Intel汇编语言程序设计(第7版)第六章编程学习过程中写的小例子

1. 根据书上的例子, 自己写的4个过程, 改了一部分

include irvine32.inc
includelib irvine32.lib
include msvcrt.inc
includelib msvcrt.lib

.data 
dwNum0 DWORD 15
dwNum1 DWORD 21

PDWORD TYPEDEF PTR DWORD 

dwNumAry DWORD 25, 39, 14, 59
NumAryLen DWORD LENGTHOF dwNumAry

.code 
; 找到两个数中的更大数
BigOne PROC Num0:DWORD, Num1:DWORD
	
	mov eax, Num0
	cmp eax, Num1
	ja NUM0BIG
	je EQUAL
	mov eax, Num1
	jmp NUM0BIG
EQUAL:
	xor eax, eax
NUM0BIG:
	ret
BigOne ENDP

; 数组求最大值
Biggest PROC USES esi ebx ecx pdwAry:PDWORD, dwCnt:DWORD

	mov ebx, pdwAry
	mov ecx, dwCnt
	mov esi, 1
	mov eax, DWORD PTR [ebx]
L0:
	cmp eax, DWORD PTR [ebx + esi * TYPE DWORD]
	jae NOMAX
	mov eax, DWORD PTR [ebx + esi * TYPE DWORD]
NOMAX:
	inc esi 
	dec ecx
	or ecx, ecx
	jnz L0

	ret
Biggest ENDP

; 直到按下按键在退出循环
BrkUntilPushKey PROC
	
L0:
	mov eax, 100
	call Delay
	call ReadKey
	jz L0

	ret
BrkUntilPushKey ENDP

; 在数组中找到对应值, 找到返回1否则0
SearchNum PROC USES esi ecx pdwAry:PDWORD, dwAryCnt:DWORD, dwObj:DWORD

	mov esi, pdwAry
	mov eax, dwObj
	mov ecx, dwAryCnt
L0:
	cmp eax, DWORD PTR [esi]
	je found
	add esi, TYPE dwAryCnt
	dec ecx
	test ecx, ecx
	jnz L0
	jmp notfound
found:
	mov eax, 1
	jmp quit
notfound:
	xor eax, eax
quit:
	ret
SearchNum ENDP

start:
	push 39
	push NumAryLen
	push OFFSET dwNumAry
	call SearchNum
	test eax, eax
	jz Ending
	
	call WriteDec
	call WaitMsg
Ending:
	invoke ExitProcess, 0
end	start

2. 书上实现xor加密的例子

include irvine32.inc
includelib irvine32.lib
include msvcrt.inc
includelib msvcrt.lib

.data 
; 字节类型的指针
PBYTE TYPEDEF PTR BYTE 

INPUTBUFSIZE = 256

RetLine			BYTE 0dh, 0ah, 0
szInputPrompt	BYTE "输入明文: ", 0
szOutputPrompt	BYTE "解密后的明文: ", 0
pszInput		PBYTE OFFSET szInputPrompt

szInputBuf		BYTE INPUTBUFSIZE DUP(0)
pszInputBuf		PBYTE OFFSET szInputBuf
g_dwInputLen	DWORD 0
g_bKey BYTE 0
.code 

GenKey PROC 

	call Randomize
	call Random32
	and eax, 0FFh
	ret

GenKey ENDP

NextLine PROC

	push eax
	mov edx, OFFSET RetLine
	call WriteString
	pop eax

	ret
NextLine ENDP

SymCryptic PROC USES esi pbTextBuf:PBYTE, dwTextSize:DWORD, bKey:BYTE
	
	xor esi, esi
	xor eax, eax
	mov ebx, pbTextBuf
L0:
	mov al, BYTE PTR [ebx + esi]
	xor al, bKey
	mov BYTE PTR [ebx + esi], al
	inc esi 
	cmp esi, dwTextSize
	jb L0

	ret

SymCryptic ENDP

; 显示提示内容的封装函数
PrintPrompt PROC USES edx pShownString:PBYTE, pInputBuf:PBYTE, dwInputBufSize:DWORD

