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sdrangel/plugins/samplesource/rtlsdr/rtlsdrthread.cpp

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///////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2012 maintech GmbH, Otto-Hahn-Str. 15, 97204 Hoechberg, Germany //
// written by Christian Daniel //
// //
// This program is free software; you can redistribute it and/or modify //
// it under the terms of the GNU General Public License as published by //
// the Free Software Foundation as version 3 of the License, or //
// //
// This program is distributed in the hope that it will be useful, //
// but WITHOUT ANY WARRANTY; without even the implied warranty of //
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
// GNU General Public License V3 for more details. //
// //
// You should have received a copy of the GNU General Public License //
// along with this program. If not, see <http://www.gnu.org/licenses/>. //
///////////////////////////////////////////////////////////////////////////////////
#include <stdio.h>
#include <errno.h>
#include "rtlsdrthread.h"
#include "dsp/samplefifo.h"
#define BLOCKSIZE 16384
RTLSDRThread::RTLSDRThread(rtlsdr_dev_t* dev, SampleFifo* sampleFifo, QObject* parent) :
QThread(parent),
m_running(false),
m_dev(dev),
m_convertBuffer(BLOCKSIZE),
m_sampleFifo(sampleFifo),
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m_decimation(2)
{
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m_localdecimation = 0;
}
RTLSDRThread::~RTLSDRThread()
{
stopWork();
}
void RTLSDRThread::startWork()
{
m_startWaitMutex.lock();
start();
while(!m_running)
m_startWaiter.wait(&m_startWaitMutex, 100);
m_startWaitMutex.unlock();
}
void RTLSDRThread::stopWork()
{
m_running = false;
wait();
}
void RTLSDRThread::setDecimation(int decimation)
{
m_decimation = decimation;
}
void RTLSDRThread::run()
{
int res;
m_running = true;
m_startWaiter.wakeAll();
while(m_running) {
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if((res = rtlsdr_read_async(m_dev, &RTLSDRThread::callbackHelper, this, 32, BLOCKSIZE)) < 0) {
qCritical("RTLSDRThread: async error: %s", strerror(errno));
break;
}
}
m_running = false;
}
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void RTLSDRThread::decimate2(SampleVector::iterator* it, const quint8* buf, qint32 len)
{
qint16 xreal, yimag;
for (int pos = 0; pos < len + 7; pos += 8) {
xreal = buf[pos+0] - buf[pos+3];
yimag = buf[pos+1] + buf[pos+2] - 255;
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Sample s( xreal << 3, yimag << 3 );
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**it = s;
(*it)++;
xreal = buf[pos+7] - buf[pos+4];
yimag = 255 - buf[pos+5] - buf[pos+6];
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Sample t( xreal << 3, yimag << 3 );
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**it = t;
(*it)++;
}
}
void RTLSDRThread::decimate4(SampleVector::iterator* it, const quint8* buf, qint32 len)
{
qint16 xreal, yimag;
for (int pos = 0; pos < len + 7; pos += 8) {
xreal = buf[pos+0] - buf[pos+3] + buf[pos+7] - buf[pos+4];
yimag = buf[pos+1] - buf[pos+5] + buf[pos+2] - buf[pos+6];
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Sample s( xreal << 3, yimag << 3 );
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**it = s;
(*it)++;
}
}
void RTLSDRThread::decimate8(SampleVector::iterator* it, const quint8* buf, qint32 len)
{
qint16 xreal, yimag;
for (int pos = 0; pos < len + 15; pos += 8) {
xreal = buf[pos+0] - buf[pos+3] + buf[pos+7] - buf[pos+4];
yimag = buf[pos+1] - buf[pos+5] + buf[pos+2] - buf[pos+6];
pos += 8;
xreal += buf[pos+0] - buf[pos+3] + buf[pos+7] - buf[pos+4];
yimag += buf[pos+1] - buf[pos+5] + buf[pos+2] - buf[pos+6];
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Sample s( xreal << 3, yimag << 3 );
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**it = s;
(*it)++;
}
}
void RTLSDRThread::decimate16(SampleVector::iterator* it, const quint8* buf, qint32 len)
{
// Offset tuning: 4x downsample and rotate, then
// downsample 4x more. [ rotate: 0, 1, -3, 2, -4, -5, 7, -6]
qint16 xreal, yimag;
for (int step = 0; step < len - 31; step +=32) {
xreal = yimag = 0;
for (int pos = step; pos < step + 32; pos += 8) {
xreal += buf[pos+0] - buf[pos+3] + buf[pos+7] - buf[pos+4];
yimag += buf[pos+1] - buf[pos+5] + buf[pos+2] - buf[pos+6];
}
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Sample s( xreal << 3, yimag << 3 );
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**it = s;
(*it)++;
}
}
void RTLSDRThread::callback(const quint8* buf, qint32 len)
{
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qint16 xreal, yimag, phase;
SampleVector::iterator it = m_convertBuffer.begin();
int decimationFactor[] = {1, 1, 1, 2, 4, 0};
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if (++m_localdecimation < decimationFactor[m_decimation]) return;
m_localdecimation = 0;
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switch(4 - m_decimation) {
case 0: // 1:1 = no decimation
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// just rotation
phase = -(1<<2);
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for (int pos = 0; pos < len + 3; pos += 4) {
phase *= -1;
xreal = phase * (2 * buf[pos+0] - 255);
yimag = phase * (2 * buf[pos+1] - 255);
*it++ = Sample(xreal, yimag);
xreal = phase * (255 - 2 * buf[pos+3]);
yimag = phase * (2 * buf[pos+2] - 255);
*it++ = Sample(xreal, yimag);
}
break;
case 1: // 1:2
decimate2(&it, buf, len);
break;
case 2: // 1:4
decimate4(&it, buf, len);
break;
case 3: // 1:8
decimate8(&it, buf, len);
break;
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default:
case 4: // 1:16
decimate16(&it, buf, len);
break;
}
m_sampleFifo->write(m_convertBuffer.begin(), it);
if(!m_running)
rtlsdr_cancel_async(m_dev);
}
void RTLSDRThread::callbackHelper(unsigned char* buf, uint32_t len, void* ctx)
{
RTLSDRThread* thread = (RTLSDRThread*)ctx;
thread->callback(buf, len);
}