fixed_point.h

/*
MIT License
 
Copyright (c) 2026 Coreware Limited
 
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
 
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
 
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
#pragma once
 
#include <cassert>
#include <cstdint>
#include <cstddef>
#include <string>
 
#include "../../core/utilities/converters.h"
 
namespace llfix
{
 
class FixedPoint
{
public:
 
    void set_decimal_points(uint32_t n)
    {
        assert(n>0 && n <= MAX_ALLOWED_DECIMAL_POINTS);
        m_decimal_points = n;
    }
 
    uint32_t get_decimal_points() const
    {
        return m_decimal_points;
    }
 
    void set_raw_value(uint64_t raw_value)
    {
        m_raw_value = raw_value;
    }
 
    uint64_t get_raw_value() const
    {
        return m_raw_value;
    }
 
    void set_from_chars(const char* buffer, std::size_t length)
    {
        assert(m_decimal_points >0 && m_decimal_points <= MAX_ALLOWED_DECIMAL_POINTS);
        assert(buffer != nullptr);
        assert(length > 0);
 
        char temp_buffer[MAX_DIGITS];
        std::size_t temp_buffer_length = 0;
 
        std::size_t length_fractal_part = 0;
        bool in_fractal_part = false;
 
        for (std::size_t i = 0; i < length; i++)
        {
            char current_char = buffer[i];
 
            if (current_char != '.')
            {
                assert(temp_buffer_length < MAX_DIGITS);
 
                temp_buffer[temp_buffer_length] = current_char;
                temp_buffer_length++;
 
                if (in_fractal_part )
                {
                    length_fractal_part++;
                }
            }
            else
            {
                in_fractal_part = true;
            }
        }
 
        assert(length_fractal_part <= m_decimal_points && length_fractal_part <= MAX_ALLOWED_DECIMAL_POINTS);
 
        uint64_t scale = POWERS_OF_TEN[m_decimal_points];
        scale /= static_cast<uint64_t>(POWERS_OF_TEN[length_fractal_part]);
 
        auto value = Converters::chars_to_unsigned_int<uint64_t>(temp_buffer, temp_buffer_length);
 
        m_raw_value = static_cast<uint64_t>(value * scale);
    }
 
    std::size_t to_chars(char* buffer) const
    {
        assert(m_decimal_points >0 && m_decimal_points <= MAX_ALLOWED_DECIMAL_POINTS);
        assert(buffer != nullptr);
 
        char temp_buffer[MAX_DIGITS];
        Converters::unsigned_int_to_chars<uint64_t>(m_raw_value, temp_buffer);
 
        std::size_t length = Converters::get_chars_length_of_uint64_t(m_raw_value);
 
        assert(length > 0);
 
        if (length > m_decimal_points)
        {
            assert(length + 1 < MAX_DIGITS);
 
            std::size_t integer_part_length = length - m_decimal_points;
 
            // Copy integer part
            for (std::size_t i = 0; i < integer_part_length; i++)
            {
                buffer[i] = temp_buffer[i];
            }
 
            buffer[integer_part_length] = '.';
 
            // Copy fractal part
            for (std::size_t i = 0; i < m_decimal_points; i++)
            {
                buffer[integer_part_length + 1 + i] = temp_buffer[integer_part_length + i];
            }
 
            return length + 1; // +1 is because of '.'
        }
        else
        {
            assert(2 + m_decimal_points < MAX_DIGITS);
 
            buffer[0] = '0';
            buffer[1] = '.';
 
            std::size_t max_buffer_index = 2 + m_decimal_points - 1;
 
            for (std::size_t i = 0; i < length; i++)
            {
                buffer[max_buffer_index - i] = temp_buffer[length-1-i];
            }
 
            for (std::size_t i = 0; i < m_decimal_points-length; i++)
            {
                buffer[2 + i] = '0';
            }
 
            return 2 + m_decimal_points; // +2 is because of "0."
        }
    }
 
    std::string to_string() const
    {
        assert(m_decimal_points >0 && m_decimal_points <= MAX_ALLOWED_DECIMAL_POINTS);
 
        char temp_buffer[MAX_DIGITS];
        auto length = to_chars(temp_buffer);
        temp_buffer[length] = '\0';
 
        std::string ret = temp_buffer;
        return ret;
    }
 
    bool operator ==(const FixedPoint& other) const
    {
        assert(m_decimal_points > 0 && m_decimal_points <= MAX_ALLOWED_DECIMAL_POINTS);
        assert(m_decimal_points == other.m_decimal_points);
 
        return m_raw_value == other.m_raw_value;
    }
 
    bool operator !=(const FixedPoint& other) const
    {
        assert(m_decimal_points > 0 && m_decimal_points <= MAX_ALLOWED_DECIMAL_POINTS);
        assert(m_decimal_points == other.m_decimal_points);
 
        return m_raw_value != other.m_raw_value;
    }
 
    bool operator >(const FixedPoint& other) const
    {
        assert(m_decimal_points > 0 && m_decimal_points <= MAX_ALLOWED_DECIMAL_POINTS);
        assert(m_decimal_points == other.m_decimal_points);
        return m_raw_value > other.m_raw_value;
    }
 
    bool operator >=(const FixedPoint& other) const
    {
        assert(m_decimal_points > 0 && m_decimal_points <= MAX_ALLOWED_DECIMAL_POINTS);
        assert(m_decimal_points == other.m_decimal_points);
        return m_raw_value >= other.m_raw_value;
    }
 
    bool operator <(const FixedPoint& other) const
    {
        assert(m_decimal_points > 0 && m_decimal_points <= MAX_ALLOWED_DECIMAL_POINTS);
        assert(m_decimal_points == other.m_decimal_points);
        return m_raw_value < other.m_raw_value;
    }
 
    bool operator <=(const FixedPoint& other) const
    {
        assert(m_decimal_points > 0 && m_decimal_points <= MAX_ALLOWED_DECIMAL_POINTS);
        assert(m_decimal_points == other.m_decimal_points);
        return m_raw_value <= other.m_raw_value;
    }
 
private:
    uint64_t m_raw_value = 0;
    uint32_t m_decimal_points = 0;
 
    static constexpr inline std::size_t MAX_DIGITS = 64;
    static constexpr inline std::size_t MAX_ALLOWED_DECIMAL_POINTS = 9;
 
    static constexpr inline uint64_t POWERS_OF_TEN[] =
    {
        UINT64_C(1),          UINT64_C(10),       UINT64_C(100),
        UINT64_C(1000),       UINT64_C(10000),    UINT64_C(100000),
        UINT64_C(1000000),    UINT64_C(10000000), UINT64_C(100000000),
        UINT64_C(1000000000),
    };
};
 
} // namespace