tbf/rlc: Big change and move the window handling out to the rlc

The send and receive window is now managed by an external object.
There are some issues that can only be solved with C++11 but it
is progres and removes some of the spaghetti code. For GPRS the
sns and ws is hardcoded. Move that into the window code.

1 files changed, 53 insertions, 65 deletions

diff --git a/src/tbf.cpp b/src/tbf.cpp
index a75fe4a1..eca72296 100644
--- a/src/tbf.cpp
+++ b/src/tbf.cpp
@@ -520,8 +520,6 @@ struct gprs_rlcmac_tbf *tbf_alloc(struct gprs_rlcmac_bts *bts,
 	tbf->m_tfi = tfi;
 	tbf->trx = &bts->trx[trx];
 	tbf->ms_class = ms_class;
-	tbf->m_ws = 64;
-	tbf->m_sns = 128;
 	/* select algorithm */
 	rc = bts->alloc_algorithm(bts, old_tbf, tbf, bts->alloc_algorithm_curst,
 		single_slot);
@@ -836,20 +834,17 @@ int gprs_rlcmac_tbf::assemble_forward_llc(const gprs_rlc_data *_data)
  */
 struct msgb *gprs_rlcmac_tbf::create_dl_acked_block(uint32_t fn, uint8_t ts)
 {
-	const uint16_t mod_sns = m_sns - 1;
-	const uint16_t mod_sns_half = (m_sns >> 1) - 1;
-
 	LOGP(DRLCMACDL, LOGL_DEBUG, "%s downlink (V(A)==%d .. "
-		"V(S)==%d)\n", tbf_name(this), dir.dl.v_a, dir.dl.v_s);
+		"V(S)==%d)\n", tbf_name(this),
+		dir.dl.window.v_a(), dir.dl.window.v_s());
 
 do_resend:
 	/* check if there is a block with negative acknowledgement */
-	int resend_bsn = dir.dl.v_b.resend_needed(dir.dl.v_a, dir.dl.v_s,
-							mod_sns, mod_sns_half);
+	int resend_bsn = dir.dl.v_b.resend_needed(dir.dl.window);
 	if (resend_bsn >= 0) {
 		LOGP(DRLCMACDL, LOGL_DEBUG, "- Resending BSN %d\n", resend_bsn);
 
-		uint16_t index = resend_bsn & mod_sns_half;
+		uint16_t index = resend_bsn & dir.dl.window.mod_sns_half();
 		/* re-send block with negative aknowlegement */
 		dir.dl.v_b.mark_unacked(index);
 		bts->rlc_resent();
@@ -862,12 +857,12 @@ do_resend:
 		if (state_is(GPRS_RLCMAC_FINISHED)) {
 			LOGP(DRLCMACDL, LOGL_DEBUG, "- Restarting at BSN %d, "
 				"because all blocks have been transmitted.\n",
-					dir.dl.v_a);
+					dir.dl.window.v_a());
 			bts->rlc_restarted();
 		} else {
 			LOGP(DRLCMACDL, LOGL_NOTICE, "- Restarting at BSN %d, "
 				"because all window is stalled.\n",
-					dir.dl.v_a);
+					dir.dl.window.v_a());
 			bts->rlc_stalled();
 		}
 		/* If V(S) == V(A) and finished state, we would have received
@@ -876,18 +871,17 @@ do_resend:
 		 * from MS. But in this case we did not receive the final ack
 		 * indication from MS. This should never happen if MS works
 		 * correctly. */
-		if (dir.dl.v_s == dir.dl.v_a) {
+		if (dir.dl.window.window_empty()) {
 			LOGP(DRLCMACDL, LOGL_DEBUG, "- MS acked all blocks, "
 				"so we re-transmit final block!\n");
 			/* we just send final block again */
-			int16_t index = (dir.dl.v_s - 1) & mod_sns_half;
+			int16_t index = dir.dl.window.v_s_mod_half(-1);
 			bts->rlc_resent();
 			return create_dl_acked_block(fn, ts, index, false);
 		}
 		
