262 lines
6.8 KiB
C++
262 lines
6.8 KiB
C++
/*
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* Radio device interface with sample rate conversion
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* Written by Thomas Tsou <tom@tsou.cc>
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*
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* Copyright 2011, 2012, 2013 Free Software Foundation, Inc.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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* See the COPYING file in the main directory for details.
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*/
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#include <radioInterface.h>
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#include <Logger.h>
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#include "Resampler.h"
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extern "C" {
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#include "convert.h"
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}
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/* Resampling parameters for 64 MHz clocking */
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#define RESAMP_64M_INRATE 65
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#define RESAMP_64M_OUTRATE 96
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/* Resampling parameters for 100 MHz clocking */
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#define RESAMP_100M_INRATE 52
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#define RESAMP_100M_OUTRATE 75
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/* Universal resampling parameters */
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#define NUMCHUNKS 24
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/*
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* Resampling filter bandwidth scaling factor
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* This narrows the filter cutoff relative to the output bandwidth
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* of the polyphase resampler. At 4 samples-per-symbol using the
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* 2 pulse Laurent GMSK approximation gives us below 0.5 degrees
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* RMS phase error at the resampler output.
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*/
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#define RESAMP_TX4_FILTER 0.45
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static Resampler *upsampler = NULL;
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static Resampler *dnsampler = NULL;
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static int resamp_inrate = 0;
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static int resamp_inchunk = 0;
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static int resamp_outrate = 0;
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static int resamp_outchunk = 0;
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RadioInterfaceResamp::RadioInterfaceResamp(RadioDevice *wRadio,
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int wReceiveOffset,
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size_t sps, size_t chan,
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GSM::Time wStartTime)
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: RadioInterface(wRadio, wReceiveOffset, sps, chan, wStartTime),
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innerSendBuffer(NULL), outerSendBuffer(NULL),
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innerRecvBuffer(NULL), outerRecvBuffer(NULL)
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{
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}
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RadioInterfaceResamp::~RadioInterfaceResamp()
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{
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close();
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}
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void RadioInterfaceResamp::close()
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{
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delete innerSendBuffer;
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delete outerSendBuffer;
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delete innerRecvBuffer;
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delete outerRecvBuffer;
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delete upsampler;
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delete dnsampler;
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innerSendBuffer = NULL;
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outerSendBuffer = NULL;
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innerRecvBuffer = NULL;
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outerRecvBuffer = NULL;
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upsampler = NULL;
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dnsampler = NULL;
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if (sendBuffer.size())
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sendBuffer[0] = NULL;
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if (recvBuffer.size())
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recvBuffer[0] = NULL;
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RadioInterface::close();
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}
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/* Initialize I/O specific objects */
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bool RadioInterfaceResamp::init(int type)
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{
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float cutoff = 1.0f;
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if (mChans != 1) {
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LOG(ALERT) << "Unsupported channel configuration " << mChans;
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return false;
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}
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close();
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sendBuffer.resize(1);
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recvBuffer.resize(1);
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convertSendBuffer.resize(1);
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convertRecvBuffer.resize(1);
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mReceiveFIFO.resize(1);
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switch (type) {
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case RadioDevice::RESAMP_64M:
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resamp_inrate = RESAMP_64M_INRATE;
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resamp_outrate = RESAMP_64M_OUTRATE;
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break;
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case RadioDevice::RESAMP_100M:
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resamp_inrate = RESAMP_100M_INRATE;
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resamp_outrate = RESAMP_100M_OUTRATE;
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break;
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case RadioDevice::NORMAL:
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default:
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LOG(ALERT) << "Invalid device configuration";
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return false;
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}
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resamp_inchunk = resamp_inrate * 4;
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resamp_outchunk = resamp_outrate * 4;
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if (resamp_inchunk * NUMCHUNKS < 157 * mSPSTx * 2) {
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LOG(ALERT) << "Invalid inner chunk size " << resamp_inchunk;
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return false;
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}
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if (mSPSTx == 4)
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cutoff = RESAMP_TX4_FILTER;
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dnsampler = new Resampler(resamp_inrate, resamp_outrate);
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if (!dnsampler->init()) {
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LOG(ALERT) << "Rx resampler failed to initialize";
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return false;
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}
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upsampler = new Resampler(resamp_outrate, resamp_inrate);
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if (!upsampler->init(cutoff)) {
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LOG(ALERT) << "Tx resampler failed to initialize";
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return false;
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}
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/*
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* Allocate high and low rate buffers. The high rate receive
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* buffer and low rate transmit vectors feed into the resampler
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* and requires headroom equivalent to the filter length. Low
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* rate buffers are allocated in the main radio interface code.
