CSI 212 Other, Spring 2012

CREF.DOC (C) Copyright Microsoft Corporation, 1992 This file contains information on the purpose and use of the Microsoft(R) Cross-Reference Utility (CREF) Version 6.00. ================================< Contents >================================ This file has 4 parts: Part Contents ---- -------- 1 Introduction 2 Using CREF 3 Reading Cross-Reference Listings 4 Difference from Previous Releases ==========================< Part 1: Introduction >========================== The Microsoft Cross-Reference Utility (CREF) creates a cross-reference listing of all symbols in an assembly-language program. A cross-reference listing is an alphabetical list of symbols followed by references to where a symbol appears in the source code. CREF is intended for use as a debugging aid to speed up the search for symbols encountered during a debugging session. The cross-reference listing, together with the symbol table created by the assembler, can make debugging and correcting a program easier. ============================< Part 2: Using CREF >========================== CREF creates a cross-reference listing for a program by converting PWB Source Browser database files (those ending with a BSC or an SBR extension) into a readable ASCII file. Command-Line Syntax ------------------- CREF crossreferencefile [, crossreferencelisting] [;] crossreferencefile Source Browser database file. Default filename extension is BSC. crossreferencelisting Readable ASCII cross-reference listing. Default filename extension is REF. If this filename is not supplied on the command line, the base filename of the database file is used and the REF extension is added. Using Prompts to Create a Cross-Reference Listing ------------------------------------------------- You can direct CREF to prompt you for the files it needs by starting CREF with just the command name (CREF). CREF prompts you for the input it needs by displaying the following lines, one at a time: Cross-Reference [.BSC]: Listing [filename.REF]: The prompts correspond to the fields of the CREF command lines. CREF waits for you to respond to each prompt before printing the next one. You must type a cross-reference filename (extension is optional) at the first prompt. For the second prompt, you can either type a filename or press the ENTER key to accept the default displayed in brackets after the prompt. Use of PWBRMAKE with CREF ------------------------- Note that the CREF utility can create reports only from the final form of the Source Browser database files. These files end in BSC (Browser Source Cache), and are created by the utility PWBRMAKE. Because ML creates an intermediate Source Browser file (with the filename extension SBR), CREF will invoke PWBRMAKE to create a BSC file from a single SBR file input. PWBRMAKE takes as input the SBR files created by ML, merges them with other SBR files created from other assembly-language source modules (if any exist), and creates a BSC file as the result. The BSC file contains all of the information (across multiple modules, if necessary) to provide a comprehensive cross-listing file for an entire project. CREF will invoke PWBRMAKE only when a single SBR file is given as input to the utility; therefore, you must create a BSC database file from the assembler-generated SBR files before invoking CREF. An example of running PWBRMAKE is: PWBRMAKE FILENAME.SBR FILE2.SBR FILE3.SBR ... FILEN.SBR This example creates a BSC file using the base name of the first SBR file on the command line. In this case, the resultant file would be named FILENAME.BSC. By using the BSC Source Browser database files, CREF is able to provide cross-reference files for either a single assembly-language module or for an entire