Irvine chapter 10

1
Irvine chapter 10

• Structures and macros

2
A simple point struct used in next program

• COORD STRUCT
• X WORD ?
• Y WORD ?
• COORD ENDS struct requires end-struct

3
3 points initialized to (1,1), (2,2), (3,3)

• TITLE Loop Through Array (AllPoints.asm)
• Loop through the array of points and set their
• X and Y values.
• Last update 11/26/01
• INCLUDE Irvine32.inc
• coor is already defined in smallwin referenced
  by irvine32.inc
• .dataI added a message up here
• Create instances of the COORD structure,
• assigning values to both X and Y
• point1 COORD lt5,10gt
• point2 COORD lt10,20gt
• NumPoints 3
• AllPoints COORD NumPoints DUP(lt0,0gt)3 sets of
  int points
• .code
• main PROC
• mov edi,0 array index
• mov ecx,NumPoints loop counter
• mov ax,1 starting X, Y values
• L1

4
An employee

• typEmployee STRUCT
• Idnum BYTE 9 DUP(0)
• Lastname BYTE 30 DUP(0)
• Years WORD 0
• SalaryHistory DWORD 10 DUP(0)
• typEmployee ENDS

5
Employee slide 1

• TITLE Intro to STRUCT (Struct1.asm)
• INCLUDE Irvine32.inc
• typEmployee STRUCT
• Idnum BYTE 9 DUP(0)
• Lastname BYTE 30 DUP(0)
• Years WORD 0
• SalaryHistory DWORD 10 DUP(0)
• typEmployee ENDS
• .data
• worker typEmployee ltgt
• override all fields. Either angle brackets
• or curly braces can be used
• person1 typEmployee "555223333"

6
Employee slide 2

• .code
• main PROC
• Get the offset of a field within a structure
• mov edx,OFFSET typEmployee.SalaryHistory
• The following generates an "undefined
  identifier" error
• mov edx,OFFSET Salary
• The TYPE, LENGTH, and SIZE operators can be
  applied
• to the structure and its fields
• mov eax,TYPE typEmployee 82
• mov eax,SIZE typEmployee
• mov eax,SIZE worker
• mov eax,SIZEOF worker
• mov eax,TYPE typEmployee.SalaryHistory 4
• mov eax,LENGTH typEmployee.SalaryHistory 10
• mov eax,SIZE typEmployee.SalaryHistory 40
• The TYPE, LENGTH and SIZE operators can be
  applied
• to instances of the structure

7
Structs can be nesteda rectangle consists of
upper left/lower right coords

• TITLE Nested Structures
  (Struct2.asm)
• This program shows how to declare nested
• structures, and how to access the members.
• Last update 8/14/01.
• INCLUDE Irvine32.inc
• Rectangle STRUCT
• UpperLeft COORD ltgt
• LowerRight COORD ltgt
• Rectangle ENDS
• .data
• rect1 Rectangle ltgt
• rect2 Rectangle
• rect3 Rectangle 10,20, 5,15
• rect4 Rectangle lt lt10,20gt, lt5,15gt gt
• .code
• main PROC
• Direct reference to a nested member.

8
Showtime system time struct output (I added
clrscr)

• SYSTEMTIME STRUCT
• wYear WORD ?
• wMonth WORD ?
• wDayOfWeek WORD ?
• wDay WORD ?
• wHour WORD ?
• wMinute WORD ?
• wSecond WORD ?
• wMilliseconds WORD ?
• SYSTEMTIME ENDS
• I added a bunch of output to the original

9
The rest of showtime

• .data
• sysTime SYSTEMTIME ltgt
• XYPos COORD lt10,5gt
• consoleHandle DWORD ?
• colonStr BYTE "",0
• TheTimeIs BYTE "The time is ",0
• .code
• main PROC
• call clrscr
• Get the standard output handle for the Win32
  Console.
• INVOKE GetStdHandle, STD_OUTPUT_HANDLE
• mov consoleHandle,eax
• Set the cursor position and get the local time
  zone.
• INVOKE SetConsoleCursorPosition, consoleHandle,
  XYPos
• INVOKE GetLocalTime,ADDR sysTime
• mov edx,offset year
• call writestring
• movzx eax,sysTime.wYear year
• call WriteDec

10
A drunkards walk

• C\Masm615gtwalk
• 25,25
• 24,25
• 23,25
• 24,25
• 24,24
• 25,24
• 25,25
• 24,25
• 24,26
• 24,25
• 23,25
• 23,26
• 23,25
• 23,26
• 23,27
• 23,26
• 23,25
• 23,24

