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
你还在为不知道DOS操作系统源码相关资料知识而烦恼么?接下来是小编为大家收集的DOS操作系统源码相关资料知识教程，希望能帮到大家。
DOS操作系统源码相关资料知识
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
学习啦在线学习网 ; 0.42 02/25/81 32-byte directory entries added
; 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
学习啦在线学习网 ; 0.75 04/17/81 Improve and correct buffer handling
学习啦在线学习网 ; 0.76 04/23/81 Correct directory size when not 2^N entries
学习啦在线学习网 ; 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'
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
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
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)
学习啦在线学习网 ; 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;
; Add FLUSH and MAPDEV calls; allow disk mapping in DSKCHG;
; Lots of smaller improvements
学习啦在线学习网 ; 1.21 01/06/82 HIGHMEM switch to run DOS in high memory
; 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
学习啦在线学习网 ; 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
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:
学习啦在线学习网 ; INTBASE: ABORT
学习啦在线学习网 ; INTBASE+4: COMMAND
; INTBASE+8: BASE EXIT ADDRESS
学习啦在线学习网 ; 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
CANCEL EQU 1BH ;Cancel with ESC
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
学习啦在线学习网 ZEROEXT EQU TRUE
ELSE
学习啦在线学习网 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
学习啦在线学习网 INTBASE EQU 80H
INTTAB EQU 20H
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
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
学习啦在线学习网 ; Field definition for FCBs
学习啦在线学习网 FCBLOCK STRUC
DB 12 DUP (?) ;Drive code and name
EXTENT DW ?
RECSIZ DW ? ;Size of record (user settable)
学习啦在线学习网 FILSIZ DW ? ;Size of file in bytes
学习啦在线学习网 DRVBP DW ? ;BP for SEARCH FIRST and SEARCH NEXT
FDATE DW ? ;Date of last writing
学习啦在线学习网 FTIME DW ? ;Time of last writing
DEVID DB ? ;Device ID number, bits 0-5
;bit 7=0 for file, bit 7=1 for I/O device
学习啦在线学习网 ;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
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
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)
学习啦在线学习网 ; 11 1 Attributes. Bits 1 or 2 make file hidden
学习啦在线学习网 ; 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.)
;
学习啦在线学习网 ; 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
; 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
; 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
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
; entry size (if SMALLDIR selected). Entry 1 is reserved for future use. The
学习啦在线学习网 ; 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
学习啦在线学习网 ; 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.
学习啦在线学习网 ; 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
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
FAT DW ? ;Pointer to start of FAT
DPBLOCK ENDS
DPBSIZ EQU 20 ;Size of the structure in bytes
学习啦在线学习网 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)
学习啦在线学习网 ;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
CODE ENDS
学习啦在线学习网 CONSTANTS SEGMENT BYTE
学习啦在线学习网 CONSTANTS ENDS
DATA SEGMENT WORD
DATA ENDS
DOSGROUP GROUP CODE,CONSTANTS,DATA
SEGBIOS SEGMENT
SEGBIOS ENDS
学习啦在线学习网 ; BOIS entry point definitions
IF IBM
学习啦在线学习网 BIOSSEG EQU 60H
ENDIF
IF NOT IBM
BIOSSEG EQU 40H
ENDIF
SEGBIOS SEGMENT AT BIOSSEG
ORG 0
学习啦在线学习网 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
BIOSAUXOUT DB 3 DUP (?) ;Output byte to auxilliary
BIOSREAD DB 3 DUP (?) ;Disk read
BIOSWRITE DB 3 DUP (?) ;Disk write
学习啦在线学习网 BIOSDSKCHG DB 3 DUP (?) ;Dsik-change status
学习啦在线学习网 BIOSSETDATE DB 3 DUP (?) ;Set date
BIOSSETTIME DB 3 DUP (?) ;Set time
BIOSGETTIME DB 3 DUP (?) ;Get time and date
BIOSFLUSH DB 3 DUP (?) ;Clear console input buffer
BIOSMAPDEV DB 3 DUP (?) ;Dynamic disk table mapper
SEGBIOS ENDS
; 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 ?
学习啦在线学习网 CXSAVE DW ?
学习啦在线学习网 DXSAVE DW ?
学习啦在线学习网 SISAVE DW ?
学习啦在线学习网 DISAVE DW ?
BPSAVE DW ?
DSSAVE DW ?
ESSAVE DW ?
IPSAVE DW ?
CSSAVE DW ?
学习啦在线学习网 FSAVE DW ?
学习啦在线学习网 STKPTRS ENDS
; Start of code
学习啦在线学习网 CODE SEGMENT
ASSUME CS:DOSGROUP,DS:DOSGROUP,ES:DOSGROUP,SS:DOSGROUP
ORG 0
CODSTRT EQU $
学习啦在线学习网 JMP DOSINIT
学习啦在线学习网 ESCCHAR DB ESCCH ;Lead-in character for escape sequences
ESCTAB:
IF NOT IBM
DB "S" ;Copy one char
学习啦在线学习网 DB "V" ;Skip one char
DB "T" ;Copy to char
DB "W" ;Skip to char
DB "U" ;Copy line
学习啦在线学习网 DB "E" ;Kill line (no change in template)
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
学习啦在线学习网 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 - -->
学习啦在线学习网 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
DB 62 ;Skip to char - F4
学习啦在线学习网 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
DB 75 ;Backspace - <--
学习啦在线学习网 DB 82 ;Enter insert mode - INS (toggle)
学习啦在线学习网 DB 65 ;Escape character - F7
DB 65 ;End of table
ENDIF
ESCTABLEN EQU $-ESCTAB
IF NOT IBM
HEADER DB 13,10,"MS-DOS version 1.25"
学习啦在线学习网 IF HIGHMEM
DB "H"
ENDIF
IF DSKTEST
学习啦在线学习网 DB "D"
ENDIF
学习啦在线学习网 DB 13,10
DB "Copyright 1981,82 Microsoft, Inc.",13,10,"$"
ENDIF
QUIT:
MOV AH,0
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
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
PUSH CS:[TEMP] ;Stack now ordered as if INT had been used
学习啦在线学习网 CMP CL,MAXCALL ;This entry point doesn't get as many calls
学习啦在线学习网 JA BADCALL
MOV AH,CL
SAVREGS:
PUSH ES
PUSH DS
PUSH BP
PUSH DI
PUSH SI
PUSH DX
PUSH CX
PUSH BX
PUSH AX
IF DSKTEST
学习啦在线学习网 MOV AX,CS:[SPSAVE]
学习啦在线学习网 MOV CS:[NSP],AX
学习啦在线学习网 MOV AX,CS:[SSSAVE]
学习啦在线学习网 MOV CS:[NSS],AX
POP AX
PUSH AX
ENDIF
学习啦在线学习网 MOV CS:[SPSAVE],SP
学习啦在线学习网 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
学习啦在线学习网 MOV BL,AH
MOV BH,0
SHL BX,1
CLD
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]
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
学习啦在线学习网 ; Standard Functions
DISPATCH DW ABORT ;0
DW CONIN
学习啦在线学习网 DW CONOUT
DW READER
学习啦在线学习网 DW PUNCH
DW LIST ;5
DW RAWIO
DW RAWINP
DW IN
DW PRTBUF
学习啦在线学习网 DW BUFIN ;10
DW CONSTAT
DW FLUSHKB
DW DSKRESET
DW SELDSK
DW OPEN ;15
DW CLOSE
DW SRCHFRST
DW SRCHNXT
DW DELETE
DW SEQRD ;20
DW SEQWRT
DW CREATE
DW RENAME
DW INUSE
DW GETDRV ;25
DW SETDMA
DW GETFATPT
DW GETFATPTDL
学习啦在线学习网 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
学习啦在线学习网 DW SETRNDREC
; Extended Functions
DW SETVECT
学习啦在线学习网 DW NEWBASE
学习啦在线学习网 DW BLKRD
学习啦在线学习网 DW BLKWRT ;40
学习啦在线学习网 DW MAKEFCB
DW GETDATE
学习啦在线学习网 DW SETDATE
DW GETTIME
学习啦在线学习网 DW SETTIME ;45
学习啦在线学习网 DW VERIFY
INUSE:
GETIO:
SETIO:
GETRDONLY:
SETATTRIB:
学习啦在线学习网 USERCODE:
MOV AL,0
RET
VERIFY:
AND AL,1
MOV CS:VERFLG,AL
RET
学习啦在线学习网 FLUSHKB:
PUSH AX
CALL FAR PTR BIOSFLUSH
POP AX
MOV AH,AL
学习啦在线学习网 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
CMP AL,7
学习啦在线学习网 JZ REDISPJ
学习啦在线学习网 CMP AL,8
JZ REDISPJ
CMP AL,10
学习啦在线学习网 JZ REDISPJ
学习啦在线学习网 MOV AL,0
RET
REDISPJ:JMP REDISP
READER:
AUXIN:
CALL STATCHK
CALL FAR PTR BIOSAUXIN
RET
PUNCH:
MOV AL,DL
AUXOUT:
PUSH AX
CALL STATCHK
POP AX
CALL FAR PTR BIOSAUXOUT
RET
UNPACK:
; Inputs:
学习啦在线学习网 ; 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
; Outputs:
; DI = Contents of FAT for given cluster
; Zero set means DI=0 (free cluster)
; No other registers affected. Fatal error if cluster too big.
