汇编语言-004（LABEL 、间接寻址、变址操作数、指针使用、TypeDef、LOOP、DWORD变量交换高位低位字）

1： LABEL : 为一个标号定义大小属性，但不分配内存与下一个变量共用内存，与C中UNION类似

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCoed:DWORD.data
val16 LABEL WORD
val32 DWORD 12345678hLongValue LABEL DWORD
val1 WORD 5678h
val2 WORD 1234h.code
main PROCmov ax,val16    ;5678hmov dx,[val16+2];1234hmov eax,LongValue  ;12345678hINVOKE ExitProcess,0
main ENDP
END main

2：间接寻址，因为常数偏移量寻址多个数组元素时，直接寻址不实用，反之，用寄存器作为指针（称为间接寻址）并控制寄存器的值，如果一个操作数使用的间接寻址，就称为间接操作数

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data
byteVal BYTE 10h.code
main PROCmov esi,OFFSET byteValmov al,[esi];PTR与间接操作数一起使用;inc [esi] 一个操作数的大小无法从指令看出，报错inc BYTE PTR [esi] INVOKE ExitProcess,0
main ENDP
END main

3：间接寻址访问数组案例

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data
arrayB BYTE 10h,20h,30h
arrayW WORD 1000h,2000h,3000h
arrayD DWORD 10000h,20000h,30000h.code
main PROCmov esi,OFFSET arrayBmov al,[esi]inc esimov al,[esi]inc esimov al,[esi]mov esi,OFFSET arrayWmov ax,[esi]add esi,2mov ax,[esi]add esi,2mov ax,[esi]mov esi,OFFSET arrayDmov eax,[esi]add esi,4mov eax,[esi]add esi,4mov eax,[esi]INVOKE ExitProcess,0
main ENDP
END main

4：变址操作数，访问数组更灵活

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data
arrayB BYTE 10h,20h,30h
arrayW WORD 1000h,2000h,3000h
arrayD DWORD 10000h,20000h,30000h.code
main PROCmov esi,0mov al,arrayB[esi]  ;第一种格式constant [reg]mov esi,OFFSET arrayW ;第二种格式 [constant + reg]mov ax,[esi]mov ax,[esi+2]mov ax,[esi+4];比例因子mov esi,3 * TYPE arrayDmov eax,arrayD[esi];更简单的做法mov esi,3 ;下标mov eax,arrayD[esi * 4];使用TYPE 更灵活mov eax,arrayD[esi * TYPE arrayD]INVOKE ExitProcess,0
main ENDP
END main

5：指针使用

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data
arrayB BYTE 10h,20h,30h,40h
arrayW WORD 1000h,2000h,3000h,4000h
ptrB DWORD arrayB
ptrW DWORD arrayW
;使用OFFSET运算符使这种关系更加准确
optrB DWORD OFFSET arrayB
optrW DWORD OFFSET arrayW.code
main PROCINVOKE ExitProcess,0
main ENDP
END main

6： TypeDef : 定义新类型，与C的typedef 类似，不在.data段内定义的

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORDPBYTE TYPEDEF PTR BYTE     ;字节指针
PWORD TYPEDEF PTR WORD     ;字指针
PDWORD TYPEDEF PTR DWORD  ;双字指针.data
arrayB BYTE 10h,20h,30h,40h
arrayW WORD 1,2,3
arrayD DWORD 4,5,6ptr0 PBYTE ? ;未初始化
ptr1 PBYTE arrayB
ptr2 PWORD arrayW
ptr3 PDWORD arrayD.code
main PROCmov esi,ptr1mov al,[esi]mov esi,ptr2mov ax,[esi]mov esi,ptr3mov eax,[esi]INVOKE ExitProcess,0
main ENDP
END main

7： LOOP : 循环伪指令使用

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data
count DWORD ?
bytes BYTE 1,2,3,4
.code
main PROCmov ecx,100     ;设置外层循环计数
L1:mov count,ecx    ;保存外层计数mov ecx,20       ;设置内层计数
L2:mov eax,ecxloop L2       ;重复内层mov ecx,count ;恢复外层计数loop L1       ;重复外层INVOKE ExitProcess,0
main ENDP
END main

8： LOOP_ARRAY : 数组元素求和例子

.386
.model flat,stdcall
.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data
intarray DWORD 10000h,20000h,30000h,40000h.code
main PROCmov edi,OFFSET intarray    ;EDI=intarray地址 作变址操作数mov ecx,LENGTHOF intarray  ;循环计数器初始化为元素个数mov eax,0                  ;EAX 记录总数
L1:add eax,[edi]              ;加一个元素add edi,TYPE intarray      ;指向下一个元素loop L1                    ;重复INVOKE ExitProcess,0
main ENDP
END main

9： LOOP_STRAING : 复制字符串例子

.386
.model flat,stdcall
.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data
source BYTE "This is the source string",0
target BYTE  SIZEOF source DUP(0).code
main PROCmov esi,0               ;变址计数器mov ecx,SIZEOF source   ;循环计数器
L1:mov al,source[esi]      ;从源字符串取一个字符mov target[esi],al      ;保存到目标字符串inc esi                 ;指向下一个字节loop L1                 ;重复INVOKE ExitProcess,0
main ENDP
END main

10: DWORD变量交换高位低位字

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data
tword LABEL WORD
three DWORD 12345678h  ;56781234.code
main PROCmov si,tword            ;或者用WORD PTR threemov di,[tword+2]        ;WORD PTR [three + 2]mov tword,di            ;WORD PTR threemov [tword+2],si        ;WORD PTR [three + 2]mov eax,threeINVOKE ExitProcess,0
main ENDP
END main