汇编语言-005（XCHG、标志位操作、算术操作、比例因子的变址寻址、多个常用运算符运用、大端转小端、数组操作）

1: 用不超过3条XCHG指令对4个8位寄存器的值重新排序，A,B,C,D调整为D,C,B,A

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data.code
main PROCmov al,'A'mov bl,'B'mov cl,'C'mov dl,'D'xchg al,dlxchg bl,clINVOKE ExitProcess,0
main ENDP
END main

2: 用一条算术运算指令和奇偶标志位判断信息字节是偶校验还是奇校验，设AL中的信息字节为0111 0101

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data.code
main PROC     mov al,75h   ;假设信息字节为 0111 0101add al,1     ;加1，如果奇偶标志位为1，那么信息字节就是偶校验否则是奇校验INVOKE ExitProcess,0
main ENDP
END main

3: 用字节操作数实现两个负整数相加，使溢出标志位为1 用加法使零标志位和进位标志位同时置1 用减法使进位标志位为1 使用进位标志位与溢出标志位同时为1

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data.code
main PROCmov al,81hadd al,80h ;溢出标志位为1mov al,80hadd al,80h ;零标志位与进位标志位为1mov al,70hsub al,80h ;进位标志位为1mov al,81hadd al,80h ;进位标志位与溢出标志位都为1INVOKE ExitProcess,0
main ENDP
END main

4: 实现算术 EAX = -val2+7-val3+val1 AX = (val4+BX)-val5

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data
val1 DWORD 11
val2 DWORD 22
val3 DWORD 33val4 WORD 44
val5 WORD 55 .code
main PROC;EAX = -val2+7-val3+val1neg val2mov eax,val2add eax,7sub eax,val3add eax,val1;AX = (val4+BX)-val5mov ax,val4add ax,bxsub ax,val5INVOKE ExitProcess,0
main ENDP
END main

5: 在一个双字数组中迭代，用带比例因子的变址寻址，计算元素总和

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data
listD DWORD 1,2,3,4,5,6.code
main PROCmov eax,0mov ecx,LENGTHOF listDmov esi,ecx
L1:   sub esi,1add eax,listD[esi * TYPE listD]loop L1INVOKE ExitProcess,0
main ENDP
END main

6: 多个常用运算符运用例子

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data
lMyBytes LABEL WORD  ;插入LABEL定义类型使用myBytes直接送入16位寄存器
myBytes BYTE 10h,20h,30h,40h
ALIGN 1              ;使用myBytes对齐到偶数地址
lMyWords LABEL DWORD  ;插入LABEL定义类型使用myWords直接送入32位寄存器
myWords WORD 3 DUP(?),2000h
myStrings BYTE "ABCDE".code
main PROCmov eax,TYPE myBytes ;1mov eax,LENGTHOF myBytes ;4mov eax,SIZEOF myBytes ;4mov eax,TYPE myWords ;2mov eax,LENGTHOF myWords;4mov eax,SIZEOF myWords  ;8mov eax,SIZEOF myStrings ;5mov dx,WORD PTR myBytes  ;将myBytes前两个字节送往DX,值为2010hmov al,BYTE PTR [myWords+1] ;将myWords的第二个字节送入ALmov eax,DWORD PTR myBytes  ;将myBytes全部四个字节送入EAXmov eax,lMyWords   ;使用LABEL定义的类型将myWords直接送入32位寄存器mov ax,lMyBytes   ;使用LABEL定义的类型将myBytes直接送入16位寄存器INVOKE ExitProcess,0main ENDP
END main

7: 大端转小端

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data
bigEndian BYTE 12h,34h,56h,78h
littleEndian DWORD ?.code
main PROCmov eax,DWORD PTR bigEndianmov littleEndian,eaxINVOKE ExitProcess,0
main ENDP
END main

8: 交换数组元素对，元素i与元素i+1交换，元素i+2与元素i+3交换

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data
dwordList DWORD 1,2,3,4,5,6.code
main PROCmov ecx,LENGTHOF dwordListmov eax,0
L1:	mov esi,dwordList[eax * TYPE dwordList]inc eaxxchg esi,dwordList [eax * TYPE dwordList]dec eaxmov dwordList [eax * TYPE dwordList],esiadd eax,2dec ecxloop L1INVOKE ExitProcess,0
main ENDP
END main

9: 数组元素间隔之和，假设数组为0、2、5、9、10,则元素间隔为2、3、4、1,总和为10

.386 
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data
dwordList DWORD 0,2,5,9,10.code
main PROCmov ecx,LENGTHOF dwordList -1mov eax,0
L1:	 mov ebx,ecxmov esi,dwordList[ebx * TYPE dwordList]dec ebxsub esi,dwordList[ebx * TYPE dwordList]add eax,esiloop L1INVOKE ExitProcess,0
main ENDP
END main

10: 将字数组复制到双字数组

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data
wordList WORD 1,2,3,4,5,6
dwordList DWORD 5 DUP(?).code
main PROCmov ecx,LENGTHOF wordList
L1:   dec ecxmovzx eax,wordList[ecx * TYPE wordList]mov dwordList[ecx * TYPE dwordList],eaxinc ecxloop L1INVOKE ExitProcess,0
main ENDP
END main