DOS操作系统源码相关资料知识
DOS操作系统源码相关资料知识
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DOS操作系统源码相关资料知识
学习啦在线学习网 微软DOS早期源码，现已公开;下了一份，看下其大致结构;
包括1.1和2.0版本的源码和编译后的结果;
贴出其1.1版本 MSDOS.ASM 源码;有空研究;
[plain] view plain copy ; 86-DOS High-performance operating system for the 8086 version 1.25; by Tim Paterson
; ****************** Revision History *************************
; >> EVERY change must noted below!! <<
;
; 0.34 12/29/80 General release, updating all past customers
; 0.42 02/25/81 32-byte directory entries added
学习啦在线学习网 ; 0.56 03/23/81 Variable record and sector sizes
; 0.60 03/27/81 Ctrl-C exit changes, including register save on user stack
; 0.74 04/15/81 Recognize I/O devices with file names
; 0.75 04/17/81 Improve and correct buffer handling
; 0.76 04/23/81 Correct directory size when not 2^N entries
; 0.80 04/27/81 Add console input without echo, Functions 7 & 8
; 1.00 04/28/81 Renumber for general release
; 1.01 05/12/81 Fix bug in `STORE'
; 1.10 07/21/81 Fatal error trapping, NUL device, hidden files, date & time,
; RENAME fix, general cleanup
学习啦在线学习网 ; 1.11 09/03/81 Don't set CURRENT BLOCK to 0 on open; fix SET FILE SIZE
; 1.12 10/09/81 Zero high half of CURRENT BLOCK after all (CP/M programs don't)
; 1.13 10/29/81 Fix classic "no write-through" error in buffer handling
; 1.20 12/31/81 Add time to FCB; separate FAT from DPT; Kill SMALLDIR;
学习啦在线学习网 ; Add FLUSH and MAPDEV calls; allow disk mapping in DSKCHG;
; Lots of smaller improvements
; 1.21 01/06/82 HIGHMEM switch to run DOS in high memory
学习啦在线学习网 ; 1.22 01/12/82 Add VERIFY system call to enable/disable verify after write
学习啦在线学习网 ; 1.23 02/11/82 Add defaulting to parser; use variable escape character
学习啦在线学习网 ; Don't zero extent field in IBM version (back to 1.01!)
; 1.24 03/01/82 Restore fcn. 27 to 1.0 level; add fcn. 28
学习啦在线学习网 ; 1.25 03/03/82 Put marker (00) at end of directory to speed searches
;
; *************************************************************
学习啦在线学习网 ; Interrupt Entry Points:
; INTBASE: ABORT
; INTBASE+4: COMMAND
; INTBASE+8: BASE EXIT ADDRESS
; INTBASE+C: CONTROL-C ABORT
; INTBASE+10H: FATAL ERROR ABORT
学习啦在线学习网 ; INTBASE+14H: BIOS DISK READ
; INTBASE+18H: BIOS DISK WRITE
; INTBASE+40H: Long jump to CALL entry point
IF IBM
学习啦在线学习网 ESCCH EQU 0
学习啦在线学习网 CANCEL EQU 1BH ;Cancel with ESC
学习啦在线学习网 TOGLINS EQU TRUE ;One key toggles insert mode
TOGLPRN EQU TRUE ;One key toggles printer echo
学习啦在线学习网 NUMDEV EQU 6 ;Include "COM1" as I/O device name
ZEROEXT EQU TRUE
ELSE
ESCCH EQU 1BH
CANCEL EQU "X"-"@" ;Cancel with Ctrl-X
TOGLINS EQU FALSE ;Separate keys for insert mode on and off
TOGLPRN EQU FALSE ;Separate keys for printer echo on and off
NUMDEV EQU 5 ;Number of I/O device names
学习啦在线学习网 ZEROEXT EQU FALSE
ENDIF
MAXCALL EQU 36
MAXCOM EQU 46
INTBASE EQU 80H
学习啦在线学习网 INTTAB EQU 20H
学习啦在线学习网 ENTRYPOINTSEG EQU 0CH
学习啦在线学习网 ENTRYPOINT EQU INTBASE+40H
学习啦在线学习网 CONTC EQU INTTAB+3
学习啦在线学习网 EXIT EQU INTBASE+8
LONGJUMP EQU 0EAH
LONGCALL EQU 9AH
MAXDIF EQU 0FFFH
SAVEXIT EQU 10
; Field definition for FCBs
学习啦在线学习网 FCBLOCK STRUC
DB 12 DUP (?) ;Drive code and name
EXTENT DW ?
学习啦在线学习网 RECSIZ DW ? ;Size of record (user settable)
FILSIZ DW ? ;Size of file in bytes
DRVBP DW ? ;BP for SEARCH FIRST and SEARCH NEXT
FDATE DW ? ;Date of last writing
FTIME DW ? ;Time of last writing
学习啦在线学习网 DEVID DB ? ;Device ID number, bits 0-5
;bit 7=0 for file, bit 7=1 for I/O device
;If file, bit 6=0 if dirty
学习啦在线学习网 ;If I/O device, bit 6=0 if EOF (input)
FIRCLUS DW ? ;First cluster of file
LSTCLUS DW ? ;Last cluster accessed
学习啦在线学习网 CLUSPOS DW ? ;Position of last cluster accessed
DB ? ;Forces NR to offset 32
NR DB ? ;Next record
RR DB 3 DUP (?) ;Random record
FCBLOCK ENDS
学习啦在线学习网 FILDIRENT = FILSIZ ;Used only by SEARCH FIRST and SEARCH NEXT
学习啦在线学习网 ; Description of 32-byte directory entry (same as returned by SEARCH FIRST
; and SEARCH NEXT, functions 17 and 18).
;
; Location bytes Description
;
; 0 11 File name and extension ( 0E5H if empty)
; 11 1 Attributes. Bits 1 or 2 make file hidden
; 12 10 Zero field (for expansion)
; 22 2 Time. Bits 0-4=seconds/2, bits 5-10=minute, 11-15=hour
; 24 2 Date. Bits 0-4=day, bits 5-8=month, bits 9-15=year-1980
学习啦在线学习网 ; 26 2 First allocation unit ( < 4080 )
; 28 4 File size, in bytes (LSB first, 30 bits max.)
;
; The File Allocation Table uses a 12-bit entry for each allocation unit on
; the disk. These entries are packed, two for every three bytes. The contents
学习啦在线学习网 ; of entry number N is found by 1) multiplying N by 1.5; 2) adding the result
学习啦在线学习网 ; to the base address of the Allocation Table; 3) fetching the 16-bit word at
学习啦在线学习网 ; this address; 4) If N was odd (so that N*1.5 was not an integer), shift the
学习啦在线学习网 ; word right four bits; 5) mask to 12 bits (AND with 0FFF hex). Entry number
学习啦在线学习网 ; zero is used as an end-of-file trap in the OS and as a flag for directory
学习啦在线学习网 ; entry size (if SMALLDIR selected). Entry 1 is reserved for future use. The
; first available allocation unit is assigned entry number two, and even
; though it is the first, is called cluster 2. Entries greater than 0FF8H are
; end of file marks; entries of zero are unallocated. Otherwise, the contents
学习啦在线学习网 ; of a FAT entry is the number of the next cluster in the file.
; Field definition for Drive Parameter Block
DPBLOCK STRUC
DEVNUM DB ? ;I/O driver number
学习啦在线学习网 DRVNUM DB ? ;Physical Unit number
SECSIZ DW ? ;Size of physical sector in bytes
CLUSMSK DB ? ;Sectors/cluster - 1
CLUSSHFT DB ? ;Log2 of sectors/cluster
FIRFAT DW ? ;Starting record of FATs
学习啦在线学习网 FATCNT DB ? ;Number of FATs for this drive
学习啦在线学习网 MAXENT DW ? ;Number of directory entries
学习啦在线学习网 FIRREC DW ? ;First sector of first cluster
学习啦在线学习网 MAXCLUS DW ? ;Number of clusters on drive + 1
学习啦在线学习网 FATSIZ DB ? ;Number of records occupied by FAT
学习啦在线学习网 FIRDIR DW ? ;Starting record of directory
学习啦在线学习网 FAT DW ? ;Pointer to start of FAT
学习啦在线学习网 DPBLOCK ENDS
DPBSIZ EQU 20 ;Size of the structure in bytes
DIRSEC = FIRREC ;Number of dir. sectors (init temporary)
学习啦在线学习网 DSKSIZ = MAXCLUS ;Size of disk (temp used during init only)
;The following are all of the segments used
学习啦在线学习网 ;They are declared in the order that they should be placed in the executable
CODE SEGMENT
学习啦在线学习网 CODE ENDS
CONSTANTS SEGMENT BYTE
CONSTANTS ENDS
DATA SEGMENT WORD
DATA ENDS
学习啦在线学习网 DOSGROUP GROUP CODE,CONSTANTS,DATA
SEGBIOS SEGMENT
SEGBIOS ENDS
; BOIS entry point definitions
IF IBM
BIOSSEG EQU 60H
ENDIF
IF NOT IBM
BIOSSEG EQU 40H
ENDIF
SEGBIOS SEGMENT AT BIOSSEG
ORG 0
DB 3 DUP (?) ;Reserve room for jump to init code
学习啦在线学习网 BIOSSTAT DB 3 DUP (?) ;Console input status check
BIOSIN DB 3 DUP (?) ;Get console character
BIOSOUT DB 3 DUP (?) ;Output console character
学习啦在线学习网 BIOSPRINT DB 3 DUP (?) ;Output to printer
BIOSAUXIN DB 3 DUP (?) ;Get byte from auxilliary
学习啦在线学习网 BIOSAUXOUT DB 3 DUP (?) ;Output byte to auxilliary
BIOSREAD DB 3 DUP (?) ;Disk read
学习啦在线学习网 BIOSWRITE DB 3 DUP (?) ;Disk write
学习啦在线学习网 BIOSDSKCHG DB 3 DUP (?) ;Dsik-change status
BIOSSETDATE DB 3 DUP (?) ;Set date
BIOSSETTIME DB 3 DUP (?) ;Set time
BIOSGETTIME DB 3 DUP (?) ;Get time and date
学习啦在线学习网 BIOSFLUSH DB 3 DUP (?) ;Clear console input buffer
BIOSMAPDEV DB 3 DUP (?) ;Dynamic disk table mapper
学习啦在线学习网 SEGBIOS ENDS
; Location of user registers relative user stack pointer
学习啦在线学习网 STKPTRS STRUC
AXSAVE DW ?
BXSAVE DW ?
CXSAVE DW ?
学习啦在线学习网 DXSAVE DW ?
SISAVE DW ?
DISAVE DW ?
学习啦在线学习网 BPSAVE DW ?
DSSAVE DW ?
学习啦在线学习网 ESSAVE DW ?
学习啦在线学习网 IPSAVE DW ?
学习啦在线学习网 CSSAVE DW ?
FSAVE DW ?
STKPTRS ENDS
; Start of code
CODE SEGMENT
ASSUME CS:DOSGROUP,DS:DOSGROUP,ES:DOSGROUP,SS:DOSGROUP
ORG 0
学习啦在线学习网 CODSTRT EQU $
学习啦在线学习网 JMP DOSINIT
ESCCHAR DB ESCCH ;Lead-in character for escape sequences
ESCTAB:
IF NOT IBM
学习啦在线学习网 DB "S" ;Copy one char
DB "V" ;Skip one char
DB "T" ;Copy to char
学习啦在线学习网 DB "W" ;Skip to char
DB "U" ;Copy line
DB "E" ;Kill line (no change in template)
学习啦在线学习网 DB "J" ;Reedit line (new template)
DB "D" ;Backspace
DB "P" ;Enter insert mode
DB "Q" ;Exit insert mode
学习啦在线学习网 DB "R" ;Escape character
DB "R" ;End of table
ENDIF
IF IBM
DB 64 ;Crtl-Z - F6
DB 77 ;Copy one char - -->
学习啦在线学习网 DB 59 ;Copy one char - F1
DB 83 ;Skip one char - DEL
学习啦在线学习网 DB 60 ;Copy to char - F2
学习啦在线学习网 DB 62 ;Skip to char - F4
DB 61 ;Copy line - F3
DB 61 ;Kill line (no change to template ) - Not used
学习啦在线学习网 DB 63 ;Reedit line (new template) - F5
学习啦在线学习网 DB 75 ;Backspace - <--
DB 82 ;Enter insert mode - INS (toggle)
DB 65 ;Escape character - F7
学习啦在线学习网 DB 65 ;End of table
ENDIF
ESCTABLEN EQU $-ESCTAB
学习啦在线学习网 IF NOT IBM
学习啦在线学习网 HEADER DB 13,10,"MS-DOS version 1.25"
学习啦在线学习网 IF HIGHMEM
DB "H"
ENDIF
IF DSKTEST
DB "D"
ENDIF
DB 13,10
DB "Copyright 1981,82 Microsoft, Inc.",13,10,"$"
ENDIF
QUIT:
MOV AH,0
学习啦在线学习网 JMP SHORT SAVREGS
COMMAND: ;Interrupt call entry point
CMP AH,MAXCOM
JBE SAVREGS
BADCALL:
学习啦在线学习网 MOV AL,0
IRET: IRET
ENTRY: ;System call entry point and dispatcher
学习啦在线学习网 POP AX ;IP from the long call at 5
POP AX ;Segment from the long call at 5
学习啦在线学习网 POP CS:[TEMP] ;IP from the CALL 5
PUSHF ;Start re-ordering the stack
CLI
PUSH AX ;Save segment
学习啦在线学习网 PUSH CS:[TEMP] ;Stack now ordered as if INT had been used
CMP CL,MAXCALL ;This entry point doesn't get as many calls
JA BADCALL
MOV AH,CL
学习啦在线学习网 SAVREGS:
PUSH ES
PUSH DS
PUSH BP
PUSH DI
PUSH SI
PUSH DX
PUSH CX
PUSH BX
PUSH AX
IF DSKTEST
MOV AX,CS:[SPSAVE]
MOV CS:[NSP],AX
MOV AX,CS:[SSSAVE]
MOV CS:[NSS],AX
POP AX
PUSH AX
ENDIF
学习啦在线学习网 MOV CS:[SPSAVE],SP
MOV CS:[SSSAVE],SS
学习啦在线学习网 MOV SP,CS
MOV SS,SP
REDISP:
MOV SP,OFFSET DOSGROUP:IOSTACK
STI ;Stack OK now
MOV BL,AH
学习啦在线学习网 MOV BH,0
SHL BX,1
CLD
学习啦在线学习网 CMP AH,12
JLE SAMSTK
学习啦在线学习网 MOV SP,OFFSET DOSGROUP:DSKSTACK
SAMSTK:
学习啦在线学习网 CALL CS:[BX+DISPATCH]
LEAVE:
CLI
MOV SP,CS:[SPSAVE]
MOV SS,CS:[SSSAVE]
学习啦在线学习网 MOV BP,SP
学习啦在线学习网 MOV BYTE PTR [BP.AXSAVE],AL
IF DSKTEST
MOV AX,CS:[NSP]
MOV CS:[SPSAVE],AX
MOV AX,CS:[NSS]
MOV CS:[SSSAVE],AX
ENDIF
POP AX
POP BX
POP CX
POP DX
POP SI
POP DI
POP BP
POP DS
POP ES
IRET
学习啦在线学习网 ; Standard Functions
学习啦在线学习网 DISPATCH DW ABORT ;0
DW CONIN
学习啦在线学习网 DW CONOUT
学习啦在线学习网 DW READER
DW PUNCH
学习啦在线学习网 DW LIST ;5
学习啦在线学习网 DW RAWIO
DW RAWINP
DW IN
DW PRTBUF
DW BUFIN ;10
DW CONSTAT
学习啦在线学习网 DW FLUSHKB
DW DSKRESET
DW SELDSK
DW OPEN ;15
学习啦在线学习网 DW CLOSE
DW SRCHFRST
DW SRCHNXT
学习啦在线学习网 DW DELETE
学习啦在线学习网 DW SEQRD ;20
DW SEQWRT
学习啦在线学习网 DW CREATE
学习啦在线学习网 DW RENAME
学习啦在线学习网 DW INUSE
学习啦在线学习网 DW GETDRV ;25
学习啦在线学习网 DW SETDMA
DW GETFATPT
学习啦在线学习网 DW GETFATPTDL
DW GETRDONLY
DW SETATTRIB ;30
学习啦在线学习网 DW GETDSKPT
学习啦在线学习网 DW USERCODE
DW RNDRD
DW RNDWRT
DW FILESIZE ;35
DW SETRNDREC
学习啦在线学习网 ; Extended Functions
DW SETVECT
DW NEWBASE
学习啦在线学习网 DW BLKRD
DW BLKWRT ;40
DW MAKEFCB
DW GETDATE
DW SETDATE
学习啦在线学习网 DW GETTIME
DW SETTIME ;45
学习啦在线学习网 DW VERIFY
INUSE:
GETIO:
SETIO:
GETRDONLY:
学习啦在线学习网 SETATTRIB:
USERCODE:
学习啦在线学习网 MOV AL,0
RET
VERIFY:
AND AL,1
MOV CS:VERFLG,AL
RET
FLUSHKB:
PUSH AX
学习啦在线学习网 CALL FAR PTR BIOSFLUSH
POP AX
MOV AH,AL
CMP AL,1
JZ REDISPJ
学习啦在线学习网 CMP AL,6
学习啦在线学习网 JZ REDISPJ
学习啦在线学习网 CMP AL,7
JZ REDISPJ
CMP AL,8
JZ REDISPJ
CMP AL,10
JZ REDISPJ
MOV AL,0
RET
REDISPJ:JMP REDISP
READER:
AUXIN:
CALL STATCHK
学习啦在线学习网 CALL FAR PTR BIOSAUXIN
RET
PUNCH:
MOV AL,DL
AUXOUT:
PUSH AX
学习啦在线学习网 CALL STATCHK
POP AX
CALL FAR PTR BIOSAUXOUT
RET
UNPACK:
学习啦在线学习网 ; Inputs:
; DS = CS
学习啦在线学习网 ; BX = Cluster number
学习啦在线学习网 ; BP = Base of drive parameters
学习啦在线学习网 ; SI = Pointer to drive FAT
学习啦在线学习网 ; Outputs:
学习啦在线学习网 ; DI = Contents of FAT for given cluster
; Zero set means DI=0 (free cluster)
; No other registers affected. Fatal error if cluster too big.
