Update the function immediate assignment for EGPRS

Encode the EGPRS fields of immediate assignment message in uplink
when EGPRS PACKET CHANNEL REQUEST (11 bit RACH) is received.
The series of patches for 11 bit RACH are dependent on libosmocore
and osmo-bts patches for 11 bit RACH.

Change-Id: Ie5e309156e5dbbb6add74a1b4d257c4ee2332e52

3 files changed, 85 insertions, 12 deletions

diff --git a/src/bts.cpp b/src/bts.cpp
index 015bf9f6..73ec1f77 100644
--- a/src/bts.cpp
+++ b/src/bts.cpp
@@ -556,7 +556,7 @@ int BTS::rcv_rach(uint16_t ra, uint32_t Fn, int16_t qta, uint8_t is_11bit,
 	plen = Encoding::write_immediate_assignment(
 		tbf, immediate_assignment, 0, ra, Fn, ta,
 		m_bts.trx[trx_no].arfcn, ts_no, tsc, usf, 0, sb_fn,
-		m_bts.alpha, m_bts.gamma, -1);
+		m_bts.alpha, m_bts.gamma, -1, burst_type, sb);
 
 	if (plen >= 0) {
 		pcu_l1if_tx_agch(immediate_assignment, plen);
diff --git a/src/encoding.cpp b/src/encoding.cpp
index 41e0d105..7d3fa144 100644
--- a/src/encoding.cpp
+++ b/src/encoding.cpp
@@ -147,11 +147,71 @@ static int write_ia_rest_egprs_uplink(
 	gprs_rlcmac_ul_tbf *tbf,
 	bitvec * dest, unsigned& wp,
 	uint8_t usf, uint32_t fn,
-	uint8_t alpha, uint8_t gamma, int8_t ta_idx)
+	uint8_t alpha, uint8_t gamma, int8_t ta_idx,
+	enum ph_burst_type burst_type, uint16_t ra)
 {
-	LOGP(DRLCMACUL, LOGL_ERROR,
-		"EGPRS Packet Uplink Assignment is not yet implemented\n");
-	return -EINVAL;
+	unsigned int ws_enc = 0;
+	uint8_t extended_ra = 0;
+
+	extended_ra = (ra & 0x1F);
+
+	bitvec_write_field(dest, wp, 1, 2);    /* LH */
+	bitvec_write_field(dest, wp, 0, 2);    /* 0 EGPRS Uplink Assignment */
+	bitvec_write_field(dest, wp, extended_ra, 5);    /* Extended RA */
+	bitvec_write_field(dest, wp, 0, 1);    /* Access technology Request */
+
+	if (tbf == NULL) {
+
+		bitvec_write_field(dest, wp, 0, 1); /* multiblock allocation */
+
+		if (alpha) {
+			bitvec_write_field(dest, wp, 0x1, 1); /* ALPHA =yes */
+			bitvec_write_field(dest, wp, alpha, 4); /* ALPHA */
+		} else {
+			bitvec_write_field(dest, wp, 0x0, 1); /* ALPHA = no */
+		}
+
+		bitvec_write_field(dest, wp, gamma, 5); /* GAMMA power contrl */
+		bitvec_write_field(dest, wp, (fn / (26 * 51)) % 32, 5);/* T1' */
+		bitvec_write_field(dest, wp, fn % 51, 6);              /* T3 */
+		bitvec_write_field(dest, wp, fn % 26, 5);              /* T2 */
+		bitvec_write_field(dest, wp, 0, 2); /* Radio block allocation */
+
+		bitvec_write_field(dest, wp, 0, 1);
+
+	} else {
+
+		ws_enc = (tbf->m_window.ws() - 64) / 32;
+
+		bitvec_write_field(dest, wp, 1, 1);     /* single block alloc */
+		bitvec_write_field(dest, wp, tbf->tfi(), 5);/* TFI assignment */
+		bitvec_write_field(dest, wp, 0, 1);     /* polling bit */
+		bitvec_write_field(dest, wp, 0, 1);     /* constant */
+		bitvec_write_field(dest, wp, usf, 3);   /* USF bit */
+		bitvec_write_field(dest, wp, 0, 1);     /* USF granularity */
+		bitvec_write_field(dest, wp, 0, 1);     /* P0 */
+		/* MCS */
+		bitvec_write_field(dest, wp, tbf->current_cs().to_num()-1, 4);
+		/* tlli channel block */
+		bitvec_write_field(dest, wp, tbf->tlli(), 1);
+		bitvec_write_field(dest, wp, 0, 1);   /* BEP period present */
+		bitvec_write_field(dest, wp, 0, 1);   /* resegmentation */
+		bitvec_write_field(dest, wp, ws_enc, 5);/* egprs window_size */
+
+		if (alpha) {
+			bitvec_write_field(dest, wp, 0x1, 1);   /* ALPHA =yes */
+			bitvec_write_field(dest, wp, alpha, 4); /* ALPHA */
+		} else {
+			bitvec_write_field(dest, wp, 0x0, 1);   /* ALPHA = no */
+		}
+
+		bitvec_write_field(dest, wp, gamma, 5); /* GAMMA power contrl */
+		bitvec_write_field(dest, wp, 0, 1); /* TIMING_ADVANCE_INDEX */
+		bitvec_write_field(dest, wp, 0, 1); /* TBF_STARTING_TIME_FLAG */
+		bitvec_write_field(dest, wp, 0, 1); /* NULL */
+	}
+
+	return 0;
 }
 
