Calling convention

In computer science, a calling convention is an implementation-level (low-level) scheme for how subroutines or functions receive parameters from their caller and how they return a result. When some code calls a function, design choices have been taken for where and how parameters are passed to that function, and where and how results are returned from that function, with these transfers typically done via certain registers or within a stack frame on the call stack. There are design choices for how the tasks of preparing for a function call and restoring the environment after the function has completed are divided between the caller and the callee. Some calling convention specifies the way every function should get called. The correct calling convention should be used for every function call, to allow the correct and reliable execution of the whole program using these functions. Calling conventions are usually considered part of the application binary interface (ABI). The names or meanings of the parameters and return values are defined in the application programming interface (API, as opposed to ABI), which is a separate though related concept to ABI and calling convention. The names of members within passed structures and objects would also be considered part of the API, and not ABI. Sometimes APIs do include keywords to specify the calling convention for functions. Calling conventions do not typically include information on handling lifespan of dynamically-allocated structures and objects. Calling conventions are unlikely to specify the layout of items within structures and objects, such as byte ordering or structure packing. For some languages, the calling convention includes details of error or exception handling, (e.g. Go, Java) and for others, it does not (e.g. C++). For Remote procedure calls, there is an analogous concept called Marshalling.