multimodule assembly-language project. Below are the steps necessary for both scenarios. For more information on PWBRMAKE and its available switches, see the "Tools" section of the Macro Assembler Reference manual, or type PWBRMAKE /? at the command line to get a quick-reference screen. Creating Single-Module Cross-Reference Listings ----------------------------------------------- - Using ML with the /FR switch, create an SBR file for the assembly-language module. An example is: ML /c /FR filename.ASM This creates a file FILENAME.SBR (as well as FILENAME.OBJ). - Invoke CREF using the database file created above (FILENAME.SBR) as the input cross-reference file. An example of this is: CREF FILENAME.SBR, FILENAME.REF This creates the cross-reference listing FILENAME.REF. Note that because CREF is capable only of reading Source Browser BSC database files, the PWBRMAKE utility is automatically invoked to convert the SBR on the command line into a BSC file. Creating Multimodule Cross-Reference Listings ---------------------------------------------- - Using ML with the /FR switch, create an SBR file for each of the assembly-language modules. An example is: ML /c /FR *.ASM This creates a file FILENAME.SBR (as well as FILENAME.OBJ). - Invoke CREF using the database file created above (FILENAME.BSC) as the input cross-reference file. An example of this is: CREF FILENAME.BSC, FILENAME.REF The cross-reference listing FILENAME.REF is created. This particular example will have all of the symbols from all of the modules in one cross-reference listing file. =================< Part 3: Reading Cross-Reference Listings >============== The cross-reference listing contains the name of each symbol defined in your program. Each name is followed by a list of source filenames in which the symbol appears. Each source name is then followed by a list of line numbers representing the line or lines in the source file in which a symbol is referenced. Line numbers in which a symbol is defined are marked with the number sign (#). Example ------- Below is a sample assembly-language source-code module, followed by the resulting cross-reference listing file. .DOSSEG .MODEL small, os_dos, pascal .STACK 100h .DATA PUBLIC message, lmessage message BYTE "Hello World!!!!" lmessage EQU $-message .CODE .STARTUP EXTERN display:NEAR call display mov ax, 4C00h int 21h .EXIT END Example Reference Listing (Created from above source-code module) ----------------------------------------------------------------- Microsoft Cross-Reference Version 6.00 Mon Nov 18 15:47:26 1991 Symbol Cross-Reference (# definition) Cref-1 @code ..\hello.asm . . . . . . . . 2# @CodeSize ..\hello.asm . . . . . . . . 2# @data ..\hello.asm . . . . . . . . 2# @DataSize ..\hello.asm . . . . . . . . 2# @fardata ..\hello.asm . . . . . . . . 2# @fardata? ..\hello.asm . . . . . . . . 2# @Interface ..\hello.asm . . . . . . . . 2# @Model ..\hello.asm . . . . . . . . 2# @stack ..\hello.asm . . . . . . . . 2# @Startup ..\hello.asm . . . . . . . . 14# _DATA ..\hello.asm . . . . . . . . 2# _TEXT ..\hello.asm . . . . . . . . 2# 12 DGROUP ..\hello.asm . . . . . . . . 2# 2 14 display ..\hello.asm . . . . . . . . 16 17 <Unknown>. . . . . . . . . . 1# hello.asm ..\hello.asm . . . . . . . . 1# lmessage ..\hello.asm . . . . . . . . 10# 7 message ..\hello.asm . . . . . . . . 9# 10 7 STACK ..\hello.asm . . . . . . . . 