学习啦在线学习网 CMP BX,[BP.MAXCLUS]
JA HURTFAT
LEA DI,[SI+BX]
SHR BX,1
MOV DI,[DI+BX]
JNC HAVCLUS
SHR DI,1
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
STC
学习啦在线学习网 HAVCLUS:
RCL BX,1
AND DI,0FFFH
RET
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)
学习啦在线学习网 CALL FATAL
POP AX ;Try to ignore bad FAT
RET
PACK:
; Inputs:
; DS = CS
; BX = Cluster number
学习啦在线学习网 ; 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
学习啦在线学习网 MOV DI,BX
学习啦在线学习网 SHR BX,1
ADD BX,SI
ADD BX,DI
学习啦在线学习网 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
学习啦在线学习网 SHL DX,1
SHL DX,1
学习啦在线学习网 SHL DX,1
AND DI,0FH
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
学习啦在线学习网 MOV CX,4 ;All devices are 4 letters
学习啦在线学习网 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
MOV AX,2020H
学习啦在线学习网 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
CALL MOVNAME
JC RET1
PUSH DX
PUSH DS
CALL FINDNAME
POP ES
POP DI
RET2: RET
GETNAME:
学习啦在线学习网 ; Inputs:
学习啦在线学习网 ; DS,DX point to FCB
学习啦在线学习网 ; Function:
; Find file name in disk directory. First byte is
; drive number (0=current disk). "?" matches any
; character.
; 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
; ES = CS
; 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
学习啦在线学习网 ; [NAME1] has file name
学习啦在线学习网 ; All other registers destroyed.
学习啦在线学习网 CALL MOVNAME
学习啦在线学习网 JC RET2 ;Bad file name?
学习啦在线学习网 FINDNAME:
学习啦在线学习网 MOV AX,CS
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
学习啦在线学习网 MOV SI,BX
学习啦在线学习网 MOV DI,OFFSET DOSGROUP:NAME1
MOV CX,11
WILDCRD:
REPE CMPSB
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
学习啦在线学习网 JNC SRCH
RET3: RET
FREE:
CMP [ENTFREE],-1 ;Found a free entry before?
JNZ TSTALL ;If so, ignore this one
MOV CX,[LASTENT]
学习啦在线学习网 MOV [ENTFREE],CX
TSTALL:
学习啦在线学习网 CMP AH,[DELALL] ;At end of directory?
JZ NEXTENT ;No - continue search
学习啦在线学习网 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
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:
; Inputs:
; [LASTENT] has previously searched directory entry
; Function:
学习啦在线学习网 ; Locates next sequential directory entry in preparation for search
; Outputs:
学习啦在线学习网 ; Carry set if none
; ELSE
; AL = Current directory block
学习啦在线学习网 ; 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
; [LASTENT] = New directory entry number
学习啦在线学习网 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
学习啦在线学习网 MOV CL,4
SHL AX,CL
XOR DX,DX
SHL AX,1
RCL DX,1 ;Account for overflow in last shift
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.
学习啦在线学习网 CMP AX,[DIRBUFID]
JZ HAVDIRBUF
PUSH BX
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
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
CALL DIRREAD
POP DX
学习啦在线学习网 MOV BX,OFFSET DOSGROUP:DIRBUF
HAVIT:
CLC
RET
NONE:
学习啦在线学习网 CALL CHKDIRWRITE
STC
学习啦在线学习网 RET4: RET
DELETE: ; System call 19
CALL MOVNAME
MOV AL,-1
JC RET4
学习啦在线学习网 MOV AL,CS:[ATTRIB]
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,"?"
MOV DI,OFFSET DOSGROUP:NAME1
学习啦在线学习网 REPE SCASB ;See if name is *.*
学习啦在线学习网 JNZ NOTALL
学习啦在线学习网 MOV BYTE PTR CS:[DELALL],0 ;DEL *.* - flag deleting all
NOTALL:
CALL FINDNAME
MOV AL,-1
JC RET4
学习啦在线学习网 OR BH,BH ;Check if device name
JS RET4 ;Can't delete I/O devices
DELFILE:
学习啦在线学习网 MOV BYTE PTR [DIRTYDIR],-1
MOV AH,[DELALL]
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
JZ DELNXT
CMP BX,[BP.MAXCLUS]
JA DELNXT
CALL RELEASE
DELNXT:
CALL CONTSRCH
JNC DELFILE
CALL FATWRT
CALL CHKDIRWRITE
XOR AL,AL
RET
RENAME: ;System call 23
学习啦在线学习网 CALL MOVNAME
JC ERRET
学习啦在线学习网 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
学习啦在线学习网 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
MOV CX,6 ;6 words (12 bytes)--include attribute byte
学习啦在线学习网 REP MOVSW ;Copy name to search for
RENFIL:
学习啦在线学习网 MOV DI,OFFSET DOSGROUP:NAME1
学习啦在线学习网 MOV SI,OFFSET DOSGROUP:NAME2
MOV CX,11
NEWNAM:
LODSB
CMP AL,"?"
JNZ NOCHG
MOV AL,[BX]
NOCHG:
STOSB
INC BX
学习啦在线学习网 LOOP NEWNAM
MOV BYTE PTR [DI],6 ;Stop duplicates with any attributes
学习啦在线学习网 CALL DEVNAME ;Check if giving it a device name
JNC RENERR
学习啦在线学习网 PUSH [LASTENT] ;Save position of match
学习啦在线学习网 MOV [LASTENT],-1 ;Search entire directory for duplicate
学习啦在线学习网 CALL CONTSRCH ;See if new name already exists
POP AX
JNC RENERR ;Error if found
学习啦在线学习网 CALL GETENT ;Re-read matching entry
MOV DI,BX
学习啦在线学习网 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
学习啦在线学习网 CALL CONTSRCH
学习啦在线学习网 JNC RENFIL
CALL CHKDIRWRITE
学习啦在线学习网 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:
; DS, DX point to FCB or extended FCB
学习啦在线学习网 ; Outputs:
学习啦在线学习网 ; DS:DX point to normal FCB
; ES = CS
; If file name OK:
学习啦在线学习网 ; 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
; Carry set if bad file name or drive
学习啦在线学习网 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
学习啦在线学习网 MOV DI,OFFSET DOSGROUP:NAME1
学习啦在线学习网 MOV SI,DX
LODSB
MOV CS:[EXTFCB],AL ;Set flag if extended FCB in use
MOV AH,0 ;Set default attributes
学习啦在线学习网 CMP AL,-1 ;Is it an extended FCB?