CMP BX,[BP.MAXCLUS]
JA HURTFAT
LEA DI,[SI+BX]
SHR BX,1
MOV DI,[DI+BX]
JNC HAVCLUS
SHR DI,1
SHR DI,1
SHR DI,1
学习啦在线学习网 SHR DI,1
STC
HAVCLUS:
RCL BX,1
AND DI,0FFFH
RET
学习啦在线学习网 HURTFAT:
PUSH AX
MOV AH,80H ;Signal Bad FAT to INT 24H handler
学习啦在线学习网 MOV DI,0FFFH ;In case INT 24H returns (it shouldn't)
CALL FATAL
POP AX ;Try to ignore bad FAT
RET
PACK:
; Inputs:
学习啦在线学习网 ; DS = CS
; BX = Cluster number
; DX = Data
; SI = Pointer to drive FAT
学习啦在线学习网 ; Outputs:
; The data is stored in the FAT at the given cluster.
; BX,DX,DI all destroyed
学习啦在线学习网 ; No other registers affected
MOV DI,BX
SHR BX,1
ADD BX,SI
ADD BX,DI
SHR DI,1
学习啦在线学习网 MOV DI,[BX]
JNC ALIGNED
SHL DX,1
SHL DX,1
学习啦在线学习网 SHL DX,1
学习啦在线学习网 SHL DX,1
AND DI,0FH
JMP SHORT PACKIN
学习啦在线学习网 ALIGNED:
学习啦在线学习网 AND DI,0F000H
PACKIN:
学习啦在线学习网 OR DI,DX
学习啦在线学习网 MOV [BX],DI
RET
DEVNAME:
学习啦在线学习网 MOV SI,OFFSET DOSGROUP:IONAME ;List of I/O devices with file names
MOV BH,NUMDEV ;BH = number of device names
LOOKIO:
MOV DI,OFFSET DOSGROUP:NAME1
MOV CX,4 ;All devices are 4 letters
REPE CMPSB ;Check for name in list
JZ IOCHK ;If first 3 letters OK, check for the rest
学习啦在线学习网 ADD SI,CX ;Point to next device name
DEC BH
学习啦在线学习网 JNZ LOOKIO
CRET:
STC ;Not found
RET
IOCHK:
IF IBM
学习啦在线学习网 CMP BH,NUMDEV ;Is it the first device?
JNZ NOTCOM1
学习啦在线学习网 MOV BH,2 ;Make it the same as AUX
学习啦在线学习网 NOTCOM1:
ENDIF
NEG BH
MOV CX,2 ;Check rest of name but not extension
学习啦在线学习网 MOV AX,2020H
REPE SCASW ;Make sure rest of name is blanks
JNZ CRET
学习啦在线学习网 RET1: RET ;Zero set so CREATE works
GETFILE:
学习啦在线学习网 ; Same as GETNAME except ES:DI points to FCB on successful return
学习啦在线学习网 CALL MOVNAME
JC RET1
PUSH DX
PUSH DS
CALL FINDNAME
POP ES
POP DI
RET2: RET
GETNAME:
; Inputs:
学习啦在线学习网 ; DS,DX point to FCB
; Function:
; Find file name in disk directory. First byte is
; drive number (0=current disk). "?" matches any
; character.
学习啦在线学习网 ; Outputs:
; Carry set if file not found
; ELSE
; Zero set if attributes match (always except when creating)
学习啦在线学习网 ; BP = Base of drive parameters
学习啦在线学习网 ; DS = CS
学习啦在线学习网 ; ES = CS
学习啦在线学习网 ; BX = Pointer into directory buffer
学习啦在线学习网 ; SI = Pointer to First Cluster field in directory entry
学习啦在线学习网 ; [DIRBUF] has directory record with match
; [NAME1] has file name
; All other registers destroyed.
CALL MOVNAME
学习啦在线学习网 JC RET2 ;Bad file name?
FINDNAME:
MOV AX,CS
MOV DS,AX
CALL DEVNAME
JNC RET2
学习啦在线学习网 CALL STARTSRCH
学习啦在线学习网 CONTSRCH:
CALL GETENTRY
JC RET2
SRCH:
学习啦在线学习网 MOV AH,BYTE PTR [BX]
OR AH,AH ;End of directory?
JZ FREE
CMP AH,[DELALL] ;Free entry?
JZ FREE
MOV SI,BX
MOV DI,OFFSET DOSGROUP:NAME1
学习啦在线学习网 MOV CX,11
学习啦在线学习网 WILDCRD:
REPE CMPSB
学习啦在线学习网 JZ FOUND
CMP BYTE PTR [DI-1],"?"
学习啦在线学习网 JZ WILDCRD
学习啦在线学习网 NEXTENT:
CALL NEXTENTRY
JNC SRCH
RET3: RET
FREE:
学习啦在线学习网 CMP [ENTFREE],-1 ;Found a free entry before?
学习啦在线学习网 JNZ TSTALL ;If so, ignore this one
学习啦在线学习网 MOV CX,[LASTENT]
MOV [ENTFREE],CX
TSTALL:
CMP AH,[DELALL] ;At end of directory?
学习啦在线学习网 JZ NEXTENT ;No - continue search
STC ;Report not found
RET
FOUND:
学习啦在线学习网 ;Check if attributes allow finding it
MOV AH,[ATTRIB] ;Attributes of search
NOT AH
学习啦在线学习网 AND AH,[SI] ;Compare with attributes of file
学习啦在线学习网 ADD SI,15
学习啦在线学习网 AND AH,6 ;Only look at bits 1 and 2
JZ RET3
学习啦在线学习网 TEST BYTE PTR [CREATING],-1 ;Pass back mismatch if creating
JZ NEXTENT ;Otherwise continue searching
RET
学习啦在线学习网 GETENTRY:
; Inputs:
; [LASTENT] has previously searched directory entry
; Function:
; Locates next sequential directory entry in preparation for search
; Outputs:
; Carry set if none
; ELSE
; AL = Current directory block
; BX = Pointer to next directory entry in [DIRBUF]
; DX = Pointer to first byte after end of DIRBUF
; [LASTENT] = New directory entry number
MOV AX,[LASTENT]
学习啦在线学习网 INC AX ;Start with next entry
CMP AX,[BP.MAXENT]
学习啦在线学习网 JAE NONE
GETENT:
MOV [LASTENT],AX
学习啦在线学习网 MOV CL,4
SHL AX,CL
XOR DX,DX
学习啦在线学习网 SHL AX,1
RCL DX,1 ;Account for overflow in last shift
学习啦在线学习网 MOV BX,[BP.SECSIZ]
AND BL,255-31 ;Must be multiple of 32
DIV BX
MOV BX,DX ;Position within sector
MOV AH,[BP.DEVNUM] ;AL=Directory sector no.
CMP AX,[DIRBUFID]
学习啦在线学习网 JZ HAVDIRBUF
PUSH BX
学习啦在线学习网 CALL DIRREAD
POP BX
HAVDIRBUF:
学习啦在线学习网 MOV DX,OFFSET DOSGROUP:DIRBUF
ADD BX,DX
ADD DX,[BP.SECSIZ]
RET
学习啦在线学习网 NEXTENTRY:
; Inputs:
学习啦在线学习网 ; Same as outputs of GETENTRY, above
学习啦在线学习网 ; Function:
; Update AL, BX, and [LASTENT] for next directory entry.
; Carry set if no more.
MOV DI,[LASTENT]
INC DI
学习啦在线学习网 CMP DI,[BP.MAXENT]
JAE NONE
MOV [LASTENT],DI
学习啦在线学习网 ADD BX,32
CMP BX,DX
学习啦在线学习网 JB HAVIT
学习啦在线学习网 INC AL ;Next directory sector
PUSH DX ;Save limit
CALL DIRREAD
POP DX
MOV BX,OFFSET DOSGROUP:DIRBUF
HAVIT:
CLC
RET
NONE:
学习啦在线学习网 CALL CHKDIRWRITE
STC
RET4: RET
DELETE: ; System call 19
学习啦在线学习网 CALL MOVNAME
MOV AL,-1
JC RET4
MOV AL,CS:[ATTRIB]
学习啦在线学习网 AND AL,6 ;Look only at hidden bits
学习啦在线学习网 CMP AL,6 ;Both must be set
JNZ NOTALL
MOV CX,11
学习啦在线学习网 MOV AL,"?"
学习啦在线学习网 MOV DI,OFFSET DOSGROUP:NAME1
REPE SCASB ;See if name is *.*
学习啦在线学习网 JNZ NOTALL
MOV BYTE PTR CS:[DELALL],0 ;DEL *.* - flag deleting all
NOTALL:
学习啦在线学习网 CALL FINDNAME
MOV AL,-1
JC RET4
OR BH,BH ;Check if device name
JS RET4 ;Can't delete I/O devices
学习啦在线学习网 DELFILE:
MOV BYTE PTR [DIRTYDIR],-1
MOV AH,[DELALL]
学习啦在线学习网 MOV BYTE PTR [BX],AH
学习啦在线学习网 MOV BX,[SI]
学习啦在线学习网 MOV SI,[BP.FAT]
学习啦在线学习网 OR BX,BX
学习啦在线学习网 JZ DELNXT
CMP BX,[BP.MAXCLUS]
JA DELNXT
学习啦在线学习网 CALL RELEASE
DELNXT:
CALL CONTSRCH
学习啦在线学习网 JNC DELFILE
学习啦在线学习网 CALL FATWRT
学习啦在线学习网 CALL CHKDIRWRITE
学习啦在线学习网 XOR AL,AL
RET
RENAME: ;System call 23
CALL MOVNAME
学习啦在线学习网 JC ERRET
ADD SI,5
学习啦在线学习网 MOV DI,OFFSET DOSGROUP:NAME2
学习啦在线学习网 CALL LODNAME
JC ERRET ;Report error if second name invalid
CALL FINDNAME
JC ERRET
OR BH,BH ;Check if I/O device name
JS ERRET ;If so, can't rename it
学习啦在线学习网 MOV SI,OFFSET DOSGROUP:NAME1
MOV DI,OFFSET DOSGROUP:NAME3
学习啦在线学习网 MOV CX,6 ;6 words (12 bytes)--include attribute byte
REP MOVSW ;Copy name to search for
RENFIL:
MOV DI,OFFSET DOSGROUP:NAME1
MOV SI,OFFSET DOSGROUP:NAME2
MOV CX,11
NEWNAM:
LODSB
学习啦在线学习网 CMP AL,"?"
学习啦在线学习网 JNZ NOCHG
MOV AL,[BX]
NOCHG:
STOSB
INC BX
学习啦在线学习网 LOOP NEWNAM
学习啦在线学习网 MOV BYTE PTR [DI],6 ;Stop duplicates with any attributes
CALL DEVNAME ;Check if giving it a device name
JNC RENERR
PUSH [LASTENT] ;Save position of match
MOV [LASTENT],-1 ;Search entire directory for duplicate
CALL CONTSRCH ;See if new name already exists
POP AX
JNC RENERR ;Error if found
CALL GETENT ;Re-read matching entry
MOV DI,BX
MOV SI,OFFSET DOSGROUP:NAME1
MOV CX,5
MOVSB
学习啦在线学习网 REP MOVSW ;Replace old name with new one
MOV BYTE PTR [DIRTYDIR],-1 ;Flag change in directory
MOV SI,OFFSET DOSGROUP:NAME3
学习啦在线学习网 MOV DI,OFFSET DOSGROUP:NAME1
MOV CX,6 ;Include attribute byte
REP MOVSW ;Copy name back into search buffer
CALL CONTSRCH
学习啦在线学习网 JNC RENFIL
学习啦在线学习网 CALL CHKDIRWRITE
XOR AL,AL
RET
RENERR:
CALL CHKDIRWRITE
ERRET:
MOV AL,-1
学习啦在线学习网 RET5: RET
学习啦在线学习网 MOVNAME:
; Inputs:
学习啦在线学习网 ; DS, DX point to FCB or extended FCB
; Outputs:
学习啦在线学习网 ; DS:DX point to normal FCB
; ES = CS
学习啦在线学习网 ; If file name OK:
; BP has base of driver parameters
; [NAME1] has name in upper case
; All registers except DX destroyed
; Carry set if bad file name or drive
MOV CS:WORD PTR [CREATING],0E500H ;Not creating, not DEL *.*
MOV AX,CS
MOV ES,AX
学习啦在线学习网 MOV DI,OFFSET DOSGROUP:NAME1
MOV SI,DX
LODSB
MOV CS:[EXTFCB],AL ;Set flag if extended FCB in use
MOV AH,0 ;Set default attributes
CMP AL,-1 ;Is it an extended FCB?
JNZ HAVATTRB
学习啦在线学习网 ADD DX,7 ;Adjust to point to normal FCB
学习啦在线学习网 ADD SI,6 ;Point to drive select byte
学习啦在线学习网 MOV AH,[SI-1] ;Get attribute byte
LODSB ;Get drive select byte
HAVATTRB:
学习啦在线学习网 MOV CS:[ATTRIB],AH ;Save attributes
学习啦在线学习网 CALL GETTHISDRV
学习啦在线学习网 LODNAME:
; This entry point copies a file name from DS,SI
学习啦在线学习网 ; to ES,DI converting to upper case.
CMP BYTE PTR [SI]," " ;Don't allow blank as first letter
学习啦在线学习网 STC ;In case of error
JZ RET5
MOV CX,11
MOVCHK:
学习啦在线学习网 CALL GETLET
JB RET5
JNZ STOLET ;Is it a delimiter?
CMP AL," " ;This is the only delimiter allowed
学习啦在线学习网 STC ;In case of error
JNZ RET5
STOLET:
STOSB
LOOP MOVCHK
CLC ;Got through whole name - no error
学习啦在线学习网 RET6: RET
GETTHISDRV:
CMP CS:[NUMDRV],AL
JC RET6
DEC AL
学习啦在线学习网 JNS PHYDRV
学习啦在线学习网 MOV AL,CS:[CURDRV]
PHYDRV:
MOV CS:[THISDRV],AL
RET
学习啦在线学习网 OPEN: ;System call 15
学习啦在线学习网 CALL GETFILE
DOOPEN:
学习啦在线学习网 ; Enter here to perform OPEN on file already found
; in directory. DS=CS, BX points to directory
; entry in DIRBUF, SI points to First Cluster field, and
; ES:DI point to the FCB to be opened. This entry point
; is used by CREATE.
JC ERRET
OR BH,BH ;Check if file is I/O device
学习啦在线学习网 JS OPENDEV ;Special handler if so
学习啦在线学习网 MOV AL,[THISDRV]
INC AX
STOSB
学习啦在线学习网 XOR AX,AX
IF ZEROEXT
ADD DI,11
STOSW ;Zero low byte of extent field if IBM only
ENDIF
IF NOT ZEROEXT
学习啦在线学习网 ADD DI,12 ;Point to high half of CURRENT BLOCK field
学习啦在线学习网 STOSB ;Set it to zero (CP/M programs set low byte)
ENDIF
MOV AL,128 ;Default record size
STOSW ;Set record size
学习啦在线学习网 LODSW ;Get starting cluster
MOV DX,AX ;Save it for the moment
学习啦在线学习网 MOVSW ;Transfer size to FCB
MOVSW
MOV AX,[SI-8] ;Get date
STOSW ;Save date in FCB
MOV AX,[SI-10] ;Get time
STOSW ;Save it in FCB
MOV AL,[BP.DEVNUM]
学习啦在线学习网 OR AL,40H
STOSB
MOV AX,DX ;Restore starting cluster
学习啦在线学习网 STOSW ; first cluster
STOSW ; last cluster accessed
学习啦在线学习网 XOR AX,AX
STOSW ; position of last cluster
RET
OPENDEV:
学习啦在线学习网 ADD DI,13 ;point to 2nd half of extent field
XOR AX,AX
STOSB ;Set it to zero
MOV AL,128
STOSW ;Set record size to 128
XOR AX,AX
STOSW
STOSW ;Set current size to zero
学习啦在线学习网 CALL DATE16
STOSW ;Date is todays
学习啦在线学习网 XCHG AX,DX
STOSW ;Use current time
学习啦在线学习网 MOV AL,BH ;Get device number
STOSB
XOR AL,AL ;No error
RET
FATERR:
学习啦在线学习网 XCHG AX,DI ;Put error code in DI
MOV AH,2 ;While trying to read FAT
MOV AL,[THISDRV] ;Tell which drive
学习啦在线学习网 CALL FATAL1
学习啦在线学习网 JMP SHORT FATREAD
学习啦在线学习网 STARTSRCH:
MOV AX,-1
学习啦在线学习网 MOV [LASTENT],AX
学习啦在线学习网 MOV [ENTFREE],AX
FATREAD:
; Inputs:
学习啦在线学习网 ; DS = CS
; Function:
; If disk may have been changed, FAT is read in and buffers are
学习啦在线学习网 ; flagged invalid. If not, no action is taken.
