Simple C a C++ library for handling serial port communication.
During embedded system development is always easier to debug the communication protocol on PC, because debugging on PC and with Visual Studio is much more comfortable than on any embedded system.
However embeeded software developers are often not interrested to develop a new quite complex component for Serial port communication on Windows OS.
This library is ready to use for any embedded developer (it requires no additional research or effort), it supports BOTH styles of data receiving - calling an event immediatelly after data are received OR waiting for specific amount of data with timeout.
You can look into example projects for Visual Studio.