学习啦在线学习网 JNZ HAVATTRB
ADD DX,7 ;Adjust to point to normal FCB
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:
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:
学习啦在线学习网 ; 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
学习啦在线学习网 MOV CX,11
MOVCHK:
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
学习啦在线学习网 JNZ RET5
STOLET:
STOSB
LOOP MOVCHK
CLC ;Got through whole name - no error
学习啦在线学习网 RET6: RET
学习啦在线学习网 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:
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
学习啦在线学习网 ; entry in DIRBUF, SI points to First Cluster field, and
学习啦在线学习网 ; ES:DI point to the FCB to be opened. This entry point
学习啦在线学习网 ; is used by CREATE.
JC ERRET
OR BH,BH ;Check if file is I/O device
JS OPENDEV ;Special handler if so
学习啦在线学习网 MOV AL,[THISDRV]
INC AX
STOSB
XOR AX,AX
学习啦在线学习网 IF ZEROEXT
学习啦在线学习网 ADD DI,11
学习啦在线学习网 STOSW ;Zero low byte of extent field if IBM only
ENDIF
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
学习啦在线学习网 MOV AL,128 ;Default record size
STOSW ;Set record size
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
学习啦在线学习网 MOV AX,[SI-8] ;Get date
STOSW ;Save date in FCB
学习啦在线学习网 MOV AX,[SI-10] ;Get time
学习啦在线学习网 STOSW ;Save it in FCB
MOV AL,[BP.DEVNUM]
OR AL,40H
STOSB
学习啦在线学习网 MOV AX,DX ;Restore starting cluster
STOSW ; first cluster
学习啦在线学习网 STOSW ; last cluster accessed
学习啦在线学习网 XOR AX,AX
学习啦在线学习网 STOSW ; position of last cluster
RET
学习啦在线学习网 OPENDEV:
学习啦在线学习网 ADD DI,13 ;point to 2nd half of extent field
XOR AX,AX
学习啦在线学习网 STOSB ;Set it to zero
MOV AL,128
学习啦在线学习网 STOSW ;Set record size to 128
学习啦在线学习网 XOR AX,AX
STOSW
STOSW ;Set current size to zero
CALL DATE16
STOSW ;Date is todays
XCHG AX,DX
学习啦在线学习网 STOSW ;Use current time
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
学习啦在线学习网 MOV AH,2 ;While trying to read FAT
学习啦在线学习网 MOV AL,[THISDRV] ;Tell which drive
学习啦在线学习网 CALL FATAL1
JMP SHORT FATREAD
STARTSRCH:
MOV AX,-1
学习啦在线学习网 MOV [LASTENT],AX
MOV [ENTFREE],AX
FATREAD:
学习啦在线学习网 ; Inputs:
; DS = CS
; Function:
; If disk may have been changed, FAT is read in and buffers are
; 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
; 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
学习啦在线学习网 CALL FAR PTR BIOSDSKCHG ;See what BIOS has to say
JC FATERR
学习啦在线学习网 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
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?
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
学习啦在线学习网 MOV WORD PTR [BUFDRVNO],00FFH
BUFOK:
MOV [DIRBUFID],-1
CALL FIGFAT
NEXTFAT:
PUSH AX
学习啦在线学习网 CALL DSKREAD
POP AX
学习啦在线学习网 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]
学习啦在线学习网 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
MOV [SI-2],AX ;Set device no. and reset dirty bit
MAPDRV:
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
学习啦在线学习网 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:
MOV CX,DI
学习啦在线学习网 ADD DX,CX
DEC AL
JNZ NEXTFAT
CALL FIGFAT ;Reset registers
CALL DREAD ;Try first FAT once more
学习啦在线学习网 JMP SHORT NEWFAT
OKRET1:
MOV AL,0
RET
学习啦在线学习网 CLOSE: ;System call 16
MOV DI,DX
CMP BYTE PTR [DI],-1 ;Check for extended FCB
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
MOV AH,1 ;Look for dirty buffer
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
学习啦在线学习网 MOV BX,[BUFFER]
MOV CX,1
学习啦在线学习网 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:
学习啦在线学习网 CALL GETFILE
学习啦在线学习网 BADCLOSEJ:
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]
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]
MOV [SI-2],DX
MOV DX,ES:[DI.FTIME]
MOV [SI-4],DX
学习啦在线学习网 CALL DIRWRITE
学习啦在线学习网 CHKFATWRT:
; 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]
MOV AH,1
CMP [SI-2],AX ;See if FAT dirty and uses same driver
JNZ OKRET
FATWRT:
; Inputs:
; DS = CS
; BP = Base of drive parameter table
学习啦在线学习网 ; Function:
; Write the FAT back to disk and reset FAT
学习啦在线学习网 ; dirty bit.
学习啦在线学习网 ; Outputs:
学习啦在线学习网 ; AL = 0
; BP unchanged
; 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
学习啦在线学习网 CALL DWRITE
POP AX
POP BX
POP CX
POP DX
ADD DX,CX
DEC AL
JNZ EACHFAT
OKRET:
MOV AL,0
RET
BADCLOSE:
MOV SI,[BP.FAT]
学习啦在线学习网 MOV BYTE PTR [SI-1],0
MOV AL,-1
RET
FIGFAT:
; Loads registers with values needed to read or
; write a FAT.
学习啦在线学习网 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
学习啦在线学习网 MOV CX,1
RET
学习啦在线学习网 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
MOV AL,"?"
REPNE SCASB
JZ ERRET3
MOV CS:BYTE PTR [CREATING],-1
PUSH DX
PUSH DS
CALL FINDNAME
JNC EXISTENT
MOV AX,[ENTFREE] ;First free entry found in FINDNAME
CMP AX,-1
JZ ERRPOP
学习啦在线学习网 CALL GETENT ;Point at that free entry
JMP SHORT FREESPOT
ERRPOP:
POP DS
POP DX
ERRET3:
MOV AL,-1
RET
学习啦在线学习网 EXISTENT:
学习啦在线学习网 JNZ ERRPOP ;Error if attributes don't match
OR BH,BH ;Check if file is I/O device
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
CMP CX,[BP.MAXCLUS]
JA FREESPOT
PUSH BX
学习啦在线学习网 MOV BX,CX
学习啦在线学习网 MOV SI,[BP.FAT]
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
学习啦在线学习网 MOV CX,5
MOVSB
REP MOVSW
学习啦在线学习网 MOV AL,[ATTRIB]
STOSB
XOR AX,AX
MOV CL,5
学习啦在线学习网 REP STOSW
CALL DATE16
XCHG AX,DX
STOSW
XCHG AX,DX
STOSW
XOR AX,AX
PUSH DI
MOV CL,6
学习啦在线学习网 SMALLENT:
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
学习啦在线学习网 ; BP = Base of drive parameters
学习啦在线学习网 ; Function:
; Read the directory block into DIRBUF.
; Outputs:
; AX,BP unchanged
学习啦在线学习网 ; All other registers destroyed.
PUSH AX
CALL CHKDIRWRITE
POP AX
PUSH AX
MOV AH,[BP.DEVNUM]
学习啦在线学习网 MOV [DIRBUFID],AX
CALL DIRCOMP
学习啦在线学习网 CALL DREAD
POP AX
学习啦在线学习网 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
; DX = Absolute record number
; BP = Base of drive parameters
学习啦在线学习网 ; 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
MOV CS:BYTE PTR [READOP],0
CALL HARDERR
学习啦在线学习网 CMP AL,1 ;Check for retry
JZ DREAD
RET ;Ignore otherwise
学习啦在线学习网 HARDERR:
学习啦在线学习网 ;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)
; AX = Hardware error code
; DI = Original sector transfer count
; BP = Base of drive parameters
学习啦在线学习网 ; [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
CMP DX,[BP.FIRFAT] ;In reserved area?