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*/
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innerSendBuffer =
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new signalVector(NUMCHUNKS * resamp_inchunk, upsampler->len());
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outerSendBuffer =
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new signalVector(NUMCHUNKS * resamp_outchunk);
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outerRecvBuffer =
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new signalVector(resamp_outchunk, dnsampler->len());
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innerRecvBuffer =
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new signalVector(NUMCHUNKS * resamp_inchunk / mSPSTx);
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convertSendBuffer[0] = new short[outerSendBuffer->size() * 2];
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convertRecvBuffer[0] = new short[outerRecvBuffer->size() * 2];
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sendBuffer[0] = innerSendBuffer;
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recvBuffer[0] = innerRecvBuffer;
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return true;
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}
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/* Receive a timestamped chunk from the device */
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void RadioInterfaceResamp::pullBuffer()
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{
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bool local_underrun;
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int rc, num_recv;
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if (recvCursor > innerRecvBuffer->size() - resamp_inchunk)
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return;
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/* Outer buffer access size is fixed */
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num_recv = mRadio->readSamples(convertRecvBuffer,
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resamp_outchunk,
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&overrun,
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readTimestamp,
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&local_underrun);
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if (num_recv != resamp_outchunk) {
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LOG(ALERT) << "Receive error " << num_recv;
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return;
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}
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convert_short_float((float *) outerRecvBuffer->begin(),
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convertRecvBuffer[0], 2 * resamp_outchunk);
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underrun |= local_underrun;
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readTimestamp += (TIMESTAMP) resamp_outchunk;
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/* Write to the end of the inner receive buffer */
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rc = dnsampler->rotate((float *) outerRecvBuffer->begin(),
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resamp_outchunk,
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(float *) (innerRecvBuffer->begin() + recvCursor),
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resamp_inchunk);
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if (rc < 0) {
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LOG(ALERT) << "Sample rate upsampling error";
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}
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recvCursor += resamp_inchunk;
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}
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/* Send a timestamped chunk to the device */
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void RadioInterfaceResamp::pushBuffer()
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{
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int rc, chunks, num_sent;
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int inner_len, outer_len;
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if (sendCursor < resamp_inchunk)
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return;
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if (sendCursor > innerSendBuffer->size())
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LOG(ALERT) << "Send buffer overflow";
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chunks = sendCursor / resamp_inchunk;
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inner_len = chunks * resamp_inchunk;
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outer_len = chunks * resamp_outchunk;
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/* Always send from the beginning of the buffer */
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rc = upsampler->rotate((float *) innerSendBuffer->begin(), inner_len,
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(float *) outerSendBuffer->begin(), outer_len);
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if (rc < 0) {
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LOG(ALERT) << "Sample rate downsampling error";
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}
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convert_float_short(convertSendBuffer[0],
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(float *) outerSendBuffer->begin(),
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powerScaling, 2 * outer_len);
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num_sent = mRadio->writeSamples(convertSendBuffer,
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outer_len,
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&underrun,
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writeTimestamp);
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if (num_sent != outer_len) {
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LOG(ALERT) << "Transmit error " << num_sent;
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}
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/* Shift remaining samples to beginning of buffer */
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memmove(innerSendBuffer->begin(),
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innerSendBuffer->begin() + inner_len,
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(sendCursor - inner_len) * 2 * sizeof(float));
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writeTimestamp += outer_len;
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sendCursor -= inner_len;
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assert(sendCursor >= 0);
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}
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