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A function pointer, also called a subroutine pointer or procedure pointer, is a pointer referencing executable code, rather than data. Dereferencing the function pointer yields the referenced function, which can be invoked and passed arguments just as in a normal function call.
The order in which atomic (scalar) parameters, or individual parts of a complex parameter, are allocated; How parameters are passed (pushed on the stack, placed in registers, or a mix of both) Which registers the called function must preserve for the caller (also known as: callee-saved registers or non-volatile registers)
How functions that take a variable number of arguments (variadic functions) are handled. Options include just passed in order (presuming the first parameter is in an obvious position) or the variable parts in an array. How return values are delivered from the callee back to the caller.
Function epilogue reverses the actions of the function prologue and returns control to the calling function. It typically does the following actions (this procedure may differ from one architecture to another): Drop the stack pointer to the current base pointer, so room reserved in the prologue for local variables is freed.
At function return, the stack pointer is instead restored to the frame pointer, the value of the stack pointer just before the function was called. Each stack frame contains a stack pointer to the top of the frame immediately below. The stack pointer is a mutable register shared between all invocations.
A function signature consists of the function prototype. It specifies the general information about a function like the name, scope and parameters. Many programming languages use name mangling in order to pass along more semantic information from the compilers to the linkers. In addition to mangling, there is an excess of information in a ...
In computer programming, a callback is a function that is stored as data (a reference) and designed to be called by another function – often back to the original abstraction layer. A function that accepts a callback parameter may be designed to call back before returning to its caller which is known as synchronous or blocking.
A basic example is in the argv argument to the main function in C (and C++), which is given in the prototype as char **argv—this is because the variable argv itself is a pointer to an array of strings (an array of arrays), so *argv is a pointer to the 0th string (by convention the name of the program), and **argv is the 0th character of the ...