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//
// Copyright 2010-2012,2014 Ettus Research LLC
// Copyright 2018 Ettus Research, a National Instruments Company
// Copyright 2019 Ettus Research, A National Instruments Brand
//
// SPDX-License-Identifier: GPL-3.0-or-later
//
#include <cmath>
#include <complex>
#include <stdexcept>
#include <string>
#include <vector>
static const size_t wave_table_len = 8192;
class wave_table_class
{
public:
wave_table_class(const std::string& wave_type, const float ampl)
: _wave_table(wave_table_len)
{
// compute real wave table with 1.0 amplitude
std::vector<float> real_wave_table(wave_table_len);
if (wave_type == "CONST") {
for (size_t i = 0; i < wave_table_len; i++)
real_wave_table[i] = 1.0f;
} else if (wave_type == "SQUARE") {
for (size_t i = 0; i < wave_table_len; i++)
real_wave_table[i] = (i < wave_table_len / 2) ? 0.0f : 1.0f;
} else if (wave_type == "RAMP") {
for (size_t i = 0; i < wave_table_len; i++)
real_wave_table[i] = 2.0f * i / (wave_table_len - 1) - 1.0f;
} else if (wave_type == "SINE") {
static const double tau = 2 * std::acos(-1.0);
for (size_t i = 0; i < wave_table_len; i++) {
real_wave_table[i] =
static_cast<float>(std::sin((tau * i) / wave_table_len));
}
} else {
throw std::runtime_error("unknown waveform type: " + wave_type);
}
// compute i and q pairs with 90% offset and scale to amplitude
for (size_t i = 0; i < wave_table_len; i++) {
const size_t q = (i + (3 * wave_table_len) / 4) % wave_table_len;
_wave_table[i] =
std::complex<float>(ampl * real_wave_table[i], ampl * real_wave_table[q]);
}
}
inline std::complex<float> operator()(const size_t index) const
{
return _wave_table[index % wave_table_len];
}
private:
std::vector<std::complex<float>> _wave_table;
};
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