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#pragma once
#include "hardware/adc.h"
#include <array>
#include <cstdint>
#include <algorithm>
namespace
{
std::array<std::uint8_t, 2> previous_samples { 0xffu, 0xffu };
std::uint8_t
raw_to_midi(std::uint16_t new_raw, std::uint8_t previous_midi)
{
std::int32_t constexpr interval = 4096 / 128;
std::int32_t constexpr hysteresis = 3;
std::int32_t const lower = std::max(0l, static_cast<std::int32_t>(previous_midi) * interval - hysteresis);
std::int32_t const upper = std::min(4095l, lower + interval - 1l + hysteresis);
std::uint8_t const new_midi = static_cast<uint8_t>(new_raw * 128u / 4096u);
return new_raw > upper || new_raw < lower ? new_midi : previous_midi;
}
}
namespace adc
{
struct Sample
{
std::uint16_t raw {0};
std::uint8_t midi {0};
bool changed {false};
};
void
init()
{
adc_init();
adc_gpio_init(26);
adc_gpio_init(27);
}
std::array<Sample, 2>
get_samples()
{
std::array<Sample, 2> samples {};
for (std::size_t i = 0; i < samples.size(); i++)
{
adc_select_input(i);
auto & sample = samples[i];
sample.raw = adc_read();
sample.midi = raw_to_midi(sample.raw, sample.midi);
sample.changed = samples[i].midi != previous_samples[i];
previous_samples[i] = sample.midi;
}
return samples;
}
}
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