Function append

src/include/buffer.h:334–336

    unsigned append(const char *p, unsigned l);
#if __cplusplus >= 201703L
    inline unsigned append(std::string_view s) {
      return append(s.data(), s.length());
    }
#endif // __cplusplus >= 201703L
    void copy_in(unsigned o, unsigned l, const char *src, bool crc_reset = true);
    void zero(bool crc_reset = true);