Programming in Module. Near Call

Transcription

1 Programming in Module Main: sub1: call sub1 sub ax,ax sub1 sub1 proc near sub ax,ax endp sub1 sub1 proc Far sub ax,ax endp Near Call sub1 sub1 Main: call sub1 sub1: sub ax,ax proc near sub ax,ax endp SP AFFFF AFFFE AFFFD Memory (Procedure) Stack SP before CALL = FFFF SS before CALL = A000 IP before CALL = H 11002H 11002h h = 0FFFH F FF CALL Near CALL 1

2 Far Call sub1 sub1 Main: call sub1 sub1: sub ax,ax proc near sub ax,ax endp SP AFFFF AFFFE AFFFD AFFFC AFFFB Memory (Procedure) Stack SP before CALL = FFFF SS before CALL = A000 IP before CALL = H 11002H 1100: CALL Far CALL Register Saving center_cursor center_cursor proc near push ax push dx ah,2 bh,0 dh,12 dl,40 int 10h pop dx pop ax endp Set cursor position Int 10H, Function 2 bh = Page number dh = Row dl = Column 2

3 .model small.data public data1 public data2 data1 db 100 dup (?) data2 db 100 dup (?) Multiple file programming.model small.data extrn data1:byte extrn data2:byte.code extrn read:near.code start: ds,ax call read ah,4ch al,0 int 21h END start public read read: proc near ah,6 al,0ffh int 21h je read read endp end Parameter Passing by Stack CallProc(i,j,k i,j,k+4); push I push j ax, k add ax, 4 push ax call CallProc 3

4 CallProc proc CallProc endp Getting Parameter in Stack near pop RtnAdrs pop kparm pop jparm pop iparm push RtnAdrs... StdProc StdProc Getting Parameter using BP proc near push bp bp,, sp. ax,[bp bp+4] ;Third Parameter ax,[bp bp+6] ;Second Parameter. pop bp endp bp+2 = Rurn address 4

5 Parameter Passing in Pascal xyz(a, a,3,4); procedure xyz(var i:integer; integer; j,k:integer integer); begin i := j+k; end; Note: I -> > pass by reference J,K -> > pass by value Proc xyz(var i:integer; integer; j,k:integer integer); xyz_i equ 8[bp] xyz_j equ 6[bp] xyz_k equ 4[bp] xyz proc near push bp bp,, sp push es push ax push bx les bx,, xyz_i ; Get addr. of I to ES:BX ax, xyz_j ; Get J parameter add ax, xyz_k ; Add to K parameter es:[ :[bx],, ax ; Store result to I para pop bx pop ax pop es pop bp 8 xyz endp 5

6 Using of xyz ax, seg a push ax ax, offset a push ax ax, 3 push ax ax, 4 push ax call xyz ;This parameter is passed by ; reference, so pass its ; address on the stack. ;This is the second parameter ;This is the third parameter. Interrupt Interrupt Request Interrupt Acknowledge Interrupt Service Routine (ISR) Interrupt V.S. V Call Hardware Interrupt (INTR and NMI) Interrupt Vector and Interrupt Vector Table Software Interrupt 6

7 Interrupt V.S. V Call 1) PUSHF 2) TF = 0; ; IF = 0 3) Push CS 4) Push IP 5) CS:IP = Addr of ISR ISR SimpleISR SimpleISR pushf cli popf proc ; cli i endp near cli : if reentrance not allow must place cli hear ax,0 ax,0 es,ax ax,es es:[ :[IntNumber*4] IntVectSave,ax ax, es:[ :[IntNumber*4+2] IntVectSave+2,, ax word ptr es:[ :[IntNumber*4],, offset SimpleISR word ptr es:[ :[IntNumber*4+2], seg SimpleISR Or using Int 21H Function 25H 7

8 DOS Structure Command.Com transient portion (executing programs may erase it) Available for programs use Command.Com resident portion (resides permanently) System files IO.SYS and MSDOS.SYS BIOS data area Interrupt Service Tables Cold boot and DOS startup Reset 80x86 86,, All memory is 0,, Check parity CS:IP = FFFF:0000 -> > Monitor program (BIOS) BIOS Setup all device and I/OI Create Interrupt Vector Table Create Data area 0040:0000 Check boot disk, Load bootstrap loader Load IO.sys, MSDOS.sys Pass control to IO.sys to config device driver Pass control to MSDOS to create DOS function Load Config.sys, Load Command.com Pass controlto Command.com, Load Autoexec.bat Command.com has to part, Resident and Transient portion 8