 		/* cycle through all unacked blocks */
-		int resend = dir.dl.v_b.mark_for_resend(dir.dl.v_a, dir.dl.v_s,
-							mod_sns, mod_sns_half);
+		int resend = dir.dl.v_b.mark_for_resend(dir.dl.window);
 
 		/* At this point there should be at least one unacked block
 		 * to be resent. If not, this is an software error. */
@@ -896,7 +890,7 @@ do_resend:
 				"There are no unacknowledged blocks, but V(A) "
 				" != V(S). PLEASE FIX!\n");
 			/* we just send final block again */
-			int16_t index = (dir.dl.v_s - 1) & mod_sns_half;
+			int16_t index = dir.dl.window.v_s_mod_half(-1);
 			bts->rlc_resent();
 			return create_dl_acked_block(fn, ts, index, false);
 		}
@@ -916,11 +910,8 @@ struct msgb *gprs_rlcmac_tbf::create_new_bsn(const uint32_t fn, const uint8_t ts
 	uint16_t space, chunk;
 	bool first_fin_ack = false;
 
-	const uint16_t mod_sns = m_sns - 1;
-	const uint16_t mod_sns_half = (m_sns >> 1) - 1;
-
 	LOGP(DRLCMACDL, LOGL_DEBUG, "- Sending new block at BSN %d\n",
-		dir.dl.v_s);
+		dir.dl.window.v_s());
 
 #warning "Selection of the CS doesn't belong here"
 	if (cs == 0) {
@@ -934,7 +925,7 @@ struct msgb *gprs_rlcmac_tbf::create_new_bsn(const uint32_t fn, const uint8_t ts
 	const uint8_t block_data_len = gprs_rlcmac_cs[cs].block_data;
 
 	/* now we still have untransmitted LLC data, so we fill mac block */
-	index = dir.dl.v_s & mod_sns_half;
+	index = dir.dl.window.v_s_mod_half(0);
 	data = m_rlc.blocks[index].prepare(block_data_len);
 
 	rh = (struct rlc_dl_header *)data;
@@ -944,7 +935,7 @@ struct msgb *gprs_rlcmac_tbf::create_new_bsn(const uint32_t fn, const uint8_t ts
 	rh->pr = 0; /* FIXME: power reduction */
 	rh->tfi = m_tfi; /* TFI */
 	rh->fbi = 0; /* Final Block Indicator, set late, if true */
-	rh->bsn = dir.dl.v_s; /* Block Sequence Number */
+	rh->bsn = dir.dl.window.v_s(); /* Block Sequence Number */
 	rh->e = 0; /* Extension bit, maybe set later */
 	e_pointer = data + 2; /* points to E of current chunk */
 	data += sizeof(*rh);
@@ -1070,7 +1061,7 @@ struct msgb *gprs_rlcmac_tbf::create_new_bsn(const uint32_t fn, const uint8_t ts
 	m_rlc.blocks[index].len = block_length;
 	/* raise send state and set ack state array */
 	dir.dl.v_b.mark_unacked(index);
-	dir.dl.v_s = (dir.dl.v_s + 1) & mod_sns; /* inc send state */
+	dir.dl.window.increment_send();
 
 	return create_dl_acked_block(fn, ts, index, first_fin_ack);
 }
@@ -1365,10 +1356,9 @@ int gprs_rlcmac_tbf::update_window(const uint8_t ssn, const uint8_t *rbb)
 {
 	int16_t dist; /* must be signed */
 	uint16_t lost = 0, received = 0;
-	const uint16_t mod_sns = m_sns - 1;
-	const uint16_t mod_sns_half = (m_sns >> 1) - 1;
 	char show_rbb[65];
 	char show_v_b[RLC_MAX_SNS + 1];
+	const uint16_t mod_sns = dir.dl.window.mod_sns();
 
 	Decoding::extract_rbb(rbb, show_rbb);
 	/* show received array in debug (bit 64..1) */
@@ -1378,9 +1368,9 @@ int gprs_rlcmac_tbf::update_window(const uint8_t ssn, const uint8_t *rbb)
 
