units.h

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#pragma once
 
#include <stdint.h>
 
template <typename TUser,
          typename TRaw>
struct conversionFactor {
    uint16_t scale;    
    int16_t translate; 
 
    constexpr TUser toUser(TRaw raw) const {
        return ((TUser)raw + (TUser)translate) * (TUser)scale;
    }
 
    constexpr TRaw toRaw(TUser user) const {
        // Since all conversionFactor instances are constexpr, compiler will heavily
        // optimize this. E.g. removing division or replacing with shift & multiply.
        return scaleUser(user) - (TRaw)translate;
    }
private:
    constexpr TRaw scaleUser(TUser user) const {
        // Since all conversionFactor instances are constexpr, compiler will heavily
        // optimize this. E.g. removing division or replacing with shift & multiply.
        return user / (TUser)scale;
    }
};
 
static constexpr conversionFactor<uint16_t, uint8_t> RPM_COARSE = { .scale=100U, .translate=0U };
 
static constexpr conversionFactor<uint16_t, uint8_t> RPM_MEDIUM = { .scale=10U, .translate=0U };
 
static constexpr conversionFactor<uint16_t, uint8_t> RPM_FINE = { .scale=5U, .translate=0U };
 
static constexpr conversionFactor<uint32_t, uint8_t> TIME_TENTH_MILLIS = { .scale=10000U, .translate=0U };
 
static constexpr conversionFactor<uint16_t, uint8_t> TIME_TWENTY_MILLIS = { .scale=5U, .translate=0U };
 
static constexpr conversionFactor<uint16_t, uint8_t> TIME_TEN_MILLIS = { .scale=100U, .translate=0U };
 
static constexpr conversionFactor<uint16_t, uint8_t> MAP = { .scale=2U, .translate=0U };
 
static constexpr conversionFactor<int16_t, uint8_t> MAP_DOT = { .scale=10U, .translate=0U };
 
static constexpr conversionFactor<int16_t, uint8_t> TPS_DOT = { .scale=10U, .translate=0U };
 
static constexpr conversionFactor<uint16_t, uint8_t> CRANKING_ENRICHMENT = { .scale=5U, .translate=0U };
 
static constexpr conversionFactor<int8_t, uint8_t> IGNITION_ADVANCE_LARGE = { .scale=1U, .translate=-40 };
 
static constexpr conversionFactor<int8_t, uint8_t> IGNITION_ADVANCE_SMALL = { .scale=1U, .translate=-15 };
 
static constexpr conversionFactor<int16_t, uint8_t> TEMPERATURE = { .scale=1U, .translate=-40 };
 
 
static inline constexpr uint8_t temperatureAddOffset(int16_t temp) {
    // TODO: remove this function, replace with TEMPERATURE.toRaw()
    return TEMPERATURE.toRaw(temp);
}
 
static inline constexpr int16_t temperatureRemoveOffset(uint8_t temp) {
    // TODO: remove this function, replace with TEMPERATURE.toUser()
    return TEMPERATURE.toUser(temp);
}