; Outputs:
; BP = Base of drive parameters
; Carry set if invalid drive returned by MAPDEV
; All other registers destroyed
MOV AL,[THISDRV]
XOR AH,AH ;Set default response to zero & clear carry
学习啦在线学习网 CALL FAR PTR BIOSDSKCHG ;See what BIOS has to say
JC FATERR
CALL GETBP
MOV AL,[THISDRV] ;Use physical unit number
MOV SI,[BP.FAT]
学习啦在线学习网 OR AH,[SI-1] ;Dirty byte for FAT
学习啦在线学习网 JS NEWDSK ;If either say new disk, then it's so
JNZ MAPDRV
MOV AH,1
学习啦在线学习网 CMP AX,WORD PTR [BUFDRVNO] ;Does buffer have dirty sector of this drive?
JZ MAPDRV
NEWDSK:
CMP AL,[BUFDRVNO] ;See if buffer is for this drive
学习啦在线学习网 JNZ BUFOK ;If not, don't touch it
MOV [BUFSECNO],0 ;Flag buffers invalid
MOV WORD PTR [BUFDRVNO],00FFH
BUFOK:
MOV [DIRBUFID],-1
学习啦在线学习网 CALL FIGFAT
NEXTFAT:
PUSH AX
CALL DSKREAD
POP AX
JC BADFAT
SUB AL,[BP.FATCNT]
JZ NEWFAT
学习啦在线学习网 CALL FATWRT
NEWFAT:
MOV SI,[BP.FAT]
MOV AL,[BP.DEVNUM]
MOV AH,[SI] ;Get first byte of FAT
学习啦在线学习网 OR AH,0F8H ;Put in range
CALL FAR PTR BIOSMAPDEV
MOV AH,0
MOV [SI-2],AX ;Set device no. and reset dirty bit
MAPDRV:
MOV AL,[SI-2] ;Get device number
GETBP:
学习啦在线学习网 MOV BP,[DRVTAB] ;Just in case drive isn't valid
学习啦在线学习网 AND AL,3FH ;Mask out dirty bit
CMP AL,[NUMIO]
CMC
JC RET7
PUSH AX
MOV AH,DPBSIZ
MUL AH
学习啦在线学习网 ADD BP,AX
POP AX
RET7: RET
BADFAT:
学习啦在线学习网 MOV CX,DI
学习啦在线学习网 ADD DX,CX
DEC AL
JNZ NEXTFAT
CALL FIGFAT ;Reset registers
学习啦在线学习网 CALL DREAD ;Try first FAT once more
学习啦在线学习网 JMP SHORT NEWFAT
OKRET1:
学习啦在线学习网 MOV AL,0
RET
CLOSE: ;System call 16
MOV DI,DX
学习啦在线学习网 CMP BYTE PTR [DI],-1 ;Check for extended FCB
学习啦在线学习网 JNZ NORMFCB3
ADD DI,7
学习啦在线学习网 NORMFCB3:
TEST BYTE PTR [DI.DEVID],0C0H ;Allow only dirty files
JNZ OKRET1 ;can't close if I/O device, or not writen
MOV AL,[DI] ;Get physical unit number
DEC AL ;Make zero = drive A
学习啦在线学习网 MOV AH,1 ;Look for dirty buffer
学习啦在线学习网 CMP AX,CS:WORD PTR [BUFDRVNO]
JNZ FNDDIR
学习啦在线学习网 ;Write back dirty buffer if on same drive
PUSH DX
PUSH DS
PUSH CS
POP DS
学习啦在线学习网 MOV BYTE PTR [DIRTYBUF],0
MOV BX,[BUFFER]
MOV CX,1
MOV DX,[BUFSECNO]
学习啦在线学习网 MOV BP,[BUFDRVBP]
学习啦在线学习网 CALL DWRITE
POP DS
POP DX
FNDDIR:
CALL GETFILE
学习啦在线学习网 BADCLOSEJ:
学习啦在线学习网 JC BADCLOSE
MOV CX,ES:[DI.FIRCLUS]
学习啦在线学习网 MOV [SI],CX
MOV DX,ES:WORD PTR [DI.FILSIZ]
学习啦在线学习网 MOV [SI+2],DX
学习啦在线学习网 MOV DX,ES:WORD PTR [DI.FILSIZ+2]
学习啦在线学习网 MOV [SI+4],DX
MOV DX,ES:[DI.FDATE]
MOV [SI-2],DX
MOV DX,ES:[DI.FTIME]
学习啦在线学习网 MOV [SI-4],DX
学习啦在线学习网 CALL DIRWRITE
CHKFATWRT:
学习啦在线学习网 ; Do FATWRT only if FAT is dirty and uses same I/O driver
学习啦在线学习网 MOV SI,[BP.FAT]
学习啦在线学习网 MOV AL,[BP.DEVNUM]
学习啦在线学习网 MOV AH,1
CMP [SI-2],AX ;See if FAT dirty and uses same driver
学习啦在线学习网 JNZ OKRET
FATWRT:
; Inputs:
学习啦在线学习网 ; DS = CS
; BP = Base of drive parameter table
; Function:
学习啦在线学习网 ; Write the FAT back to disk and reset FAT
学习啦在线学习网 ; dirty bit.
; Outputs:
学习啦在线学习网 ; AL = 0
; BP unchanged
学习啦在线学习网 ; All other registers destroyed
CALL FIGFAT
MOV BYTE PTR [BX-1],0
学习啦在线学习网 EACHFAT:
PUSH DX
PUSH CX
PUSH BX
PUSH AX
CALL DWRITE
POP AX
POP BX
POP CX
POP DX
ADD DX,CX
DEC AL
学习啦在线学习网 JNZ EACHFAT
OKRET:
MOV AL,0
RET
BADCLOSE:
MOV SI,[BP.FAT]
MOV BYTE PTR [SI-1],0
MOV AL,-1
RET
FIGFAT:
; Loads registers with values needed to read or
; write a FAT.
MOV AL,[BP.FATCNT]
MOV BX,[BP.FAT]
MOV CL,[BP.FATSIZ] ;No. of records occupied by FAT
MOV CH,0
MOV DX,[BP.FIRFAT] ;Record number of start of FATs
RET
DIRCOMP:
; Prepare registers for directory read or write
CBW
学习啦在线学习网 ADD AX,[BP.FIRDIR]
MOV DX,AX
MOV BX,OFFSET DOSGROUP:DIRBUF
MOV CX,1
RET
CREATE: ;System call 22
学习啦在线学习网 CALL MOVNAME
JC ERRET3
学习啦在线学习网 MOV DI,OFFSET DOSGROUP:NAME1
学习啦在线学习网 MOV CX,11
学习啦在线学习网 MOV AL,"?"
REPNE SCASB
JZ ERRET3
MOV CS:BYTE PTR [CREATING],-1
PUSH DX
PUSH DS
CALL FINDNAME
JNC EXISTENT
学习啦在线学习网 MOV AX,[ENTFREE] ;First free entry found in FINDNAME
CMP AX,-1
JZ ERRPOP
CALL GETENT ;Point at that free entry
学习啦在线学习网 JMP SHORT FREESPOT
ERRPOP:
POP DS
POP DX
ERRET3:
MOV AL,-1
RET
EXISTENT:
学习啦在线学习网 JNZ ERRPOP ;Error if attributes don't match
学习啦在线学习网 OR BH,BH ;Check if file is I/O device
学习啦在线学习网 JS OPENJMP ;If so, no action
学习啦在线学习网 MOV CX,[SI] ;Get pointer to clusters
JCXZ FREESPOT
CMP CX,[BP.MAXCLUS]
JA FREESPOT
PUSH BX
MOV BX,CX
学习啦在线学习网 MOV SI,[BP.FAT]
学习啦在线学习网 CALL RELEASE ;Free any data already allocated
CALL FATWRT
POP BX
学习啦在线学习网 FREESPOT:
学习啦在线学习网 MOV DI,BX
MOV SI,OFFSET DOSGROUP:NAME1
MOV CX,5
MOVSB
REP MOVSW
MOV AL,[ATTRIB]
STOSB
XOR AX,AX
MOV CL,5
REP STOSW
学习啦在线学习网 CALL DATE16
XCHG AX,DX
STOSW
学习啦在线学习网 XCHG AX,DX
STOSW
XOR AX,AX
PUSH DI
MOV CL,6
SMALLENT:
学习啦在线学习网 REP STOSB
PUSH BX
CALL DIRWRITE
POP BX
POP SI
OPENJMP:
学习啦在线学习网 CLC ;Clear carry so OPEN won't fail
POP ES
POP DI
JMP DOOPEN
DIRREAD:
; Inputs:
学习啦在线学习网 ; DS = CS
; AL = Directory block number
; BP = Base of drive parameters
; Function:
; Read the directory block into DIRBUF.
学习啦在线学习网 ; Outputs:
学习啦在线学习网 ; AX,BP unchanged
; All other registers destroyed.
PUSH AX
学习啦在线学习网 CALL CHKDIRWRITE
POP AX
PUSH AX
学习啦在线学习网 MOV AH,[BP.DEVNUM]
学习啦在线学习网 MOV [DIRBUFID],AX
CALL DIRCOMP
CALL DREAD
POP AX
学习啦在线学习网 RET8: RET
DREAD:
; Inputs:
学习啦在线学习网 ; BX,DS = Transfer address
; CX = Number of sectors
学习啦在线学习网 ; DX = Absolute record number
; BP = Base of drive parameters
; Function:
; Calls BIOS to perform disk read. If BIOS reports
学习啦在线学习网 ; errors, will call HARDERR for further action.
学习啦在线学习网 ; BP preserved. All other registers destroyed.
学习啦在线学习网 CALL DSKREAD
JNC RET8
学习啦在线学习网 MOV CS:BYTE PTR [READOP],0
CALL HARDERR
CMP AL,1 ;Check for retry
JZ DREAD
学习啦在线学习网 RET ;Ignore otherwise
HARDERR:
学习啦在线学习网 ;Hard disk error handler. Entry conditions:
学习啦在线学习网 ; DS:BX = Original disk transfer address
学习啦在线学习网 ; DX = Original logical sector number
; CX = Number of sectors to go (first one gave the error)
学习啦在线学习网 ; AX = Hardware error code
学习啦在线学习网 ; DI = Original sector transfer count
学习啦在线学习网 ; BP = Base of drive parameters
; [READOP] = 0 for read, 1 for write
XCHG AX,DI ;Error code in DI, count in AX
学习啦在线学习网 SUB AX,CX ;Number of sectors successfully transferred
ADD DX,AX ;First sector number to retry
PUSH DX
学习啦在线学习网 MUL [BP.SECSIZ] ;Number of bytes transferred
POP DX
ADD BX,AX ;First address for retry
MOV AH,0 ;Flag disk section in error
学习啦在线学习网 CMP DX,[BP.FIRFAT] ;In reserved area?
JB ERRINT
INC AH ;Flag for FAT
学习啦在线学习网 CMP DX,[BP.FIRDIR] ;In FAT?
JB ERRINT
INC AH
CMP DX,[BP.FIRREC] ;In directory?
JB ERRINT
学习啦在线学习网 INC AH ;Must be in data area
ERRINT:
学习啦在线学习网 SHL AH,1 ;Make room for read/write bit
OR AH,CS:[READOP]
FATAL:
学习啦在线学习网 MOV AL,[BP.DRVNUM] ;Get drive number
FATAL1:
学习啦在线学习网 PUSH BP ;The only thing we preserve
学习啦在线学习网 MOV CS:[CONTSTK],SP
学习啦在线学习网 CLI ;Prepare to play with stack
学习啦在线学习网 MOV SS,CS:[SSSAVE]
MOV SP,CS:[SPSAVE] ;User stack pointer restored
INT 24H ;Fatal error interrupt vector
MOV CS:[SPSAVE],SP
MOV CS:[SSSAVE],SS
MOV SP,CS
学习啦在线学习网 MOV SS,SP
学习啦在线学习网 MOV SP,CS:[CONTSTK]
STI
POP BP
学习啦在线学习网 CMP AL,2
学习啦在线学习网 JZ ERROR
RET
DSKREAD:
MOV AL,[BP.DEVNUM]
PUSH BP
PUSH BX
PUSH CX
PUSH DX
学习啦在线学习网 CALL FAR PTR BIOSREAD
POP DX
POP DI
POP BX
POP BP
RET9: RET
CHKDIRWRITE:
TEST BYTE PTR [DIRTYDIR],-1
JZ RET9
DIRWRITE:
; Inputs:
学习啦在线学习网 ; DS = CS
学习啦在线学习网 ; AL = Directory block number
; BP = Base of drive parameters
; Function:
学习啦在线学习网 ; Write the directory block into DIRBUF.
; Outputs:
; BP unchanged
; All other registers destroyed.
MOV BYTE PTR [DIRTYDIR],0
学习啦在线学习网 MOV AL,BYTE PTR [DIRBUFID]
CALL DIRCOMP
DWRITE:
学习啦在线学习网 ; Inputs:
学习啦在线学习网 ; BX,DS = Transfer address
学习啦在线学习网 ; CX = Number of sectors
; DX = Absolute record number
学习啦在线学习网 ; BP = Base of drive parameters
; Function:
学习啦在线学习网 ; Calls BIOS to perform disk write. If BIOS reports
学习啦在线学习网 ; errors, will call HARDERR for further action.
学习啦在线学习网 ; BP preserved. All other registers destroyed.
学习啦在线学习网 MOV AL,[BP.DEVNUM]
学习啦在线学习网 MOV AH,CS:VERFLG
PUSH BP
PUSH BX
PUSH CX
PUSH DX
CALL FAR PTR BIOSWRITE
POP DX
POP DI
POP BX
POP BP
JNC RET9
MOV CS:BYTE PTR [READOP],1
学习啦在线学习网 CALL HARDERR
学习啦在线学习网 CMP AL,1 ;Check for retry
学习啦在线学习网 JZ DWRITE
RET
ABORT:
学习啦在线学习网 LDS SI,CS:DWORD PTR [SPSAVE]
MOV DS,[SI.CSSAVE]
学习啦在线学习网 XOR AX,AX
MOV ES,AX
MOV SI,SAVEXIT
MOV DI,EXIT
MOVSW
MOVSW
MOVSW
MOVSW
MOVSW
MOVSW
ERROR:
学习啦在线学习网 MOV AX,CS
学习啦在线学习网 MOV DS,AX
MOV ES,AX
CALL WRTFATS
学习啦在线学习网 XOR AX,AX
CLI
MOV SS,[SSSAVE]
MOV SP,[SPSAVE]
学习啦在线学习网 MOV DS,AX
MOV SI,EXIT
MOV DI,OFFSET DOSGROUP:EXITHOLD
MOVSW
MOVSW
POP AX
POP BX
POP CX
POP DX
POP SI
POP DI
POP BP
POP DS
POP ES
学习啦在线学习网 STI ;Stack OK now
JMP CS:DWORD PTR [EXITHOLD]
学习啦在线学习网 SEQRD: ;System call 20
CALL GETREC
CALL LOAD
JMP SHORT FINSEQ
SEQWRT: ;System call 21
学习啦在线学习网 CALL GETREC
CALL STORE
FINSEQ:
JCXZ SETNREX
学习啦在线学习网 ADD AX,1
ADC DX,0
JMP SHORT SETNREX
学习啦在线学习网 RNDRD: ;System call 33
学习啦在线学习网 CALL GETRRPOS1
学习啦在线学习网 CALL LOAD
学习啦在线学习网 JMP SHORT FINRND
RNDWRT: ;System call 34
CALL GETRRPOS1
学习啦在线学习网 CALL STORE
JMP SHORT FINRND
BLKRD: ;System call 39
学习啦在线学习网 CALL GETRRPOS
学习啦在线学习网 CALL LOAD
JMP SHORT FINBLK
学习啦在线学习网 BLKWRT: ;System call 40
CALL GETRRPOS
CALL STORE
FINBLK:
学习啦在线学习网 LDS SI,DWORD PTR [SPSAVE]
MOV [SI.CXSAVE],CX
JCXZ FINRND
ADD AX,1
ADC DX,0
FINRND:
学习啦在线学习网 MOV ES:WORD PTR [DI.RR],AX
MOV ES:[DI.RR+2],DL
OR DH,DH
JZ SETNREX
MOV ES:[DI.RR+3],DH ;Save 4 byte of RECPOS only if significant
SETNREX:
MOV CX,AX
AND AL,7FH
学习啦在线学习网 MOV ES:[DI.NR],AL
学习啦在线学习网 AND CL,80H
SHL CX,1
RCL DX,1
MOV AL,CH
学习啦在线学习网 MOV AH,DL
MOV ES:[DI.EXTENT],AX
MOV AL,CS:[DSKERR]
RET
GETRRPOS1:
学习啦在线学习网 MOV CX,1
学习啦在线学习网 GETRRPOS:
MOV DI,DX
CMP BYTE PTR [DI],-1
学习啦在线学习网 JNZ NORMFCB1
ADD DI,7
NORMFCB1:
MOV AX,WORD PTR [DI.RR]
MOV DX,WORD PTR [DI.RR+2]
RET
NOFILERR:
学习啦在线学习网 XOR CX,CX
学习啦在线学习网 MOV BYTE PTR [DSKERR],4
POP BX
RET
SETUP:
; Inputs:
; DS:DI point to FCB
; DX:AX = Record position in file of disk transfer
; CX = Record count
; Outputs:
; DS = CS
; ES:DI point to FCB
; BL = DEVID from FCB
学习啦在线学习网 ; CX = No. of bytes to transfer
; BP = Base of drive parameters
学习啦在线学习网 ; SI = FAT pointer
学习啦在线学习网 ; [RECCNT] = Record count
学习啦在线学习网 ; [RECPOS] = Record position in file
; [FCB] = DI
; [NEXTADD] = Displacement of disk transfer within segment
学习啦在线学习网 ; [SECPOS] = Position of first sector
; [BYTPOS] = Byte position in file
; [BYTSECPOS] = Byte position in first sector
学习啦在线学习网 ; [CLUSNUM] = First cluster
; [SECCLUSPOS] = Sector within first cluster
; [DSKERR] = 0 (no errors yet)
学习啦在线学习网 ; [TRANS] = 0 (No transfers yet)
; [THISDRV] = Physical drive unit number
学习啦在线学习网 ; If SETUP detects no records will be transfered, it returns 1 level up
; with CX = 0.
