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Assembly Source File | 1993-05-10 | 15.3 KB | 355 lines

; ; Program Volume ( Chapter 9 ) ; page 55,132 ;************************************************************************** ; * ; VOLUME - Reading/modifying the disk label * ; * ; Author: A.I.Sopin, VSU 1992, Version 1.4 * ; 03-03-92 03:32pm * ;************************************************************************** .MODEL SMALL EXTRN DIAM00 : FAR, DIAM01 : FAR, COLOR : FAR , INSYM4 : FAR ; ; Save registers used PUSHR MACRO REGLST IFB <REGLST> push ax push bx push cx push dx push si push di push ds push es push bp ENDIF IRP REG,<REGLST> push REG ENDM ENDM ; Restore registers used POPR MACRO REGLST IFB <REGLST> pop bp pop es pop ds pop di pop si pop dx pop cx pop bx pop ax ENDIF IRP REG,<REGLST> pop REG ENDM ENDM ; DIAM0 MACRO TEXT$,OP$,M$,N$,U$,V$ mov TOFF,offset TEXT$ ; address of text string mov OP,OP$ ; working mode mov bx,M$ ; mov M,bx ; first line for output mov bx,N$ ; mov N,bx ; last line for output mov bx,U$ ; cursor line or buffer address mov U,bx ; mov bx,V$ ; mov V,bx ; mov L,80 ; lea bx,PARM ; push bx ; address of parameter list Call DIAM00 ; ENDM ; Call subroutine for screen cleaning and color setting CLR MACRO M$,N$,C$ mov ch, &M$ mov dh, &N$ mov ah, &C$ Call Color ENDM ;---------------------------------------------------------- .STACK ;---------------------------------------------------------- .DATA MODE0 DB 0 ; screen mode DISK0 DB 0 ; screen mode TEXT0 DB ' Reading/modifying the disk label Version 1.4 ',0 TEXT1 DB ' Drive : A (Esc - exit) ', 0 TEXT2 DB ' Disk label: XXXXXXXXXXX (PgUp - write modified label) ',0 TEXT3 DB ' New label written. Press Enter ', 0 TEXT4 DB ' Start sector: =XXXXX ', 0 ERR1 DB ' Error reading disk label. ',0 ERR2 DB ' Error writing disk label. ',0 ERR3 DB ' The disk has no label. Press F2 to create new one',0 SECTOR DB 512 dup (0) CX0 DW 0 SI0 DW 0 ; Parameter list for subroutines DIAM00, DIAM01 EVEN PARM LABEL WORD ; parameter list (address in stack) OP dw 0 ; operation code M dw 0 ; number of first line N dw 0 ; number of last line TOFF dw 0 ; offset of text string L dw 80 ; length of text string U dw 0 ; cursor line (1---25) V dw 0 ; cursor column (1---80) Q dw 0 ; accepted cursor line S dw 0 ; accepted cursor location W db 4 dup (0) ; interrupt key code IOFF dw 0 ; address of screen parameters list ;---------------------------------------------------------- .CODE .Startup mov ah,0Fh ; function 0Fh - get video mode int 10h ; BIOS video service call mov MODE0,al ; save original video mode mov ah,19h ; function 19h - get current drive int 21h ; MS-DOS service call mov DISK0,al ; drive number CLR 1,25,07h ; clear screen DIAM0 TEXT0,1,2,2,0,0 ;---------------------------------------------------------- ; Ask for disk drive (line 3) MAIN: CLR 3,25,07h ; clear screen mov ax,@DATA ; address of data segment mov ds,ax ; DIAM0 TEXT1,3,3,-3,3,12 cmp W+1,1 ; Esc key? jne M0 jmp Exit ; entry M0: mov al,TEXT1+11 ; and al,0DFh ; force uppercase cmp al,'A' ; drive A ? jb MAIN ; error cmp al,'Z' ; drive Z ? ja MAIN ; error sub al,41h ; 0 -A, 1 -B, 2 -C ... mov CS:Disk,al ; save drive number mov ah,0Eh ; function 0Eh - set drive int 21h ; DOS service call ;---------------------------------------------------------- ; Determining disk parameters (Disk Info) DosInfo:mov ah,30h ; int 21h ; MS-DOS Version mov dl,al ; save version mov ah,52h ; DosInfo int 21h ; ES:(BX-2) -pDiskInfo LDS bx,ES:[bx] ; DS:BX -pFirstDrive mov cx,26 ; number of performances of cycle ; Read disk info block for next disks M10: mov al,[bx] ; drive number (0 -A, 1 -B) cmp al,CS:Disk ; disk found ? je M13 ; add bx,24 ; address of next block (or 0FFFFh) cmp dl,4 ; DOS version < 4.0 ? jl M11 ; inc bx ; for DOS 4.0 and higher offset is 25 M11: LDS bx,[bx] ; address of next block cmp bx,0FFFFh ; end of chain? je M12 ; loop M10 ; to cycle beginning M12: jmp MAIN ; error in path string ;---------------------------------------------------------- ; Calculating sector number from cluster number M13: mov al,[bx]+4 ; sectors per cluster - 1 inc al ; cbw ; mov CS:SecClus,ax ; sectors per cluster mov cx,4 ; elements in sector shl ax,cl ; mov CS:Clus32,ax ; directory entries per cluster mov ax,[bx]+6 ; SecRes mov CS:SecRes,ax ; reserve sectors mov al,[bx]+8 ; mov CS:Fats,al ; number of FATs mov ax,[bx]+9 ; MaxDir mov CS:MaxDir,ax ; entries in root directory mov ax,[bx]+11 ; SecData mov CS:SecData,ax ; start sector of data area mov al,[bx]+15 ; SecFat cbw ; mov CS:SecFat,ax ; sectors per FAT mov ax,[bx]+16 ; SecDir (VER =3.xx) cmp dl,4 ; DOS version < 4.0 ? jl M14 ; mov ax,[bx]+17 ; SecDir (VER =4.01, 5.00) M14: mov CS:SecDir,ax ; start sector of root directory mov CS:SEC,ax ; start sector of root directory ; Output message about start sector (line =4) mov dx,@DATA ; mov ds,dx ; DS:BP - output buffer lea bp,TEXT4+19 ; address of buffer for editing xor dx,dx ; clear high part mov si,5 ; number of digits Call INSYM4 ; number in DX:AX DIAM0 TEXT4,1,4,-4,0,0 ;---------------------------------------------------------- ; Read sectors of root directory mov ax,CS:MaxDir ; entries in root directory mov cl,4 ; shr ax,cl ; sectors in directory mov CX0,ax ; M20: Call READ ; read sector lea si,SECTOR ; address of first sector mov cx,16 ; entries per sectors ; Cycle for processing directory entries in sector read M21: mov SI0,si ; save address of entry mov ax,[si] ; and ax,ax ; empty entry ? jz M23 ; cmp ax,0F600h ; empty entry ? (Pctools) je M23 ; mov al,[si]+11 ; file attribute and al,08h ; cmp al,08h ; label read ? jne M22 ; jmp M25 ; label found M22: add si,32 ; address of next entry loop M21 ; to next cycle performance inc CS:SEC ; modify number sector dec CX0 ; sectors left jg M20 ; read next sector ; Output message "label not found" M23: DIAM0 ERR3,2,5,-5,0,0 cmp W+1,1 ; Esc key? jne M24 ; jmp MAIN ; exit M24: cmp W+1,3Ch ; F2 - create label ? jne M23 ; ; Ask for creating a new label (line 6) DIAM0 TEXT2,3,6,-6,6,15 cmp W+1,1 ; Esc key? jne M27 ; jmp MAIN ; exit ; Output label read (DS:SI - address of directory entry) M25: mov cx,13 ; length of label mov ax,@DATA ; mov es,ax ; ES points to data segment lea di,TEXT2+14 ; target address cld ; right direction mov al,' ' ; space character rep stosb ; clear label area mov cx,11 ; length of label lea di,TEXT2+14 ; target address rep movsb ; send label ; Input new label for modification and writing (line 7) M26: DIAM0 TEXT2,3,6,-6,6,15 cmp W+1,1 ; Esc key? jne M27 ; jmp MAIN ; exit M27: cmp W+1,49h ; PgUp - write label ? je