JB ERRINT
学习啦在线学习网 INC AH ;Flag for FAT
CMP DX,[BP.FIRDIR] ;In FAT?
学习啦在线学习网 JB ERRINT
INC AH
CMP DX,[BP.FIRREC] ;In directory?
学习啦在线学习网 JB ERRINT
INC AH ;Must be in data area
ERRINT:
SHL AH,1 ;Make room for read/write bit
学习啦在线学习网 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
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
MOV CS:[SPSAVE],SP
MOV CS:[SSSAVE],SS
MOV SP,CS
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
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
RET9: RET
学习啦在线学习网 CHKDIRWRITE:
TEST BYTE PTR [DIRTYDIR],-1
JZ RET9
DIRWRITE:
; Inputs:
; DS = CS
; AL = Directory block number
学习啦在线学习网 ; BP = Base of drive parameters
学习啦在线学习网 ; 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
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
; CX = Number of sectors
; DX = Absolute record number
; BP = Base of drive parameters
学习啦在线学习网 ; Function:
; Calls BIOS to perform disk write. If BIOS reports
; errors, will call HARDERR for further action.
; 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
学习啦在线学习网 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
JZ DWRITE
RET
ABORT:
LDS SI,CS:DWORD PTR [SPSAVE]
学习啦在线学习网 MOV DS,[SI.CSSAVE]
学习啦在线学习网 XOR AX,AX
学习啦在线学习网 MOV ES,AX
MOV SI,SAVEXIT
MOV DI,EXIT
MOVSW
MOVSW
MOVSW
MOVSW
MOVSW
MOVSW
ERROR:
MOV AX,CS
学习啦在线学习网 MOV DS,AX
学习啦在线学习网 MOV ES,AX
CALL WRTFATS
学习啦在线学习网 XOR AX,AX
CLI
MOV SS,[SSSAVE]
学习啦在线学习网 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
JMP CS:DWORD PTR [EXITHOLD]
SEQRD: ;System call 20
CALL GETREC
学习啦在线学习网 CALL LOAD
JMP SHORT FINSEQ
学习啦在线学习网 SEQWRT: ;System call 21
CALL GETREC
CALL STORE
FINSEQ:
JCXZ SETNREX
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
CALL LOAD
JMP SHORT FINRND
RNDWRT: ;System call 34
学习啦在线学习网 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
学习啦在线学习网 CALL GETRRPOS
CALL LOAD
学习啦在线学习网 JMP SHORT FINBLK
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
学习啦在线学习网 JCXZ FINRND
ADD AX,1
ADC DX,0
FINRND:
学习啦在线学习网 MOV ES:WORD PTR [DI.RR],AX
学习啦在线学习网 MOV ES:[DI.RR+2],DL
学习啦在线学习网 OR DH,DH
JZ SETNREX
学习啦在线学习网 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
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
学习啦在线学习网 MOV AL,CS:[DSKERR]
RET
GETRRPOS1:
学习啦在线学习网 MOV CX,1
GETRRPOS:
MOV DI,DX
学习啦在线学习网 CMP BYTE PTR [DI],-1
JNZ NORMFCB1
学习啦在线学习网 ADD DI,7
NORMFCB1:
学习啦在线学习网 MOV AX,WORD PTR [DI.RR]
学习啦在线学习网 MOV DX,WORD PTR [DI.RR+2]
RET
NOFILERR:
XOR CX,CX
学习啦在线学习网 MOV BYTE PTR [DSKERR],4
POP BX
RET
SETUP:
学习啦在线学习网 ; Inputs:
学习啦在线学习网 ; DS:DI point to FCB
学习啦在线学习网 ; DX:AX = Record position in file of disk transfer
学习啦在线学习网 ; 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
; BP = Base of drive parameters
; SI = FAT pointer
; [RECCNT] = Record count
; [RECPOS] = Record position in file
学习啦在线学习网 ; [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
; [SECCLUSPOS] = Sector within first cluster
学习啦在线学习网 ; [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
MOV CS:[THISDRV],AL
MOV AL,[DI.DEVID]
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
学习啦在线学习网 JC NOFILERR
CMP SI,64 ;Check if highest byte of RECPOS is significant
学习啦在线学习网 JB SMALREC
学习啦在线学习网 MOV DH,0 ;Ignore MSB if record >= 64 bytes
SMALREC:
MOV [RECCNT],CX
学习啦在线学习网 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]
MOV [NEXTADD],BX
学习啦在线学习网 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
学习啦在线学习网 MOV AX,BX
MUL SI
POP BX
学习啦在线学习网 ADD AX,BX
ADC DX,0 ;Ripple carry
JNZ EOFERR
MOV WORD PTR [BYTPOS+2],AX
学习啦在线学习网 MOV DX,AX
MOV AX,WORD PTR [BYTPOS]
学习啦在线学习网 MOV BX,[BP.SECSIZ]
学习啦在线学习网 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
MOV DX,AX
AND AL,[BP.CLUSMSK]
学习啦在线学习网 MOV [SECCLUSPOS],AL
学习啦在线学习网 MOV AX,CX ;Record count
MOV CL,[BP.CLUSSHFT]
SHR DX,CL
学习啦在线学习网 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:
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?
学习啦在线学习网 MOV [RECCNT],AX
MUL SI ;Translate that back into bytes
学习啦在线学习网 MOV BYTE PTR [DSKERR],2 ;Flag that trimming took place
MOV CX,AX
JCXZ NOROOM
OK:
MOV BL,ES:[DI.DEVID]
学习啦在线学习网 MOV SI,[BP.FAT]
RET
EOFERR:
MOV BYTE PTR [DSKERR],1
XOR CX,CX
NOROOM:
学习啦在线学习网 POP BX ;Kill return address
RET
BREAKDOWN:
;Inputs:
; DS = CS
; CX = Length of disk transfer in bytes
; 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
学习啦在线学习网 ; [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]
MOV BX,CX
学习啦在线学习网 OR AX,AX
学习啦在线学习网 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
学习啦在线学习网 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
XOR DX,DX
学习啦在线学习网 DIV [BP.SECSIZ] ;How many whole sectors?
MOV [SECCNT],AX
MOV [BYTCNT2],DX ;Bytes remaining for last sector
学习啦在线学习网 RET10: RET
学习啦在线学习网 FNDCLUS:
; Inputs:
; DS = CS
; CX = No. of clusters to skip
; BP = Base of drive parameters
学习啦在线学习网 ; SI = FAT pointer
; ES:DI point to FCB
; Outputs:
学习啦在线学习网 ; BX = Last cluster skipped to
学习啦在线学习网 ; CX = No. of clusters remaining (0 unless EOF)
学习啦在线学习网 ; DX = Position of last cluster
学习啦在线学习网 ; DI destroyed. No other registers affected.
学习啦在线学习网 MOV BX,ES:[DI.LSTCLUS]
MOV DX,ES:[DI.CLUSPOS]
OR BX,BX
学习啦在线学习网 JZ NOCLUS
学习啦在线学习网 SUB CX,DX
JNB FINDIT
学习啦在线学习网 ADD CX,DX
XOR DX,DX
MOV BX,ES:[DI.FIRCLUS]
FINDIT:
JCXZ RET10
SKPCLP:
学习啦在线学习网 CALL UNPACK
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:
; Inputs:
; AL = 0 if buffer must be read, 1 if no pre-read needed
; BP = Base of drive parameters
学习啦在线学习网 ; [CLUSNUM] = Physical cluster number
; [SECCLUSPOS] = Sector position of transfer within cluster
; [BYTCNT1] = Size of transfer
; Function:
学习啦在线学习网 ; Insure specified sector is in buffer, flushing buffer before
; 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
学习啦在线学习网 MOV DX,[CLUSNUM]
MOV BL,[SECCLUSPOS]
CALL FIGREC
MOV [PREREAD],AL
CMP DX,[BUFSECNO]
学习啦在线学习网 JNZ GETSEC
MOV AL,[BUFDRVNO]
学习啦在线学习网 CMP AL,[THISDRV]
学习啦在线学习网 JZ FINBUF ;Already have it?