11
Main proc for drunkards walk

• INCLUDE Irvine32.inc
• WalkMax 30
• StartX 25
• StartY 25
• DrunkardWalk STRUCT
• path COORD WalkMax DUP(lt0,0gt)
• pathsUsed WORD 0
• DrunkardWalk ENDS
• DisplayPosition PROTO currXWORD, currYWORD
• .data
• aWalk DrunkardWalk ltgt
• .code
• main PROC
• mov esi,offset aWalk
• call TakeDrunkenWalk
• exit
• main ENDP

12
The take-a-walk proc

• TakeDrunkenWalk PROC
• LOCAL currXWORD, currYWORD
• Take a walk in random directions (north, south,
  east,
• west).
• Receives ESI points to a DrunkardWalk
  structure
• Returns the structure is initialized with
  random values
• -------------------------------------------------
  ------
• pushad
• Point EDI to the array of COORD objects.
• mov edi,esi
• add edi,OFFSET DrunkardWalk.path
• mov ecx,WalkMax loop counter
• mov currX,StartX current X-location
• mov currY,StartY current Y-location
• Again
• Insert current location in array.
• mov ax,currX
• mov (COORD PTR edi).X,ax

13
A bunch of useful macros

• TITLE Useful Macros (Macro2.ASM)
• This program demonstrates several useful
  macros
• mGotoxy, mWrite, mWriteLn, mWriteStr, mReadStr,
• and mDumpMem.
• Last update 8/17/01.
• INCLUDE Irvine32.inc
• -------------------------------------------------
  ----
• mWriteStr MACRO buffer
• Improved version of mWriteStr that checks for
• a blank argument.
• -------------------------------------------------
  ----
• IFB ltbuffergt
• ECHO -----------------------------------------
• ECHO Error parameter missing in mWriteStr
• ECHO (no code generated)

14
useful macros continued

• -------------------------------------------------
  ----
• mWrite MACRO text
• No changes to this macro.
• -------------------------------------------------
  ----
• LOCAL string
• .data local data
• string BYTE text,0 define the string
• .code
• push edx
• mov edx,OFFSET string
• call Writestring
• pop edx
• ENDM
• -------------------------------------------------
  ----
• This version supplies a default argument.
• mWriteLn MACRO text lt " " gt

15
useful macros continued

• -------------------------------------------------
  ----
• mGotoxyConst MACRO XREQ, YREQ
• Set the cursor position
• This version checks the ranges of X and Y.
• are not used.
• -------------------------------------------------
  -----
• LOCAL ERRS local constant
• ERRS 0
• IF (X LT 0) OR (X GT 79)
• ECHO Warning First argument to mGotoxy (X)
  is out of range.
• ECHO
  
• ERRS 1
• ENDIF
• IF (Y LT 0) OR (Y GT 24)
• ECHO Warning Second argument to mGotoxy (Y)
  is out of range.
• ECHO
  
• ERRS ERRS 1
• ENDIF

16
useful macros continued

• -------------------------------------------------
  -----
• mReadStr MACRO bufferPtr, maxChars
• Read from standard input into a buffer.
• EDX cannot be the second argument.
• -------------------------------------------------
  -----
• IFIDNI ltmaxCharsgt , ltEDXgt
• ECHO Warning EDX cannot be second argument
  to mReadStr.
• ECHO
  
• EXITM
• ENDIF
• push ecx
• push edx
• mov edx,bufferPtr
• mov ecx,maxChars
• call ReadString
• pop edx
• pop ecx
• ENDM

17
useful macros continued

• -------------------------------------------------
  --
• ShowRegister MACRO regName
• LOCAL tempStr
• Display a register's name and contents.
• -------------------------------------------------
  --
• .data
• tempStr BYTE " regName",0
• .code
• push eax
• Display the register name
• push edx
• mov edx,offset tempStr
• call WriteString
• pop edx
• Display the register contents
• mov eax,regName

18
useful macros a main driver

• count 4
• sumVal TEXTEQU 5 count sumVal 9
• .code
• main PROC
• mGotoxyConst 5 10, 3 4
• ShowWarning BadYValue
• call Crlf
• call Crlf
• ShowRegister ECX
• mReadStr OFFSET buffer,50 ok
• mov edx,50
• mReadStr buffer,edx generates warning

19
Run of macro2 (I added clrscr)

• ECX0012FFB0
• Line one
• Line two
• Line three
• C\Masm615gt

20
Macro redefinition

• Macros can be redefined. For example, if you
  define a macro using
• Somemac macro
• ---
• Endm
• All invocations to the macro use the current
  definition. But if, later, you use the same name
  again to (re)define the macro, the macro has been
  redefined and all subsequent invocations will use
  the new definition.