4# =================< Part 4: Difference from Previous Releases >============== Use Differences --------------- - ML/MASM no longer generates a CRF assembler-specific binary file. Instead, CREF 6.0 uses the generic Source Browser database file (BSC). Because of this, CREF can actually be used with any source-code module or project that is compiled/assembled by a Microsoft product that creates SBR files. Creating multimodule cross-reference listing files is another advantage of using BSC Browser database files. Previous releases of CREF were limited to single modules. Listing Differences ------------------- - All line numbers that are reported are relative to the actual source- code module, not the assembler-generated listing file. This is a direct result of using the Source Browser database files (BSC). These files are not directly related to MASM listings and are generic across Microsoft language products. LIST OF EXAMPLE PROGRAMS (FileList.txt) The programs in this list are supplied with the book: Assembly Language for Intel-Based Computers, 4th Edition by Kip R. Irvine. Prentice-Hall Publishing, 2002. Last update: 12/13/2002 \ (Examples root) b16.asm (blank 16-bit program template) b32.asm (blank 32-bit program template) FileList.txt (this file) \ch03: 16-bit.asm AddSub.asm AddSub2.asm AddSub2r.asm AddSubAlt.asm AddSubR.asm DataDef.asm template.asm \ch04: AddSub3.asm CopyStr.asm Moves.asm Operator.asm Pointers.asm Scale.asm SumArray.asm \ch05: RevStr.asm Stack.asm Sum1.asm Sum2.asm TestLib.asm \ch06: ArryScan.asm Encrypt.asm Finite.asm Loopnz.asm ProcTble.asm Regist.asm RegistAlt.asm SetCur.asm \ch07: Bmult.asm Divide32.asm Express.asm ExtAdd.asm Multiply.asm MultiShf.asm WriteBin.asm \ch08: AddTwo.asm ArryFill.asm ArrySum.asm CSum.asm Endless.asm Fact.asm Params.asm Recurse.asm Reglist.asm Swap.asm \ch08\ModSum: _arrysum.asm _display.asm _prompt.asm make32.bat readme.txt sum.inc Sum_main.asm \ch09: Cmpsb.asm Compare.asm CopyStr.asm Length.asm Mult.asm Table.asm Table2.asm Trim.asm Ucase.asm \ch09\Bsearch: B_main.asm Bsearch.asm Bsearch.inc Bsort.asm FillArry.asm make32.bat PrtArray.asm readme.txt \ch10: AllPoints.asm Fibon.asm HelloNew.asm List.asm Macro1.asm Macro2.asm Macro3.asm MacTest.asm makeHello16.bat readme.txt Repeat.asm ShowTime.asm Struct1.asm Struct2.asm TestDump.asm Union.asm Walk.asm Wraps.asm \ch11: AppendFile.asm BuildKeybd.bat Console1.asm Console2.asm Keybd.asm output.txt ReadConsole.asm ReadFile.asm Scroll.asm ShowTime.asm Timer.asm TimingLoop.asm WriteColors.asm WriteFile.asm \ch11\WinApp: make32.bat readme.txt WinApp.asm WinApp.exe \ch12\BorlandCPP\LongRand longrand.~de LongRand.asm longrand.csm longrand.DSW longrand.exe longrand.ide longrand.mbt longrand.mrt LONGRAND.OBJ longrand.r$p main.cpp main.obj \ch12\BorlandCPP\ReadSec Ex1.~de ex1.csm ex1,DSW ex1.exe Ex1.ide ex1.mbt ex1.mrt ex1.r$p EX1.TR main.cpp main.obj ReadSec.asm READSEC.OBJ \ch12\strings readme.txt Strings.cpp strings.dsp strings.dsw strings.ncb strings.opt strings.plg \ch12\strings\debug strings.asm strings.exe strings.ilk strings.obj vc60.idb vc60.pdb \ch12VisualCPP Visual C++ Workspace files: VisualCPP.dsw VisualCPP.ncb VisualCPP.opt \ch12\VisualCPP\Addem addem.asm addMain.cpp Addem.dsp Addem.dsw Addem.ncb ADDEM.obj Addem.opt Addem.plg \ch12\VisualCPP\ArraySum ArraySum.cpp ArraySum.asm ArraySum.dsw ArraySum.ncb ArraySum.opt ArraySum.plg \ch12\VisualCPP\Encode Encode.cpp Encode2.cpp Encode.dsp Encode.dsw Encode.ncb Encode.opt Encode.plg infile.txt outfile.txt Translat.cpp Translat.h \ch12\VisualCPP\FindArray FindArr.cpp FindArr.h FindArray.dsp FindArray.plg main.asm main.cpp Scasd.asm \ch12\VisualCPP\InlineTest InlineTest.dsp InlineTest.plg test1.cpp \ch13: binary_array file.bin Binfile.asm DateTime.asm Encrypt.asm Fileio.asm Hello.asm Keybd.asm long_filename.txt my_output_file.txt my_text_file.txt Readfile.asm \ch14: Cluster.asm DiskSpc.asm Sector32.asm \ch15: ClearKbd.asm Colorstr.asm Colorst2.asm Delay.asm GetVideo.asm Keybd.asm Mode13.asm Mouse.asm Pixel1.asm Pixel2.asm TextWin.asm \ch16: CtrlBrk.asm HelloCom.asm MultCode.asm MultData.asm MultiSeg.asm