tbf: Move the llc handling into the tbf (from the bts)

This will be moved to a LLC class in the future but after this
we can make the sns/ws private now and have little to update
outside the tbf.

1 files changed, 194 insertions, 0 deletions

diff --git a/src/tbf.cpp b/src/tbf.cpp
index 356984f5..e571f703 100644
--- a/src/tbf.cpp
+++ b/src/tbf.cpp
@@ -26,6 +26,7 @@
 #include <gprs_rlcmac.h>
 #include <gprs_debug.h>
 #include <gprs_bssgp_pcu.h>
+#include <decoding.h>
 
 extern "C" {
 #include <osmocom/core/msgb.h>
@@ -37,6 +38,9 @@ extern "C" {
 
 /* After sending these frames, we poll for ack/nack. */
 #define POLL_ACK_AFTER_FRAMES 20
+/* After receiving these frames, we send ack/nack. */
+#define SEND_ACK_AFTER_FRAMES 20
+
 
 /* If acknowledgement to downlink assignment should be polled */
 #define POLLING_ASSIGNMENT_DL 1
@@ -1650,6 +1654,196 @@ void gprs_rlcmac_tbf::update_tlli(uint32_t tlli)
 	m_tlli = tlli;
 }
 
+int gprs_rlcmac_tbf::rcv_data_block_acknowledged(const uint8_t *data, size_t len, int8_t rssi)
+{
+	uint16_t mod_sns, mod_sns_half, offset_v_q, offset_v_r, index;
+	struct rlc_ul_header *rh = (struct rlc_ul_header *)data;
+	int rc;
+
+	this->state_flags |= (1 << GPRS_RLCMAC_FLAG_UL_DATA);
+
+	LOGP(DRLCMACUL, LOGL_DEBUG, "UL DATA TFI=%d received (V(Q)=%d .. "
+		"V(R)=%d)\n", rh->tfi, this->dir.ul.v_q, this->dir.ul.v_r);
+
+	/* process RSSI */
+	gprs_rlcmac_rssi(this, rssi);
+
+	/* get TLLI */
+	if (!this->is_tlli_valid()) {
+		struct gprs_rlcmac_tbf *dl_tbf, *ul_tbf;
+		uint32_t tlli;
+
+		/* no TLLI yet */
+		if (!rh->ti) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "UL DATA TFI=%d without "
+				"TLLI, but no TLLI received yet\n", rh->tfi);
+			return 0;
+		}
+		rc = Decoding::tlli_from_ul_data(data, len, &tlli);
+		if (rc) {
+			bts->decode_error();
+			LOGP(DRLCMACUL, LOGL_NOTICE, "Failed to decode TLLI "
+				"of UL DATA TFI=%d.\n", rh->tfi);
+			return 0;
+		}
+		this->update_tlli(tlli);
+		LOGP(DRLCMACUL, LOGL_INFO, "Decoded premier TLLI=0x%08x of "
+			"UL DATA TFI=%d.\n", this->tlli(), rh->tfi);
+		if ((dl_tbf = bts->tbf_by_tlli(this->tlli(), GPRS_RLCMAC_DL_TBF))) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "Got RACH from "
+				"TLLI=0x%08x while %s still exists. "
+				"Killing pending DL TBF\n", this->tlli(),
+				tbf_name(dl_tbf));
+			tbf_free(dl_tbf);
+		}
+		/* tbf_by_tlli will not find your TLLI, because it is not
+		 * yet marked valid */
+		if ((ul_tbf = bts->tbf_by_tlli(this->tlli(), GPRS_RLCMAC_UL_TBF))) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "Got RACH from "
+				"TLLI=0x%08x while %s still exists. "
+				"Killing pending UL TBF\n", this->tlli(),
+				tbf_name(ul_tbf));
+			tbf_free(ul_tbf);
+		}
+		/* mark TLLI valid now */
+		this->tlli_mark_valid();
+		/* store current timing advance */
+		bts->timing_advance()->remember(this->tlli(), this->ta);
+	/* already have TLLI, but we stille get another one */
+	} else if (rh->ti) {
+		uint32_t tlli;
+		rc = Decoding::tlli_from_ul_data(data, len, &tlli);
+		if (rc) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "Failed to decode TLLI "
+				"of UL DATA TFI=%d.\n", rh->tfi);
+			return 0;
+		}
+		if (tlli != this->tlli()) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "TLLI mismatch on UL "
+				"DATA TFI=%d. (Ignoring due to contention "
+				"resolution)\n", rh->tfi);
+			return 0;
+		}
+	}
+
+	mod_sns = this->sns - 1;
+	mod_sns_half = (this->sns >> 1) - 1;
+
+	/* restart T3169 */
+	tbf_timer_start(this, 3169, bts_data()->t3169, 0);
+
+	/* Increment RX-counter */
+	this->dir.ul.rx_counter++;
+
+	/* current block relative to lowest unreceived block */
+	offset_v_q = (rh->bsn - this->dir.ul.v_q) & mod_sns;
+	/* If out of window (may happen if blocks below V(Q) are received
+	 * again. */
+	if (offset_v_q >= this->ws) {
+		LOGP(DRLCMACUL, LOGL_DEBUG, "- BSN %d out of window "
+			"%d..%d (it's normal)\n", rh->bsn, this->dir.ul.v_q,
+			(this->dir.ul.v_q + this->ws - 1) & mod_sns);
+		return 0;