9 Screen in Text mode 80 Characters; 0 79 (0 4FH) Memory map B800B 800: Offset 0000 = 1st Char ASCII 0001 = 1st Char Attribute 25 Lines 0 24 (0 18H) Position n,m = B800:( :(n*160+2*m) Frequently use of Screen function Set Cursor Position Input : AH = 02 BH = Page Number DH = Row DL = Column Get Cursor Position and Cursor Size Input : AH = 03 BH = Page Number Return: DH = Row DL = Column Clear Screen Input : AH =06 AL = Number of line scroll (AL=0 mean Full Screen) BH = Attribute CH = Start Row CL = Start Column DH = End Row DL = End Column Set Cursor Size Input : AH = 1 CH = Start line 0-15 CL = End Line 9

10 Attribute for Monochrome Background Foreground Feature Background BL R G B Foreground I R G B Hex Black Black Black Black White White Black White White White Black Black Nondisplay h Normal h Blinking h Intense Fh Reverse h Reverse Blink F0h Underline h Attribute for Color monitor Color I R G B Color I R G B Black Gray Blue Light Blue Green Light Green Cyan Light Cyan Red Light Red Magenta Light Megenta Brown Yellow White High-Intensity White

11 Keyboard Keyboard Buffer ASCII Scan Code 0000:041EH = Keyboard Circular Buffer (21 bytes) 0000:041AH = Keyboard Buffer Head Pointer 0000: CH = Keyboard Buffer Tail Pointer 11

12 Keyboard Status 0000: H 0000: H Int 16H Keyboard Functions Read Char Input : Return : Note AH = 0 AH = Scan Code AL = ASCII Note : Read char from keyboard buffer, Wait if buffer empty Check Key Pressed Input : AH = 1 Return: AH = Scan Code AL = ASCII Z = clear if present Note : Not wait if buffer empty, And not ree key from buffer Read Status Input : Return : Note AH = 2 AL = 0000: :0417 Note : Return and data in 0000:

13 Int 16H Extended Read Char Input : Return : Note Note : Same as Function 00 Keyboard Functions AH = 10h AH = Scan Code AL = ASCII 00h, But use with 101/102 Keyboard Check Key Pressed Input : Return Note Note : Same as Function 00 AH = 11h AH = Scan Code AL = ASCII 00h, But use with 101/ /102 Keyboard Z = clear if present Read Status Input : Return : Note Note : Same as Function 00 AH = 12h AL = 0000: h, But use with 101/102 Keyboard Filename db FileHandle Open File Filename.txt,0 dw 00 lea dx,, Filename ; assume DS Point to text ah, 3dh al, 0 int 21h jc OpenError FileHandle,, ax Open File Input : Return : AH AL = 3Dh = Open Mode ;0 = Read, 1 = Write, 2 = Read/Write DS:DX DX = File name (ASCIIZ) AX = File Handle, CF set if Error (call 59H H for Detail) 13

14 Create File Filename FileHandle db Filename.txt,0 dw 00 lea dx,, Filename ; assume DS Point to text ah, 3ch cx, 0 int 21h jc CreateError FileHandle,, ax Create File Input : AH CX Return :AX = 3Ch = File Attribute DS:DX DX = File name (ASCIIZ) = File Handle, CF set if Error (call 59H H for Detail) Bit Meaning 0 File is a Read-Only file 1 File is a hidden file 2 File is a system file 3 File is a volume label name 4 File is a subdirectory 5 File has been archived Read File ah,3fh ; Read data from the file lea dx,, Buffer ; Address of data buffer cx, 1 ; Read one byte bx, FileHandle ; Get file handle value int 21h jc ReadError cmp ax, cx ; EOF reached? jne EOF al, Buffer ; Get character read Read File Input : AH BX CX Return :AX = 3Fh = File Handle = Number of bytes to read DS:DX DX = Address of Buffer = Number of bytes read or Error code, CF set if Error (call 59H H for Detail) 14

15 Write File ah,40 40h ; Write data to the file lea dx,, Buffer ; Address of data buffer cx, 1 ; Write one byte bx, FileHandle ; Set file handle value int 21h jc WriteError Read File Input : AH = 40h BX CX Return :AX = File Handle = Number of bytes to write DS:DX DX = Address of Buffer = Number of bytes write or Error code, CF set if Error (call 59H H for Detail) Close File bx, FileHandle ah, 3Eh int 21h Close File Input : AH BX Return :AX = 3Eh = File Handle = Error code, CF set if Error (call 59H H for Detail) 15

16 Other function of File Function 42H : Move file pointer 41H : Delete file 39H : Create directory 3AH: Ree directory 3BH: Change directory 36H: Get disk free space 43H: Set or Get file attribute 16