汇编语言-017（SCASW 、STRUCT 、STRUCT_ALLPOINTS 、STRUCT_ALIGN 、SYSTEMTIME、UNION 、 STRUCTTEST ）

1：SCASW : 在wordArray中扫描16位数值0100h,将匹配元素的偏移量复制到EAX

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data
wordArray WORD 0500h,0400h,0300h,0200h,0100h.code
main PROCmov ax,0100hmov edi,OFFSET wordArraymov ecx,LENGTHOF wordArraycld repne scaswjne L1sub edi,TYPE wordArraymov eax,edijmp quit
L1:mov eax,0
quit:INVOKE ExitProcess,0
main ENDP
END main

2： STRUCT : 伪指令STRUCT 结构的使用

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORD.data
;定义结构
COORD STRUCTX WORD ?Y WORD ?
COORD ENDS
Employee STRUCTIdNum BYTE "000000000"   ;9字节LastName BYTE 30 DUP(0)  ;30字节ALIGN  WORD              ;加1个字节Years WORD 0             ;2ALIGN  DWORD             ;加2个字节SalaryHistory DWORD 0,0,0,0 ;16字节
Employee ENDS     ;共60point1 COORD <5,10>  ;x=5,y=10
point2 COORD <20>    ;x=20,y=?
point3 COORD <>      ;x=?,y=?
worker Employee<>   ;默认初始值
person1 Employee<"555223333">  ;IdNum初始值，其他默认
person2 Employee <,,,2 DUP(20000)> ;只初始化SalaryHistory前两个值，剩下两个0;对齐结构变量
ALIGN DWORD   ;要与结构中最大结构成员对齐
person Employee <>;结构数组
AllPoints COORD 3 DUP(<0,0>)  ;3个结构的X，Y都为0department Employee 5 DUP(<>).code
main PROCmov eax,TYPE Employee  ;60mov eax,SIZEOF Employee;60mov eax,SIZEOF worker  ;60;引用成员mov dx,worker.Yearsmov worker.SalaryHistory,20000  ;第一个工资mov [worker.SalaryHistory+4],3000;第二个工资mov worker.SalaryHistory+4,4000;第二个工资mov edx,OFFSET worker.SalaryHistory ;得到字段的地址;间接寻址操作数mov esi,OFFSET workermov ax,(Employee PTR[esi]).Years;变址操作数可以访问结构数组mov esi,TYPE Employee   ;索引 = 1mov department[esi].Years ,4INVOKE ExitProcess,0
main ENDP
END main

3：STRUCT_ALLPOINTS : 变址寻址操作数遍历结构数组

include Irvine32.incNumPoints = 3
.data
ALIGN WORD
AllPoints COORD NumPoints DUP(<0,0>).code
main PROCmov edi,0  ;数组索引mov ecx,NumPointsmov ax,1  ;起始X,Y的值
L1:mov (COORD PTR AllPoints[edi]).X,axmov AllPoints[edi].Y,axadd edi,TYPE COORDinc axloop L1exit
main ENDP
END main

4：STRUCT_ALIGN : 比较结构内有对齐处理与无对齐处理的访问时间，照道理是有对齐的快，但这里反而是无对齐快

include Irvine32.incEmployeeBad STRUCTIdNum BYTE "000000000"LastName BYTE 30 DUP(0)Years WORD 0SalaryHistory DWORD 0,0,0,0
EmployeeBad ENDSEmployee STRUCTIdNum BYTE "000000000"LastName BYTE 30 DUP(0)ALIGN WORDYears WORD 0ALIGN DWORDSalaryHistory DWORD 0,0,0,0
Employee ENDS.data
ALIGN DWORD
startTime DWORD ? 
emp Employee <>   ;或：EmployeeBad
.code
main PROCcall GetMSecondsmov startTime,eaxmov ecx,0FFFFFFFFh  
L1:mov emp.Years,5mov emp.SalaryHistory,35000loop L1call GetMSecondssub eax,startTimecall WriteDecexit
main ENDP
END main

