digitStr BYTE \ ; 9
6.LABEL伪指令
?Assigns an alternate label name and type to an existing storage location
?LABEL does not allocate any storage of its own ?Removes the need for the PTR operator
用例： .data
dwList LABEL DWORD wordList LABEL WORD
intList BYTE 00h,10h,00h,20h .code
mov eax,dwList ; 20001000h mov cx,wordList ; 1000h mov dl,intList ; 00h
1. 间接寻址
0 间接操作数
（1）An indirect operand holds the address of a variable, usually an array or string. It can be dereferenced (just like a pointer).
（2）Use PTR to clarify the size attribute of a memory operand. 用例： .data
myCount WORD 0
.code
mov esi,OFFSET myCount
inc [esi] ; error: ambiguous inc WORD PTR [esi] ; ok
2.变址操作数：把常量和寄存器相加以得到一个有效地址
有两种格式：[label + reg] 用例： .data
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label[reg]
arrayW WORD 1000h,2000h,3000h .code
mov esi,0
mov ax,[arrayW + esi] ; AX = 1000h
mov ax,arrayW[esi] ; alternate format add esi,2
add ax,[arrayW + esi] 3.指针：包含其他变量地址的变量 用例： .data
arrayW WORD 1000h,2000h,3000h ptrW DWORD arrayW .code
mov esi,ptrW
mov ax,[esi] ; AX = 1000h
练习题：书P96 第7题 ，第8题 作业题
5、JMP 和LOOP
1.JMP指令导致向代码段内的目的地址做无条件转移。目的标号的偏移地址被装入指令 指针中。
格式：JMP 目的地址
JMP指令是无条件的，因此循环会屋休止地持续下去，知道满足其他条件退 出为止。
创建一个循环 top: . .
jmp top ；无限循环
2.LOOP指令：重复执行一块语句，执行的次数是特定的。
ECX被自动用作计数器，在每次循环后减1 格式：LOOP 目的地址
执行LOOP指令两步：
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首先ECX减1
接着，与0比较。如果ECX!=0,跳转到目的地址； 如果ECX=0， 不发生跳转。
注意：循环开始之前将ECX初始化为0，结果循环
4292967296次。 循环的目的地址与当前地址只能在相距-128~+127字节范围内。 3.循环的嵌套：
.data
count DWORD ? .code
mov ecx,100 ; set outer loop count L1:
mov count,ecx ; save outer loop count mov ecx,20 ; set inner loop count L2: . .
loop L2 ; repeat the inner loop mov ecx,count ; restore outer loop count loop L1 ; repeat the outer loop
例题：书P98 整数数组求和
书P99 复制字符串
第五章 过程
一．与数据库链接
链接库是一个文件，其中包含了已经编译成机器码的过程 命令： link hello.obj irvine32.lib
二．书中的链接库
CloseFile – Closes an open disk file
Clrscr - Clears console, locates cursor at upper left corner
CreateOutputFile - Creates new disk file for writing in output mode Crlf - Writes end of line sequence to standard output
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Delay - Pauses program execution for n millisecond interval DumpMem - Writes block of memory to standard output in hex DumpRegs – Displays general-purpose registers and flags (hex) GetCommandtail - Copies command-line args into array of bytes GetMaxXY - Gets number of cols, rows in console window buffer GetMseconds - Returns milliseconds elapsed since midnight
GetTextColor - Returns active foreground and background text colors in the console window
Gotoxy - Locates cursor at row and column on the console
IsDigit - Sets Zero flag if AL contains ASCII code for decimal digit (0–9) MsgBox, MsgBoxAsk – Display popup message boxes OpenInputFile – Opens existing file for input
ParseDecimal32 – Converts unsigned integer string to binary ParseInteger32 - Converts signed integer string to binary
Random32 - Generates 32-bit pseudorandom integer in the range 0 to FFFFFFFFh
Randomize - Seeds the random number generator
RandomRange - Generates a pseudorandom integer within a specified range ReadChar - Reads a single character from standard input ReadFromFile – Reads input disk file into buffer
ReadDec - Reads 32-bit unsigned decimal integer from keyboard ReadHex - Reads 32-bit hexadecimal integer from keyboard ReadInt - Reads 32-bit signed decimal integer from keyboard ReadKey – Reads character from keyboard input buffer
ReadString - Reads string from standard input, terminated by [Enter]
SetTextColor - Sets foreground and background colors of all subsequent console text output
StrLength – Returns length of a string
WaitMsg - Displays message, waits for Enter key to be pressed WriteBin - Writes unsigned 32-bit integer in ASCII binary format.
WriteBinB – Writes binary integer in byte, word, or doubleword format WriteChar - Writes a single character to standard output
WriteDec - Writes unsigned 32-bit integer in decimal format WriteHex - Writes an unsigned 32-bit integer in hexadecimal format
WriteHexB – Writes byte, word, or doubleword in hexadecimal format WriteInt - Writes signed 32-bit integer in decimal format
WriteString - Writes null-terminated string to console window WriteToFile - Writes buffer to output file
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