学 Win32 汇编[13]: 定义符号常量(=、EQU、TEXTEQU)
=、EQU、TEXTEQU 功能差不多, 它们定义的符号都将在编译前辈替换成它们指定的常量值.
相比之下 EQU 更好用些.
= 举例
; Test13_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 .data n = 1 ; = 伪指令只能定义整数或整数表达式 n = n + 1 ; 可重复定义 .code main proc PrintDec n ;2 ret main endp end main
EQU 例一
; Test13_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 num1 equ 2 ; equ 可以定义整数和整数表达式 num2 equ 3 ; 它不能像 = 一样重复定义 num3 equ num1+num2 ; (我尝试了重复定义, 竟然有时也可以, 只是偶尔) txt equ <'Asm'> ; 可用 equ 定义字符串, 应使用 <> szTxt db txt, 0 ; 使用 equ 定义的常量 .code main proc PrintDec num3 ;5 PrintString szTxt ;Asm ret main endp end main
EQU 例二
; Test13_3.asm .386 .model flat, stdcall include windows.inc include kernel32.inc includelib kernel32.lib include user32.inc includelib user32.lib ; 用 equ 给函数重命名 Msg equ MessageBox Exit equ <ExitProcess> ;尖括号可保证字符串的完整、并避免和关键字冲突 ; 甚至代替整个表达式 ShowMsg equ <invoke MessageBox, NULL, addr szMsg, addr szCaption, MB_OK> .data szMsg db 'Hello World!', 0 szCaption db 'Hi', 0 .code main proc invoke Msg, NULL, addr szMsg, addr szCaption, MB_OK ShowMsg invoke Exit, NULL main endp end main
用 TEXTEQU 重做上一个例子, 完全可行:
; Test13_4.asm .386 .model flat, stdcall include windows.inc include kernel32.inc includelib kernel32.lib include user32.inc includelib user32.lib Msg textequ MessageBox Exit textequ <ExitProcess> ShowMsg textequ <invoke MessageBox, NULL, addr szMsg, addr szCaption, MB_OK> .data szMsg db 'Hello World!', 0 szCaption db 'Hi', 0 .code main proc invoke Msg, NULL, addr szMsg, addr szCaption, MB_OK ShowMsg invoke Exit, NULL main endp end main
用 TEXTEQU 重做 EQU 的第一个例子(Test13_2.asm), 有区别:
; Test13_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 .data num1 equ 2 ; 这里的 equ 换做 textequ 不行 num2 textequ <3> ; 如果用 textequ 定义整数或表达式也要放在 <> 中 num3 textequ <num1+num2> ; 这曾是 num3 equ num1+num2 txt textequ <'Asm'> ; txt textequ <'Delphi'> ; textequ 可重复定义 szTxt db txt, 0 .code main proc PrintDec num3 ;5 PrintString szTxt ;Delphi ret main endp end main
posted on 2010-04-07 17:24 万一 阅读(4648) 评论(0) 编辑 收藏