+	}
+	/* Write block to buffer and set receive state array. */
+	index = rh->bsn & mod_sns_half; /* memory index of block */
+	memcpy(this->rlc_block[index], data, len); /* Copy block. */
+	this->rlc_block_len[index] = len;
+	this->dir.ul.v_n[index] = 'R'; /* Mark received block. */
+	LOGP(DRLCMACUL, LOGL_DEBUG, "- BSN %d storing in window (%d..%d)\n",
+		rh->bsn, this->dir.ul.v_q,
+		(this->dir.ul.v_q + this->ws - 1) & mod_sns);
+	/* Raise V(R) to highest received sequence number not received. */
+	offset_v_r = (rh->bsn + 1 - this->dir.ul.v_r) & mod_sns;
+	if (offset_v_r < (this->sns >> 1)) { /* Positive offset, so raise. */
+		while (offset_v_r--) {
+			if (offset_v_r) /* all except the received block */
+				this->dir.ul.v_n[this->dir.ul.v_r & mod_sns_half]
+					= 'N'; /* Mark block as not received */
+			this->dir.ul.v_r = (this->dir.ul.v_r + 1) & mod_sns;
+				/* Inc V(R). */
+		}
+		LOGP(DRLCMACUL, LOGL_DEBUG, "- Raising V(R) to %d\n",
+			this->dir.ul.v_r);
+	}
+
+	#warning "Move to TBF and remove the index side effect.."
+	/* Raise V(Q) if possible, and retrieve LLC frames from blocks.
+	 * This is looped until there is a gap (non received block) or
+	 * the window is empty.*/
+	while (this->dir.ul.v_q != this->dir.ul.v_r && this->dir.ul.v_n[
+			(index = this->dir.ul.v_q & mod_sns_half)] == 'R') {
+		LOGP(DRLCMACUL, LOGL_DEBUG, "- Taking block %d out, raising "
+			"V(Q) to %d\n", this->dir.ul.v_q,
+			(this->dir.ul.v_q + 1) & mod_sns);
+		/* get LLC data from block */
+		this->assemble_forward_llc(this->rlc_block[index], this->rlc_block_len[index]);
+		/* raise V(Q), because block already received */
+		this->dir.ul.v_q = (this->dir.ul.v_q + 1) & mod_sns;
+	}
+
+	/* Check CV of last frame in buffer */
+	if (this->state_is(GPRS_RLCMAC_FLOW) /* still in flow state */
+	 && this->dir.ul.v_q == this->dir.ul.v_r) { /* if complete */
+		struct rlc_ul_header *last_rh = (struct rlc_ul_header *)
+			this->rlc_block[(this->dir.ul.v_r - 1) & mod_sns_half];
+		LOGP(DRLCMACUL, LOGL_DEBUG, "- No gaps in received block, "
+			"last block: BSN=%d CV=%d\n", last_rh->bsn,
+			last_rh->cv);
+		if (last_rh->cv == 0) {
+			LOGP(DRLCMACUL, LOGL_DEBUG, "- Finished with UL "
+				"TBF\n");
+			tbf_new_state(this, GPRS_RLCMAC_FINISHED);
+			/* Reset N3103 counter. */
+			this->dir.ul.n3103 = 0;
+		}
+	}
+
+	/* If TLLI is included or if we received half of the window, we send
+	 * an ack/nack */
+	if (rh->si || rh->ti || this->state_is(GPRS_RLCMAC_FINISHED)
+	 || (this->dir.ul.rx_counter % SEND_ACK_AFTER_FRAMES) == 0) {
+		if (rh->si) {
+			LOGP(DRLCMACUL, LOGL_NOTICE, "- Scheduling Ack/Nack, "
+				"because MS is stalled.\n");
+		}
+		if (rh->ti) {
+			LOGP(DRLCMACUL, LOGL_DEBUG, "- Scheduling Ack/Nack, "
+				"because TLLI is included.\n");
+		}
+		if (this->state_is(GPRS_RLCMAC_FINISHED)) {
+			LOGP(DRLCMACUL, LOGL_DEBUG, "- Scheduling Ack/Nack, "
+				"because last block has CV==0.\n");
+		}
+		if ((this->dir.ul.rx_counter % SEND_ACK_AFTER_FRAMES) == 0) {
+			LOGP(DRLCMACUL, LOGL_DEBUG, "- Scheduling Ack/Nack, "
+				"because %d frames received.\n",
+				SEND_ACK_AFTER_FRAMES);
+		}
+		if (this->ul_ack_state == GPRS_RLCMAC_UL_ACK_NONE) {
+#ifdef DEBUG_DIAGRAM
+			if (rh->si)
+				debug_diagram(bts->bts, this->diag, "sched UL-ACK stall");
+			if (rh->ti)
+				debug_diagram(bts->bts, this->diag, "sched UL-ACK TLLI");
+			if (this->state_is(GPRS_RLCMAC_FINISHED))
+				debug_diagram(bts->bts, this->diag, "sched UL-ACK CV==0");
+			if ((this->dir.ul.rx_counter % SEND_ACK_AFTER_FRAMES) == 0)
+				debug_diagram(bts->bts, this->diag, "sched UL-ACK n=%d",
+					this->dir.ul.rx_counter);
+#endif
+			/* trigger sending at next RTS */
+			this->ul_ack_state = GPRS_RLCMAC_UL_ACK_SEND_ACK;
+		} else {
+			/* already triggered */
+			LOGP(DRLCMACUL, LOGL_DEBUG, "-  Sending Ack/Nack is "
+				"already triggered, don't schedule!\n");
+		}
+	}
+
+	return 0;
+}
+
 const char *tbf_name(gprs_rlcmac_tbf *tbf)
 {
 	static char buf[40];