PUSH AX
MOV AL,[DI]
DEC AL
学习啦在线学习网 MOV CS:[THISDRV],AL
学习啦在线学习网 MOV AL,[DI.DEVID]
学习啦在线学习网 MOV SI,[DI.RECSIZ]
学习啦在线学习网 OR SI,SI
JNZ HAVRECSIZ
学习啦在线学习网 MOV SI,128
学习啦在线学习网 MOV [DI.RECSIZ],SI
HAVRECSIZ:
PUSH DS
学习啦在线学习网 POP ES ;Set ES to DS
PUSH CS
学习啦在线学习网 POP DS ;Set DS to CS
学习啦在线学习网 OR AL,AL ;Is it a device?
学习啦在线学习网 JNS NOTDEVICE
学习啦在线学习网 MOV AL,0 ;Fake in drive 0 so we can get SP
NOTDEVICE:
学习啦在线学习网 CALL GETBP
POP AX
学习啦在线学习网 JC NOFILERR
学习啦在线学习网 CMP SI,64 ;Check if highest byte of RECPOS is significant
学习啦在线学习网 JB SMALREC
MOV DH,0 ;Ignore MSB if record >= 64 bytes
SMALREC:
学习啦在线学习网 MOV [RECCNT],CX
MOV WORD PTR [RECPOS],AX
MOV WORD PTR [RECPOS+2],DX
学习啦在线学习网 MOV [FCB],DI
MOV BX,[DMAADD]
学习啦在线学习网 MOV [NEXTADD],BX
MOV BYTE PTR [DSKERR],0
MOV BYTE PTR [TRANS],0
学习啦在线学习网 MOV BX,DX
MUL SI
学习啦在线学习网 MOV WORD PTR [BYTPOS],AX
PUSH DX
MOV AX,BX
MUL SI
POP BX
学习啦在线学习网 ADD AX,BX
学习啦在线学习网 ADC DX,0 ;Ripple carry
学习啦在线学习网 JNZ EOFERR
学习啦在线学习网 MOV WORD PTR [BYTPOS+2],AX
MOV DX,AX
MOV AX,WORD PTR [BYTPOS]
MOV BX,[BP.SECSIZ]
CMP DX,BX ;See if divide will overflow
JNC EOFERR
DIV BX
学习啦在线学习网 MOV [SECPOS],AX
MOV [BYTSECPOS],DX
MOV DX,AX
AND AL,[BP.CLUSMSK]
MOV [SECCLUSPOS],AL
MOV AX,CX ;Record count
学习啦在线学习网 MOV CL,[BP.CLUSSHFT]
学习啦在线学习网 SHR DX,CL
MOV [CLUSNUM],DX
MUL SI ;Multiply by bytes per record
学习啦在线学习网 MOV CX,AX
ADD AX,[DMAADD] ;See if it will fit in one segment
ADC DX,0
JZ OK ;Must be less than 64K
学习啦在线学习网 MOV AX,[DMAADD]
NEG AX ;Amount of room left in segment
学习啦在线学习网 JNZ PARTSEG ;All 64K available?
学习啦在线学习网 DEC AX ;If so, reduce by one
PARTSEG:
XOR DX,DX
DIV SI ;How many records will fit?
学习啦在线学习网 MOV [RECCNT],AX
MUL SI ;Translate that back into bytes
MOV BYTE PTR [DSKERR],2 ;Flag that trimming took place
MOV CX,AX
学习啦在线学习网 JCXZ NOROOM
OK:
学习啦在线学习网 MOV BL,ES:[DI.DEVID]
MOV SI,[BP.FAT]
RET
EOFERR:
MOV BYTE PTR [DSKERR],1
XOR CX,CX
NOROOM:
POP BX ;Kill return address
RET
BREAKDOWN:
学习啦在线学习网 ;Inputs:
; DS = CS
; CX = Length of disk transfer in bytes
; BP = Base of drive parameters
; [BYTSECPOS] = Byte position witin first sector
;Outputs:
; [BYTCNT1] = Bytes to transfer in first sector
; [SECCNT] = No. of whole sectors to transfer
学习啦在线学习网 ; [BYTCNT2] = Bytes to transfer in last sector
学习啦在线学习网 ;AX, BX, DX destroyed. No other registers affected.
MOV AX,[BYTSECPOS]
学习啦在线学习网 MOV BX,CX
OR AX,AX
学习啦在线学习网 JZ SAVFIR ;Partial first sector?
SUB AX,[BP.SECSIZ]
NEG AX ;Max number of bytes left in first sector
学习啦在线学习网 SUB BX,AX ;Subtract from total length
JAE SAVFIR
ADD AX,BX ;Don't use all of the rest of the sector
XOR BX,BX ;And no bytes are left
SAVFIR:
MOV [BYTCNT1],AX
MOV AX,BX
XOR DX,DX
DIV [BP.SECSIZ] ;How many whole sectors?
学习啦在线学习网 MOV [SECCNT],AX
MOV [BYTCNT2],DX ;Bytes remaining for last sector
RET10: RET
FNDCLUS:
; Inputs:
学习啦在线学习网 ; DS = CS
学习啦在线学习网 ; CX = No. of clusters to skip
; BP = Base of drive parameters
; SI = FAT pointer
; ES:DI point to FCB
学习啦在线学习网 ; Outputs:
; BX = Last cluster skipped to
; CX = No. of clusters remaining (0 unless EOF)
学习啦在线学习网 ; DX = Position of last cluster
; DI destroyed. No other registers affected.
MOV BX,ES:[DI.LSTCLUS]
学习啦在线学习网 MOV DX,ES:[DI.CLUSPOS]
学习啦在线学习网 OR BX,BX
JZ NOCLUS
SUB CX,DX
JNB FINDIT
ADD CX,DX
XOR DX,DX
MOV BX,ES:[DI.FIRCLUS]
FINDIT:
学习啦在线学习网 JCXZ RET10
SKPCLP:
CALL UNPACK
CMP DI,0FF8H
学习啦在线学习网 JAE RET10
学习啦在线学习网 XCHG BX,DI
INC DX
学习啦在线学习网 LOOP SKPCLP
RET
NOCLUS:
INC CX
DEC DX
RET
BUFSEC:
; Inputs:
; AL = 0 if buffer must be read, 1 if no pre-read needed
; BP = Base of drive parameters
; [CLUSNUM] = Physical cluster number
; [SECCLUSPOS] = Sector position of transfer within cluster
; [BYTCNT1] = Size of transfer
; Function:
; Insure specified sector is in buffer, flushing buffer before
; read if necessary.
学习啦在线学习网 ; Outputs:
; SI = Pointer to buffer
学习啦在线学习网 ; DI = Pointer to transfer address
; CX = Number of bytes
; [NEXTADD] updated
学习啦在线学习网 ; [TRANS] set to indicate a transfer will occur
MOV DX,[CLUSNUM]
MOV BL,[SECCLUSPOS]
CALL FIGREC
学习啦在线学习网 MOV [PREREAD],AL
学习啦在线学习网 CMP DX,[BUFSECNO]
JNZ GETSEC
学习啦在线学习网 MOV AL,[BUFDRVNO]
学习啦在线学习网 CMP AL,[THISDRV]
JZ FINBUF ;Already have it?
GETSEC:
XOR AL,AL
XCHG [DIRTYBUF],AL ;Read dirty flag and reset it
OR AL,AL
学习啦在线学习网 JZ RDSEC
PUSH DX
PUSH BP
MOV BP,[BUFDRVBP]
MOV BX,[BUFFER]
学习啦在线学习网 MOV CX,1
学习啦在线学习网 MOV DX,[BUFSECNO]
CALL DWRITE
POP BP
POP DX
RDSEC:
学习啦在线学习网 TEST BYTE PTR [PREREAD],-1
JNZ SETBUF
学习啦在线学习网 XOR AX,AX
学习啦在线学习网 MOV [BUFSECNO],AX ;Set buffer valid in case of disk error
DEC AX
学习啦在线学习网 MOV [BUFDRVNO],AL
MOV BX,[BUFFER]
MOV CX,1
PUSH DX
CALL DREAD
POP DX
SETBUF:
MOV [BUFSECNO],DX
学习啦在线学习网 MOV AL,[THISDRV]
MOV [BUFDRVNO],AL
MOV [BUFDRVBP],BP
FINBUF:
学习啦在线学习网 MOV BYTE PTR [TRANS],1 ;A transfer is taking place
学习啦在线学习网 MOV DI,[NEXTADD]
MOV SI,DI
MOV CX,[BYTCNT1]
ADD SI,CX
学习啦在线学习网 MOV [NEXTADD],SI
MOV SI,[BUFFER]
ADD SI,[BYTSECPOS]
RET
BUFRD:
XOR AL,AL ;Pre-read necessary
CALL BUFSEC
PUSH ES
MOV ES,[DMAADD+2]
SHR CX,1
学习啦在线学习网 JNC EVENRD
MOVSB
EVENRD:
学习啦在线学习网 REP MOVSW
POP ES
RET
BUFWRT:
MOV AX,[SECPOS]
学习啦在线学习网 INC AX ;Set for next sector
MOV [SECPOS],AX
学习啦在线学习网 CMP AX,[VALSEC] ;Has sector been written before?
学习啦在线学习网 MOV AL,1
JA NOREAD ;Skip preread if SECPOS>VALSEC
MOV AL,0
NOREAD:
CALL BUFSEC
XCHG DI,SI
PUSH DS
PUSH ES
PUSH CS
POP ES
MOV DS,[DMAADD+2]
学习啦在线学习网 SHR CX,1
JNC EVENWRT
MOVSB
学习啦在线学习网 EVENWRT:
REP MOVSW
POP ES
POP DS
MOV BYTE PTR [DIRTYBUF],1
RET
NEXTSEC:
学习啦在线学习网 TEST BYTE PTR [TRANS],-1
学习啦在线学习网 JZ CLRET
学习啦在线学习网 MOV AL,[SECCLUSPOS]
INC AL
CMP AL,[BP.CLUSMSK]
JBE SAVPOS
学习啦在线学习网 MOV BX,[CLUSNUM]
CMP BX,0FF8H
JAE NONEXT
MOV SI,[BP.FAT]
学习啦在线学习网 CALL UNPACK
学习啦在线学习网 MOV [CLUSNUM],DI
INC [LASTPOS]
MOV AL,0
SAVPOS:
学习啦在线学习网 MOV [SECCLUSPOS],AL
CLRET:
CLC
RET
NONEXT:
STC
RET
学习啦在线学习网 TRANBUF:
LODSB
STOSB
学习啦在线学习网 CMP AL,13 ;Check for carriage return
JNZ NORMCH
学习啦在线学习网 MOV BYTE PTR [SI],10
NORMCH:
CMP AL,10
学习啦在线学习网 LOOPNZ TRANBUF
JNZ ENDRDCON
CALL OUT ;Transmit linefeed
XOR SI,SI
学习啦在线学习网 OR CX,CX
JNZ GETBUF
OR AL,1 ;Clear zero flag--not end of file
ENDRDCON:
学习啦在线学习网 MOV [CONTPOS],SI
学习啦在线学习网 ENDRDDEV:
学习啦在线学习网 MOV [NEXTADD],DI
POP ES
学习啦在线学习网 JNZ SETFCBJ ;Zero set if Ctrl-Z found in input
学习啦在线学习网 MOV DI,[FCB]
AND ES:BYTE PTR [DI.DEVID],0FFH-40H ;Mark as no more data available
SETFCBJ:
JMP SETFCB
READDEV:
PUSH ES
LES DI,DWORD PTR [DMAADD]
INC BL
JZ READCON
INC BL
学习啦在线学习网 JNZ ENDRDDEV
学习啦在线学习网 READAUX:
CALL AUXIN
STOSB
CMP AL,1AH
学习啦在线学习网 LOOPNZ READAUX
JMP SHORT ENDRDDEV
学习啦在线学习网 READCON:
PUSH CS
POP DS
MOV SI,[CONTPOS]
OR SI,SI
JNZ TRANBUF
学习啦在线学习网 CMP BYTE PTR [CONBUF],128
学习啦在线学习网 JZ GETBUF
MOV WORD PTR [CONBUF],0FF80H ;Set up 128-byte buffer with no template
GETBUF:
PUSH CX
PUSH ES
PUSH DI
MOV DX,OFFSET DOSGROUP:CONBUF
CALL BUFIN ;Get input buffer
POP DI
POP ES
POP CX
学习啦在线学习网 MOV SI,2 + OFFSET DOSGROUP:CONBUF
CMP BYTE PTR [SI],1AH ;Check for Ctrl-Z in first character
JNZ TRANBUF
学习啦在线学习网 MOV AL,1AH
STOSB
MOV AL,10
CALL OUT ;Send linefeed
XOR SI,SI
JMP SHORT ENDRDCON
RDERR:
XOR CX,CX
JMP WRTERR
RDLASTJ:JMP RDLAST
LOAD:
学习啦在线学习网 ; Inputs:
; DS:DI point to FCB
学习啦在线学习网 ; DX:AX = Position in file to read
; CX = No. of records to read
; Outputs:
; DX:AX = Position of last record read
; CX = No. of bytes read
; ES:DI point to FCB
学习啦在线学习网 ; LSTCLUS, CLUSPOS fields in FCB set
CALL SETUP
学习啦在线学习网 OR BL,BL ;Check for named device I/O
JS READDEV
MOV AX,ES:WORD PTR [DI.FILSIZ]
学习啦在线学习网 MOV BX,ES:WORD PTR [DI.FILSIZ+2]
学习啦在线学习网 SUB AX,WORD PTR [BYTPOS]
学习啦在线学习网 SBB BX,WORD PTR [BYTPOS+2]
JB RDERR
JNZ ENUF
OR AX,AX
JZ RDERR
CMP AX,CX
学习啦在线学习网 JAE ENUF
学习啦在线学习网 MOV CX,AX
ENUF:
CALL BREAKDOWN
MOV CX,[CLUSNUM]
学习啦在线学习网 CALL FNDCLUS
OR CX,CX
JNZ RDERR
MOV [LASTPOS],DX
学习啦在线学习网 MOV [CLUSNUM],BX
学习啦在线学习网 CMP [BYTCNT1],0
JZ RDMID
学习啦在线学习网 CALL BUFRD
RDMID:
学习啦在线学习网 CMP [SECCNT],0
学习啦在线学习网 JZ RDLASTJ
学习啦在线学习网 CALL NEXTSEC
JC SETFCB
MOV BYTE PTR [TRANS],1 ;A transfer is taking place
ONSEC:
学习啦在线学习网 MOV DL,[SECCLUSPOS]
MOV CX,[SECCNT]
MOV BX,[CLUSNUM]
RDLP:
CALL OPTIMIZE
PUSH DI
PUSH AX
PUSH DS
MOV DS,[DMAADD+2]
PUSH DX
PUSH BX
PUSHF ;Save carry flag
CALL DREAD
学习啦在线学习网 POPF ;Restore carry flag
POP DI ;Initial transfer address
学习啦在线学习网 POP AX ;First sector transfered
POP DS
JC NOTBUFFED ;Was one of those sectors in the buffer?
CMP BYTE PTR [DIRTYBUF],0 ;Is buffer dirty?
学习啦在线学习网 JZ NOTBUFFED ;If not no problem
;We have transfered in a sector from disk when a dirty copy of it is in the buffer.
学习啦在线学习网 ;We must transfer the sector from the buffer to correct memory address
SUB AX,[BUFSECNO] ;How many sectors into the transfer?
NEG AX
MOV CX,[BP.SECSIZ]
学习啦在线学习网 MUL CX ;How many bytes into the transfer?
