spectrum_sm125.h

/*
 * This file is a part of the project "fbgsense", which is released under MIT license.
 * Copyright (c) 2022 Daniel Múèka, Masaryk University, Faculty of Informatics
 * See file LICENSE or visit https://opensource.org/licenses/MIT for full license details.
 */
 
#pragma once
 
#include "interrogator/constants/sm125.h"
#include "spectrum/spectrum.h"
 
// disable padding, so we can overlay this structure over raw tcp data.
#pragma pack(1)
struct sm125_spectrum_subheader_t
{
    uint32_t m_subHeaderSize;
    uint32_t m_minWavelength;
    uint32_t m_increment;
    uint32_t m_sampleCount;
    uint32_t m_index;
    int16_t  m_intensities[sm125_samples];
};
 
struct sm125_spectrum_header_t
{
    uint32_t m_headerSize;
    uint32_t m_protocolVersion;
    uint32_t m_channelCount;
    uint32_t m_reserved;
    uint32_t m_counter;
    sm125_spectrum_subheader_t m_channels[spectrum_max_channels];
};
#pragma pack()
 
// we are exploiting the fact that fft works best on factorizable sample counts.
// unfortunately, sm125 gives out a prime number of samples. thus, the easiest way to
// make the computation faster is to subtract one sample.
// this change makes the computation ~4x faster.
 
class spectrum_sm125 : public spectrum
{
    bool m_initialized = false;
public:
    spectrum_sm125();
 
    void update(uint8_t* data);
};