#include <bit>
#include <climits>
#include <cmath>
#include <cstdio>

class BinaryEncoder {
private:
    unsigned char *const buffer;
    std::size_t index;

public:
    BinaryEncoder(unsigned char *b) noexcept : buffer(b) {}

    void write(unsigned char val, unsigned char width = 0)
    {
        if (width == 0)
            width = std::bit_width(val);

        const unsigned char bitindex = index % CHAR_BIT;
        const std::size_t byteindex = index / CHAR_BIT;

        buffer[byteindex] &= compl(UCHAR_MAX << bitindex);
        buffer[byteindex] |= val << bitindex;

        const unsigned char bitsWritten = CHAR_BIT - bitindex;

        if (width <= bitsWritten) {
            index += width;
        } else {
            index += bitsWritten;
            this->write(val >> bitsWritten);
        } 
    }
};


int main() {
    unsigned char buf[1];
    BinaryEncoder be(buf);

    be.write(0b111u);
    be.write(0b100u);

    if (buf[0] == 39) std::puts("miku");
}