Assembler MASM Win64.asm

; ---------------------------------------------
; Hello World for Win64 Intel x64 Assembly
;
; by fruel (https://github.com/fruel)
; 13 June 2016
; ---------------------------------------------

GetStdHandle PROTO
ExitProcess PROTO
WriteConsoleA PROTO

.data
msg BYTE "Hello World",0
bytesWritten DWORD ?

.code
main PROC
    sub rsp, 5 * 8  

    mov rcx, -11           
    call GetStdHandle

    mov  rcx, rax       
    lea  rdx, msg    
    mov  r8, LENGTHOF msg - 1
    lea  r9, bytesWritten  
    mov  QWORD PTR [rsp + 4 * SIZEOF QWORD], 0
    call WriteConsoleA

    mov rcx, 0      
    call ExitProcess
main ENDP
END