纯64位汇编：

includelib ucrt.lib
includelib legacy_stdio_definitions.lib
includelib user32.lib

extern printf:proc
extern MessageBoxA:proc

.data
szFormat db "%s",0
szHello db "HelloWorld",0
szRk db "123",0

.code
start proc
	sub rsp,28h
	mov rdx,offset szHello
	mov rcx,offset szFormat
	call printf
	mov r9,0
	mov r8,offset szHello
	mov rdx,offset szRk
	mov rcx,0
	call MessageBoxA
	add rsp,28h
	ret
start endp
end 

注意：

1.平台工具集要选VS2015

2.属性->生成依赖项->masm

3.链接器->高级->入口点

---

64位混合编程（C++/Asm）：

1.asm:

includelib legacy_stdio_definitions.lib
includelib user32.lib

extern printf:proc

.data
	szformat db "%s\n",0

.code
Myadd proc
	sub rsp,28h
	add rcx,rdx
	mov	rax,rcx
	add rsp,28h
	ret
Myadd endp

Myprintf proc
	sub rsp,28h
	mov rdx,rcx
	lea rcx,szformat
	call printf
	add rsp,28h
	ret
Myprintf endp
end 

main.cpp:

#include <iostream>
#include <windows.h>

EXTERN_C UINT64 Myadd(UINT64 a, UINT64 b); 
EXTERN_C void Myprintf(const char* szbuffer);

int main()
{
	UINT64 num = Myadd(1, 2);
	printf("%lld\r\n", num);
	Myprintf("hello word");
	system("pause");
	return 0;
}

注意：

如果生成报错，并且没有属性里面没有Microsoft Macro Assembler,换成VS2015也没有的话，

就在源文件里面找到.asm后缀的文件右键属性->常规->项类型->Microsoft Macro Assembler即可。