ADD DI,AX
MOV SI,[BUFFER]
PUSH ES
学习啦在线学习网 MOV ES,[DMAADD+2] ;Get disk transfer segment
学习啦在线学习网 SHR CX,1
学习啦在线学习网 REP MOVSW
JNC EVENMOV
MOVSB
学习啦在线学习网 EVENMOV:
POP ES
NOTBUFFED:
POP CX
POP BX
JCXZ RDLAST
CMP BX,0FF8H
JAE SETFCB
MOV DL,0
学习啦在线学习网 INC [LASTPOS] ;We'll be using next cluster
JMP SHORT RDLP
SETFCB:
MOV SI,[FCB]
MOV AX,[NEXTADD]
MOV DI,AX
学习啦在线学习网 SUB AX,[DMAADD] ;Number of bytes transfered
学习啦在线学习网 XOR DX,DX
MOV CX,ES:[SI.RECSIZ]
学习啦在线学习网 DIV CX ;Number of records
CMP AX,[RECCNT] ;Check if all records transferred
学习啦在线学习网 JZ FULLREC
学习啦在线学习网 MOV BYTE PTR [DSKERR],1
OR DX,DX
学习啦在线学习网 JZ FULLREC ;If remainder 0, then full record transfered
MOV BYTE PTR [DSKERR],3 ;Flag partial last record
SUB CX,DX ;Bytes left in last record
PUSH ES
MOV ES,[DMAADD+2]
XCHG AX,BX ;Save the record count temporarily
学习啦在线学习网 XOR AX,AX ;Fill with zeros
SHR CX,1
JNC EVENFIL
STOSB
EVENFIL:
REP STOSW
学习啦在线学习网 XCHG AX,BX ;Restore record count to AX
POP ES
INC AX ;Add last (partial) record to total
学习啦在线学习网 FULLREC:
学习啦在线学习网 MOV CX,AX
学习啦在线学习网 MOV DI,SI ;ES:DI point to FCB
SETCLUS:
MOV AX,[CLUSNUM]
MOV ES:[DI.LSTCLUS],AX
学习啦在线学习网 MOV AX,[LASTPOS]
MOV ES:[DI.CLUSPOS],AX
ADDREC:
MOV AX,WORD PTR [RECPOS]
MOV DX,WORD PTR [RECPOS+2]
JCXZ RET28 ;If no records read, don't change position
DEC CX
ADD AX,CX ;Update current record position
ADC DX,0
INC CX
RET28: RET
RDLAST:
学习啦在线学习网 MOV AX,[BYTCNT2]
学习啦在线学习网 OR AX,AX
学习啦在线学习网 JZ SETFCB
MOV [BYTCNT1],AX
学习啦在线学习网 CALL NEXTSEC
JC SETFCB
学习啦在线学习网 MOV [BYTSECPOS],0
CALL BUFRD
学习啦在线学习网 JMP SHORT SETFCB
WRTDEV:
PUSH DS
LDS SI,DWORD PTR [DMAADD]
OR BL,40H
INC BL
学习啦在线学习网 JZ WRTCON
INC BL
JZ WRTAUX
INC BL
学习啦在线学习网 JZ ENDWRDEV ;Done if device is NUL
WRTLST:
LODSB
CMP AL,1AH
JZ ENDWRDEV
CALL LISTOUT
LOOP WRTLST
JMP SHORT ENDWRDEV
WRTAUX:
LODSB
CALL AUXOUT
学习啦在线学习网 CMP AL,1AH
LOOPNZ WRTAUX
JMP SHORT ENDWRDEV
WRTCON:
LODSB
学习啦在线学习网 CMP AL,1AH
JZ ENDWRDEV
学习啦在线学习网 CALL OUT
学习啦在线学习网 LOOP WRTCON
ENDWRDEV:
POP DS
MOV CX,[RECCNT]
MOV DI,[FCB]
JMP SHORT ADDREC
学习啦在线学习网 HAVSTART:
学习啦在线学习网 MOV CX,AX
CALL SKPCLP
JCXZ DOWRTJ
CALL ALLOCATE
学习啦在线学习网 JNC DOWRTJ
WRTERR:
学习啦在线学习网 MOV BYTE PTR [DSKERR],1
LVDSK:
学习啦在线学习网 MOV AX,WORD PTR [RECPOS]
MOV DX,WORD PTR [RECPOS+2]
MOV DI,[FCB]
RET
DOWRTJ: JMP DOWRT
WRTEOFJ:
JMP WRTEOF
STORE:
; Inputs:
; DS:DI point to FCB
; DX:AX = Position in file of disk transfer
; CX = Record count
学习啦在线学习网 ; Outputs:
; DX:AX = Position of last record written
; CX = No. of records written
学习啦在线学习网 ; ES:DI point to FCB
学习啦在线学习网 ; LSTCLUS, CLUSPOS fields in FCB set
学习啦在线学习网 CALL SETUP
CALL DATE16
MOV ES:[DI.FDATE],AX
学习啦在线学习网 MOV ES:[DI.FTIME],DX
OR BL,BL
学习啦在线学习网 JS WRTDEV
学习啦在线学习网 AND BL,3FH ;Mark file as dirty
MOV ES:[DI.DEVID],BL
CALL BREAKDOWN
学习啦在线学习网 MOV AX,WORD PTR [BYTPOS]
MOV DX,WORD PTR [BYTPOS+2]
JCXZ WRTEOFJ
DEC CX
ADD AX,CX
ADC DX,0 ;AX:DX=last byte accessed
学习啦在线学习网 DIV [BP.SECSIZ] ;AX=last sector accessed
MOV CL,[BP.CLUSSHFT]
学习啦在线学习网 SHR AX,CL ;Last cluster to be accessed
PUSH AX
MOV AX,ES:WORD PTR [DI.FILSIZ]
MOV DX,ES:WORD PTR [DI.FILSIZ+2]
DIV [BP.SECSIZ]
学习啦在线学习网 OR DX,DX
学习啦在线学习网 JZ NORNDUP
INC AX ;Round up if any remainder
学习啦在线学习网 NORNDUP:
学习啦在线学习网 MOV [VALSEC],AX ;Number of sectors that have been written
POP AX
学习啦在线学习网 MOV CX,[CLUSNUM] ;First cluster accessed
CALL FNDCLUS
MOV [CLUSNUM],BX
学习啦在线学习网 MOV [LASTPOS],DX
SUB AX,DX ;Last cluster minus current cluster
JZ DOWRT ;If we have last clus, we must have first
JCXZ HAVSTART ;See if no more data
PUSH CX ;No. of clusters short of first
MOV CX,AX
CALL ALLOCATE
POP AX
JC WRTERR
MOV CX,AX
MOV DX,[LASTPOS]
INC DX
DEC CX
学习啦在线学习网 JZ NOSKIP
学习啦在线学习网 CALL SKPCLP
NOSKIP:
学习啦在线学习网 MOV [CLUSNUM],BX
MOV [LASTPOS],DX
DOWRT:
CMP [BYTCNT1],0
学习啦在线学习网 JZ WRTMID
MOV BX,[CLUSNUM]
学习啦在线学习网 CALL BUFWRT
WRTMID:
MOV AX,[SECCNT]
OR AX,AX
学习啦在线学习网 JZ WRTLAST
ADD [SECPOS],AX
CALL NEXTSEC
学习啦在线学习网 MOV BYTE PTR [TRANS],1 ;A transfer is taking place
学习啦在线学习网 MOV DL,[SECCLUSPOS]
学习啦在线学习网 MOV BX,[CLUSNUM]
MOV CX,[SECCNT]
WRTLP:
学习啦在线学习网 CALL OPTIMIZE
学习啦在线学习网 JC NOTINBUF ;Is one of the sectors buffered?
MOV [BUFSECNO],0 ;If so, invalidate the buffer since we're
MOV WORD PTR [BUFDRVNO],0FFH ; completely rewritting it
学习啦在线学习网 NOTINBUF:
PUSH DI
PUSH AX
PUSH DS
MOV DS,[DMAADD+2]
CALL DWRITE
POP DS
POP CX
POP BX
学习啦在线学习网 JCXZ WRTLAST
MOV DL,0
INC [LASTPOS] ;We'll be using next cluster
JMP SHORT WRTLP
WRTLAST:
学习啦在线学习网 MOV AX,[BYTCNT2]
OR AX,AX
学习啦在线学习网 JZ FINWRT
MOV [BYTCNT1],AX
CALL NEXTSEC
学习啦在线学习网 MOV [BYTSECPOS],0
学习啦在线学习网 CALL BUFWRT
FINWRT:
学习啦在线学习网 MOV AX,[NEXTADD]
学习啦在线学习网 SUB AX,[DMAADD]
ADD AX,WORD PTR [BYTPOS]
学习啦在线学习网 MOV DX,WORD PTR [BYTPOS+2]
学习啦在线学习网 ADC DX,0
学习啦在线学习网 MOV CX,DX
MOV DI,[FCB]
学习啦在线学习网 CMP AX,ES:WORD PTR [DI.FILSIZ]
学习啦在线学习网 SBB CX,ES:WORD PTR [DI.FILSIZ+2]
JB SAMSIZ
学习啦在线学习网 MOV ES:WORD PTR [DI.FILSIZ],AX
学习啦在线学习网 MOV ES:WORD PTR [DI.FILSIZ+2],DX
SAMSIZ:
MOV CX,[RECCNT]
JMP SETCLUS
WRTERRJ:JMP WRTERR
WRTEOF:
学习啦在线学习网 MOV CX,AX
学习啦在线学习网 OR CX,DX
JZ KILLFIL
SUB AX,1
SBB DX,0
DIV [BP.SECSIZ]
MOV CL,[BP.CLUSSHFT]
学习啦在线学习网 SHR AX,CL
MOV CX,AX
CALL FNDCLUS
JCXZ RELFILE
CALL ALLOCATE
学习啦在线学习网 JC WRTERRJ
UPDATE:
MOV DI,[FCB]
MOV AX,WORD PTR [BYTPOS]
MOV ES:WORD PTR [DI.FILSIZ],AX
学习啦在线学习网 MOV AX,WORD PTR [BYTPOS+2]
学习啦在线学习网 MOV ES:WORD PTR [DI.FILSIZ+2],AX
学习啦在线学习网 XOR CX,CX
JMP ADDREC
学习啦在线学习网 RELFILE:
学习啦在线学习网 MOV DX,0FFFH
学习啦在线学习网 CALL RELBLKS
SETDIRT:
MOV BYTE PTR [SI-1],1
JMP SHORT UPDATE
学习啦在线学习网 KILLFIL:
学习啦在线学习网 XOR BX,BX
学习啦在线学习网 XCHG BX,ES:[DI.FIRCLUS]
学习啦在线学习网 OR BX,BX
JZ UPDATE
学习啦在线学习网 CALL RELEASE
学习啦在线学习网 JMP SHORT SETDIRT
OPTIMIZE:
; Inputs:
; DS = CS
学习啦在线学习网 ; BX = Physical cluster
学习啦在线学习网 ; CX = No. of records
; DL = sector within cluster
; BP = Base of drives parameters
; [NEXTADD] = transfer address
; Outputs:
学习啦在线学习网 ; AX = No. of records remaining
学习啦在线学习网 ; BX = Transfer address
学习啦在线学习网 ; CX = No. or records to be transferred
; DX = Physical sector address
; DI = Next cluster
; Carry clear if a sector to transfer is in the buffer
; Carry set otherwise
; [CLUSNUM] = Last cluster accessed
学习啦在线学习网 ; [NEXTADD] updated
学习啦在线学习网 ; BP unchanged. Note that segment of transfer not set.
PUSH DX
PUSH BX
MOV AL,[BP.CLUSMSK]
INC AL ;Number of sectors per cluster
MOV AH,AL
SUB AL,DL ;AL = Number of sectors left in first cluster
学习啦在线学习网 MOV DX,CX
学习啦在线学习网 MOV SI,[BP.FAT]
MOV CX,0
学习啦在线学习网 OPTCLUS:
;AL has number of sectors available in current cluster
;AH has number of sectors available in next cluster
学习啦在线学习网 ;BX has current physical cluster
学习啦在线学习网 ;CX has number of sequential sectors found so far
;DX has number of sectors left to transfer
;SI has FAT pointer
CALL UNPACK
ADD CL,AL
ADC CH,0
学习啦在线学习网 CMP CX,DX
学习啦在线学习网 JAE BLKDON
MOV AL,AH
INC BX
CMP DI,BX
JZ OPTCLUS
DEC BX
学习啦在线学习网 FINCLUS:
MOV [CLUSNUM],BX ;Last cluster accessed
SUB DX,CX ;Number of sectors still needed
PUSH DX
MOV AX,CX
MUL [BP.SECSIZ] ;Number of sectors times sector size
MOV SI,[NEXTADD]
ADD AX,SI ;Adjust by size of transfer
MOV [NEXTADD],AX
POP AX ;Number of sectors still needed
POP DX ;Starting cluster
学习啦在线学习网 SUB BX,DX ;Number of new clusters accessed
ADD [LASTPOS],BX
学习啦在线学习网 POP BX ;BL = sector postion within cluster
CALL FIGREC
MOV BX,SI
学习啦在线学习网 ;Now let's see if any of these sectors are already in the buffer
学习啦在线学习网 CMP [BUFSECNO],DX
学习啦在线学习网 JC RET100 ;If DX > [BUFSECNO] then not in buffer
学习啦在线学习网 MOV SI,DX
学习啦在线学习网 ADD SI,CX ;Last sector + 1
CMP [BUFSECNO],SI
CMC
JC RET100 ;If SI <= [BUFSECNO] then not in buffer
PUSH AX
学习啦在线学习网 MOV AL,[BP.DEVNUM]
CMP AL,[BUFDRVNO] ;Is buffer for this drive?
POP AX
学习啦在线学习网 JZ RET100 ;If so, then we match
学习啦在线学习网 STC ;No match
学习啦在线学习网 RET100: RET
BLKDON:
学习啦在线学习网 SUB CX,DX ;Number of sectors in cluster we don't want
SUB AH,CL ;Number of sectors in cluster we accepted
学习啦在线学习网 DEC AH ;Adjust to mean position within cluster
MOV [SECCLUSPOS],AH
MOV CX,DX ;Anyway, make the total equal to the request
JMP SHORT FINCLUS
FIGREC:
;Inputs:
; DX = Physical cluster number
; BL = Sector postion within cluster
; BP = Base of drive parameters
学习啦在线学习网 ;Outputs:
; DX = physical sector number
学习啦在线学习网 ;No other registers affected.
PUSH CX
学习啦在线学习网 MOV CL,[BP.CLUSSHFT]
DEC DX
DEC DX
SHL DX,CL
OR DL,BL
学习啦在线学习网 ADD DX,[BP.FIRREC]
POP CX
RET
GETREC:
; Inputs:
学习啦在线学习网 ; DS:DX point to FCB
学习啦在线学习网 ; Outputs:
; CX = 1
学习啦在线学习网 ; DX:AX = Record number determined by EXTENT and NR fields
; DS:DI point to FCB
学习啦在线学习网 ; No other registers affected.
学习啦在线学习网 MOV DI,DX
学习啦在线学习网 CMP BYTE PTR [DI],-1 ;Check for extended FCB
JNZ NORMFCB2
ADD DI,7
NORMFCB2:
MOV CX,1
MOV AL,[DI.NR]
MOV DX,[DI.EXTENT]
SHL AL,1
SHR DX,1
学习啦在线学习网 RCR AL,1
MOV AH,DL
MOV DL,DH
学习啦在线学习网 MOV DH,0
RET
ALLOCATE:
; Inputs:
; DS = CS
; ES = Segment of FCB
学习啦在线学习网 ; BX = Last cluster of file (0 if null file)
; CX = No. of clusters to allocate
; DX = Position of cluster BX
学习啦在线学习网 ; BP = Base of drive parameters
; SI = FAT pointer
; [FCB] = Displacement of FCB within segment
; Outputs:
; IF insufficient space
; THEN
; Carry set
; CX = max. no. of records that could be added to file
; ELSE
; Carry clear
学习啦在线学习网 ; BX = First cluster allocated
; FAT is fully updated including dirty bit
学习啦在线学习网 ; FIRCLUS field of FCB set if file was null
学习啦在线学习网 ; SI,BP unchanged. All other registers destroyed.
学习啦在线学习网 PUSH [SI]
PUSH DX
PUSH CX
PUSH BX
MOV AX,BX
ALLOC:
学习啦在线学习网 MOV DX,BX
FINDFRE:
INC BX
CMP BX,[BP.MAXCLUS]
学习啦在线学习网 JLE TRYOUT
学习啦在线学习网 CMP AX,1
学习啦在线学习网 JG TRYIN
POP BX
MOV DX,0FFFH
学习啦在线学习网 CALL RELBLKS
POP AX ;No. of clusters requested
SUB AX,CX ;AX=No. of clusters allocated
POP DX
学习啦在线学习网 POP [SI]
INC DX ;Position of first cluster allocated
ADD AX,DX ;AX=max no. of cluster in file
MOV DL,[BP.CLUSMSK]
MOV DH,0
INC DX ;DX=records/cluster
MUL DX ;AX=max no. of records in file
MOV CX,AX
学习啦在线学习网 SUB CX,WORD PTR [RECPOS] ;CX=max no. of records that could be written
学习啦在线学习网 JA MAXREC
学习啦在线学习网 XOR CX,CX ;If CX was negative, zero it
MAXREC:
STC
RET11: RET
TRYOUT:
CALL UNPACK
学习啦在线学习网 JZ HAVFRE
TRYIN:
DEC AX
学习啦在线学习网 JLE FINDFRE
学习啦在线学习网 XCHG AX,BX
CALL UNPACK
JZ HAVFRE
学习啦在线学习网 XCHG AX,BX
学习啦在线学习网 JMP SHORT FINDFRE
HAVFRE:
XCHG BX,DX
学习啦在线学习网 MOV AX,DX
学习啦在线学习网 CALL PACK
MOV BX,AX
LOOP ALLOC
学习啦在线学习网 MOV DX,0FFFH
CALL PACK
MOV BYTE PTR [SI-1],1
POP BX
POP CX ;Don't need this stuff since we're successful
POP DX
CALL UNPACK
POP [SI]
学习啦在线学习网 XCHG BX,DI
OR DI,DI
JNZ RET11
MOV DI,[FCB]
MOV ES:[DI.FIRCLUS],BX
RET12: RET
学习啦在线学习网 RELEASE:
; Inputs:
学习啦在线学习网 ; DS = CS
学习啦在线学习网 ; BX = Cluster in file
学习啦在线学习网 ; SI = FAT pointer
学习啦在线学习网 ; BP = Base of drive parameters
; Function:
; Frees cluster chain starting with [BX]
学习啦在线学习网 ; AX,BX,DX,DI all destroyed. Other registers unchanged.
XOR DX,DX
RELBLKS:
; Enter here with DX=0FFFH to put an end-of-file mark
; in the first cluster and free the rest in the chain.
