学 Win32 汇编[9]: 子过程中的变量声明

定义子过程的伪指令: PROC、ENDP

---

; Test9_1.asm

.386

.model flat, stdcall



include    windows.inc

include    kernel32.inc

include    masm32.inc

include    debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib



.code

    ;子过程 proc1:

    proc1 proc

        PrintText 'proc1'

    proc1 endp

    

    ;子过程 proc2:

    proc2 proc

        PrintText 'proc2'

    proc2 endp

    

    ;子过程 proc3:

    proc3 proc

        PrintText 'proc3'

    proc3 endp



    ret

end proc1  ;end 后面的 proc1 是入口的子过程名; 这也就是指定主过程.



;可以把 end proc1 分别换做 end proc2 和 end proc3 尝试,

;如果这是一个供其他程序调用的代码文件, 那么 end 后面就不需要指定.


 
   

模仿 C 语言的样子, 以后的程序结构应该这样:

---

; Test9_2.asm

.386

.model flat, stdcall



include    windows.inc

include    kernel32.inc

include    masm32.inc

include    debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib



.data

    szText db 'Hello World!', 0DH, 0AH, 0

    

.code

main proc

    PrintString szText  ;Hello World!

    ret

main endp

end main


 
   

局部变量要用 local 声明, 和全局变量区别不小:

---

; Test9_3.asm

.386

.model flat, stdcall



include    windows.inc

include    kernel32.inc

include    masm32.inc

include    debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib



.code

main proc

    ;局部变量中的类型不能使用缩写

    LOCAL v1: dword

    

    ;可用逗号间隔写在一行

    LOCAL v2: dword, v3: dword

    

    ;不指定类型时默认 DWORD(在 Win32 下)

    LOCAL v4

    

    ;数组

    LOCAL v5[3]: dword

    

    ;在手动初始化前, 局部变量中都是些垃圾值:

    PrintDec v1

    PrintDec v2

    PrintDec v3

    PrintDec v4

    mov eax, v5[0]

    PrintDec eax

    ret

main endp

end main


 
   

调用子过程:

---

; Test9_4.asm

.386

.model flat, stdcall



include    windows.inc

include    kernel32.inc

include    masm32.inc

include    debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib



.code

;

proc1 proc

    PrintDec 1

    ret

proc1 endp

;

proc2 proc

    PrintDec 2

    ret

proc2 endp

;

main proc

    PrintDec 0

    call proc2

    call proc1

    ret

main endp

end main



;注释:

;最后一行 end main 决定了子过程将被率先调用, 这样它就成了主过程

;然后主过程又通过 call 指令顺序调用了 proc2、proc1

;这样最后的显示结果将是: 0 / 2 / 1

;子过程应该用 ret 指令返回


 
   

一个求和函数的例子:

---

; Test9_5.asm

.386

.model flat, stdcall



include    windows.inc

include    kernel32.inc

include    masm32.inc

include    debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib



.code

;求和的函数, 函数返回值在 eax

;sum proc v1:dword, v2:dword, v3:dword

sum proc v1, v2, v3 ;这是上一行的简化, 其类型也是默认为 dword

    mov eax, v1

    add eax, v2

    add eax, v3

    ret

sum endp

;

main proc

    invoke sum, 11, 22, 33

    PrintDec eax  ;66

    ret

main endp

end main