iface: Add inner ring-buffer implementation

Two buffers, inner and outer, are used in the transceiver
implementation. The outer buffer interfaces with the device receive
interface to guarantee timestamp aligned and contiguously allocated
sample buffers. The inner buffer absorbs vector size differences between
GSM bursts (156 or 157 samples) and the resampler interface (typically
fixed multiples of 65).

Reimplement the inner buffer with a ring buffer that allows fixed size
segments on the outer (resampler) portion and variable lengths (GSM
side) on the inner side. Compared to the previous stack-like version,
this implementation removes unnecessary copying of buffer contents.

Signed-off-by: Tom Tsou <tom.tsou@ettus.com>

1 files changed, 21 insertions, 26 deletions

diff --git a/Transceiver52M/radioInterfaceDiversity.cpp b/Transceiver52M/radioInterfaceDiversity.cpp
index 8e921b1..b3973e5 100644
--- a/Transceiver52M/radioInterfaceDiversity.cpp
+++ b/Transceiver52M/radioInterfaceDiversity.cpp
@@ -65,14 +65,11 @@ RadioInterfaceDiversity::~RadioInterfaceDiversity()
 void RadioInterfaceDiversity::close()
 {
 	delete outerRecvBuffer;
+	delete dnsampler;
 
+	dnsampler = NULL;
 	outerRecvBuffer = NULL;
 
-	for (size_t i = 0; i < dnsamplers.size(); i++) {
-		delete dnsamplers[i];
-		dnsamplers[i] = NULL;
-	}
-
 	if (recvBuffer.size())
 		recvBuffer[0] = NULL;
 
@@ -98,15 +95,16 @@ bool RadioInterfaceDiversity::setupDiversityChannels()
 		return false;
 	}
 
+	dnsampler = new Resampler(resamp_inrate, resamp_outrate);
+	if (!dnsampler->init()) {
+		LOG(ALERT) << "Rx resampler failed to initialize";
+		return false;
+	}
+
 	/* One Receive buffer and downsampler per diversity channel */
 	for (size_t i = 0; i < mMIMO * mChans; i++) {
-		dnsamplers[i] = new Resampler(resamp_inrate, resamp_outrate);
-		if (!dnsamplers[i]->init()) {
-			LOG(ALERT) << "Rx resampler failed to initialize";
-			return false;
-		}
-
-		recvBuffer[i] = new signalVector(inner_rx_len);
+		recvBuffer[i] = new RadioBuffer(NUMCHUNKS,
+						resamp_inchunk, 0, false);
 	}
 
 	return true;
@@ -115,7 +113,7 @@ bool RadioInterfaceDiversity::setupDiversityChannels()
 /* Initialize I/O specific objects */
 bool RadioInterfaceDiversity::init(int type)
 {
-	int tx_len, outer_rx_len;
+	int outer_rx_len;
 
 	if ((mMIMO != 2) || (mChans != 2)) {
 		LOG(ALERT) << "Unsupported channel configuration " << mChans;
@@ -128,13 +126,11 @@ bool RadioInterfaceDiversity::init(int type)
 	convertSendBuffer.resize(mChans);
 	convertRecvBuffer.resize(mChans);
 	mReceiveFIFO.resize(mChans);
-	dnsamplers.resize(mChans * mMIMO);
 	phases.resize(mChans);
 
 	if (!setupDiversityChannels())
 		return false;
 
-	tx_len = CHUNK * mSPSTx;
 	outer_rx_len = resamp_outchunk;
 
 	for (size_t i = 0; i < mChans; i++) {
@@ -142,11 +138,11 @@ bool RadioInterfaceDiversity::init(int type)
 		convertRecvBuffer[i] = new short[outer_rx_len * 2];
 
 		/* Send buffers (not-resampled) */
-		sendBuffer[i] = new signalVector(tx_len);
-		convertSendBuffer[i] = new short[tx_len * 2];
+		sendBuffer[i] = new RadioBuffer(NUMCHUNKS, CHUNK * mSPSTx, 0, true);
+		convertSendBuffer[i] = new short[CHUNK * mSPSTx * 2];
 	}
 
-	outerRecvBuffer = new signalVector(outer_rx_len, dnsamplers[0]->len());
+	outerRecvBuffer = new signalVector(outer_rx_len, dnsampler->len());
 
 	return true;
 }
@@ -182,7 +178,7 @@ void RadioInterfaceDiversity::pullBuffer()
 	signalVector *shift, *base;
 	float *in, *out, rate = -mFreqSpacing * 2.0 * M_PI / 1.08333333e6;
 
-	if (recvCursor > recvBuffer[0]->size() - resamp_inchunk)
+	if (recvBuffer[0]->getFreeSegments() <= 0)
 		return;
 
 	/* Outer buffer access size is fixed */
@@ -211,10 +207,10 @@ void RadioInterfaceDiversity::pullBuffer()
 		/* Diversity path 1 */
 		base = outerRecvBuffer;
 		in = (float *) base->begin();
-		out = (float *) (recvBuffer[path0]->begin() + recvCursor);
+		out = (float *) recvBuffer[path0]->getWriteSegment();
 
-		rc = dnsamplers[2 * i + 0]->rotate(in, resamp_outchunk,
-						   out, resamp_inchunk);
+		rc = dnsampler->rotate(in, resamp_outchunk,
+				       out, resamp_inchunk);
 		if (rc < 0) {
 			LOG(ALERT) << "Sample rate downsampling error";
 		}
@@ -226,15 +222,15 @@ void RadioInterfaceDiversity::pullBuffer()
 		/* Diversity path 2 */
 		shift = new signalVector(base->size(), base->getStart());
 		in = (float *) shift->begin();
-		out = (float *) (recvBuffer[path1]->begin() + recvCursor);
+		out = (float *) recvBuffer[path1]->getWriteSegment();
 
 		rate = i ? -rate : rate;
 		if (!frequencyShift(shift, base, rate, phases[i], &phases[i])) {
 			LOG(ALERT) << "Frequency shift failed";
 		}
 
-		rc = dnsamplers[2 * i + 1]->rotate(in, resamp_outchunk,
-						   out, resamp_inchunk);
+		rc = dnsampler->rotate(in, resamp_outchunk,
+				       out, resamp_inchunk);
 		if (rc < 0) {
 			LOG(ALERT) << "Sample rate downsampling error";
 		}
@@ -244,5 +240,4 @@ void RadioInterfaceDiversity::pullBuffer()
 
 	underrun |= local_underrun;
 	readTimestamp += (TIMESTAMP) resamp_outchunk;
-	recvCursor += resamp_inchunk;
 }