GETSEC:
XOR AL,AL
XCHG [DIRTYBUF],AL ;Read dirty flag and reset it
学习啦在线学习网 OR AL,AL
学习啦在线学习网 JZ RDSEC
PUSH DX
PUSH BP
学习啦在线学习网 MOV BP,[BUFDRVBP]
MOV BX,[BUFFER]
MOV CX,1
MOV DX,[BUFSECNO]
CALL DWRITE
POP BP
POP DX
RDSEC:
学习啦在线学习网 TEST BYTE PTR [PREREAD],-1
学习啦在线学习网 JNZ SETBUF
XOR AX,AX
MOV [BUFSECNO],AX ;Set buffer valid in case of disk error
DEC AX
MOV [BUFDRVNO],AL
MOV BX,[BUFFER]
学习啦在线学习网 MOV CX,1
PUSH DX
CALL DREAD
POP DX
SETBUF:
学习啦在线学习网 MOV [BUFSECNO],DX
学习啦在线学习网 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
学习啦在线学习网 MOV DI,[NEXTADD]
MOV SI,DI
学习啦在线学习网 MOV CX,[BYTCNT1]
ADD SI,CX
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
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
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
EVENWRT:
学习啦在线学习网 REP MOVSW
POP ES
POP DS
学习啦在线学习网 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
学习啦在线学习网 CMP AL,[BP.CLUSMSK]
JBE SAVPOS
MOV BX,[CLUSNUM]
学习啦在线学习网 CMP BX,0FF8H
学习啦在线学习网 JAE NONEXT
MOV SI,[BP.FAT]
CALL UNPACK
MOV [CLUSNUM],DI
INC [LASTPOS]
学习啦在线学习网 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
CMP AL,13 ;Check for carriage return
学习啦在线学习网 JNZ NORMCH
学习啦在线学习网 MOV BYTE PTR [SI],10
NORMCH:
CMP AL,10
LOOPNZ TRANBUF
JNZ ENDRDCON
CALL OUT ;Transmit linefeed
XOR SI,SI
学习啦在线学习网 OR CX,CX
学习啦在线学习网 JNZ GETBUF
OR AL,1 ;Clear zero flag--not end of file
ENDRDCON:
学习啦在线学习网 MOV [CONTPOS],SI
ENDRDDEV:
MOV [NEXTADD],DI
POP ES
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
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
学习啦在线学习网 READAUX:
学习啦在线学习网 CALL AUXIN
STOSB
学习啦在线学习网 CMP AL,1AH
学习啦在线学习网 LOOPNZ READAUX
学习啦在线学习网 JMP SHORT ENDRDDEV
READCON:
PUSH CS
POP DS
MOV SI,[CONTPOS]
OR SI,SI
学习啦在线学习网 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
学习啦在线学习网 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
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
JMP SHORT ENDRDCON
RDERR:
XOR CX,CX
JMP WRTERR
RDLASTJ:JMP RDLAST
LOAD:
; Inputs:
学习啦在线学习网 ; DS:DI point to FCB
; DX:AX = Position in file to read
学习啦在线学习网 ; CX = No. of records to read
; Outputs:
学习啦在线学习网 ; DX:AX = Position of last record read
; CX = No. of bytes read
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
OR BL,BL ;Check for named device I/O
学习啦在线学习网 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]
学习啦在线学习网 JB RDERR
学习啦在线学习网 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
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
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
JZ RDLASTJ
学习啦在线学习网 CALL NEXTSEC
学习啦在线学习网 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]
学习啦在线学习网 MOV BX,[CLUSNUM]
RDLP:
CALL OPTIMIZE
PUSH DI
PUSH AX
PUSH DS
学习啦在线学习网 MOV DS,[DMAADD+2]
PUSH DX
PUSH BX
学习啦在线学习网 PUSHF ;Save carry flag
CALL DREAD
POPF ;Restore carry flag
POP DI ;Initial transfer address
POP AX ;First sector transfered
POP DS
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?
学习啦在线学习网 JZ NOTBUFFED ;If not no problem
学习啦在线学习网 ;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
学习啦在线学习网 MOV CX,[BP.SECSIZ]
MUL CX ;How many bytes into the transfer?
学习啦在线学习网 ADD DI,AX
MOV SI,[BUFFER]
PUSH ES
MOV ES,[DMAADD+2] ;Get disk transfer segment
SHR CX,1
REP MOVSW
JNC EVENMOV
MOVSB
EVENMOV:
POP ES
NOTBUFFED:
POP CX
POP BX
JCXZ RDLAST
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]
学习啦在线学习网 MOV AX,[NEXTADD]
学习啦在线学习网 MOV DI,AX
SUB AX,[DMAADD] ;Number of bytes transfered
XOR DX,DX
学习啦在线学习网 MOV CX,ES:[SI.RECSIZ]
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
学习啦在线学习网 OR DX,DX
JZ FULLREC ;If remainder 0, then full record transfered
MOV BYTE PTR [DSKERR],3 ;Flag partial last record
学习啦在线学习网 SUB CX,DX ;Bytes left in last record
PUSH ES
学习啦在线学习网 MOV ES,[DMAADD+2]
学习啦在线学习网 XCHG AX,BX ;Save the record count temporarily
XOR AX,AX ;Fill with zeros
SHR CX,1
JNC EVENFIL
STOSB
EVENFIL:
REP STOSW
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:
MOV CX,AX
MOV DI,SI ;ES:DI point to FCB
SETCLUS:
MOV AX,[CLUSNUM]
MOV ES:[DI.LSTCLUS],AX
MOV AX,[LASTPOS]
学习啦在线学习网 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
ADD AX,CX ;Update current record position
ADC DX,0
INC CX
RET28: RET
RDLAST:
MOV AX,[BYTCNT2]
OR AX,AX
JZ SETFCB
MOV [BYTCNT1],AX
CALL NEXTSEC
JC SETFCB
学习啦在线学习网 MOV [BYTSECPOS],0
CALL BUFRD
JMP SHORT SETFCB
WRTDEV:
PUSH DS
学习啦在线学习网 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
学习啦在线学习网 JZ ENDWRDEV
学习啦在线学习网 CALL LISTOUT
LOOP WRTLST
JMP SHORT ENDWRDEV
WRTAUX:
LODSB
CALL AUXOUT
CMP AL,1AH
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
LOOP WRTCON
学习啦在线学习网 ENDWRDEV:
POP DS
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
JNC DOWRTJ
WRTERR:
学习啦在线学习网 MOV BYTE PTR [DSKERR],1
LVDSK:
MOV AX,WORD PTR [RECPOS]
MOV DX,WORD PTR [RECPOS+2]
学习啦在线学习网 MOV DI,[FCB]
RET
DOWRTJ: JMP DOWRT
学习啦在线学习网 WRTEOFJ:
JMP WRTEOF
STORE:
; Inputs:
; DS:DI point to FCB
学习啦在线学习网 ; DX:AX = Position in file of disk transfer
学习啦在线学习网 ; CX = Record count
学习啦在线学习网 ; Outputs:
学习啦在线学习网 ; DX:AX = Position of last record written
; CX = No. of records written
; ES:DI point to FCB
; LSTCLUS, CLUSPOS fields in FCB set
学习啦在线学习网 CALL SETUP
CALL DATE16
MOV ES:[DI.FDATE],AX
MOV ES:[DI.FTIME],DX
学习啦在线学习网 OR BL,BL
JS WRTDEV
AND BL,3FH ;Mark file as dirty
学习啦在线学习网 MOV ES:[DI.DEVID],BL
CALL BREAKDOWN
MOV AX,WORD PTR [BYTPOS]
学习啦在线学习网 MOV DX,WORD PTR [BYTPOS+2]
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]
SHR AX,CL ;Last cluster to be accessed
PUSH AX
MOV AX,ES:WORD PTR [DI.FILSIZ]
学习啦在线学习网 MOV DX,ES:WORD PTR [DI.FILSIZ+2]
DIV [BP.SECSIZ]
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
MOV CX,[CLUSNUM] ;First cluster accessed
CALL FNDCLUS
MOV [CLUSNUM],BX
学习啦在线学习网 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
CALL ALLOCATE
POP AX
JC WRTERR
MOV CX,AX
学习啦在线学习网 MOV DX,[LASTPOS]
INC DX
DEC CX
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
JZ WRTMID
学习啦在线学习网 MOV BX,[CLUSNUM]
学习啦在线学习网 CALL BUFWRT
WRTMID:
MOV AX,[SECCNT]
OR AX,AX
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]
MOV BX,[CLUSNUM]
MOV CX,[SECCNT]
WRTLP:
学习啦在线学习网 CALL OPTIMIZE
JC NOTINBUF ;Is one of the sectors buffered?