CALL UNPACK
学习啦在线学习网 JZ RET12
MOV AX,DI
CALL PACK
CMP AX,0FF8H
MOV BX,AX
JB RELEASE
RET13: RET
GETEOF:
; Inputs:
学习啦在线学习网 ; BX = Cluster in a file
; SI = Base of drive FAT
学习啦在线学习网 ; DS = CS
; Outputs:
; BX = Last cluster in the file
; DI destroyed. No other registers affected.
CALL UNPACK
学习啦在线学习网 CMP DI,0FF8H
JAE RET13
MOV BX,DI
JMP SHORT GETEOF
SRCHFRST: ;System call 17
CALL GETFILE
学习啦在线学习网 SAVPLCE:
; Search-for-next enters here to save place and report
学习啦在线学习网 ; findings.
JC KILLSRCH
OR BH,BH
学习啦在线学习网 JS SRCHDEV
MOV AX,[LASTENT]
学习啦在线学习网 MOV ES:[DI.FILDIRENT],AX
MOV ES:[DI.DRVBP],BP
;Information in directory entry must be copied into the first
学习啦在线学习网 ; 33 bytes starting at the disk transfer address.
学习啦在线学习网 MOV SI,BX
学习啦在线学习网 LES DI,DWORD PTR [DMAADD]
MOV AX,00FFH
CMP AL,[EXTFCB]
学习啦在线学习网 JNZ NORMFCB
STOSW
INC AL
STOSW
STOSW
MOV AL,[ATTRIB]
STOSB
学习啦在线学习网 NORMFCB:
MOV AL,[THISDRV]
INC AL
STOSB ;Set drive number
学习啦在线学习网 MOV CX,16
学习啦在线学习网 REP MOVSW ;Copy remaining 10 characters of name
学习啦在线学习网 XOR AL,AL
RET
学习啦在线学习网 KILLSRCH:
KILLSRCH1 EQU KILLSRCH+1
学习啦在线学习网 ;The purpose of the KILLSRCH1 label is to provide a jump label to the following
学习啦在线学习网 ; instruction which leaves out the segment override.
MOV WORD PTR ES:[DI.FILDIRENT],-1
学习啦在线学习网 MOV AL,-1
RET
学习啦在线学习网 SRCHDEV:
MOV ES:[DI.FILDIRENT],BX
学习啦在线学习网 LES DI,DWORD PTR [DMAADD]
XOR AX,AX
学习啦在线学习网 STOSB ;Zero drive byte
学习啦在线学习网 SUB SI,4 ;Point to device name
MOVSW
MOVSW
MOV AX,2020H
STOSB
STOSW
STOSW
STOSW ;Fill with 8 blanks
学习啦在线学习网 XOR AX,AX
MOV CX,10
学习啦在线学习网 REP STOSW
STOSB
RET14: RET
学习啦在线学习网 SRCHNXT: ;System call 18
CALL MOVNAME
学习啦在线学习网 MOV DI,DX
JC NEAR PTR KILLSRCH1
MOV BP,[DI.DRVBP]
学习啦在线学习网 MOV AX,[DI.FILDIRENT]
学习啦在线学习网 OR AX,AX
学习啦在线学习网 JS NEAR PTR KILLSRCH1
PUSH DX
PUSH DS
PUSH CS
POP DS
MOV [LASTENT],AX
CALL CONTSRCH
POP ES
POP DI
JMP SAVPLCE
FILESIZE: ;System call 35
CALL GETFILE
MOV AL,-1
学习啦在线学习网 JC RET14
ADD DI,33 ;Write size in RR field
MOV CX,ES:[DI.RECSIZ-33]
OR CX,CX
学习啦在线学习网 JNZ RECOK
MOV CX,128
RECOK:
XOR AX,AX
学习啦在线学习网 XOR DX,DX ;Intialize size to zero
OR BH,BH ;Check for named I/O device
学习啦在线学习网 JS DEVSIZ
INC SI
INC SI ;Point to length field
MOV AX,[SI+2] ;Get high word of size
DIV CX
PUSH AX ;Save high part of result
LODSW ;Get low word of size
DIV CX
OR DX,DX ;Check for zero remainder
POP DX
JZ DEVSIZ
学习啦在线学习网 INC AX ;Round up for partial record
JNZ DEVSIZ ;Propagate carry?
INC DX
DEVSIZ:
STOSW
学习啦在线学习网 MOV AX,DX
STOSB
MOV AL,0
CMP CX,64
JAE RET14 ;Only 3-byte field if RECSIZ >= 64
学习啦在线学习网 MOV ES:[DI],AH
RET
SETDMA: ;System call 26
学习啦在线学习网 MOV CS:[DMAADD],DX
MOV CS:[DMAADD+2],DS
RET
NOSUCHDRV:
学习啦在线学习网 MOV AL,-1
RET
GETFATPT: ;System call 27
MOV DL,0 ;Use default drive
GETFATPTDL: ;System call 28
PUSH CS
POP DS
MOV AL,DL
CALL GETTHISDRV
学习啦在线学习网 JC NOSUCHDRV
CALL FATREAD
学习啦在线学习网 MOV BX,[BP.FAT]
MOV AL,[BP.CLUSMSK]
INC AL
学习啦在线学习网 MOV DX,[BP.MAXCLUS]
DEC DX
MOV CX,[BP.SECSIZ]
LDS SI,DWORD PTR [SPSAVE]
MOV [SI.BXSAVE],BX
MOV [SI.DXSAVE],DX
学习啦在线学习网 MOV [SI.CXSAVE],CX
学习啦在线学习网 MOV [SI.DSSAVE],CS
RET
学习啦在线学习网 GETDSKPT: ;System call 31
PUSH CS
POP DS
MOV AL,[CURDRV]
MOV [THISDRV],AL
CALL FATREAD
学习啦在线学习网 LDS SI,DWORD PTR [SPSAVE]
学习啦在线学习网 MOV [SI.BXSAVE],BP
学习啦在线学习网 MOV [SI.DSSAVE],CS
RET
学习啦在线学习网 DSKRESET: ;System call 13
PUSH CS
POP DS
WRTFATS:
学习啦在线学习网 ; DS=CS. Writes back all dirty FATs. All registers destroyed.
学习啦在线学习网 XOR AL,AL
学习啦在线学习网 XCHG AL,[DIRTYBUF]
学习啦在线学习网 OR AL,AL
学习啦在线学习网 JZ NOBUF
MOV BP,[BUFDRVBP]
学习啦在线学习网 MOV DX,[BUFSECNO]
MOV BX,[BUFFER]
MOV CX,1
CALL DWRITE
NOBUF:
学习啦在线学习网 MOV CL,[NUMIO]
MOV CH,0
学习啦在线学习网 MOV BP,[DRVTAB]
WRTFAT:
PUSH CX
CALL CHKFATWRT
POP CX
ADD BP,DPBSIZ
LOOP WRTFAT
RET
学习啦在线学习网 GETDRV: ;System call 25
MOV AL,CS:[CURDRV]
学习啦在线学习网 RET15: RET
学习啦在线学习网 SETRNDREC: ;System call 36
CALL GETREC
MOV [DI+33],AX
学习啦在线学习网 MOV [DI+35],DL
CMP [DI.RECSIZ],64
学习啦在线学习网 JAE RET15
MOV [DI+36],DH ;Set 4th byte only if record size < 64
RET16: RET
学习啦在线学习网 SELDSK: ;System call 14
MOV AL,CS:[NUMDRV]
CMP DL,AL
学习啦在线学习网 JNB RET17
学习啦在线学习网 MOV CS:[CURDRV],DL
学习啦在线学习网 RET17: RET
学习啦在线学习网 BUFIN: ;System call 10
MOV AX,CS
MOV ES,AX
学习啦在线学习网 MOV SI,DX
MOV CH,0
LODSW
OR AL,AL
学习啦在线学习网 JZ RET17
学习啦在线学习网 MOV BL,AH
MOV BH,CH
学习啦在线学习网 CMP AL,BL
JBE NOEDIT
CMP BYTE PTR [BX+SI],0DH
JZ EDITON
NOEDIT:
学习啦在线学习网 MOV BL,CH
EDITON:
学习啦在线学习网 MOV DL,AL
DEC DX
NEWLIN:
MOV AL,CS:[CARPOS]
MOV CS:[STARTPOS],AL
PUSH SI
MOV DI,OFFSET DOSGROUP:INBUF
MOV AH,CH
学习啦在线学习网 MOV BH,CH
MOV DH,CH
GETCH:
CALL IN
CMP AL,"F"-"@" ;Ignore ^F
学习啦在线学习网 JZ GETCH
CMP AL,CS:ESCCHAR
JZ ESC
学习啦在线学习网 CMP AL,7FH
JZ BACKSP
CMP AL,8
JZ BACKSP
CMP AL,13
JZ ENDLIN
CMP AL,10
JZ PHYCRLF
CMP AL,CANCEL
JZ KILNEW
SAVCH:
CMP DH,DL
学习啦在线学习网 JAE BUFFUL
STOSB
INC DH
学习啦在线学习网 CALL BUFOUT
OR AH,AH
学习啦在线学习网 JNZ GETCH
CMP BH,BL
JAE GETCH
INC SI
INC BH
学习啦在线学习网 JMP SHORT GETCH
BUFFUL:
MOV AL,7
CALL OUT
JMP SHORT GETCH
ESC:
CALL IN
MOV CL,ESCTABLEN
PUSH DI
MOV DI,OFFSET DOSGROUP:ESCTAB
学习啦在线学习网 REPNE SCASB
POP DI
SHL CX,1
学习啦在线学习网 MOV BP,CX
学习啦在线学习网 JMP [BP+OFFSET DOSGROUP:ESCFUNC]
ENDLIN:
STOSB
CALL OUT
POP DI
学习啦在线学习网 MOV [DI-1],DH
INC DH
学习啦在线学习网 COPYNEW:
MOV BP,ES
学习啦在线学习网 MOV BX,DS
MOV ES,BX
MOV DS,BP
MOV SI,OFFSET DOSGROUP:INBUF
MOV CL,DH
学习啦在线学习网 REP MOVSB
RET
CRLF:
MOV AL,13
CALL OUT
学习啦在线学习网 MOV AL,10
JMP OUT
PHYCRLF:
CALL CRLF
学习啦在线学习网 JMP SHORT GETCH
KILNEW:
学习啦在线学习网 MOV AL,"\"
学习啦在线学习网 CALL OUT
POP SI
PUTNEW:
学习啦在线学习网 CALL CRLF
MOV AL,CS:[STARTPOS]
CALL TAB
JMP NEWLIN
BACKSP:
OR DH,DH
JZ OLDBAK
CALL BACKUP
学习啦在线学习网 MOV AL,ES:[DI]
CMP AL," "
学习啦在线学习网 JAE OLDBAK
学习啦在线学习网 CMP AL,9
学习啦在线学习网 JZ BAKTAB
CALL BACKMES
OLDBAK:
学习啦在线学习网 OR AH,AH
JNZ GETCH1
OR BH,BH
学习啦在线学习网 JZ GETCH1
DEC BH
DEC SI
GETCH1:
学习啦在线学习网 JMP GETCH
BAKTAB:
PUSH DI
DEC DI
STD
学习啦在线学习网 MOV CL,DH
学习啦在线学习网 MOV AL," "
PUSH BX
学习啦在线学习网 MOV BL,7
学习啦在线学习网 JCXZ FIGTAB
FNDPOS:
SCASB
学习啦在线学习网 JNA CHKCNT
CMP ES:BYTE PTR [DI+1],9
JZ HAVTAB
DEC BL
CHKCNT:
学习啦在线学习网 LOOP FNDPOS
FIGTAB:
学习啦在线学习网 SUB BL,CS:[STARTPOS]
HAVTAB:
学习啦在线学习网 SUB BL,DH
ADD CL,BL
AND CL,7
CLD
POP BX
POP DI
学习啦在线学习网 JZ OLDBAK
TABBAK:
CALL BACKMES
LOOP TABBAK
学习啦在线学习网 JMP SHORT OLDBAK
BACKUP:
DEC DH
DEC DI
BACKMES:
MOV AL,8
学习啦在线学习网 CALL OUT
MOV AL," "
CALL OUT
MOV AL,8
JMP OUT
TWOESC:
MOV AL,ESCCH
学习啦在线学习网 JMP SAVCH
COPYLIN:
MOV CL,BL
SUB CL,BH
学习啦在线学习网 JMP SHORT COPYEACH
学习啦在线学习网 COPYSTR:
学习啦在线学习网 CALL FINDOLD
JMP SHORT COPYEACH
COPYONE:
MOV CL,1
COPYEACH:
MOV AH,0
学习啦在线学习网 CMP DH,DL
JZ GETCH2
学习啦在线学习网 CMP BH,BL
JZ GETCH2
LODSB
STOSB
CALL BUFOUT
INC BH
INC DH
LOOP COPYEACH
GETCH2:
JMP GETCH
SKIPONE:
CMP BH,BL
JZ GETCH2
INC BH
INC SI
JMP GETCH
SKIPSTR:
学习啦在线学习网 CALL FINDOLD
学习啦在线学习网 ADD SI,CX
学习啦在线学习网 ADD BH,CL
学习啦在线学习网 JMP GETCH
学习啦在线学习网 FINDOLD:
CALL IN
MOV CL,BL
SUB CL,BH
学习啦在线学习网 JZ NOTFND
DEC CX
JZ NOTFND
PUSH ES
PUSH DS
POP ES
PUSH DI
学习啦在线学习网 MOV DI,SI
INC DI
学习啦在线学习网 REPNE SCASB
POP DI
POP ES
JNZ NOTFND
NOT CL
学习啦在线学习网 ADD CL,BL
SUB CL,BH
RET30: RET
NOTFND:
POP BP
学习啦在线学习网 JMP GETCH
REEDIT:
学习啦在线学习网 MOV AL,"@"
学习啦在线学习网 CALL OUT
POP DI
PUSH DI
PUSH ES
PUSH DS
学习啦在线学习网 CALL COPYNEW
POP DS
POP ES
POP SI
学习啦在线学习网 MOV BL,DH
JMP PUTNEW
ENTERINS:
学习啦在线学习网 IF TOGLINS
NOT AH
JMP GETCH
ENDIF
IF NOT TOGLINS
学习啦在线学习网 MOV AH,-1
JMP GETCH
学习啦在线学习网 EXITINS:
MOV AH,0
学习啦在线学习网 JMP GETCH
ENDIF
学习啦在线学习网 ESCFUNC DW GETCH
DW TWOESC
学习啦在线学习网 IF NOT TOGLINS
DW EXITINS
ENDIF
DW ENTERINS
学习啦在线学习网 DW BACKSP
DW REEDIT
DW KILNEW
学习啦在线学习网 DW COPYLIN
DW SKIPSTR
学习啦在线学习网 DW COPYSTR
学习啦在线学习网 DW SKIPONE
DW COPYONE
IF IBM
DW COPYONE
DW CTRLZ
CTRLZ:
MOV AL,"Z"-"@"
JMP SAVCH
ENDIF
BUFOUT:
学习啦在线学习网 CMP AL," "
JAE OUT
CMP AL,9
JZ OUT
PUSH AX
学习啦在线学习网 MOV AL,"^"
CALL OUT
POP AX
学习啦在线学习网 OR AL,40H
学习啦在线学习网 JMP SHORT OUT
NOSTOP:
CMP AL,"P"-"@"
学习啦在线学习网 JZ INCHK
学习啦在线学习网 IF NOT TOGLPRN
学习啦在线学习网 CMP AL,"N"-"@"
学习啦在线学习网 JZ INCHK
ENDIF
学习啦在线学习网 CMP AL,"C"-"@"
JZ INCHK
RET
CONOUT: ;System call 2
学习啦在线学习网 MOV AL,DL
OUT:
学习啦在线学习网 CMP AL,20H
学习啦在线学习网 JB CTRLOUT
学习啦在线学习网 CMP AL,7FH
JZ OUTCH
INC CS:BYTE PTR [CARPOS]
OUTCH:
PUSH AX
CALL STATCHK
POP AX
CALL FAR PTR BIOSOUT
TEST CS:BYTE PTR [PFLAG],-1
学习啦在线学习网 JZ RET18
学习啦在线学习网 CALL FAR PTR BIOSPRINT
RET18: RET
学习啦在线学习网 STATCHK:
CALL FAR PTR BIOSSTAT
JZ RET18
CMP AL,'S'-'@'
JNZ NOSTOP
学习啦在线学习网 CALL FAR PTR BIOSIN ;Eat Cntrl-S
INCHK:
学习啦在线学习网 CALL FAR PTR BIOSIN
学习啦在线学习网 CMP AL,'P'-'@'
学习啦在线学习网 JZ PRINTON
IF NOT TOGLPRN
学习啦在线学习网 CMP AL,'N'-'@'
JZ PRINTOFF
ENDIF
CMP AL,'C'-'@'
JNZ RET18
学习啦在线学习网 ; Ctrl-C handler.
; "^C" and CR/LF is printed. Then the user registers are restored and the
; user CTRL-C handler is executed. At this point the top of the stack has
; 1) the interrupt return address should the user CTRL-C handler wish to
; allow processing to continue; 2) the original interrupt return address
学习啦在线学习网 ; to the code that performed the function call in the first place. If the
; user CTRL-C handler wishes to continue, it must leave all registers
; unchanged and IRET. The function that was interrupted will simply be
学习啦在线学习网 ; repeated.
