使用YASM编程 - 02

/*********************************************************
* Gnu asm 注释和字符串风格和C风格一样
* 还支持单行注释#
* gas                                                NASM
* movl (movb movw)                           mov
* pushl(pushb pushw)                        push
* addl                                               add
* xorl                                                xor
* ...
* ...
* ...
* 指令有(b w l 后缀)                              没有后缀
* .global  _start                                 global  _start
* hello: .string "hello\n"                      hello:  "hello",0x0a,0
* %eax (%在寄存器使用的前缀)               eax(没有前缀)
* $11                                               11(数字没有前缀)
* .extern                                           extern
*
* 如果是二元操作
* 操作符 目的操作数,源操作数
*********************************************************/
#testGas.asm
#os:windows
.data
hello: .string "hello GAS\n"
resultString: .string "Add1(%d,%d)=%d\n"
msg: .string "hello\n"
tlt: .string "msg\n"
one: .int 100
two: .int 200
.extern _MessageBoxA@16
.extern _printf
.global _start

#build.bat
/*****************************************************************************
vsyasm -p gas -w -f win32 testGAS.asm
link /entry:start /subsystem:console /libpath:C:\masm32\lib user32.lib msvcrt.lib testGAS.obj
*****************************************************************************/
.text
add1:
pushl %ebp
movl  %esp,%ebp
movl  8(%ebp),%eax
movl  12(%ebp),%edx
addl   %edx,%eax
popl   %ebp
ret
callMessageBox:
xorl %eax,%eax
pushl %eax
pushl $msg
pushl $tlt
pushl %eax
call _MessageBoxA@16
ret

_start:
pushl one
pushl two
call add1
addl $8,%esp
pushl  %eax
pushl  two
pushl  one
pushl $resultString
call _printf

addl $0x10,%esp
ret