飘云阁源码阅读之hello.asm - Powered by Discuz! Archiver

surge 发表于 2006-9-29 13:51:08

源码阅读之hello.asm

;以下为\masm32\tutorial\console\demo1\hello.asm中的内容：
;<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
;             Build this with the "Project" menu using
;                   "Console Assemble and Link"
;
;<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

.486                                  ; create 32 bit code
.model flat, stdcall                ; 32 bit memory model
option casemap :none                ; case sensitive

include \masm32\include\windows.inc ; always first
include \masm32\macros\macros.asm    ; MASM support macros

; -----------------------------------------------------------------
; include files that have MASM format prototypes for function calls
; -----------------------------------------------------------------
include \masm32\include\masm32.inc
include \masm32\include\gdi32.inc
include \masm32\include\user32.inc
include \masm32\include\kernel32.inc

; ------------------------------------------------
; Library files that have definitions for function
; exports and tested reliable prebuilt code.
; ------------------------------------------------
includelib \masm32\lib\masm32.lib
includelib \masm32\lib\gdi32.lib
includelib \masm32\lib\user32.lib
includelib \masm32\lib\kernel32.lib

.code                   ; Tell MASM where the code starts

;<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

start:                      ; The CODE entry point to the program

print chr$("Hey, this actually works.",13,10)
exit

;<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

end start                   ; Tell MASM where the program ends

;可以用Quick Editor(masm32安装目录中qeditor.exe)来构建这个程序
;必需先File->Set Current Directory(或直接Ctrl+F12)设置为hello.asm所在目录
;然后Project->Console Assenble and Link就可以构建了
;这是一个工作在控制台下的程序,打开一个cmd窗口,切换到生成的hello.exe所在目录
;运行之后显示:Hey, this actually works.

;print是一个宏，在maxros.asm中定义如下,这个文件已经被包含进来了
;include \masm32\macros\macros.asm    ; MASM support macros

print MACRO arg1:REQ,varname:VARARG    ;; 显示一个0结束的字符串
   invoke StdOut,reparg(arg1)
   IFNB <varname>
   invoke StdOut,chr$(varname)
   ENDIF
ENDM
;调用StdOut函数,在控制台显示一个字符串

;repareg是一个宏，在maxros.asm中定义如下,这个文件已经被包含进来了
; -----------------------------------------------------------
; This macro replaces quoted text with a DATA section OFFSET
; and returns it in ADDR "name" format. It is used by other
; macros that handle optional quoted text as a parameter.
; -----------------------------------------------------------
reparg MACRO arg
   LOCAL nustr
   quot SUBSTR <arg>,1,1
   IFIDN quot,<">          ;; if 1st char = "
   .data
      nustr db arg,0    ;; write arg to .DATA section
   .code
   EXITM <ADDR nustr>    ;; append name to ADDR operator
   ELSE
   EXITM <arg>          ;; else return arg
   ENDIF
ENDM
;如果arg是一个字符串地址,直接返回这个地址,
;如果arg是一个"字符串",在.data中声明并返回
;这个偏移地址

;chr$是一个宏，在macros.asm中定义如下

   chr$ MACRO any_text:VARARG
   LOCAL txtname
   .data
      txtname db any_text,0
   .code
   EXITM <OFFSET txtname>
   ENDM
;chr$("Hey, this actually works.",13,10)
;经编译器处理后变为
;.data
;txtname db Hey, this actually works.",13,10,0
;.code
;并返回textname的偏移给print继续展开
;invoke StdOut,addr textname

;exit是一个宏，在macros.asm中定义如下
; --------------------------------------------------------
; exit macro with an optional return value for ExitProcess
; --------------------------------------------------------
exit MACRO optional_return_value
   IFNDEF optional_return_value
   invoke ExitProcess, 0
   ELSE
   invoke ExitProcess,optional_return_value
   ENDIF
ENDM
;exit直接展开为
;invoke ExitProcess, 0

;关于宏的详细参考D:\masm32\help\masm32.hlp中的MACRO Reference
;也可以参考也可以参考masm程序员指南.