学习啦在线学习网 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
学习啦在线学习网 MOV DS,[DMAADD+2]
CALL DWRITE
POP DS
POP CX
POP BX
JCXZ WRTLAST
MOV DL,0
INC [LASTPOS] ;We'll be using next cluster
JMP SHORT WRTLP
学习啦在线学习网 WRTLAST:
MOV AX,[BYTCNT2]
OR AX,AX
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]
学习啦在线学习网 MOV DX,WORD PTR [BYTPOS+2]
ADC DX,0
MOV CX,DX
学习啦在线学习网 MOV DI,[FCB]
CMP AX,ES:WORD PTR [DI.FILSIZ]
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
MOV ES:WORD PTR [DI.FILSIZ+2],DX
SAMSIZ:
学习啦在线学习网 MOV CX,[RECCNT]
JMP SETCLUS
学习啦在线学习网 WRTERRJ:JMP WRTERR
WRTEOF:
学习啦在线学习网 MOV CX,AX
OR CX,DX
JZ KILLFIL
学习啦在线学习网 SUB AX,1
SBB DX,0
DIV [BP.SECSIZ]
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]
MOV ES:WORD PTR [DI.FILSIZ+2],AX
学习啦在线学习网 XOR CX,CX
学习啦在线学习网 JMP ADDREC
RELFILE:
MOV DX,0FFFH
CALL RELBLKS
学习啦在线学习网 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
XCHG BX,ES:[DI.FIRCLUS]
OR BX,BX
学习啦在线学习网 JZ UPDATE
学习啦在线学习网 CALL RELEASE
JMP SHORT SETDIRT
OPTIMIZE:
; Inputs:
; DS = CS
; BX = Physical cluster
; CX = No. of records
; DL = sector within cluster
; BP = Base of drives parameters
学习啦在线学习网 ; [NEXTADD] = transfer address
; Outputs:
学习啦在线学习网 ; AX = No. of records remaining
; BX = Transfer address
; 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
学习啦在线学习网 ; Carry set otherwise
; [CLUSNUM] = Last cluster accessed
学习啦在线学习网 ; [NEXTADD] updated
; BP unchanged. Note that segment of transfer not set.
PUSH DX
PUSH BX
学习啦在线学习网 MOV AL,[BP.CLUSMSK]
INC AL ;Number of sectors per cluster
学习啦在线学习网 MOV AH,AL
SUB AL,DL ;AL = Number of sectors left in first cluster
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
学习啦在线学习网 ;AH has number of sectors available in next cluster
;BX has current physical cluster
学习啦在线学习网 ;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
;SI has FAT pointer
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
FINCLUS:
学习啦在线学习网 MOV [CLUSNUM],BX ;Last cluster accessed
学习啦在线学习网 SUB DX,CX ;Number of sectors still needed
PUSH DX
学习啦在线学习网 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
学习啦在线学习网 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
学习啦在线学习网 ADD [LASTPOS],BX
POP BX ;BL = sector postion within cluster
CALL FIGREC
学习啦在线学习网 MOV BX,SI
;Now let's see if any of these sectors are already in the buffer
CMP [BUFSECNO],DX
学习啦在线学习网 JC RET100 ;If DX > [BUFSECNO] then not in buffer
MOV SI,DX
ADD SI,CX ;Last sector + 1
学习啦在线学习网 CMP [BUFSECNO],SI
CMC
学习啦在线学习网 JC RET100 ;If SI <= [BUFSECNO] then not in buffer
PUSH AX
MOV AL,[BP.DEVNUM]
学习啦在线学习网 CMP AL,[BUFDRVNO] ;Is buffer for this drive?
POP AX
JZ RET100 ;If so, then we match
学习啦在线学习网 STC ;No match
RET100: RET
BLKDON:
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
学习啦在线学习网 MOV [SECCLUSPOS],AH
MOV CX,DX ;Anyway, make the total equal to the request
JMP SHORT FINCLUS
FIGREC:
学习啦在线学习网 ;Inputs:
; DX = Physical cluster number
学习啦在线学习网 ; 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
学习啦在线学习网 SHL DX,CL
学习啦在线学习网 OR DL,BL
学习啦在线学习网 ADD DX,[BP.FIRREC]
POP CX
RET
GETREC:
学习啦在线学习网 ; Inputs:
学习啦在线学习网 ; DS:DX point to FCB
; Outputs:
学习啦在线学习网 ; CX = 1
; DX:AX = Record number determined by EXTENT and NR fields
; DS:DI point to FCB
; No other registers affected.
学习啦在线学习网 MOV DI,DX
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]
学习啦在线学习网 MOV DX,[DI.EXTENT]
学习啦在线学习网 SHL AL,1
SHR DX,1
学习啦在线学习网 RCR AL,1
MOV AH,DL
学习啦在线学习网 MOV DL,DH
学习啦在线学习网 MOV DH,0
RET
ALLOCATE:
; Inputs:
; DS = CS
学习啦在线学习网 ; ES = Segment of FCB
; BX = Last cluster of file (0 if null file)
; CX = No. of clusters to allocate
学习啦在线学习网 ; 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
学习啦在线学习网 ; CX = max. no. of records that could be added to file
; ELSE
; Carry clear
; BX = First cluster allocated
; FAT is fully updated including dirty bit
; FIRCLUS field of FCB set if file was null
; SI,BP unchanged. All other registers destroyed.
PUSH [SI]
PUSH DX
PUSH CX
PUSH BX
学习啦在线学习网 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
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
JG TRYIN
POP BX
MOV DX,0FFFH
CALL RELBLKS
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
MOV DL,[BP.CLUSMSK]
MOV DH,0
INC DX ;DX=records/cluster
学习啦在线学习网 MUL DX ;AX=max no. of records in file
学习啦在线学习网 MOV CX,AX
SUB CX,WORD PTR [RECPOS] ;CX=max no. of records that could be written
JA MAXREC
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
JLE FINDFRE
XCHG AX,BX
CALL UNPACK
JZ HAVFRE
学习啦在线学习网 XCHG AX,BX
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
学习啦在线学习网 MOV BX,AX
学习啦在线学习网 LOOP ALLOC
MOV DX,0FFFH
CALL PACK
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
学习啦在线学习网 CALL UNPACK
POP [SI]
学习啦在线学习网 XCHG BX,DI
OR DI,DI
学习啦在线学习网 JNZ RET11
MOV DI,[FCB]
学习啦在线学习网 MOV ES:[DI.FIRCLUS],BX
RET12: RET
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]
; AX,BX,DX,DI all destroyed. Other registers unchanged.