No_Reset.asm No_Reset.com \ch16\Seg2: make16.bat Seg2.asm Seg2a.asm \ch17: Expr.asm Math.asm Speaker.asm \Lib16: Irvine16.asm TestLib.asm Irvine16.inc IRVINE16.LIB LIB.EXE asm16.bat make16.bat makeLib.bat \Lib32: Irvine32.asm LibTest.asm Irvine32.inc Irvine32.lib Macros.inc make32.bat makeLib.bat SmallWin.inc \supplements encode.asm getVideo.asm input.txt xlat.asm TITLE Link Library Functions (Irvine16.asm) Comment @ This library was created exlusively for use with the book, "Assembly Language for Intel-Based Computers, 4th Edition", by Kip R. Irvine, 2002. Copyright 2002, Prentice-Hall Incorporated. No part of this file may be reproduced, in any form or by any other means, without permission in writing from the publisher. Updates to this file will be posted on the book's site: www.nuvisionmiami.com/books/asm Recent update history: 10/20/2002: GetMaxXY added. ReadInt fixed so it sets the Overflow flag (rather than Carry) 10/28/2002: Changed capitalization of GetCommandtail 11/06/2002: Removed ShowRegister macro (it is now mShowRegister, in Macros.inc) 11/24/2002: ReadString 12/11/2002: Added WriteBinB and WriteHexB. Modified WriteBin and WriteHex. Acknowledgements: ------------------------------ Most of the code in this library was written by Kip Irvine. Special thanks to Gerald Cahill for his many insights, suggestions, and bug fixes! Also to Courtney Amor, a student at UCLA. Alphabetical Listing of Procedures ---------------------------------- (Unless otherwise marked, all procedures are documented in Chapter 5.) ClrScr Crlf Delay DumpMem DumpRegs GetCommandtail GetMaxXY Added 10/20/2002 GetMseconds Added 10/21/2002 Gotoxy IsDigit Random32 Randomize RandomRange ReadChar ReadHex ReadInt ReadString Str_compare Chapter 9 Str_copy Chapter 9 Str_length Chapter 9 Str_trim Chapter 9 Str_ucase Chapter 9 WaitMsg WriteBin WriteChar WriteDec WriteHex WriteInt WriteString =================================@ INCLUDE Irvine16.inc INCLUDE Macros.inc ; Write <count< spaces to standard output WriteSpace MACRO count Local spaces .data spaces BYTE count dup(' '),0 .code mov dx,OFFSET spaces call WriteString ENDM ; Send a newline sequence to standard output NewLine MACRO Local temp .data temp BYTE 13,10,0 .code push dx mov dx,OFFSET temp call WriteString pop dx ENDM Comment ! ;------------------------------------- mShowRegister MACRO regName, regVal Local str ; ; Show a single register value ;------------------------------------- .data str BYTE " &regName=",0 .code push eax push edx ; save EDX mov dx,OFFSET str call WriteString pop edx ; must restore EDX now IF (TYPE regVal) EQ 4 mov eax,regVal ; register value ELSE mov eax,0 mov ax,regVal ENDIF call WriteHex pop eax ENDM ! ;------------------------------------- ShowFlag MACRO flagName,shiftCount LOCAL flagStr, flagVal, L1 ; ; Display a single flag value ;------------------------------------- .data flagStr BYTE " &flagName=" flagVal BYTE ?,0 .code push ax push dx mov ax,flags ; retrieve the flags mov flagVal,'1' shr ax,shiftCount ; shift into carry flag jc L1 mov flagVal,'0' L1: mov dx,OFFSET flagStr ; display flag name and value call WriteString pop dx pop ax ENDM ;--------- END OF MACRO DEFINITIONS --------------------------- ;********************* SHARED DATA AREA ********************** .data? buffer BYTE 512 dup(?) ;************************************************************* .code ;------------------------------------------------------ Clrscr PROC ; ; Clears the screen (video page 0) and locates the cursor ; at row 0, column 0. ; Receives: nothing ; Returns: nothing ;------------------------------------------------------- pusha mov ax,0600h ; scroll window up mov cx,0 ; upper left corner (0,0) mov dx,184Fh ; lower right corner (24,79) mov