MOV AL,3 ;Display "^C"
CALL BUFOUT
CALL CRLF
CLI ;Prepare to play with stack
学习啦在线学习网 MOV SS,CS:[SSSAVE]
MOV SP,CS:[SPSAVE] ;User stack now restored
POP AX
POP BX
POP CX
POP DX
POP SI
POP DI
POP BP
POP DS
学习啦在线学习网 POP ES ;User registers now restored
学习啦在线学习网 INT CONTC ;Execute user Ctrl-C handler
学习啦在线学习网 JMP COMMAND ;Repeat command otherwise
学习啦在线学习网 PRINTON:
学习啦在线学习网 IF TOGLPRN
学习啦在线学习网 NOT CS:BYTE PTR [PFLAG]
RET
ENDIF
学习啦在线学习网 IF NOT TOGLPRN
MOV CS:BYTE PTR [PFLAG],1
RET
PRINTOFF:
学习啦在线学习网 MOV CS:BYTE PTR [PFLAG],0
RET
ENDIF
CTRLOUT:
学习啦在线学习网 CMP AL,13
JZ ZERPOS
CMP AL,8
学习啦在线学习网 JZ BACKPOS
学习啦在线学习网 CMP AL,9
JNZ OUTCHJ
学习啦在线学习网 MOV AL,CS:[CARPOS]
OR AL,0F8H
NEG AL
TAB:
PUSH CX
学习啦在线学习网 MOV CL,AL
学习啦在线学习网 MOV CH,0
JCXZ POPTAB
TABLP:
学习啦在线学习网 MOV AL," "
CALL OUT
LOOP TABLP
POPTAB:
POP CX
学习啦在线学习网 RET19: RET
ZERPOS:
学习啦在线学习网 MOV CS:BYTE PTR [CARPOS],0
学习啦在线学习网 OUTCHJ: JMP OUTCH
BACKPOS:
DEC CS:BYTE PTR [CARPOS]
JMP OUTCH
CONSTAT: ;System call 11
CALL STATCHK
MOV AL,0
JZ RET19
OR AL,-1
RET
CONIN: ;System call 1
CALL IN
PUSH AX
CALL OUT
POP AX
RET
IN: ;System call 8
CALL INCHK
JZ IN
RET29: RET
学习啦在线学习网 RAWIO: ;System call 6
学习啦在线学习网 MOV AL,DL
学习啦在线学习网 CMP AL,-1
JNZ RAWOUT
LDS SI,DWORD PTR CS:[SPSAVE] ;Get pointer to register save area
CALL FAR PTR BIOSSTAT
学习啦在线学习网 JNZ RESFLG
OR BYTE PTR [SI.FSAVE],40H ;Set user's zero flag
学习啦在线学习网 XOR AL,AL
RET
RESFLG:
学习啦在线学习网 AND BYTE PTR [SI.FSAVE],0FFH-40H ;Reset user's zero flag
RAWINP: ;System call 7
CALL FAR PTR BIOSIN
RET
RAWOUT:
学习啦在线学习网 CALL FAR PTR BIOSOUT
RET
LIST: ;System call 5
学习啦在线学习网 MOV AL,DL
学习啦在线学习网 LISTOUT:
PUSH AX
CALL STATCHK
POP AX
CALL FAR PTR BIOSPRINT
学习啦在线学习网 RET20: RET
学习啦在线学习网 PRTBUF: ;System call 9
MOV SI,DX
OUTSTR:
LODSB
CMP AL,"$"
JZ RET20
学习啦在线学习网 CALL OUT
学习啦在线学习网 JMP SHORT OUTSTR
OUTMES: ;String output for internal messages
LODS CS:BYTE PTR [SI]
CMP AL,"$"
学习啦在线学习网 JZ RET20
CALL OUT
学习啦在线学习网 JMP SHORT OUTMES
MAKEFCB: ;Interrupt call 41
学习啦在线学习网 DRVBIT EQU 2
NAMBIT EQU 4
EXTBIT EQU 8
MOV DL,0 ;Flag--not ambiguous file name
TEST AL,DRVBIT ;Use current drive field if default?
学习啦在线学习网 JNZ DEFDRV
MOV BYTE PTR ES:[DI],0 ;No - use default drive
DEFDRV:
INC DI
学习啦在线学习网 MOV CX,8
学习啦在线学习网 TEST AL,NAMBIT ;Use current name fiels as defualt?
学习啦在线学习网 XCHG AX,BX ;Save bits in BX
学习啦在线学习网 MOV AL," "
JZ FILLB ;If not, go fill with blanks
学习啦在线学习网 ADD DI,CX
XOR CX,CX ;Don't fill any
FILLB:
REP STOSB
MOV CL,3
TEST BL,EXTBIT ;Use current extension as default
学习啦在线学习网 JZ FILLB2
ADD DI,CX
XOR CX,CX
FILLB2:
REP STOSB
学习啦在线学习网 XCHG AX,CX ;Put zero in AX
STOSW
学习啦在线学习网 STOSW ;Initialize two words after to zero
SUB DI,16 ;Point back at start
学习啦在线学习网 TEST BL,1 ;Scan off separators if not zero
学习啦在线学习网 JZ SKPSPC
学习啦在线学习网 CALL SCANB ;Peel off blanks and tabs
CALL DELIM ;Is it a one-time-only delimiter?
学习啦在线学习网 JNZ NOSCAN
INC SI ;Skip over the delimiter
SKPSPC:
学习啦在线学习网 CALL SCANB ;Always kill preceding blanks and tabs
NOSCAN:
学习啦在线学习网 CALL GETLET
JBE NODRV ;Quit if termination character
CMP BYTE PTR[SI],":" ;Check for potential drive specifier
JNZ NODRV
学习啦在线学习网 INC SI ;Skip over colon
SUB AL,"@" ;Convert drive letter to binary drive number
JBE BADDRV ;Valid drive numbers are 1-15
学习啦在线学习网 CMP AL,CS:[NUMDRV]
JBE HAVDRV
BADDRV:
MOV DL,-1
HAVDRV:
STOSB ;Put drive specifier in first byte
INC SI
DEC DI ;Counteract next two instructions
NODRV:
DEC SI ;Back up
INC DI ;Skip drive byte
学习啦在线学习网 MOV CX,8
CALL GETWORD ;Get 8-letter file name
CMP BYTE PTR [SI],"."
JNZ NODOT
学习啦在线学习网 INC SI ;Skip over dot if present
MOV CX,3 ;Get 3-letter extension
学习啦在线学习网 CALL MUSTGETWORD
NODOT:
LDS BX,CS:DWORD PTR [SPSAVE]
MOV [BX.SISAVE],SI
MOV AL,DL
RET
NONAM:
学习啦在线学习网 ADD DI,CX
DEC SI
RET
学习啦在线学习网 GETWORD:
CALL GETLET
JBE NONAM ;Exit if invalid character
DEC SI
MUSTGETWORD:
学习啦在线学习网 CALL GETLET
JBE FILLNAM
学习啦在线学习网 JCXZ MUSTGETWORD
DEC CX
CMP AL,"*" ;Check for ambiguous file specifier
学习啦在线学习网 JNZ NOSTAR
MOV AL,"?"
学习啦在线学习网 REP STOSB
NOSTAR:
STOSB
CMP AL,"?"
学习啦在线学习网 JNZ MUSTGETWORD
学习啦在线学习网 OR DL,1 ;Flag ambiguous file name
学习啦在线学习网 JMP MUSTGETWORD
FILLNAM:
MOV AL," "
学习啦在线学习网 REP STOSB
DEC SI
RET21: RET
SCANB:
LODSB
CALL SPCHK
JZ SCANB
DEC SI
RET
GETLET:
;Get a byte from [SI], convert it to upper case, and compare for delimiter.
学习啦在线学习网 ;ZF set if a delimiter, CY set if a control character (other than TAB).
LODSB
AND AL,7FH
CMP AL,"a"
JB CHK
学习啦在线学习网 CMP AL,"z"
JA CHK
SUB AL,20H ;Convert to upper case
CHK:
CMP AL,"."
学习啦在线学习网 JZ RET21
CMP AL,'"'
JZ RET21
学习啦在线学习网 CMP AL,"/"
JZ RET21
学习啦在线学习网 CMP AL,"["
JZ RET21
学习啦在线学习网 CMP AL,"]"
JZ RET21
IF IBM
DELIM:
ENDIF
CMP AL,":" ;Allow ":" as separator in IBM version
JZ RET21
IF NOT IBM
DELIM:
ENDIF
学习啦在线学习网 CMP AL,"+"
JZ RET101
CMP AL,"="
JZ RET101
CMP AL,";"
学习啦在线学习网 JZ RET101
CMP AL,","
JZ RET101
SPCHK:
CMP AL,9 ;Filter out tabs too
JZ RET101
学习啦在线学习网 ;WARNING! " " MUST be the last compare
学习啦在线学习网 CMP AL," "
学习啦在线学习网 RET101: RET
SETVECT: ; Interrupt call 37
XOR BX,BX
学习啦在线学习网 MOV ES,BX
学习啦在线学习网 MOV BL,AL
SHL BX,1
SHL BX,1
MOV ES:[BX],DX
MOV ES:[BX+2],DS
RET
学习啦在线学习网 NEWBASE: ; Interrupt call 38
学习啦在线学习网 MOV ES,DX
LDS SI,CS:DWORD PTR [SPSAVE]
MOV DS,[SI.CSSAVE]
学习啦在线学习网 XOR SI,SI
学习啦在线学习网 MOV DI,SI
MOV AX,DS:[2]
学习啦在线学习网 MOV CX,80H
学习啦在线学习网 REP MOVSW
SETMEM:
; Inputs:
学习啦在线学习网 ; AX = Size of memory in paragraphs
; DX = Segment
; Function:
; Completely prepares a program base at the
; specified segment.
; Outputs:
; DS = DX
学习啦在线学习网 ; ES = DX
学习啦在线学习网 ; [0] has INT 20H
; [2] = First unavailable segment ([ENDMEM])
; [5] to [9] form a long call to the entry point
; [10] to [13] have exit address (from INT 22H)
; [14] to [17] have ctrl-C exit address (from INT 23H)
学习啦在线学习网 ; [18] to [21] have fatal error address (from INT 24H)
; DX,BP unchanged. All other registers destroyed.
学习啦在线学习网 XOR CX,CX
学习啦在线学习网 MOV DS,CX
学习啦在线学习网 MOV ES,DX
MOV SI,EXIT
学习啦在线学习网 MOV DI,SAVEXIT
MOVSW
MOVSW
MOVSW
MOVSW
MOVSW
MOVSW
学习啦在线学习网 MOV ES:[2],AX
学习啦在线学习网 SUB AX,DX
CMP AX,MAXDIF
JBE HAVDIF
MOV AX,MAXDIF
HAVDIF:
学习啦在线学习网 MOV BX,ENTRYPOINTSEG
SUB BX,AX
学习啦在线学习网 SHL AX,1
学习啦在线学习网 SHL AX,1
SHL AX,1
学习啦在线学习网 SHL AX,1
学习啦在线学习网 MOV DS,DX
学习啦在线学习网 MOV DS:[6],AX
MOV DS:[8],BX
MOV DS:[0],20CDH ;"INT INTTAB"
MOV DS:(BYTE PTR [5]),LONGCALL
RET
DATE16:
PUSH CX
CALL READTIME
SHL CL,1 ;Minutes to left part of byte
SHL CL,1
SHL CX,1 ;Push hours and minutes to left end
SHL CX,1
SHL CX,1
SHR DH,1 ;Count every two seconds
OR CL,DH ;Combine seconds with hours and minutes
MOV DX,CX
POP CX
学习啦在线学习网 MOV AX,WORD PTR [MONTH] ;Fetch month and year
SHL AL,1 ;Push month to left to make room for day
学习啦在线学习网 SHL AL,1
SHL AL,1
学习啦在线学习网 SHL AL,1
学习啦在线学习网 SHL AX,1
学习啦在线学习网 OR AL,[DAY]
学习啦在线学习网 RET22: RET
FOURYEARS EQU 3*365+366
学习啦在线学习网 READTIME:
学习啦在线学习网 ;Gets time in CX:DX. Figures new date if it has changed.
;Uses AX, CX, DX.
CALL FAR PTR BIOSGETTIME
学习啦在线学习网 CMP AX,[DAYCNT] ;See if day count is the same
学习啦在线学习网 JZ RET22
CMP AX,FOURYEARS*30 ;Number of days in 120 years
学习啦在线学习网 JAE RET22 ;Ignore if too large
MOV [DAYCNT],AX
PUSH SI
PUSH CX
PUSH DX ;Save time
学习啦在线学习网 XOR DX,DX
MOV CX,FOURYEARS ;Number of days in 4 years
学习啦在线学习网 DIV CX ;Compute number of 4-year units
学习啦在线学习网 SHL AX,1
SHL AX,1
学习啦在线学习网 SHL AX,1 ;Multiply by 8 (no. of half-years)
学习啦在线学习网 MOV CX,AX ;<240 implies AH=0
学习啦在线学习网 MOV SI,OFFSET DOSGROUP:YRTAB ;Table of days in each year
CALL DSLIDE ;Find out which of four years we're in
SHR CX,1 ;Convert half-years to whole years
学习啦在线学习网 JNC SK ;Extra half-year?
ADD DX,200
SK:
CALL SETYEAR
学习啦在线学习网 MOV CL,1 ;At least at first month in year
MOV SI,OFFSET DOSGROUP:MONTAB ;Table of days in each month
CALL DSLIDE ;Find out which month we're in
学习啦在线学习网 MOV [MONTH],CL
INC DX ;Remainder is day of month (start with one)
学习啦在线学习网 MOV [DAY],DL
学习啦在线学习网 CALL WKDAY ;Set day of week
POP DX
POP CX
POP SI
学习啦在线学习网 RET23: RET
DSLIDE:
学习啦在线学习网 MOV AH,0
DSLIDE1:
LODSB ;Get count of days
CMP DX,AX ;See if it will fit
学习啦在线学习网 JB RET23 ;If not, done
SUB DX,AX
学习啦在线学习网 INC CX ;Count one more month/year
JMP SHORT DSLIDE1
学习啦在线学习网 SETYEAR:
学习啦在线学习网 ;Set year with value in CX. Adjust length of February for this year.
学习啦在线学习网 MOV BYTE PTR [YEAR],CL
CHKYR:
学习啦在线学习网 TEST CL,3 ;Check for leap year
MOV AL,28
JNZ SAVFEB ;28 days if no leap year
INC AL ;Add leap day
SAVFEB:
MOV [MONTAB+1],AL ;Store for February
RET
学习啦在线学习网 ;Days in year
学习啦在线学习网 YRTAB DB 200,166 ;Leap year
学习啦在线学习网 DB 200,165
学习啦在线学习网 DB 200,165
DB 200,165
;Days of each month
MONTAB DB 31 ;January
DB 28 ;February--reset each time year changes
DB 31 ;March
学习啦在线学习网 DB 30 ;April
学习啦在线学习网 DB 31 ;May
学习啦在线学习网 DB 30 ;June
学习啦在线学习网 DB 31 ;July
DB 31 ;August
DB 30 ;September
学习啦在线学习网 DB 31 ;October
DB 30 ;November
学习啦在线学习网 DB 31 ;December
GETDATE: ;Function call 42
PUSH CS
POP DS
CALL READTIME ;Check for rollover to next day
MOV AX,[YEAR]
MOV BX,WORD PTR [DAY]
学习啦在线学习网 LDS SI,DWORD PTR [SPSAVE] ;Get pointer to user registers
MOV [SI.DXSAVE],BX ;DH=month, DL=day
ADD AX,1980 ;Put bias back
MOV [SI.CXSAVE],AX ;CX=year
MOV AL,CS:[WEEKDAY]
RET24: RET
SETDATE: ;Function call 43
MOV AL,-1 ;Be ready to flag error
SUB CX,1980 ;Fix bias in year
学习啦在线学习网 JC RET24 ;Error if not big enough
CMP CX,119 ;Year must be less than 2100
JA RET24
学习啦在线学习网 OR DH,DH
学习啦在线学习网 JZ RET24
学习啦在线学习网 OR DL,DL
JZ RET24 ;Error if either month or day is 0
CMP DH,12 ;Check against max. month
JA RET24
PUSH CS
POP DS
CALL CHKYR ;Set Feb. up for new year
学习啦在线学习网 MOV AL,DH
学习啦在线学习网 MOV BX,OFFSET DOSGROUP:MONTAB-1
XLAT ;Look up days in month
学习啦在线学习网 CMP AL,DL
学习啦在线学习网 MOV AL,-1 ;Restore error flag, just in case
学习啦在线学习网 JB RET24 ;Error if too many days
CALL SETYEAR
学习啦在线学习网 MOV WORD PTR [DAY],DX ;Set both day and month
SHR CX,1
SHR CX,1
学习啦在线学习网 MOV AX,FOURYEARS
学习啦在线学习网 MOV BX,DX
MUL CX
学习啦在线学习网 MOV CL,BYTE PTR [YEAR]
学习啦在线学习网 AND CL,3
MOV SI,OFFSET DOSGROUP:YRTAB
学习啦在线学习网 MOV DX,AX
SHL CX,1 ;Two entries per year, so double count
学习啦在线学习网 CALL DSUM ;Add up the days in each year
MOV CL,BH ;Month of year
学习啦在线学习网 MOV SI,OFFSET DOSGROUP:MONTAB
DEC CX ;Account for months starting with one
CALL DSUM ;Add up days in each month
MOV CL,BL ;Day of month
DEC CX ;Account for days starting with one
ADD DX,CX ;Add in to day total
XCHG AX,DX ;Get day count in AX
MOV [DAYCNT],AX
学习啦在线学习网 CALL FAR PTR BIOSSETDATE
WKDAY:
MOV AX,[DAYCNT]
XOR DX,DX
MOV CX,7
INC AX
INC AX ;First day was Tuesday
DIV CX ;Compute day of week
MOV [WEEKDAY],DL
学习啦在线学习网 XOR AL,AL ;Flag OK
RET25: RET
DSUM:
MOV AH,0
JCXZ RET25
DSUM1:
LODSB
学习啦在线学习网 ADD DX,AX
学习啦在线学习网 LOOP DSUM1
RET
GETTIME: ;Function call 44
PUSH CS
POP DS
CALL READTIME
学习啦在线学习网 LDS SI,DWORD PTR [SPSAVE] ;Get pointer to user registers
MOV [SI.DXSAVE],DX
MOV [SI.CXSAVE],CX
学习啦在线学习网 XOR AL,AL
RET26: RET
SETTIME: ;Function call 45
;Time is in CX:DX in hours, minutes, seconds, 1/100 sec.
