50 lines
1.4 KiB
C++
50 lines
1.4 KiB
C++
/**
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* @addtogroup table_3d
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* @{
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*/
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#pragma once
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#include <stdint.h>
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#include "src/libdivide/libdivide.h"
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/** @brief Byte type. This is not defined in any C or C++ standard header. */
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typedef uint8_t byte;
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/** @brief Represents a 16-bit value as a byte. Useful for I/O.
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*
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* Often we need to deal internally with values that fit in 16-bits but do
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* not require much accuracy. E.g. table axes in RPM. For these values we can
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* save storage space (EEPROM) by scaling to/from 8-bits using a fixed divisor.
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*/
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class int16_byte
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{
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public:
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/**
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* @brief Construct
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*
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* @param factor The factor to multiply when converting \c byte to \c int16_t
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* @param divider The factor to divide by when converting \c int16_t to \c byte
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*
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* \c divider could be computed from \c factor, but including it as a parameter
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* allows callers to create \c factor instances at compile time.
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*/
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constexpr int16_byte(uint8_t factor, const libdivide::libdivide_s16_t ÷r)
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: _factor(factor), _divider(divider)
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{
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}
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/** @brief Convert to a \c byte */
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inline byte to_byte(int16_t value) const { return _factor==1 ? value : _factor==2 ? value>>1 : (byte)libdivide::libdivide_s16_do(value, &_divider); }
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/** @brief Convert from a \c byte */
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inline int16_t from_byte( byte in ) const { return (int16_t)in * _factor; }
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private:
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uint8_t _factor;
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libdivide::libdivide_s16_t _divider;
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};
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/** @} */
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