bh,7 ; normal attribute int 10h ; call BIOS mov ah,2 ; locate cursor at 0,0 mov bh,0 ; video page 0 mov dx,0 ; row 0, column 0 int 10h popa ret Clrscr ENDP ;----------------------------------------------------- Crlf PROC ; ; Writes a carriage return / linefeed ; sequence (0Dh,0Ah) to standard output. ;----------------------------------------------------- NewLine ; invoke a macro ret Crlf ENDP ;----------------------------------------------------------- Delay PROC ; ; Create an n-millisecond delay. ; Receives: EAX = milliseconds ; Returns: nothing ; Remarks: May only used under Windows 95, 98, or ME. Does ; not work under Windows NT, 2000, or XP, because it ; directly accesses hardware ports. ; Source: "The 80x86 IBM PC & Compatible Computers" by ; Mazidi and Mazidi, page 343. Prentice-Hall, 1995. ;----------------------------------------------------------- MsToMicro = 1000000 ; convert ms to microseconds ClockFrequency = 15085 ; microseconds per tick .code pushad ; Convert milliseconds to microseconds. mov ebx,MsToMicro mul ebx ; Divide by clock frequency of 15.085 microseconds, ; producing the counter for port 61h. mov ebx,ClockFrequency div ebx ; eax = counter mov ecx,eax ; Begin checking port 61h, watching bit 4 toggle ; between 1 and 0 every 15.085 microseconds. L1: in al,61h ; read port 61h and al,10h ; clear all bits except bit 4 cmp al,ah ; has it changed? je L1 ; no: try again mov ah,al ; yes: save status dec ecx cmp ecx,0 ; loop finished yet? ja L1 quit: popad ret Delay ENDP ;--------------------------------------------------- DumpMem PROC LOCAL unitsize:word, byteCount:word ; ; Writes a range of memory to standard output ; in hexadecimal. ; Receives: SI = starting OFFSET, CX = number of units, ; BX = unit size (1=byte, 2=word, or 4=doubleword) ; Returns: nothing ;--------------------------------------------------- .data oneSpace BYTE ' ',0 dumpPrompt BYTE 13,10,"Dump of offset ",0 .code pushad mov dx,OFFSET dumpPrompt call WriteString movzx eax,si call WriteHex NewLine mov byteCount,0 mov unitsize,bx cmp bx,4 ; select output size je L1 cmp bx,2 je L2 jmp L3 L1: ; doubleword output mov eax,[si] call WriteHex WriteSpace 2 add si,bx Loop L1 jmp L4 L2: ; word output mov ax,[si] ; get a word from memory ror ax,8 ; display high byte call HexByte ror ax,8 ; display low byte call HexByte WriteSpace 1 ; display 1 space add si,unitsize ; point to next word Loop L2 jmp L4 ; Byte output: 16 bytes per line L3: mov al,[si] call HexByte inc byteCount WriteSpace 1 inc si ; if( byteCount mod 16 == 0 ) call Crlf mov dx,0 mov ax,byteCount mov bx,16 div bx cmp dx,0 jne L3B NewLine L3B: Loop L3 jmp L4 L4: NewLine popad ret DumpMem ENDP ;-------------------------------------------------- GetCommandtail PROC ; ; Gets a copy of the DOS command tail at PSP:80h. ; Receives: DX contains the offset of the buffer ; that receives a copy of the command tail. ; Returns: CF=1 if the buffer is empty; otherwise, ; CF=0. ; Last update: 10/28/02 ;-------------------------------------------------- push es pusha ; save general registers mov ah,62h ; get PSP segment address int 21h ; returned in BX mov es,bx ; copied to ES mov si,dx ; point to buffer mov di,81h ; PSP offset of command tail mov cx,0 ; byte count mov cl,es:[di-1] ; get length byte cmp cx,0 ; is the tail empty? je L2 ; yes: exit cld ; no: scan forward mov al,20h ; space character repz scasb ; scan for non space jz L2 ; all spaces found dec di ; non space found inc cx L1: mov al,es:[di] ; copy tail to buffer mov [si],al ; pointed to by DS:SI inc si inc di loop L1 clc ; CF=0 means tail found jmp L3 L2: stc ; set carry: no command tail L3: mov byte ptr [si],0 ; store null byte popa ; restore registers pop es ret GetCommandtail ENDP ;---------------------------------------------------------------- GetMaxXY PROC ; Returns the current columns (X) and rows (Y) of the console ; window buffer. These values can change while a program is running ; if the user modifies the properties of the application window. ; Receives: nothing ; Returns: DH = rows (Y); DL = columns (X) ; (range of each is 1-255) ; ; Added to the library on 10/20/2002, on the suggestion of Ben Schwartz. ;---------------------------------------------------------------- .data videoInfo VideoInfoStruc <> str1 BYTE "Video function 1Bh is not supported",0dh,0ah,0 .code push ax push bx push cx mov ah,1Bh ; get video information mov bx,0 ; always zero push ds pop es mov di,OFFSET videoInfo int 10h cmp al,1Bh jne notSupported mov dh,videoInfo.numCharRows mov dl,BYTE PTR videoInfo.numCharColumns jmp finished notSupported: mov dx,OFFSET str1 call WriteString finished: pop cx pop bx pop ax ret GetMaxXY ENDP ;------------------------------------------------------- GetMseconds PROC LOCAL hours:BYTE, minutes:BYTE, seconds:BYTE, hhss:BYTE ; ; Returns the number of milliseconds that have elapsed ; since midnight of the current day. ; Receives: nothing ; Returns: EAX = milliseconds, accurate to 50 milliseconds ;-------------------------------------------------------- .data timerec TimeRecord <> mSec DWORD ? .code push ebx push ecx push edx ; get system time (see Section 13.2.4) mov ah,2Ch int 21h mov hours,ch mov minutes,cl mov seconds,dh mov hhss,dl ; (mSec = hours * 3600000) movzx eax,hours mov ebx,3600000 mul ebx mov mSec,eax ; mSec = mSec + (minutes * 60000) movzx eax,minutes mov ebx,60000 mul ebx add mSec,eax ; mSec = mSec + (seconds * 1000) movzx eax,seconds mov ebx,1000 mul ebx add mSec,eax ; mSec = mSec + (hundredths * 10) movzx eax,hhss mov ebx,10 mul ebx add mSec,eax ; Return mSec in EAX mov eax,mSec pop edx pop ecx pop ebx ret GetMseconds ENDP ;--------------------------------------------------- Gotoxy PROC ; ; Sets the cursor position on video page 0. ; display page. ; Receives: DH,DL = row, column ; Returns: nothing ;--------------------------------------------------- pusha mov ah,2 mov bh,0 int 10h popa ret Gotoxy ENDP HexByte PROC LOCAL theByte:BYTE ; Display the byte in AL in hexadecimal ; Called only by DumpMem. Updated 9/21/01 pusha mov theByte,al ; save the byte mov cx,2 HB1: rol theByte,4 mov al,theByte and al,0Fh mov bx,OFFSET xtable xlat ; insert hex char in the buffer ; and display using WriteString mov buffer,al mov [buffer+1],0 mov dx,OFFSET buffer call WriteString Loop HB1 popa ret HexByte ENDP ;--------------------------------------------------- DumpRegs PROC ; ; Displays EAX, EBX, ECX, EDX, ESI, EDI, EBP, ESP in ; hexadecimal. Also displays the Zero, Sign, Carry, and ; Overflow flags. ; Receives: nothing. ; Returns: nothing. ; ; Warning: do not create any local variables or stack ; parameters, because they will alter the EBP register. ;--------------------------------------------------- .data flags WORD ? saveIP WORD ? saveSP WORD ? .code pop saveIP ; get current IP mov saveSP,sp ; save SP's value at entry push saveIP ; replace it on stack push eax pushfd ; push flags pushf ; copy flags to a variable pop flags NewLine mShowRegister EAX,EAX mShowRegister EBX,EBX mShowRegister ECX,ECX mShowRegister EDX,EDX NewLine mShowRegister ESI,ESI mShowRegister EDI,EDI mShowRegister EBP,EBP movzx eax,saveSP mShowRegister ESP,EAX NewLine movzx eax,saveIP mShowRegister EIP,EAX movzx eax,flags mShowRegister EFL,EAX ; Show the flags ShowFlag CF,1 ShowFlag SF,8 ShowFlag ZF,7 ShowFlag OF,12 NewLine NewLine popfd ; restore flags pop eax ; restore EAX ret DumpRegs ENDP ;----------------------------------------------- Isdigit PROC ; ; Determines whether the character in AL is a ; valid decimal digit. ; Receives: AL = character ; Returns: ZF=1 if AL contains a valid decimal ; digit; otherwise, ZF=0. ;----------------------------------------------- cmp al,'0' jb ID1 cmp al,'9' ja ID1 test ax,0 ; set ZF = 1 ID1: ret Isdigit ENDP ;-------------------------------------------------------------- RandomRange PROC ; ; Returns an unsigned pseudo-random 32-bit integer ; in EAX, between 0 and n-1. Input parameter: ; EAX = n. ;-------------------------------------------------------------- push bp mov bp,sp push ebx push edx mov ebx,eax ; maximum value call Random32 ; eax = random number mov edx,0 div ebx ; divide by max value mov eax,edx ; return the remainder pop edx pop ebx pop bp ret RandomRange ENDP ;-------------------------------------------------------------- Random32 PROC ; ; Returns an unsigned pseudo-random 32-bit integer ; in EAX,in the range 0 - FFFFFFFFh. ;-------------------------------------------------------------- .data seed dd 1 .code push edx mov eax, 343FDh imul seed add eax, 269EC3h mov seed, eax ; save the seed for the next call ror eax,8 ; rotate out the lowest digit (10/22/00) pop edx ret Random32 ENDP ;-------------------------------------------------------- Randomize PROC ; ; Re-seeds the random number generator with the current time ; in milliseconds. ; Last update: 10/21/2002 ;-------------------------------------------------------- push eax call GetMseconds mov seed,eax pop eax ret Randomize ENDP ;--------------------------------------------------------- ReadChar PROC ; ; Reads one character from standard input. The character is ; not echoed on the screen. Waits for the character if none is ; currently in the input buffer. ; Receives: nothing ; Returns: AL = ASCII code ;---------------------------------------------------------- mov ah,1 int 21h ret ReadChar ENDP ;-------------------------------------------------------- ReadHex PROC ; ; Reads a 32-bit hexadecimal integer from standard input, ; stopping when the Enter key is pressed. ; Receives: nothing ; Returns: EAX = binary integer value ; Remarks: No error checking performed for bad digits ; or excess digits. ; Last update: 11/7/01 ;-------------------------------------------------------- .data HMAX_DIGITS = 128 Hinputarea BYTE HMAX_DIGITS dup(0),0 xbtable BYTE 0,1,2,3,4,5,6,7,8,9,7 DUP(0FFh),10,11,12,13,14,15 numVal DWORD ? charVal BYTE ? .code push ebx push ecx push edx push esi mov edx,OFFSET Hinputarea mov esi,edx ; save in ESI also mov ecx,HMAX_DIGITS call ReadString ; input the string mov ecx,eax ; save length in ECX ; Start to convert the number. B4: mov numVal,0 ; clear accumulator mov ebx,OFFSET xbtable ; translate table ; Repeat loop for each digit. B5: mov al,[esi] ; get character from buffer cmp al,'F' ; lowercase letter? jbe B6 ; no and al,11011111b ; yes: convert to uppercase B6: sub al,30h ; adjust for table xlat ; translate to binary mov charVal,al mov eax,16 ; numVal *= 16 mul numVal mov numVal,eax movzx eax,charVal ; numVal += charVal add numVal,eax inc esi ; point to next digit loop B5 ; repeat, decrement counter mov eax,numVal ; return binary result pop esi pop edx pop ecx pop ebx ret ReadHex ENDP ;-------------------------------------------------------- ReadInt PROC uses ebx ecx edx esi LOCAL Lsign:DWORD, saveDigit:DWORD ; ; Reads a 32-bit signed decimal integer from standard ; input, stopping when the Enter key is pressed. ; All valid digits occurring before a non-numeric character ; are converted to the integer value. Leading spaces are ; ignored, and an optional leading + or - sign is permitted. ; Receives: nothing ; Returns: If OF=0, the integer is valid, and EAX = binary value. ; If OF=1, the integer is invalid and EAX = 0. ; ; Credits: Thanks to Courtney Amor, a