MOV AL,-1 ;Flag in case of error
CMP CH,24 ;Check hours
JAE RET26
CMP CL,60 ;Check minutes
JAE RET26
学习啦在线学习网 CMP DH,60 ;Check seconds
学习啦在线学习网 JAE RET26
CMP DL,100 ;Check 1/100's
学习啦在线学习网 JAE RET26
CALL FAR PTR BIOSSETTIME
学习啦在线学习网 XOR AL,AL
RET
学习啦在线学习网 ; Default handler for division overflow trap
DIVOV:
PUSH SI
PUSH AX
学习啦在线学习网 MOV SI,OFFSET DOSGROUP:DIVMES
CALL OUTMES
POP AX
POP SI
INT 23H ;Use Ctrl-C abort on divide overflow
IRET
学习啦在线学习网 CODSIZ EQU $-CODSTRT ;Size of code segment
学习啦在线学习网 CODE ENDS
;***** DATA AREA *****
CONSTANTS SEGMENT BYTE
ORG 0
学习啦在线学习网 CONSTRT EQU $ ;Start of constants segment
IONAME:
学习啦在线学习网 IF NOT IBM
学习啦在线学习网 DB "PRN ","LST ","NUL ","AUX ","CON "
ENDIF
IF IBM
学习啦在线学习网 DB "COM1","PRN ","LPT1","NUL ","AUX ","CON "
ENDIF
DIVMES DB 13,10,"Divide overflow",13,10,"$"
CARPOS DB 0
学习啦在线学习网 STARTPOS DB 0
PFLAG DB 0
学习啦在线学习网 DIRTYDIR DB 0 ;Dirty buffer flag
NUMDRV DB 0 ;Number of drives
NUMIO DB ? ;Number of disk tables
学习啦在线学习网 VERFLG DB 0 ;Initialize with verify off
CONTPOS DW 0
DMAADD DW 80H ;User's disk transfer address (disp/seg)
DW ?
学习啦在线学习网 ENDMEM DW ?
MAXSEC DW 0
BUFFER DW ?
学习啦在线学习网 BUFSECNO DW 0
学习啦在线学习网 BUFDRVNO DB -1
DIRTYBUF DB 0
学习啦在线学习网 BUFDRVBP DW ?
DIRBUFID DW -1
DAY DB 0
学习啦在线学习网 MONTH DB 0
YEAR DW 0
学习啦在线学习网 DAYCNT DW -1
WEEKDAY DB 0
CURDRV DB 0 ;Default to drive A
学习啦在线学习网 DRVTAB DW 0 ;Address of start of DPBs
学习啦在线学习网 DOSLEN EQU CODSIZ+($-CONSTRT) ;Size of CODE + CONSTANTS segments
CONSTANTS ENDS
DATA SEGMENT WORD
学习啦在线学习网 ; Init code overlaps with data area below
ORG 0
INBUF DB 128 DUP (?)
CONBUF DB 131 DUP (?) ;The rest of INBUF and console buffer
LASTENT DW ?
EXITHOLD DB 4 DUP (?)
FATBASE DW ?
学习啦在线学习网 NAME1 DB 11 DUP (?) ;File name buffer
ATTRIB DB ?
NAME2 DB 11 DUP (?)
学习啦在线学习网 NAME3 DB 12 DUP (?)
EXTFCB DB ?
;WARNING - the following two items are accessed as a word
学习啦在线学习网 CREATING DB ?
DELALL DB ?
学习啦在线学习网 TEMP LABEL WORD
SPSAVE DW ?
SSSAVE DW ?
CONTSTK DW ?
SECCLUSPOS DB ? ;Position of first sector within cluster
DSKERR DB ?
TRANS DB ?
PREREAD DB ? ;0 means preread; 1 means optional
学习啦在线学习网 READOP DB ?
THISDRV DB ?
EVEN
FCB DW ? ;Address of user FCB
NEXTADD DW ?
学习啦在线学习网 RECPOS DB 4 DUP (?)
学习啦在线学习网 RECCNT DW ?
LASTPOS DW ?
CLUSNUM DW ?
SECPOS DW ? ;Position of first sector accessed
VALSEC DW ? ;Number of valid (previously written) sectors
BYTSECPOS DW ? ;Position of first byte within sector
学习啦在线学习网 BYTPOS DB 4 DUP (?) ;Byte position in file of access
BYTCNT1 DW ? ;No. of bytes in first sector
学习啦在线学习网 BYTCNT2 DW ? ;No. of bytes in last sector
学习啦在线学习网 SECCNT DW ? ;No. of whole sectors
ENTFREE DW ?
DB 80H DUP (?) ;Stack space
学习啦在线学习网 IOSTACK LABEL BYTE
DB 80H DUP (?)
DSKSTACK LABEL BYTE
学习啦在线学习网 IF DSKTEST
学习啦在线学习网 NSS DW ?
NSP DW ?
ENDIF
学习啦在线学习网 DIRBUF LABEL WORD
学习啦在线学习网 ;Init code below overlaps with data area above
ORG 0
MOVFAT:
;This section of code is safe from being overwritten by block move
学习啦在线学习网 REP MOVS BYTE PTR [DI],[SI]
CLD
学习啦在线学习网 MOV ES:[DMAADD+2],DX
MOV SI,[DRVTAB] ;Address of first DPB
MOV AL,-1
学习啦在线学习网 MOV CL,[NUMIO] ;Number of DPBs
FLGFAT:
MOV DI,ES:[SI.FAT] ;get pointer to FAT
DEC DI ;Point to dirty byte
学习啦在线学习网 STOSB ;Flag as unused
ADD SI,DPBSIZ ;Point to next DPB
LOOP FLGFAT
学习啦在线学习网 MOV AX,[ENDMEM]
学习啦在线学习网 CALL SETMEM ;Set up segment
XXX PROC FAR
RET
XXX ENDP
DOSINIT:
CLI
CLD
PUSH CS
POP ES
MOV ES:[ENDMEM],DX
LODSB ;Get no. of drives & no. of I/O drivers
MOV ES:[NUMIO],AL
MOV DI,OFFSET DOSGROUP:MEMSTRT
PERDRV:
MOV BP,DI
MOV AL,ES:[DRVCNT]
STOSB ;DEVNUM
学习啦在线学习网 LODSB ;Physical unit no.
学习啦在线学习网 STOSB ;DRVNUM
CMP AL,15
学习啦在线学习网 JA BADINIT
学习啦在线学习网 CBW ;Index into FAT size table
学习啦在线学习网 SHL AX,1
学习啦在线学习网 ADD AX,OFFSET DOSGROUP:FATSIZTAB
学习啦在线学习网 XCHG BX,AX
学习啦在线学习网 LODSW ;Pointer to DPT
PUSH SI
MOV SI,AX
LODSW
STOSW ;SECSIZ
学习啦在线学习网 MOV DX,AX
学习啦在线学习网 CMP AX,ES:[MAXSEC]
JBE NOTMAX
学习啦在线学习网 MOV ES:[MAXSEC],AX
NOTMAX:
LODSB
DEC AL
STOSB ;CLUSMSK
JZ HAVSHFT
CBW
学习啦在线学习网 FIGSHFT:
INC AH
学习啦在线学习网 SAR AL,1
JNZ FIGSHFT
MOV AL,AH
学习啦在线学习网 HAVSHFT:
学习啦在线学习网 STOSB ;CLUSSHFT
MOVSW ;FIRFAT (= number of reserved sectors)
MOVSB ;FATCNT
MOVSW ;MAXENT
MOV AX,DX ;SECSIZ again
MOV CL,5
SHR AX,CL
MOV CX,AX ;Directory entries per sector
DEC AX
ADD AX,ES:[BP.MAXENT]
XOR DX,DX
DIV CX
STOSW ;DIRSEC (temporarily)
MOVSW ;DSKSIZ (temporarily)
FNDFATSIZ:
学习啦在线学习网 MOV AL,1
MOV DX,1
学习啦在线学习网 GETFATSIZ:
PUSH DX
学习啦在线学习网 CALL FIGFATSIZ
POP DX
CMP AL,DL ;Compare newly computed FAT size with trial
JZ HAVFATSIZ ;Has sequence converged?
CMP AL,DH ;Compare with previous trial
学习啦在线学习网 MOV DH,DL
学习啦在线学习网 MOV DL,AL ;Shuffle trials
学习啦在线学习网 JNZ GETFATSIZ ;Continue iterations if not oscillating
DEC WORD PTR ES:[BP.DSKSIZ] ;Damp those oscillations
JMP SHORT FNDFATSIZ ;Try again
BADINIT:
MOV SI,OFFSET DOSGROUP:BADMES
CALL OUTMES
STI
HLT
HAVFATSIZ:
学习啦在线学习网 STOSB ;FATSIZ
学习啦在线学习网 MUL ES:BYTE PTR[BP.FATCNT] ;Space occupied by all FATs
学习啦在线学习网 ADD AX,ES:[BP.FIRFAT]
学习啦在线学习网 STOSW ;FIRDIR
ADD AX,ES:[BP.DIRSEC]
学习啦在线学习网 MOV ES:[BP.FIRREC],AX ;Destroys DIRSEC
CALL FIGMAX
学习啦在线学习网 MOV ES:[BP.MAXCLUS],CX
MOV AX,BX ;Pointer into FAT size table
STOSW ;Allocate space for FAT pointer
MOV AL,ES:[BP.FATSIZ]
XOR AH,AH
MUL ES:[BP.SECSIZ]
学习啦在线学习网 CMP AX,ES:[BX] ;Bigger than already allocated
学习啦在线学习网 JBE SMFAT
学习啦在线学习网 MOV ES:[BX],AX
SMFAT:
学习啦在线学习网 POP SI ;Restore pointer to init. table
MOV AL,ES:[DRVCNT]
INC AL
MOV ES:[DRVCNT],AL
学习啦在线学习网 CMP AL,ES:[NUMIO]
JAE CONTINIT
JMP PERDRV
BADINITJ:
JMP BADINIT
学习啦在线学习网 CONTINIT:
PUSH CS
POP DS
学习啦在线学习网 ;Calculate true address of buffers, FATs, free space
学习啦在线学习网 MOV BP,[MAXSEC]
学习啦在线学习网 MOV AX,OFFSET DOSGROUP:DIRBUF
ADD AX,BP
MOV [BUFFER],AX ;Start of buffer
学习啦在线学习网 ADD AX,BP
学习啦在线学习网 MOV [DRVTAB],AX ;Start of DPBs
SHL BP,1 ;Two sectors - directory and buffer
学习啦在线学习网 ADD BP,DI ;Allocate buffer space
学习啦在线学习网 ADD BP,ADJFAC ;True address of FATs
PUSH BP
学习啦在线学习网 MOV SI,OFFSET DOSGROUP:FATSIZTAB
MOV DI,SI
学习啦在线学习网 MOV CX,16
TOTFATSIZ:
INC BP ;Add one for Dirty byte
学习啦在线学习网 INC BP ;Add one for I/O device number
LODSW ;Get size of this FAT
XCHG AX,BP
STOSW ;Save address of this FAT
ADD BP,AX ;Compute size of next FAT
CMP AX,BP ;If size was zero done
LOOPNZ TOTFATSIZ
MOV AL,15
学习啦在线学习网 SUB AL,CL ;Compute number of FATs used
MOV [NUMDRV],AL
学习啦在线学习网 XOR AX,AX ;Set zero flag
学习啦在线学习网 REPZ SCASW ;Make sure all other entries are zero
学习啦在线学习网 JNZ BADINITJ
ADD BP,15 ;True start of free space
学习啦在线学习网 MOV CL,4
SHR BP,CL ;First free segment
学习啦在线学习网 MOV DX,CS
ADD DX,BP
MOV BX,0FH
MOV CX,[ENDMEM]
学习啦在线学习网 CMP CX,1 ;Use memory scan?
JNZ SETEND
学习啦在线学习网 MOV CX,DX ;Start scanning just after DOS
学习啦在线学习网 MEMSCAN:
INC CX
学习啦在线学习网 JZ SETEND
MOV DS,CX
MOV AL,[BX]
NOT AL
学习啦在线学习网 MOV [BX],AL
CMP AL,[BX]
NOT AL
MOV [BX],AL
JZ MEMSCAN
SETEND:
IF HIGHMEM
学习啦在线学习网 SUB CX,BP
学习啦在线学习网 MOV BP,CX ;Segment of DOS
学习啦在线学习网 MOV DX,CS ;Program segment
ENDIF
IF NOT HIGHMEM
MOV BP,CS
ENDIF
; BP has segment of DOS (whether to load high or run in place)
; DX has program segment (whether after DOS or overlaying DOS)
; CX has size of memory in paragraphs (reduced by DOS size if HIGHMEM)
MOV CS:[ENDMEM],CX
IF HIGHMEM
MOV ES,BP
XOR SI,SI
MOV DI,SI
MOV CX,(DOSLEN+1)/2
PUSH CS
POP DS
REP MOVSW ;Move DOS to high memory
ENDIF
XOR AX,AX
MOV DS,AX
学习啦在线学习网 MOV ES,AX
MOV DI,INTBASE
MOV AX,OFFSET DOSGROUP:QUIT
STOSW ;Set abort address--displacement
学习啦在线学习网 MOV AX,BP
MOV BYTE PTR DS:[ENTRYPOINT],LONGJUMP
MOV WORD PTR DS:[ENTRYPOINT+1],OFFSET DOSGROUP:ENTRY
MOV WORD PTR DS:[ENTRYPOINT+3],AX
MOV WORD PTR DS:[0],OFFSET DOSGROUP:DIVOV ;Set default divide trap address
学习啦在线学习网 MOV DS:[2],AX
学习啦在线学习网 MOV CX,9
REP STOSW ;Set 5 segments (skip 2 between each)
学习啦在线学习网 MOV WORD PTR DS:[INTBASE+4],OFFSET DOSGROUP:COMMAND
学习啦在线学习网 MOV WORD PTR DS:[INTBASE+12],OFFSET DOSGROUP:IRET ;Ctrl-C exit
MOV WORD PTR DS:[INTBASE+16],OFFSET DOSGROUP:IRET ;Fatal error exit
MOV AX,OFFSET BIOSREAD
STOSW
学习啦在线学习网 MOV AX,BIOSSEG
STOSW
学习啦在线学习网 STOSW ;Add 2 to DI
STOSW
MOV WORD PTR DS:[INTBASE+18H],OFFSET BIOSWRITE
MOV WORD PTR DS:[EXIT],100H
MOV WORD PTR DS:[EXIT+2],DX
IF NOT IBM
学习啦在线学习网 MOV SI,OFFSET DOSGROUP:HEADER
学习啦在线学习网 CALL OUTMES
ENDIF
PUSH CS
POP DS
PUSH CS
POP ES
;Move the FATs into position
MOV AL,[NUMIO]
CBW
XCHG AX,CX
学习啦在线学习网 MOV DI,OFFSET DOSGROUP:MEMSTRT.FAT
FATPOINT:
MOV SI,WORD PTR [DI] ;Get address within FAT address table
MOVSW ;Set address of this FAT
学习啦在线学习网 ADD DI,DPBSIZ-2 ;Point to next DPB
LOOP FATPOINT
学习啦在线学习网 POP CX ;True address of first FAT
学习啦在线学习网 MOV SI,OFFSET DOSGROUP:MEMSTRT ;Place to move DPBs from
学习啦在线学习网 MOV DI,[DRVTAB] ;Place to move DPBs to
SUB CX,DI ;Total length of DPBs
CMP DI,SI
JBE MOVJMP ;Are we moving to higher or lower memory?
学习啦在线学习网 DEC CX ;Move backwards to higher memory
ADD DI,CX
ADD SI,CX
INC CX
STD
MOVJMP:
学习啦在线学习网 MOV ES,BP
学习啦在线学习网 JMP MOVFAT
学习啦在线学习网 FIGFATSIZ:
MUL ES:BYTE PTR[BP.FATCNT]
学习啦在线学习网 ADD AX,ES:[BP.FIRFAT]
学习啦在线学习网 ADD AX,ES:[BP.DIRSEC]
FIGMAX:
学习啦在线学习网 ;AX has equivalent of FIRREC
SUB AX,ES:[BP.DSKSIZ]
NEG AX
MOV CL,ES:[BP.CLUSSHFT]
SHR AX,CL
INC AX
MOV CX,AX ;MAXCLUS
INC AX
MOV DX,AX
SHR DX,1
ADC AX,DX ;Size of FAT in bytes
学习啦在线学习网 MOV SI,ES:[BP.SECSIZ]
学习啦在线学习网 ADD AX,SI
DEC AX
XOR DX,DX
DIV SI
RET
BADMES:
DB 13,10,"INIT TABLE BAD",13,10,"$"
FATSIZTAB:
学习啦在线学习网 DW 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
DRVCNT DB 0
MEMSTRT LABEL WORD
ADJFAC EQU DIRBUF-MEMSTRT
DATA ENDS
END
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