How to get Windows system calls assembly statically?

Getting Windows system calls (also known as Windows API calls) in assembly language statically involves identifying the appropriate function signatures, locating the corresponding function addresses, and invoking them using assembly instructions. Here's a general overview of the process:

1. Identify the Windows API Functions:
   Determine which Windows API functions you want to call. These functions are documented in the Microsoft Windows API documentation.

2. Import Libraries:
   Windows API functions are typically provided by dynamic-link libraries (DLLs). You need to use the appropriate import libraries to link your assembly code with the required DLLs.

3. Locate Function Addresses:
   Windows API functions have addresses in memory. You need to determine the addresses of the functions you want to call. These addresses are not fixed and can change with different Windows versions or patches.

4. Call Functions Using Assembly:
   Once you have the addresses of the functions, you can call them using assembly instructions. The exact assembly instructions depend on the calling convention used by the Windows API functions.

   For x86 architecture, you might use the stdcall calling convention:

   assemblyCopy code
   extern MessageBoxA : proc
   
   extern ExitProcess : proc
   
   
   
   section .data
   
   message db "Hello, World!",0
   
   
   
   section .text
   
   global _start
   
   
   
   _start:
   
       push message
   
       push 0
   
       push 0
   
       push 0
   
       call MessageBoxA
   
   
   
       push 0
   
       call ExitProcess
   
   

   For x64 architecture, you might use the fastcall calling convention:

   assemblyCopy code
   extern MessageBoxA : proc
   
   extern ExitProcess : proc
   
   
   
   section .data
   
   message db "Hello, World!",0
   
   
   
   section .text
   
   global main
   
   
   
   main:
   
       mov rdx, 0
   
       mov rcx, 0
   
       mov r8, 0
   
       mov r9, 0
   
       lea rdi, [message]
   
       call MessageBoxA
   
   
   
       mov rcx, 0
   
       call ExitProcess
   
   

5. Linking and Assembling:
   You need to assemble and link your assembly code using the appropriate tools for your platform (e.g., NASM for assembly and linker for linking).

6. Testing and Debugging:
   Execute your program and use debugging tools to verify that the Windows API calls are executed correctly and that your program behaves as expected.

Please note that directly invoking Windows API functions in assembly can be complex, and it requires a good understanding of assembly language, calling conventions, Windows internals, and more. Additionally, the addresses of API functions can change across Windows versions, so this approach might not be as portable or reliable as using higher-level programming languages with proper API bindings.