	; 打印提示输入
	mov edx, pShownString
	call WriteString
	; 让用户输入内容
	mov edx, pInputBuf
	mov ecx, dwInputBufSize
	call ReadString

	ret

PrintPrompt ENDP

start:
	; 打印输入提示
	push SIZEOF szInputBuf
	push OFFSET szInputBuf
	push OFFSET szInputPrompt
	call PrintPrompt
	mov g_dwInputLen, eax

	; 生成密钥
	call GenKey
	mov g_bKey, al

	; 进行对称加密
	invoke SymCryptic, pszInputBuf, g_dwInputLen, g_bKey
	mov edx, OFFSET szInputBuf
	call WriteString
	; 换行
	call NextLine

	; 显示解密后的明文
	mov edx, OFFSET szOutputPrompt
	call WriteString
	; 进行对称解密
	invoke SymCryptic, pszInputBuf, g_dwInputLen, g_bKey
	mov edx, pszInputBuf
	call WriteString
	; 换行
	call NextLine

	call WaitMsg

	invoke ExitProcess, 0
end	start

3. 计算数组内比50大的元素之和

include irvine32.inc
includelib irvine32.lib
include msvcrt.inc
includelib msvcrt.lib

.data 
; 字节类型的指针
PBYTE TYPEDEF PTR BYTE 

array SDWORD 10, 60, 20, 33, 72, 89, 45, 65, 72, 18
ArraySize SDWORD ($ - array) / TYPE array

sample SDWORD 50
index SDWORD 0
sum SDWORD 0

.code 
start:
	xor ecx, ecx
	mov esi, OFFSET array
	xor eax, eax

L0:
	cmp ecx, ArraySize
	jge Ending
	mov ebx, sample
	cmp ebx, SDWORD PTR [esi]
	jge NextLoop
	add eax, SDWORD PTR [esi]
NextLoop:
	inc ecx
	add esi, TYPE array
	jmp L0
Ending:
	mov sum, eax
	call WriteInt
	call WaitMsg
	invoke ExitProcess, 0
end	start

4. 表驱动选择

如果选择分支过多可以构造一张表专门指向对应的地址

include irvine32.inc
includelib irvine32.lib
include msvcrt.inc
includelib msvcrt.lib

.data 

CaseTable			BYTE	'A'
					DWORD	Process_A
EntrySize			= ($ - CaseTable)
					BYTE	'B'
					DWORD	Process_B
					BYTE	'C'
					DWORD	Process_C
					BYTE	'D'
					DWORD	Process_D
NumberOfEntries		= ($ - CaseTable) / EntrySize
Prompt		BYTE	"Press capital A, B, C or D: ", 0

msgA		BYTE	"Process_A", 0
msgB		BYTE	"Process_B", 0
msgC		BYTE	"Process_C", 0
msgD		BYTE	"Process_D", 0

.code 
Process_A PROC
	mov edx, OFFSET msgA
	ret
Process_A ENDP

Process_B PROC
	mov edx, OFFSET msgB
	ret
Process_B ENDP

Process_C PROC
	mov edx, OFFSET msgC
	ret
Process_C ENDP

Process_D PROC
	mov edx, OFFSET msgD
	ret
Process_D ENDP

start:
	mov edx, OFFSET Prompt
	call WriteString
	call ReadChar

	mov ebx, OFFSET CaseTable
	mov ecx, NumberOfEntries
L1:
	cmp al, [ebx]
	jne L2
	call DWORD PTR [ebx + 1]
	call WriteString
	call Crlf
	jmp L3
L2:
	add ebx, EntrySize
	loop L1
	
L3:
	call WaitMsg
	invoke ExitProcess, 0
end	start

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