M28 ; jmp MAIN ; ; Write sector with the label modified onto disk M28: mov ax,@DATA ; mov es,ax ; ES points to data segment mov di,SI0 ; ES:DI - target address Call VOLMOV ; send label Call WRITE ; write logical sector ; Write label in the Boot-sector (offset 43) mov CS:SEC,0 ; Boot sector Call READ ; read sector lea di,SECTOR+43 ; target address Call VOLMOV ; send label Call WRITE ; write logical sector DIAM0 TEXT3,2,7,-7,0,0 ; output message "label written" jmp MAIN ; perform program from beginning ;---------------------------------------------------------- ; Finish of the program's work Exit: xor ah,ah ; function 00h - set video mode mov al,MODE0 ; original video mode int 10h ; BIOS video service call mov dl,DISK0 ; original disk drive mov ah,0Eh ; function 0Eh - set current drive int 21h ; DOS swervice call mov ax,4C00h ; function 4Ch - terminate process int 21h ; DOS service call ;---------------------------------------------------------- ; Data in code segment MaxDir DW 0 ; Entries in root directory NumClus DW 0 ; Cluster number SecDir DW 0 ; Start sector of root directory SecData DW 0 ; Start sector of data area SecRes DW 0 ; Number of reserve sectors SEC DW 0 ; Logical sector number SecClus DW 0 ; Sectors per cluster SecFat DW 0 ; sectors per FAT Dirs DW 0 ; Sectors in root directory Fats DB 0 ; Number of FAT TypFat DB 0 ; FAT type (12 or 16 bits) Disk DB 0 ; Drive number 0 -A, 1 -B, 2 -C... Clus32 DW 0 ; Directory entries in cluster ;---------------------------------------------------------- ; ; Subroutine for sector reading (INT 26h) ; ; SEC - number of logical sector ; ; DS:BX - address of sector buffer ; ; In case of an error the Carry Flag is set ; ;---------------------------------------------------------- READ PROC NEAR PUSHR <bp,si,di> ; save registers lea bx,SECTOR ; address of buffer for reading sector mov ax,@DATA ; mov ds,ax ; DS points to data segment mov cx,1 ; number of sectors =1 mov al,CS:Disk ; drive number (0 -A, 1 -B...) mov dx,CS:SEC ; sector number int 25h ; read logical sector add sp,2 ; adjust stack POPR <di,si,bp> ; restore registers RETN READ ENDP ;---------------------------------------------------------- ; ; Subroutine for sector writing (INT 26h) ; ; SEC - number of logical sector ; ; DS:BX - address of sector buffer ; ; In case of an error the Carry Flag is set ; ;---------------------------------------------------------- WRITE PROC NEAR lea bx,SECTOR ; address of sector buffer mov ax,@DATA ; mov ds,ax ; DS points to data segment mov cx,1 ; number of sectors =1 mov al,CS:Disk ; drive number (0 -A, 1 -B...) mov dx,CS:SEC ; sector number int 26h ; write logical sector pop cx ; adjust stack jc ERROR ; to error message RETN ; normal exit ; Output error message "label not written" ERROR: DIAM0 ERR2,2,7,-7,0,0 ; pop cx ; adjust stack jmp MAIN ; WRITE ENDP ;---------------------------------------------------------- ; ; Subroutine for sending disk label ; ; ES:DI - address where the label must be sent ; ;---------------------------------------------------------- VOLMOV PROC NEAR mov cx,11 ; length of label mov ax,@DATA ; mov ds,ax ; DS points to data segment lea si,TEXT2+14 ; DS:SI - source cld ; rigth direction rep movsb ; send label mov byte ptr ES:[di],28h ; send attribute RETN VOLMOV ENDP END