uhd: Avoid reallocation of buffers every read

Buffer size is based on num of chans and rxBuffer size is based on num
of chans and rx_spp, and both are available and set during open(), so no
need to waste time allocating and freeing them everytime we read from
the device.

Change-Id: I8c881c9c303c80f323825d85a924d74b76d2ce47

2 files changed, 10 insertions, 15 deletions

diff --git a/Transceiver52M/device/uhd/UHDDevice.cpp b/Transceiver52M/device/uhd/UHDDevice.cpp
index 34ffd57..6214666 100644
--- a/Transceiver52M/device/uhd/UHDDevice.cpp
+++ b/Transceiver52M/device/uhd/UHDDevice.cpp
@@ -516,6 +516,11 @@ int uhd_device::open(const std::string &args, int ref, bool swap_channels)
 	for (size_t i = 0; i < rx_buffers.size(); i++)
 		rx_buffers[i] = new smpl_buf(buf_len, rx_rate);
 
+	// Create vector buffer
+	pkt_bufs = std::vector<std::vector<short> >(chans, std::vector<short>(2 * rx_spp));
+	for (size_t i = 0; i < pkt_bufs.size(); i++)
+		pkt_ptrs.push_back(&pkt_bufs[i].front());
+
 	// Initialize and shadow gain values
 	init_gains();
 
@@ -549,13 +554,6 @@ bool uhd_device::flush_recv(size_t num_pkts)
 	size_t num_smpls;
 	float timeout = UHD_RESTART_TIMEOUT;
 
-	std::vector<std::vector<short> >
-		pkt_bufs(chans, std::vector<short>(2 * rx_spp));
-
-	std::vector<short *> pkt_ptrs;
-	for (size_t i = 0; i < pkt_bufs.size(); i++)
-		pkt_ptrs.push_back(&pkt_bufs[i].front());
-
 	ts_initial = 0;
 	while (!ts_initial || (num_pkts-- > 0)) {
 		num_smpls = rx_stream->recv(pkt_ptrs, rx_spp, md,
@@ -720,14 +718,6 @@ int uhd_device::readSamples(std::vector<short *> &bufs, int len, bool *overrun,
 		return 0;
 	}
 
-	// Create vector buffer
-	std::vector<std::vector<short> >
-		pkt_bufs(chans, std::vector<short>(2 * rx_spp));
-
-	std::vector<short *> pkt_ptrs;
-	for (size_t i = 0; i < pkt_bufs.size(); i++)
-		pkt_ptrs.push_back(&pkt_bufs[i].front());
-
 	// Receive samples from the usrp until we have enough
 	while (rx_buffers[0]->avail_smpls(timestamp) < len) {
 		thread_enable_cancel(false);
diff --git a/Transceiver52M/device/uhd/UHDDevice.h b/Transceiver52M/device/uhd/UHDDevice.h
index f5d0b33..05a5914 100644
--- a/Transceiver52M/device/uhd/UHDDevice.h
+++ b/Transceiver52M/device/uhd/UHDDevice.h
@@ -152,6 +152,11 @@ private:
 
 	TIMESTAMP ts_initial, ts_offset;
 	std::vector<smpl_buf *> rx_buffers;
+	/* Sample buffers used to receive samples from UHD: */
+	std::vector<std::vector<short> > pkt_bufs;
+	/* Used to call UHD API: Buffer pointer of each elem in pkt_ptrs will
+	   point to corresponding buffer of vector pkt_bufs. */
+	std::vector<short *> pkt_ptrs;
 
 	void init_gains();
 	void set_channels(bool swap);