21
Another redefinition example

• INCLUDE Irvine16.inc
• .code
• cls macro
• local skip
• jmp short skip
• cls_sub proc near
• pusha
• xor cx,cx
• mov dh,24
• mov dl,79
• mov bh, 7
• xor al,al
• mov ah,6
• int 10h
• popa
• ret
• cls_sub endp
• cls macro
• call cls_sub

22
16 bit exit to DOS macro

• Exittodos MACRO
• mov ax,4C00h
• int 21h
• ENDM
•  

23
Toupper macro

• to_upper MACRO ch
• LOCAL done
• cmp ch,'a
• jb done
• cmp ch,'z' 2 semicolons suppresses this comment
  in expansion
• ja done but this comment would be displayed
• sub ch,32
• done
• ENDM

24
Generic operation macro

• doanything MACRO op_code, dest,src
• op_code dest,src
• ENDM

25
SWAP word macro

• SWAP MACRO operand1, operand2
• xchg AX,operand1
• xchg AX,operand2
• xchg AX,operand1
• ENDM
•  

26
16 bit GOTOXY Macro

• GOTOXY MACRO Row, ColumnPUSH AXPUSH BXPUSH
  DXMOV AH, 02Hrom bios codeMOV DH, RowMOV DL,
  ColumnMOV BH, 0video pageINT 10H bios
  intPOP DXPOP BXPOP AXENDM

27
Recursive macro

•  
• pushall MACRO reg1, reg2, reg3, reg4, reg5, reg6
  
• IFNB ltreg1gt If parameter not blank
• push reg1
• push one register and
• repeat
• pushall reg2, reg3, reg4, reg5, reg6
• ENDIF
• ENDM
• example call
• pushall ax, bx, si, ds
• pushall cs, es
•  

28
Substitute operator ()

• Substitutes a parameter with the actual argument
• sort2 MACRO cond, num1, num2
• LOCAL done
• push AX
• mov AX,num1
• cmp AX,num2
• jcond done
• xchg AX,num2
• mov num1,AX
• done
• pop AX
• ENDM

29
Literal-text string operator (lt gt)

• Treats the enclosed text as a single string
  literal rather
• than separate arguments
• Syntax lttextgt
• range_error1 MACRO number,variable,range
• err_msgnumber DB 'variable out of range',0
• range_msgnumber DB 'Correct range is range',0
• ENDM
• Invoking with
• range_error1 1,ltAssignment markgt,lt0 to 25gt
• produces
• err_msg1 DB 'Assignment mark out of range',0
• range_msg1 DB 'Correct range is 0 to 25',0
•  
•  

30
Literal-character operator (!)

• Treats the character literally without its
  default meaning
• Syntax !character
• range_error2 MACRO number,variable,range
• err_msgnumber DB 'variable out of range -
  range',0
• ENDM
• Invoking with
• range_error2 3,mark,ltcan!'!'t be !gt 100gt
• produces
• err_msg3 DB 'mark out of range - can''t be gt
  100',0
• Without the ! operator, two single quotes will
  produce a single quote
• in the output

31
Expression Evaluate operator ()

• Expression is evaluated and its value is used
  to replace
• the expression itself
• Syntax expression
• init_arry MACRO element_size,name,size,init_value
• name element_size size DUP (init_value)
• ENDM
• Assuming NUM_STUDENTS EQU 47
• NUM_TESTS EQU 7
• Invoking with
• init_array Word,marks,NUM_STUDENTSNUM_TESTS,-1
• produces
• marks Word 329 DUP (-1)

32
Literal-character operator (!)

• Treats the character literally without its
  default meaning
• Syntax !character
• range_error2 MACRO number,variable,range
• err_msgnumber DB 'variable out of range -
  range',0
• ENDM
• Invoking with
• range_error2 3,mark,ltcan!'!'t be !gt 100gt
• produces
• err_msg3 DB 'mark out of range - can''t be gt
  100',0
• Without the ! operator, two single quotes will
  produce a single quote
• in the output

33
Generating data for dictionary program using
repeat macro, and

• will generate data like
• wd0 byte 20 dup(0)
• wd1 byte 20 dup(0)
• wd2 byte 20 dup(0)
• include irvine32.inc
• gen macro val
• wdval byte 20 dup(0)
• endm
• .data
• value0
• wct20
• repeat wct
• gen value
• valuevalue1
• endm
• .code
• start proc
• exit
• start endp