5： SYSTEMTIME : 使用结构获取系统时间函数

include Irvine32.incCOMMENT %
COORD STRUCTX WORD ?Y WORD ?
COORD ENDS SYSTEMTIME STRUCTwYear WORD ?wMonth WORD ?wDayOfWeek WORD ?wDay  WORD ?wHour WORD ?wMinute WORD ?wSecond WORD ?wMilliseconds WORD ?
SYSTEMTIME ENDS
%.data
sysTime SYSTEMTIME <>.code
main PROCINVOKE GetLocalTime ,ADDR sysTimemovzx eax,sysTime.wYearcall WriteDecexit
main ENDP
END main

6：结构内包括结构的使用

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORDCOORD STRUCTX WORD ?Y WORD ?
COORD ENDS
Rectangle STRUCTUpperLeft COORD <>LowerRight COORD <>
Rectangle ENDS
.data
rect1 Rectangle <>
rect2 Rectangle {}
rect3 Rectangle {{10,10},{50,20}}
rect4 Rectangle <<10,10>,<50,20>>.code
main PROCmov rect1.UpperLeft.X , 10mov esi,OFFSET rect1mov (Rectangle PTR [esi]).UpperLeft.Y,10mov edi,OFFSET rect2.LowerRightmov (COORD PTR [edi]).X,50mov edi,OFFSET rect2.LowerRight.Xmov WORD PTR[edi],50INVOKE ExitProcess,0
main ENDP
END main

7：STRUCT_WALK ：结构应用例子，醉汉行走，利用随机数，选择每一步行走方向

;醉汉行走，教授的起点坐标为25，25，并在周围徘徊include Irvine32.inc
WalkMax = 50
StartX = 25
StartY = 25DrunkardWalk STRUCTpath COORD WalkMax DUP (<0,0>)pathsUsed WORD 0
DrunkardWalk ENDSDisplayPosition PROTO currX:WORD,currY:WORD.data
aWalk DrunkardWalk <>.code
main PROCmov esi,OFFSET aWalkcall TakeDrunkenWalkexit
main ENDP;向随机方向行走（北，南，东，西）
;接收：ESI=DrunkardWalk结构的指针
;返回：结构初始化为随机数
TakeDrunkenWalk PROCLOCAL currX:WORD,currY:WORDpushad;用OFFSET 运算符获取path --COORD 对象数组--的地址，将其复制EDImov edi,esiadd edi,OFFSET DrunkardWalk.path ;OFFSET返回0mov ecx,WalkMax   ;循环计数器mov currX,StartX  ;当前X的位置mov currY,StartY  ;当前Y的位置Again:;把当前位置插入数组mov ax,currXmov (COORD PTR [edi]).X,axmov ax,currYmov (COORD PTR [edi]).Y,axINVOKE DisplayPosition,currX,currYmov eax,4   ;选择一个方向（0到3）call RandomRange.IF eax == 0        ;北dec currY.ELSEIF eax == 1    ;南inc currY.ELSEIF eax == 2    ;西dec currX.ELSEinc currX        ;东.ENDIFadd esi,TYPE COORD  ;指向下一个COORDloop AgainFinish:mov (DrunkardWalk PTR [esi]).pathsUsed,WalkMaxpopadret
TakeDrunkenWalk ENDP;显示当前X和Y的位置
DisplayPosition PROC currX:WORD,currY:WORD
.data
commaStr BYTE ",",0
.codepushadmovzx eax,currX  ;当前X的位置call WriteDecmov edx,OFFSET commaStrcall WriteStringmovzx eax,currYcall WriteDeccall Crlfpopadret
DisplayPosition ENDP
END main

8：UNION : 联合使用

.386
.model flat,stdcall.stack 4096
ExitProcess PROTO,dwExitCode:DWORDInteger UNION   ;初始值要一致，否则就被最大字段的初始值覆盖D DWORD 0W WORD 0B BYTE 0
Integer ENDS;结构中包含联合
FileInfo STRUCTFileID Integer <>FileName BYTE 64 DUP (?)
FileInfo ENDS;也可以在结构中直接定义联合
FileInfo2 STRUCTUNION FileIDD DWORD ?W WORD ?B BYTE ?ENDSFileName BYTE 64 DUP(?)
FileInfo2 ENDS.data
myInt Integer <>
val1 Integer <12345678h>
val2 Integer <100h>
val3 Integer <>.code
main PROCmov val3.B , almov val3.W,axmov val3.D,eaxINVOKE ExitProcess,0
main ENDP
END main