 	/* apply received array to receive state (SSN-64..SSN-1) */
 	/* calculate distance of ssn from V(S) */
-	dist = (dir.dl.v_s - ssn) & mod_sns;
+	dist = (dir.dl.window.v_s() - ssn) & mod_sns;
 	/* check if distance is less than distance V(A)..V(S) */
-	if (dist >= ((dir.dl.v_s - dir.dl.v_a) & mod_sns)) {
+	if (dist >= dir.dl.window.distance()) {
 		/* this might happpen, if the downlink assignment
 		 * was not received by ms and the ack refers
 		 * to previous TBF
@@ -1391,25 +1381,24 @@ int gprs_rlcmac_tbf::update_window(const uint8_t ssn, const uint8_t *rbb)
 		return 1; /* indicate to free TBF */
 	}
 
-	dir.dl.v_b.update(bts, show_rbb, ssn, dir.dl.v_a,
-			mod_sns, mod_sns_half, &lost, &received);
+	dir.dl.v_b.update(bts, show_rbb, ssn, dir.dl.window,
+			&lost, &received);
 
 	/* report lost and received packets */
 	gprs_rlcmac_received_lost(this, received, lost);
 
 	/* raise V(A), if possible */
-	dir.dl.v_a += dir.dl.v_b.move_window(dir.dl.v_a, dir.dl.v_s,
-						mod_sns, mod_sns_half) & mod_sns;
+	dir.dl.window.raise(dir.dl.v_b.move_window(dir.dl.window));
 
 	/* show receive state array in debug (V(A)..V(S)-1) */
-	dir.dl.v_b.state(show_v_b, dir.dl.v_a, dir.dl.v_s,
-				mod_sns, mod_sns_half);
+	dir.dl.v_b.state(show_v_b, dir.dl.window);
 	LOGP(DRLCMACDL, LOGL_DEBUG, "- V(B): (V(A)=%d)\"%s\""
 		"(V(S)-1=%d)  A=Acked N=Nacked U=Unacked "
-		"X=Resend-Unacked I=Invalid\n", dir.dl.v_a, show_v_b,
-		(dir.dl.v_s - 1) & mod_sns);
+		"X=Resend-Unacked I=Invalid\n",
+		dir.dl.window.v_a(), show_v_b,
+		dir.dl.window.v_s_mod(-1));
 
-	if (state_is(GPRS_RLCMAC_FINISHED) && dir.dl.v_s == dir.dl.v_a) {
+	if (state_is(GPRS_RLCMAC_FINISHED) && dir.dl.window.window_empty()) {
 		LOGP(DRLCMACDL, LOGL_NOTICE, "Received acknowledge of "
 			"all blocks, but without final ack "
 			"inidcation (don't worry)\n");
@@ -1420,15 +1409,12 @@ int gprs_rlcmac_tbf::update_window(const uint8_t ssn, const uint8_t *rbb)
 
 int gprs_rlcmac_tbf::maybe_start_new_window()
 {
-	const uint16_t mod_sns = m_sns - 1;
-	const uint16_t mod_sns_half = (m_sns >> 1) - 1;
 	struct msgb *msg;
 	uint16_t received;
 
 	LOGP(DRLCMACDL, LOGL_DEBUG, "- Final ACK received.\n");
 	/* range V(A)..V(S)-1 */
-	received = dir.dl.v_b.count_unacked(dir.dl.v_a, dir.dl.v_s,
-						mod_sns, mod_sns_half);
+	received = dir.dl.v_b.count_unacked(dir.dl.window);
 
 	/* report all outstanding packets as received */
 	gprs_rlcmac_received_lost(this, received, 0);
@@ -1534,14 +1520,19 @@ void gprs_rlcmac_tbf::update_tlli(uint32_t 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;
+	uint16_t offset_v_q, offset_v_r, index;
 	struct rlc_ul_header *rh = (struct rlc_ul_header *)data;
 	int rc;
 
+	const uint16_t mod_sns = dir.ul.window.mod_sns();
+	const uint16_t mod_sns_half = dir.ul.window.mod_sns_half();
+	const uint16_t ws = dir.ul.window.ws();
+
 	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);
+		"V(R)=%d)\n", rh->tfi, this->dir.ul.window.v_q(),
+		this->dir.ul.window.v_r());
 
