What does __ Stdcall mean?
__stdcall is a calling convention: a way of determining how parameters are passed to a function (on the stack or in registers) and who is responsible for cleaning up after the function returns (the caller or the callee).
Where is Lpvoid defined?
LPVOID. LPVOID data types are defined as being a “pointer to a void object”. This may seem strange to some people, but the ANSI-C standard allows for generic pointers to be defined as “void*” types. This means that LPVOID pointers can be used to point to different types of objects, without creating a compiler error.
What calling convention does GCC use?
In Linux, GCC sets the de facto standard for calling conventions. Since GCC version 4.5, the stack must be aligned to a 16-byte boundary when calling a function (previous versions only required a 4-byte alignment). A version of cdecl is described in System V ABI for i386 systems.
What is __ Stdcall in C?
The __stdcall calling convention is used to call Win32 API functions. The callee cleans the stack, so the compiler makes vararg functions __cdecl . Functions that use this calling convention require a function prototype.
What is calling convention in C?
Calling conventions specify how arguments are passed to a function, how return values are passed back out of a function, how the function is called, and how the function manages the stack and its stack frame. In short, the calling convention specifies how a function call in C or C++ is converted into assembly language.
What are cdecl and Stdcall used for?
__cdecl is the default calling convention for C and C++ programs. Because the stack is cleaned up by the caller, it can do vararg functions. The __cdecl calling convention creates larger executables than __stdcall, because it requires each function call to include stack cleanup code.
What is RDI register?
Architectures define a calling convention which dictates where parameters to a function and its return value are stored. In Objective-C, the RDI register is the reference of the calling NSObject , RSI is the Selector, RDX is the first parameter and so on.
What is Wm_create?
A WM_CREATE message is sent to your window procedure during the window’s CreateWindowEx call. The lp argument contains a pointer to a CREATESTRUCT which contains the arguments passed to CreateWindowEx . If an application returns 0 from WM_CREATE, the window is created.
Why do we need a calling convention?
What is Int_ptr?
INT_PTR. A signed integer type for pointer precision. Use when casting a pointer to an integer to perform pointer arithmetic.
What is difference between cdecl and Stdcall?
What is __ cdecl in C?
The __cdecl keyword instructs the compiler to read and write a parameter list by using C linkage conventions. To set the __cdecl calling convention for a function, place the linkage keyword immediately before the function name or at the beginning of the declarator.
What is the RSP register?
The first lines of the function main refers to rbp and rsp ; these are special purpose registers. rbp is the base pointer, which points to the base of the current stack frame, and rsp is the stack pointer, which points to the top of the current stack frame.
What is RDX register used for?
Registers
| Register | Purpose | Saved across calls |
|---|---|---|
| %rdx | used to pass 3rd argument to functions | No |
| %rsp | stack pointer | Yes |
| %rbp | callee-saved; base pointer | Yes |
| %rsi | used to pass 2nd argument to functions | No |