XOR DX,DX
学习啦在线学习网 RELBLKS:
; Enter here with DX=0FFFH to put an end-of-file mark
; in the first cluster and free the rest in the chain.
学习啦在线学习网 CALL UNPACK
JZ RET12
MOV AX,DI
CALL PACK
CMP AX,0FF8H
MOV BX,AX
学习啦在线学习网 JB RELEASE
RET13: RET
GETEOF:
学习啦在线学习网 ; Inputs:
; BX = Cluster in a file
; SI = Base of drive FAT
; 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
学习啦在线学习网 SRCHFRST: ;System call 17
CALL GETFILE
学习啦在线学习网 SAVPLCE:
学习啦在线学习网 ; Search-for-next enters here to save place and report
学习啦在线学习网 ; findings.
学习啦在线学习网 JC KILLSRCH
OR BH,BH
学习啦在线学习网 JS SRCHDEV
MOV AX,[LASTENT]
MOV ES:[DI.FILDIRENT],AX
学习啦在线学习网 MOV ES:[DI.DRVBP],BP
;Information in directory entry must be copied into the first
; 33 bytes starting at the disk transfer address.
学习啦在线学习网 MOV SI,BX
LES DI,DWORD PTR [DMAADD]
MOV AX,00FFH
CMP AL,[EXTFCB]
JNZ NORMFCB
STOSW
INC AL
STOSW
STOSW
MOV AL,[ATTRIB]
STOSB
NORMFCB:
MOV AL,[THISDRV]
INC AL
STOSB ;Set drive number
MOV CX,16
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:
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
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
SRCHDEV:
MOV ES:[DI.FILDIRENT],BX
学习啦在线学习网 LES DI,DWORD PTR [DMAADD]
学习啦在线学习网 XOR AX,AX
学习啦在线学习网 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
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
学习啦在线学习网 CALL MOVNAME
学习啦在线学习网 MOV DI,DX
JC NEAR PTR KILLSRCH1
学习啦在线学习网 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
JS NEAR PTR KILLSRCH1
PUSH DX
PUSH DS
PUSH CS
POP DS
MOV [LASTENT],AX
学习啦在线学习网 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
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
JS DEVSIZ
INC SI
INC SI ;Point to length field
MOV AX,[SI+2] ;Get high word of size
DIV CX
学习啦在线学习网 PUSH AX ;Save high part of result
学习啦在线学习网 LODSW ;Get low word of size
DIV CX
学习啦在线学习网 OR DX,DX ;Check for zero remainder
POP DX
JZ DEVSIZ
INC AX ;Round up for partial record
学习啦在线学习网 JNZ DEVSIZ ;Propagate carry?
INC DX
DEVSIZ:
STOSW
MOV AX,DX
STOSB
MOV AL,0
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
学习啦在线学习网 MOV CS:[DMAADD+2],DS
RET
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
学习啦在线学习网 JC NOSUCHDRV
学习啦在线学习网 CALL FATREAD
学习啦在线学习网 MOV BX,[BP.FAT]
学习啦在线学习网 MOV AL,[BP.CLUSMSK]
INC AL
学习啦在线学习网 MOV DX,[BP.MAXCLUS]
DEC DX
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
MOV [SI.DSSAVE],CS
RET
学习啦在线学习网 GETDSKPT: ;System call 31
PUSH CS
POP DS
学习啦在线学习网 MOV AL,[CURDRV]
学习啦在线学习网 MOV [THISDRV],AL
CALL FATREAD
LDS SI,DWORD PTR [SPSAVE]
MOV [SI.BXSAVE],BP
MOV [SI.DSSAVE],CS
RET
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
XCHG AL,[DIRTYBUF]
OR AL,AL
学习啦在线学习网 JZ NOBUF
学习啦在线学习网 MOV BP,[BUFDRVBP]
MOV DX,[BUFSECNO]
MOV BX,[BUFFER]
MOV CX,1
学习啦在线学习网 CALL DWRITE
NOBUF:
学习啦在线学习网 MOV CL,[NUMIO]
MOV CH,0
MOV BP,[DRVTAB]
WRTFAT:
PUSH CX
CALL CHKFATWRT
POP CX
ADD BP,DPBSIZ
LOOP WRTFAT
RET
GETDRV: ;System call 25
学习啦在线学习网 MOV AL,CS:[CURDRV]
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
JAE RET15
学习啦在线学习网 MOV [DI+36],DH ;Set 4th byte only if record size < 64
RET16: RET
SELDSK: ;System call 14
学习啦在线学习网 MOV AL,CS:[NUMDRV]
CMP DL,AL
JNB RET17
MOV CS:[CURDRV],DL
RET17: RET
BUFIN: ;System call 10
学习啦在线学习网 MOV AX,CS
学习啦在线学习网 MOV ES,AX
MOV SI,DX
学习啦在线学习网 MOV CH,0
LODSW
OR AL,AL
JZ RET17
学习啦在线学习网 MOV BL,AH
MOV BH,CH
CMP AL,BL
学习啦在线学习网 JBE NOEDIT
CMP BYTE PTR [BX+SI],0DH
JZ EDITON
NOEDIT:
MOV BL,CH
EDITON:
学习啦在线学习网 MOV DL,AL
DEC DX
NEWLIN:
学习啦在线学习网 MOV AL,CS:[CARPOS]
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
学习啦在线学习网 JZ GETCH
CMP AL,CS:ESCCHAR
JZ ESC
CMP AL,7FH
学习啦在线学习网 JZ BACKSP
CMP AL,8
学习啦在线学习网 JZ BACKSP
CMP AL,13
JZ ENDLIN
CMP AL,10
JZ PHYCRLF
CMP AL,CANCEL
学习啦在线学习网 JZ KILNEW
SAVCH:
学习啦在线学习网 CMP DH,DL
JAE BUFFUL
STOSB
INC DH
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
学习啦在线学习网 JMP SHORT GETCH
ESC:
CALL IN
学习啦在线学习网 MOV CL,ESCTABLEN
PUSH DI
MOV DI,OFFSET DOSGROUP:ESCTAB
REPNE SCASB
POP DI
学习啦在线学习网 SHL CX,1
学习啦在线学习网 MOV BP,CX
JMP [BP+OFFSET DOSGROUP:ESCFUNC]
ENDLIN:
STOSB
CALL OUT
POP DI
MOV [DI-1],DH
INC DH
COPYNEW:
MOV BP,ES
学习啦在线学习网 MOV BX,DS
MOV ES,BX
学习啦在线学习网 MOV DS,BP
学习啦在线学习网 MOV SI,OFFSET DOSGROUP:INBUF
MOV CL,DH
REP MOVSB
RET
CRLF:
学习啦在线学习网 MOV AL,13
CALL OUT
学习啦在线学习网 MOV AL,10
JMP OUT
学习啦在线学习网 PHYCRLF:
CALL CRLF
JMP SHORT GETCH
KILNEW:
MOV AL,"\"
CALL OUT
POP SI
PUTNEW:
学习啦在线学习网 CALL CRLF
学习啦在线学习网 MOV AL,CS:[STARTPOS]
CALL TAB
学习啦在线学习网 JMP NEWLIN
BACKSP:
OR DH,DH
学习啦在线学习网 JZ OLDBAK
CALL BACKUP
MOV AL,ES:[DI]
学习啦在线学习网 CMP AL," "
JAE OLDBAK
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
学习啦在线学习网 OR BH,BH
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
学习啦在线学习网 CMP ES:BYTE PTR [DI+1],9
JZ HAVTAB
DEC BL
CHKCNT:
学习啦在线学习网 LOOP FNDPOS
FIGTAB:
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
JZ OLDBAK
TABBAK:
学习啦在线学习网 CALL BACKMES
LOOP TABBAK
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
JMP SHORT COPYEACH
COPYSTR:
学习啦在线学习网 CALL FINDOLD
JMP SHORT COPYEACH
COPYONE:
学习啦在线学习网 MOV CL,1
学习啦在线学习网 COPYEACH:
学习啦在线学习网 MOV AH,0
学习啦在线学习网 CMP DH,DL
学习啦在线学习网 JZ GETCH2
CMP BH,BL
JZ GETCH2
LODSB
STOSB
学习啦在线学习网 CALL BUFOUT
INC BH
INC DH
LOOP COPYEACH
GETCH2:
JMP GETCH
SKIPONE:
学习啦在线学习网 CMP BH,BL
JZ GETCH2
INC BH
INC SI
JMP GETCH
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
学习啦在线学习网 MOV CL,BL
学习啦在线学习网 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