student at the UCLA Mathematics ; department, for pointing out improvements that have been ; implemented in this version. ; Last update: 10/20/2002 ;-------------------------------------------------------- .data LMAX_DIGITS = 80 Linputarea BYTE LMAX_DIGITS dup(0),0 overflow_msgL BYTE 0dh,0ah,"<32-bit integer overflow>",0 invalid_msgL BYTE "0dh,0ah,<invalid integer>",0 .code ; Input a string of digits using ReadString. mov edx,offset Linputarea mov esi,edx ; save offset in ESI mov ecx,LMAX_DIGITS call ReadString mov ecx,eax ; save length in CX mov Lsign,1 ; assume number is positive cmp ecx,0 ; greater than zero? jne L1 ; yes: continue mov eax,0 ; no: set return value jmp L10 ; and exit ; Skip over any leading spaces. L1: mov al,[esi] ; get a character from buffer cmp al,' ' ; space character found? jne L2 ; no: check for a sign inc esi ; yes: point to next char loop L1 jcxz L8 ; quit if all spaces ; Check for a leading sign. L2: cmp al,'-' ; minus sign found? jne L3 ; no: look for plus sign mov Lsign,-1 ; yes: sign is negative dec ecx ; subtract from counter inc esi ; point to next char jmp L4 L3: cmp al,'+' ; plus sign found? jne L4 ; no: must be a digit inc esi ; yes: skip over the sign dec ecx ; subtract from counter ; Test the first digit, and exit if it is nonnumeric. L3A:mov al,[esi] ; get first character call IsDigit ; is it a digit? jnz L7A ; no: show error message ; Start to convert the number. L4: mov eax,0 ; clear accumulator mov ebx,10 ; EBX is the divisor ; Repeat loop for each digit. L5: mov dl,[esi] ; get character from buffer cmp dl,'0' ; character < '0'? jb L9 cmp dl,'9' ; character > '9'? ja L9 and edx,0Fh ; no: convert to binary mov saveDigit,edx imul ebx ; EDX:EAX = EAX * EBX mov edx,saveDigit jo L6 ; quit if overflow add eax,edx ; add new digit to AX jo L6 ; quit if overflow inc esi ; point to next digit jmp L5 ; get next digit ; Overflow has occured, unlesss EAX = 80000000h ; and the sign is negative: L6: cmp eax,80000000h jne L7 cmp Lsign,-1 jne L7 ; overflow occurred jmp L9 ; the integer is valid ; Choose "integer overflow" messsage. L7: mov edx,OFFSET overflow_msgL jmp L8 ; Choose "invalid integer" message. L7A: mov edx,OFFSET invalid_msgL ; Display the error message pointed to by EDX and set the Overflow flag L8: call WriteString call Crlf mov al,127 add al,1 ; set Overflow flag mov eax,0 ; set return value to zero jmp L10 ; and exit ; IMUL leaves the Sign flag in an undeterminate state, so the OR instruction ; determines the sign of the iteger in EAX. L9: imul Lsign ; EAX = EAX * sign or eax,eax ; determine the number's sign L10:ret ReadInt ENDP ;-------------------------------------------------------- ReadString PROC ; Reads a string from standard input and places the ; characters in a buffer. Reads past end of line, ; and removes the CF/LF from the string. ; Receives: DS:DX points to the input buffer, ; CX = maximum input chars, plus 1. ; Returns: AX = size of the input string. ; Comments: Stops either when Enter (0Dh) is pressed, ; or (CX-1) characters have been read. ;-------------------------------------------------------- push cx ; save registers push si push cx ; save digit count again mov si,dx ; point to input buffer dec cx ; save room for null byte L1: mov ah,1 ; function: keyboard input int 21h ; DOS returns char in AL cmp al,0Dh ; end of line? je L2 ; yes: exit mov [si],al ; no: store the character inc si ; increment buffer pointer loop L1 ; loop until CX=0 L2: mov byte ptr [si],0 ; end with a null byte pop ax ; original digit count sub ax,cx ; AX = size of input string pop si ; restore registers pop cx ret ReadString ENDP ;---------------------------------------------------------- Str_compare PROC USES ax dx si di, string1:PTR BYTE, string2:P