Calling conventions

Calling conventions describe how functions are called. This includes how arguments are supplied to the function (i.e. where they go - in registers or on the stack, and how), and how the return value is received.

In Zig, the attribute callconv may be given to a function. The calling conventions available may be found in std.builtin.CallingConvention. Here we make use of the cdecl calling convention.

fn add(a: u32, b: u32) callconv(.C) u32 {
    return a + b;
}

Marking your functions with the C calling convention is crucial when you're calling Zig from C.