 /*
@@ -160,10 +220,10 @@ static int write_ia_rest_egprs_uplink(
  */
 int Encoding::write_immediate_assignment(
 	struct gprs_rlcmac_tbf *tbf,
-	bitvec * dest, uint8_t downlink, uint8_t ra,
+	bitvec * dest, uint8_t downlink, uint16_t ra,
 	uint32_t ref_fn, uint8_t ta, uint16_t arfcn, uint8_t ts, uint8_t tsc,
 	uint8_t usf, uint8_t polling, uint32_t fn, uint8_t alpha,
-	uint8_t gamma, int8_t ta_idx)
+	uint8_t gamma, int8_t ta_idx, enum ph_burst_type burst_type, uint8_t sb)
 {
 	unsigned wp = 0;
 	int plen;
@@ -189,7 +249,13 @@ int Encoding::write_immediate_assignment(
 	bitvec_write_field(dest, wp,arfcn,10); // ARFCN
 
 	//10.5.2.30 Request Reference
-	bitvec_write_field(dest, wp,ra,8);                    // RA
+	if (((burst_type == GSM_L1_BURST_TYPE_ACCESS_1) ||
+		(burst_type == GSM_L1_BURST_TYPE_ACCESS_2))) {
+		bitvec_write_field(dest, wp, 0x7f, 8);  /* RACH value */
+	} else {
+		bitvec_write_field(dest, wp, ra, 8);	/* RACH value */
+	}
+
 	bitvec_write_field(dest, wp,(ref_fn / (26 * 51)) % 32,5); // T1'
 	bitvec_write_field(dest, wp,ref_fn % 51,6);               // T3
 	bitvec_write_field(dest, wp,ref_fn % 26,5);               // T2
@@ -213,10 +279,11 @@ int Encoding::write_immediate_assignment(
 		rc = write_ia_rest_downlink(as_dl_tbf(tbf), dest, wp,
 					    polling, gsm48_ta_is_valid(ta), fn,
 			alpha, gamma, ta_idx);
-	else if (as_ul_tbf(tbf) && as_ul_tbf(tbf)->is_egprs_enabled())
+	else if (((burst_type == GSM_L1_BURST_TYPE_ACCESS_1) ||
+			(burst_type == GSM_L1_BURST_TYPE_ACCESS_2)))
 		rc = write_ia_rest_egprs_uplink(as_ul_tbf(tbf), dest, wp,
 			usf, fn,
-			alpha, gamma, ta_idx);
+			alpha, gamma, ta_idx, burst_type, ra);
 	else
 		rc = write_ia_rest_uplink(as_ul_tbf(tbf), dest, wp,
 			usf, fn,
diff --git a/src/encoding.h b/src/encoding.h
index 710de788..69f8cdc9 100644
--- a/src/encoding.h
+++ b/src/encoding.h
@@ -23,6 +23,9 @@
 #include <stdint.h>
 #include <gsm_rlcmac.h>
 #include <gprs_coding_scheme.h>
+extern "C" {
+#include <osmocom/gsm/l1sap.h>
+}
 
 struct gprs_rlcmac_bts;
 struct gprs_rlcmac_tbf;
@@ -40,11 +43,14 @@ class Encoding {
 public:
 	static int write_immediate_assignment(
 			struct gprs_rlcmac_tbf *tbf,
-			bitvec * dest, uint8_t downlink, uint8_t ra,
+			bitvec * dest, uint8_t downlink, uint16_t ra,
 			uint32_t ref_fn, uint8_t ta, uint16_t arfcn, uint8_t ts,
 			uint8_t tsc, uint8_t usf, uint8_t polling,
 			uint32_t fn, uint8_t alpha, uint8_t gamma,
-			int8_t ta_idx);
+			int8_t ta_idx,
+			enum ph_burst_type burst_type =
+				GSM_L1_BURST_TYPE_ACCESS_0,
+			uint8_t sb = 1);
 
 	static void write_packet_uplink_assignment(
 			struct gprs_rlcmac_bts *bts,