;StdOut是一个自定义的库函数，源码在\masm32\m32lib\stdout.asm
;这是对操作系统中有关控制台操作的封装。
; #########################################################################

.386
.model flat, stdcall
option casemap :none ; case sensitive

include \masm32\include\windows.inc
include \masm32\include\kernel32.inc

StrLen PROTO :DWORD

.code

; #########################################################################

StdOut proc lpszText:DWORD

LOCAL hOutPut:DWORD
LOCAL bWritten :DWORD
LOCAL sl    :DWORD

invoke GetStdHandle,STD_OUTPUT_HANDLE
mov hOutPut, eax

invoke StrLen,lpszText
mov sl, eax

invoke WriteFile,hOutPut,lpszText,sl,ADDR bWritten,NULL

mov eax, bWritten
ret

StdOut endp

; #########################################################################

end
;源码中还用到了一个自定义的库函数StrLen源码在\masm32\m32lib\strlen.asm
;<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

.486
.model flat, stdcall
option casemap :none ; case sensitive

.code

;<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

OPTION PROLOGUE:NONE
OPTION EPILOGUE:NONE

align 4

StrLen proc item:DWORD

; -------------------------------------------------------------
; This procedure has been adapted from an algorithm written by
; Agner Fog. It has the unusual characteristic of reading up to
; three bytes past the end of the buffer as it uses DWORD size
; reads. It is measurably faster than a classic byte scanner on
; large linear reads and has its place where linear read speeds
; are important.
; -------------------------------------------------------------

mov eax,          ; get pointer to string
push ebx
lea edx,          ; pointer+3 used in the end
@@:
mov ebx,             ; read first 4 bytes
add eax, 4                ; increment pointer
lea ecx, ; subtract 1 from each byte
not ebx                   ; invert all bytes
and ecx,ebx             ; and these two
and ecx, 80808080h
jz    @B                   ; no zero bytes, continue loop

test ecx,00008080h       ; test first two bytes
jnz @F
shr ecx,16                ; not in the first 2 bytes
add eax,2
@@:
shl cl,1                ; use carry flag to avoid branch
sbb eax,edx             ; compute length
pop ebx

ret 4

StrLen endp

OPTION PROLOGUE:PrologueDef
OPTION EPILOGUE:EpilogueDef

;<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

end
;GetStdHandle和WriteFile是操作系统kernel32.dll提供的函数这可查MSDN
;或者在MSHELP中找到相关C语言描述。

;最后这个程序被编译器编译成什么样子呢?
;用OllyDBG打开看一下
00401005 >/$ >jmp start
0040100A|>int3
0040100B|>int3
0040100C|>int3
0040100D|>int3
0040100E|>int3
0040100F|>int3
00401010 >|> >push offset ??0019                ; print chr$("Hey, this actually works.",13,10)
00401015|. >call StdOut
0040101A|. >push 0                            ; exit
0040101C\. >call ExitProcess
;下面是Stdout
00401028 >/$ >push ebp
00401029|. >mov ebp, esp
0040102B|. >add esp, -0C
0040102E|. >push -0B                            ; /DevType = STD_OUTPUT_HANDLE
00401030|. >call GetStdHandle                   ; \GetStdHandle
00401035|. >mov , eax
00401038|. >push dword ptr
0040103B|. >call StrLen
00401040|. >mov , eax
00401043|. >push 0                            ; /pOverlapped = NULL
00401045|. >lea eax,                   ; |
00401048|. >push eax                            ; |pBytesWritten
00401049|. >push dword ptr             ; |nBytesToWrite
0040104C|. >push dword ptr             ; |Buffer
0040104F|. >push dword ptr             ; |hFile
00401052|. >call WriteFile                      ; \WriteFile
00401057|. >mov eax,
0040105A|. >leave
0040105B\. >retn 4
;下面是StrLen
00401060 >/$ >mov eax,
00401064|. >push ebx
00401065|. >lea edx,
00401068|> >/mov ebx,
0040106A|. >|add eax, 4
0040106D|. >|lea ecx,
00401073|. >|not ebx
00401075|. >|and ecx, ebx
00401077|. >|and ecx, 80808080
0040107D|.^>\je    short 00401068
0040107F|. >test ecx, 8080
00401085|. >jnz short 0040108D
00401087|. >shr ecx, 10
0040108A|. >add eax, 2
0040108D|> >shl cl, 1
0040108F|. >sbb eax, edx
00401091|. >pop ebx
00401092\. >retn 4

;宏减少了击键次数,在一定程度上提高了可读性
;对于工具的使用应该更多关注官方发布的手册

angelwings 发表于 2007-1-26 20:47:21

支持一下,楼主应该讲解的再详细点

caterpilla 发表于 2007-1-26 22:46:55

支持一下。。。。。

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源码阅读之hello.asm