rlc: Make the RLC types only operate on the BSN

The code has an internal optimization to only use window_size
space. This means that the caller needed to know that only half
of the size was used. Change the API to work on the BSN and do
the mapping internally. The compiler should have plenty of
opportunity to propagate the constant(s) but this has not been
verified.

1 files changed, 20 insertions, 25 deletions

diff --git a/src/tbf.cpp b/src/tbf.cpp
index cc8effa2..3f4da560 100644
--- a/src/tbf.cpp
+++ b/src/tbf.cpp
@@ -839,12 +839,10 @@ do_resend:
 	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 & dir.dl.window.mod_sns_half();
 		/* re-send block with negative aknowlegement */
-		dir.dl.v_b.mark_unacked(index);
+		dir.dl.v_b.mark_unacked(resend_bsn);
 		bts->rlc_resent();
-		return create_dl_acked_block(fn, ts, index, false);
+		return create_dl_acked_block(fn, ts, resend_bsn, false);
 	}
 
 	/* if the window has stalled, or transfer is complete,
@@ -871,7 +869,7 @@ do_resend:
 			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.window.v_s_mod_half(-1);
+			int16_t index = dir.dl.window.v_s_mod(-1);
 			bts->rlc_resent();
 			return create_dl_acked_block(fn, ts, index, false);
 		}
@@ -886,8 +884,7 @@ 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.window.v_s_mod_half(-1);
-			bts->rlc_resent();
+			int16_t index = dir.dl.window.v_s_mod(-1);
 			return create_dl_acked_block(fn, ts, index, false);
 		}
 		goto do_resend;
@@ -901,10 +898,11 @@ struct msgb *gprs_rlcmac_tbf::create_new_bsn(const uint32_t fn, const uint8_t ts
 	struct rlc_dl_header *rh;
 	struct rlc_li_field *li;
 	struct msgb *msg;
-	uint16_t index;
 	uint8_t *delimiter, *data, *e_pointer;
 	uint16_t space, chunk;
+	gprs_rlc_data *rlc_data;
 	bool first_fin_ack = false;
+	const uint16_t bsn = dir.dl.window.v_s();
 
 	LOGP(DRLCMACDL, LOGL_DEBUG, "- Sending new block at BSN %d\n",
 		dir.dl.window.v_s());
@@ -921,8 +919,8 @@ 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.window.v_s_mod_half(0);
-	data = m_rlc.blocks[index].prepare(block_data_len);
+	rlc_data = m_rlc.block(bsn);
+	data = rlc_data->prepare(block_data_len);
 
 	rh = (struct rlc_dl_header *)data;
 	rh->pt = 0; /* Data Block */
@@ -931,7 +929,7 @@ 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.window.v_s(); /* Block Sequence Number */
+	rh->bsn = bsn; /* Block Sequence Number */
 	rh->e = 0; /* Extension bit, maybe set later */
 	e_pointer = data + 2; /* points to E of current chunk */
 	data += sizeof(*rh);
@@ -1052,14 +1050,14 @@ struct msgb *gprs_rlcmac_tbf::create_new_bsn(const uint32_t fn, const uint8_t ts
 		break;
 	}
 	LOGP(DRLCMACDL, LOGL_DEBUG, "data block: %s\n",
-		osmo_hexdump(m_rlc.blocks[index].block, block_length));
+		osmo_hexdump(rlc_data->block, block_length));
 #warning "move this up?"
-	m_rlc.blocks[index].len = block_length;
+	rlc_data->len = block_length;
 	/* raise send state and set ack state array */
-	dir.dl.v_b.mark_unacked(index);
+	dir.dl.v_b.mark_unacked(bsn);
 	dir.dl.window.increment_send();
 
-	return create_dl_acked_block(fn, ts, index, first_fin_ack);
+	return create_dl_acked_block(fn, ts, bsn, first_fin_ack);
 }
 
 struct msgb *gprs_rlcmac_tbf::create_dl_acked_block(
@@ -1072,8 +1070,8 @@ struct msgb *gprs_rlcmac_tbf::create_dl_acked_block(
 	uint8_t len;
 
 	/* get data and header from current block */
-	data = m_rlc.blocks[index].block;
-	len = m_rlc.blocks[index].len;
+	data = m_rlc.block(index)->block;
+	len = m_rlc.block(index)->len;
 	rh = (struct rlc_dl_header *)data;
 
 	/* Clear Polling, if still set in history buffer */
@@ -1553,12 +1551,10 @@ int gprs_rlcmac_tbf::extract_tlli(const uint8_t *data, const size_t len)
 
 int gprs_rlcmac_tbf::rcv_data_block_acknowledged(const uint8_t *data, size_t len, int8_t rssi)
 {
-	uint16_t 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);
@@ -1607,13 +1603,12 @@ int gprs_rlcmac_tbf::rcv_data_block_acknowledged(const uint8_t *data, size_t len
 	}
 
 	/* Write block to buffer and set receive state array. */
-	index = rh->bsn & mod_sns_half; /* memory index of block */
-	m_rlc.blocks[index].put_data(data, len);
+	m_rlc.block(rh->bsn)->put_data(data, len);
 	LOGP(DRLCMACUL, LOGL_DEBUG, "- BSN %d storing in window (%d..%d)\n",
 		rh->bsn, dir.ul.window.v_q(),
 		(dir.ul.window.v_q() + ws - 1) & mod_sns);
 
-	dir.ul.v_n.mark_received(index);
+	dir.ul.v_n.mark_received(rh->bsn);
 	dir.ul.window.raise_v_r(rh->bsn, &dir.ul.v_n);
 
 	/* Raise V(Q) if possible, and retrieve LLC frames from blocks.
@@ -1624,15 +1619,15 @@ int gprs_rlcmac_tbf::rcv_data_block_acknowledged(const uint8_t *data, size_t len
 
 	/* Retrieve LLC frames from blocks that are ready */
 	for (uint16_t i = 0; i < count; ++i) {
-		uint16_t index = (v_q_beg + i) & mod_sns_half;
-		assemble_forward_llc(&m_rlc.blocks[index]);
+		uint16_t index = (v_q_beg + i) & mod_sns;
+		assemble_forward_llc(m_rlc.block(index));
 	}
 
 	/* Check CV of last frame in buffer */
 	if (this->state_is(GPRS_RLCMAC_FLOW) /* still in flow state */
 	 && 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.window.v_r() - 1) & mod_sns_half].block;
+			m_rlc.block((dir.ul.window.v_r() - 1) & mod_sns)->block;
 		LOGP(DRLCMACUL, LOGL_DEBUG, "- No gaps in received block, "
 			"last block: BSN=%d CV=%d\n", last_rh->bsn,
 			last_rh->cv);