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, 9 insertions, 0 deletions

diff --git a/Transceiver52M/signalVector.cpp b/Transceiver52M/signalVector.cpp
index 4b4099e..798a3c7 100644
--- a/Transceiver52M/signalVector.cpp
+++ b/Transceiver52M/signalVector.cpp
@@ -50,6 +50,15 @@ size_t signalVector::getStart() const
 	return mStart - mData;
 }
 
+size_t signalVector::updateHistory()
+{
+	size_t num = getStart();
+
+	memmove(mData, mStart + this->size() - num, num * sizeof(complex));
+
+	return num;
+}
+
 Symmetry signalVector::getSymmetry() const
 {
 	return symmetry;