 	/* process RSSI */
 	gprs_rlcmac_rssi(this, rssi);
@@ -1604,9 +1595,6 @@ int gprs_rlcmac_tbf::rcv_data_block_acknowledged(const uint8_t *data, size_t len
 		}
 	}
 
-	mod_sns = m_sns - 1;
-	mod_sns_half = (m_sns >> 1) - 1;
-
 	/* restart T3169 */
 	tbf_timer_start(this, 3169, bts_data()->t3169, 0);
 
@@ -1614,13 +1602,14 @@ int gprs_rlcmac_tbf::rcv_data_block_acknowledged(const uint8_t *data, size_t len
 	this->dir.ul.rx_counter++;
 
 	/* current block relative to lowest unreceived block */
-	offset_v_q = (rh->bsn - this->dir.ul.v_q) & mod_sns;
+	offset_v_q = (rh->bsn - this->dir.ul.window.v_q()) & mod_sns;
 	/* If out of window (may happen if blocks below V(Q) are received
 	 * again. */
-	if (offset_v_q >= m_ws) {
+	if (offset_v_q >= dir.ul.window.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 + m_ws - 1) & mod_sns);
+			"%d..%d (it's normal)\n", rh->bsn,
+			dir.ul.window.v_q(),
+			(dir.ul.window.v_q() + ws - 1) & mod_sns);
 		return 0;
 	}
 	/* Write block to buffer and set receive state array. */
@@ -1629,42 +1618,42 @@ int gprs_rlcmac_tbf::rcv_data_block_acknowledged(const uint8_t *data, size_t len
 	m_rlc.blocks[index].len = 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 + m_ws - 1) & mod_sns);
+		rh->bsn, dir.ul.window.v_q(),
+		(dir.ul.window.v_q() + 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 < (m_sns >> 1)) { /* Positive offset, so raise. */
+	offset_v_r = (rh->bsn + 1 - dir.ul.window.v_r()) & mod_sns;
+	if (offset_v_r < (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]
+				dir.ul.v_n[dir.ul.window.v_r() & mod_sns_half]
 					= 'N'; /* Mark block as not received */
-			this->dir.ul.v_r = (this->dir.ul.v_r + 1) & mod_sns;
+			this->dir.ul.window.raise(1);
 				/* Inc V(R). */
 		}
 		LOGP(DRLCMACUL, LOGL_DEBUG, "- Raising V(R) to %d\n",
-			this->dir.ul.v_r);
+			this->dir.ul.window.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') {
+	while (this->dir.ul.window.v_q() != this->dir.ul.window.v_r() && this->dir.ul.v_n[
+			(index = this->dir.ul.window.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);
+			"V(Q) to %d\n", this->dir.ul.window.v_q(),
+			(this->dir.ul.window.v_q() + 1) & mod_sns);
 		/* get LLC data from block */
 		this->assemble_forward_llc(&m_rlc.blocks[index]);
 		/* raise V(Q), because block already received */
-		this->dir.ul.v_q = (this->dir.ul.v_q + 1) & mod_sns;
+		this->dir.ul.window.increment_q(1);
 	}
 
 	/* 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 */
+	 && this->dir.ul.window.v_q() == this->dir.ul.window.v_r()) { /* if complete */
 		struct rlc_ul_header *last_rh = (struct rlc_ul_header *)
-			m_rlc.blocks[(this->dir.ul.v_r - 1) & mod_sns_half].block;
+			m_rlc.blocks[(this->dir.ul.window.v_r() - 1) & mod_sns_half].block;
 		LOGP(DRLCMACUL, LOGL_DEBUG, "- No gaps in received block, "
 			"last block: BSN=%d CV=%d\n", last_rh->bsn,
 			last_rh->cv);
@@ -1773,6 +1762,5 @@ void gprs_rlcmac_tbf::reuse_tbf(const uint8_t *data, const uint16_t len)
 
 bool gprs_rlcmac_tbf::dl_window_stalled() const
 {
-	const uint16_t mod_sns = m_sns - 1;
-	return ((dir.dl.v_s - dir.dl.v_a) & mod_sns) == m_ws;
+	return dir.dl.window.window_stalled();
 }