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#include <Windows.h>

extern "C" void  __stdcall asm_func(const char* lpText);

extern "C" UINT GetMsgBoxType()

{

    return MB_YESNOCANCEL;

}

int main()

{

    asm_func("Hello world!");

    return 0;

}

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.data

    msgCaption  db 'Message box text',0

.code

align 16

extern GetMsgBoxType : proc

extern MessageBoxA : proc

extern __imp_MessageBoxA : qword

asm_func proc

    ; RCX = address for the string for the message box

    sub     rsp, 28h        ; shadow stack only [n]8 size

    lea     rdx, [msgCaption]

    mov     r8, rcx

    call    GetMsgBoxType

    mov     r9, rax

    xor     rcx, rcx

    ;call   [__imp_MessageBoxA]

    call MessageBoxA

    add     rsp, 28h        ; restoring shadow stack

    ret

asm_func endp

end