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adding (completely untested) software resampler option to transmitter #2

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adding (completely untested) software resampler option to transmitter #2

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32 changes: 30 additions & 2 deletions share/crts/plugins/Filters/tx.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
#include <errno.h>
#include <string>
#include <uhd/usrp/multi_usrp.hpp>
#include <liquid/liquid.h>

#include "crts/debug.h"
#include "crts/Filter.hpp"
Expand Down Expand Up @@ -48,6 +49,9 @@ class Tx : public CRTSFilter
// above.
size_t numTxChannels;

// Arbitrary rate resampler to allow dynamic bandwidth adjustment
resamp_crcf resamp;
std::complex<float> * buffer_resamp; // TODO: use std lib container instead?

////////////////////////////////////////////////////////////////
// Inline helper/wrapper utilities to set and get parameters
Expand Down Expand Up @@ -77,6 +81,16 @@ class Tx : public CRTSFilter
return true;
};

bool setRateResamp(const double &r, size_t chan=0)
{
if (r < 0.01 || r > 1.0) {
WARN("software resampling rate must be in [0.01, 1]");
return false;
}
resamp_crcf_set_rate(resamp, (float)r);
return true;
};

bool setGain(const double &g, size_t chan=0)
{
// TODO: check return?
Expand Down Expand Up @@ -299,6 +313,10 @@ Tx::Tx(int argc, const char **argv):
}
}

// instantiate arbitrary rate resampler and appropriate output buffer
resamp = resamp_crcf_create(1.0f, 12, 0.495f, 60.0f, 64);
buffer_resamp = new std::complex<float>[2048];

DSPEW();
}

Expand All @@ -311,6 +329,10 @@ Tx::~Tx(void)
// Or should stop() be the place to cleanup most of the
// libuhd stuff.

// destroy arbitrary rate resampler and free output buffer
resamp_crcf_destroy(resamp);
delete [] buffer_resamp;

DSPEW();
}

Expand Down Expand Up @@ -398,10 +420,16 @@ void Tx::input(void *buffer, size_t len, uint32_t channelNum)

size_t numFrames = len/(numTxChannels*sizeof(std::complex<float>));

// resample result; note, because the resampler is restricted to always decimate,
// the size of the output buffer only needs to be at least the same size as the input
// TODO: increase output buffer size appropriately
unsigned int numFramesResamp;
resamp_crcf_execute(resamp, buffer, numFrames, buffer_resamp, &numFramesResamp);

// TODO: check for error here, and retry?
size_t ret = tx_stream->send(buffer, numFrames, metadata);
size_t ret = tx_stream->send(buffer_resamp, numFramesResamp, metadata);

if(ret != numFrames)
if(ret != numFramesResamp)
WARN("wrote only %zu frames not %zu", ret, numFrames);

// Mark the number of bytes to advance the input buffer which is not
Expand Down