34
Similar but using for

•  include irvine16.inc
• .data
• wordval label dword
• for ctr,lt0,1,2,3,4,5,6,7,8,9gt
• wordvalctr dword ctr
• endm
• generates
• wordval0 dword 0
• etc
• .code
• main proc
• mov ax,_at_data
• mov ds,ax
• mov ecx, 9
• mov di,0
• up
• mov eax,wordvaldi
• call writeint
• add di,4

35
And using this with to add numbers up

• include irvine16.inc 32 bit ok too
• .data
• wordval label dword
• for ctr,lt0,1,2,3,4,5,6,7,8,9gt
• wordvalctr dword ctr
• endm
• sum macro c
• add eax,wordvalc
• endm
• addup macro
• count0
• while count LT 10
• sum count
• countcount1
• endm
• endm

36
continued

• .code
• main proc
• mov ax,_at_data
• mov ds,ax
• xor eax,eax
• addup
• call writedec
• exit
• main endp
• end main
•  

37
A program with I/0 similar to wordsort 

• include irvine16.inc
•  .data
• words label byte
• for ctr,lt0,1,2,3,4,5,6,7,8,9gt
• wordsctr byte 10 dup(0)
• endm
• prompt byte 0ah,0dh,"enter",0ah,0dh,''

38
getstart fill macros

• getstart macro x,c
• mov x,offset wordsc
• endm
•  fill macro
• count0
• while count LT 5
• print prompt
• getstart edx,count
• call readstring
• countcount1
• endm
• endm
•  

39
print

• print macro x
• pusha
• mov ah,9DOS printrequires terminator
• mov dx,offset x
• int 21h
• popa
• endm

40
Show macro

• show macro
• count0
• while count LT 5
• getstart edx,count
• call writestring
• call crlf
• countcount1
• endm
• endm

41
driver

• .code
• main proc
• mov ax,_at_data or could be 32 bit
• mov ds,ax
• fill
• show
• exit
• main endp
• end main

42
Linklist output

• C\Masm615gtlist
• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11
• 12
• 13
• 14
• 15

43
Linked list part1

• TITLE Creating a Linked List
  (List.asm)
• This program shows how the STRUC directive
• and the REPT directive can be combined to
• create a linked list at assembly time.
• Last update 11/8/02
• INCLUDE Irvine32.inc
• ListNode STRUCT
• NodeData DWORD ?
• NextPtr DWORD ?
• ListNode ENDS
• TotalNodeCount 15
• NULL 0
• Counter 0
• .data

44
Linked list part2

• .code
• main PROC
• mov esi,OFFSET LinkedList
• Display the integers in the NodeData members.
• NextNode
• Check for the tail node.
• mov eax,(ListNode PTR esi).NextPtr
• cmp eax,NULL
• je quit
• Display the node data.
• mov eax,(ListNode PTR esi).NodeData
• call WriteDec
• call Crlf
• Get pointer to next node.
• mov esi,(ListNode PTR esi).NextPtr
• jmp NextNode

45
Linklist2 a linklist on the stack

• C\Masm615gtlinklist2
• enter numbers... 999 to quit
• 34
• enter numbers... 999 to quit
• 56
• enter numbers... 999 to quit
• 333
• enter numbers... 999 to quit
• 12
• enter numbers... 999 to quit
• 90
• enter numbers... 999 to quit
• 609
• enter numbers... 999 to quit
• 45
• enter numbers... 999 to quit
• 32
• enter numbers... 999 to quit
• 665

46
Linklist2build arbitrary size list (up to stack
allocation)

• ListNode STRUCT
• NodeData DWORD ?
• NextPtr DWORD ?
• ListNode ENDS
• TotalNodeCount 15not used
• NULL 0
• Counter 0
• .data
• nullval dword 0
• prompt byte "enter numbers... 999 to quit",0
• LinkedList LABEL PTR ListNode
• ListNode lt0,0gt tail nodenot used
• .code

47
Linklist2 main

• main PROC
• push nullval
• push nullvalthis is the tail ptr
• mov esi,espcurrent node address
• more
• mov edx,offset prompt
• call writestring
• call crlf
• call readinthere is where we get data
• cmp eax,999
• je doneInput
• mov ebp,esi
• push ebp this is the next node ptr
• push eaxthis is the data
• mov esi,espnow this is the address of
  current node
• jmp more
• doneInput
• NextNode