf->current_cs().to_num() - 1, 4);
 	bitvec_write_field(dest, wp, 0, 1); // 0: no RESEGMENT (nyi)
 	bitvec_write_field(dest, wp, 1, 1); // PRE_EMPTIVE_TRANSMISSION, TODO: This resembles GPRS, change it?
 	bitvec_write_field(dest, wp, 0, 1); // 0: no PRR_RETRANSMISSION_REQUEST, TODO: clarify

src/gprs_ms.cpp

@@ -632,8 +632,8 @@ void GprsMs::update_cs_ul(const pcu_l1_meas *meas)
 		high = bts_data->cs_lqual_ranges[current_cs_num-1].high;
 	} else if (m_current_cs_ul.isEgprs()) {
 		/* TODO, use separate table */
-		if (current_cs_num > 4)
-			current_cs_num = 4;
+		if (current_cs_num > MAX_GPRS_CS)
+			current_cs_num = MAX_GPRS_CS;
 		low  = bts_data->cs_lqual_ranges[current_cs_num-1].low;
 		high = bts_data->cs_lqual_ranges[current_cs_num-1].high;
 	} else {

src/pcu_main.cpp

@@ -189,8 +189,8 @@ int main(int argc, char *argv[])
 	bts->cs_adj_lower_limit = 10; /* Increase CS if the error rate is below */
 	bts->max_cs_ul = 4;
 	bts->max_cs_dl = 4;
-	bts->max_mcs_ul = 4;
-	bts->max_mcs_dl = 4;
+	bts->max_mcs_ul = MAX_GPRS_CS;
+	bts->max_mcs_dl = MAX_GPRS_CS;
 	/* CS-1 to CS-4 */
 	bts->cs_lqual_ranges[0].low = -256;
 	bts->cs_lqual_ranges[0].high = 6;