Boost
C++ Libraries
...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
A pointer to the next input byte.
void const* next_in;
If there is no more input, this may be set to nullptr.
The application must update next_in
and avail_in when avail_in has dropped to zero.