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