MOV DI,SI
INC DI
REPNE SCASB
POP DI
POP ES
学习啦在线学习网 JNZ NOTFND
NOT CL
学习啦在线学习网 ADD CL,BL
SUB CL,BH
RET30: RET
NOTFND:
POP BP
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
学习啦在线学习网 JMP PUTNEW
学习啦在线学习网 ENTERINS:
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
ESCFUNC DW GETCH
DW TWOESC
IF NOT TOGLINS
DW EXITINS
ENDIF
DW ENTERINS
DW BACKSP
DW REEDIT
DW KILNEW
DW COPYLIN
DW SKIPSTR
学习啦在线学习网 DW COPYSTR
DW SKIPONE
DW COPYONE
IF IBM
学习啦在线学习网 DW COPYONE
DW CTRLZ
CTRLZ:
学习啦在线学习网 MOV AL,"Z"-"@"
JMP SAVCH
ENDIF
BUFOUT:
CMP AL," "
JAE OUT
CMP AL,9
JZ OUT
PUSH AX
学习啦在线学习网 MOV AL,"^"
学习啦在线学习网 CALL OUT
POP AX
OR AL,40H
学习啦在线学习网 JMP SHORT OUT
NOSTOP:
CMP AL,"P"-"@"
JZ INCHK
IF NOT TOGLPRN
学习啦在线学习网 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
JB CTRLOUT
学习啦在线学习网 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
CALL FAR PTR BIOSPRINT
学习啦在线学习网 RET18: RET
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
CMP AL,'P'-'@'
学习啦在线学习网 JZ PRINTON
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 PRINTOFF
ENDIF
学习啦在线学习网 CMP AL,'C'-'@'
学习啦在线学习网 JNZ RET18
学习啦在线学习网 ; Ctrl-C handler.
学习啦在线学习网 ; "^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
; 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
学习啦在线学习网 ; 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
学习啦在线学习网 CLI ;Prepare to play with stack
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
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
NOT CS:BYTE PTR [PFLAG]
RET
ENDIF
学习啦在线学习网 IF NOT TOGLPRN
学习啦在线学习网 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
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
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:
学习啦在线学习网 MOV CS:BYTE PTR [CARPOS],0
OUTCHJ: JMP OUTCH
BACKPOS:
学习啦在线学习网 DEC CS:BYTE PTR [CARPOS]
学习啦在线学习网 JMP OUTCH
学习啦在线学习网 CONSTAT: ;System call 11
学习啦在线学习网 CALL STATCHK
MOV AL,0
学习啦在线学习网 JZ RET19
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
学习啦在线学习网 IN: ;System call 8
学习啦在线学习网 CALL INCHK
JZ IN
学习啦在线学习网 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
CMP AL,-1
学习啦在线学习网 JNZ RAWOUT
学习啦在线学习网 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:
学习啦在线学习网 AND BYTE PTR [SI.FSAVE],0FFH-40H ;Reset user's zero flag
RAWINP: ;System call 7
学习啦在线学习网 CALL FAR PTR BIOSIN
RET
RAWOUT:
CALL FAR PTR BIOSOUT
RET
LIST: ;System call 5
MOV AL,DL
学习啦在线学习网 LISTOUT:
PUSH AX
学习啦在线学习网 CALL STATCHK
POP AX
学习啦在线学习网 CALL FAR PTR BIOSPRINT
RET20: RET
学习啦在线学习网 PRTBUF: ;System call 9
MOV SI,DX
OUTSTR:
LODSB
CMP AL,"$"
JZ RET20
CALL OUT
JMP SHORT OUTSTR
学习啦在线学习网 OUTMES: ;String output for internal messages
学习啦在线学习网 LODS CS:BYTE PTR [SI]
CMP AL,"$"
JZ RET20
CALL OUT
学习啦在线学习网 JMP SHORT OUTMES
学习啦在线学习网 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?
学习啦在线学习网 JNZ DEFDRV
学习啦在线学习网 MOV BYTE PTR ES:[DI],0 ;No - use default drive
DEFDRV:
INC DI
MOV CX,8
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," "
学习啦在线学习网 JZ FILLB ;If not, go fill with blanks
ADD DI,CX
XOR CX,CX ;Don't fill any
FILLB:
REP STOSB
学习啦在线学习网 MOV CL,3
学习啦在线学习网 TEST BL,EXTBIT ;Use current extension as default
JZ FILLB2
ADD DI,CX
XOR CX,CX
FILLB2:
学习啦在线学习网 REP STOSB
学习啦在线学习网 XCHG AX,CX ;Put zero in AX
STOSW
STOSW ;Initialize two words after to zero
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
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
学习啦在线学习网 CMP BYTE PTR[SI],":" ;Check for potential drive specifier
JNZ NODRV
INC SI ;Skip over colon
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
CMP AL,CS:[NUMDRV]
JBE HAVDRV
BADDRV:
学习啦在线学习网 MOV DL,-1
HAVDRV:
学习啦在线学习网 STOSB ;Put drive specifier in first byte
INC SI
学习啦在线学习网 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],"."
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
MOV CX,3 ;Get 3-letter extension
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
JCXZ MUSTGETWORD
DEC CX
学习啦在线学习网 CMP AL,"*" ;Check for ambiguous file specifier
JNZ NOSTAR
MOV AL,"?"
学习啦在线学习网 REP STOSB
NOSTAR:
STOSB
CMP AL,"?"
JNZ MUSTGETWORD
OR DL,1 ;Flag ambiguous file name
学习啦在线学习网 JMP MUSTGETWORD
FILLNAM:
学习啦在线学习网 MOV AL," "
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.
;ZF set if a delimiter, CY set if a control character (other than TAB).
LODSB
学习啦在线学习网 AND AL,7FH
CMP AL,"a"
JB CHK
CMP AL,"z"
JA CHK
SUB AL,20H ;Convert to upper case
CHK:
学习啦在线学习网 CMP AL,"."
学习啦在线学习网 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
CMP AL,"]"
学习啦在线学习网 JZ RET21
IF IBM
DELIM:
ENDIF
学习啦在线学习网 CMP AL,":" ;Allow ":" as separator in IBM version
学习啦在线学习网 JZ RET21
IF NOT IBM
DELIM:
ENDIF
学习啦在线学习网 CMP AL,"+"
学习啦在线学习网 JZ RET101
CMP AL,"="
JZ RET101
学习啦在线学习网 CMP AL,";"
JZ RET101
学习啦在线学习网 CMP AL,","
JZ RET101
SPCHK:
CMP AL,9 ;Filter out tabs too
学习啦在线学习网 JZ RET101
学习啦在线学习网 ;WARNING! " " MUST be the last compare
CMP AL," "
学习啦在线学习网 RET101: RET
学习啦在线学习网 SETVECT: ; Interrupt call 37
学习啦在线学习网 XOR BX,BX
MOV ES,BX
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
MOV ES,DX
学习啦在线学习网 LDS SI,CS:DWORD PTR [SPSAVE]
学习啦在线学习网 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
学习啦在线学习网 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:
学习啦在线学习网 ; Inputs:
; 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
; 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
学习啦在线学习网 ; [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.
学习啦在线学习网 XOR CX,CX
MOV DS,CX
MOV ES,DX
MOV SI,EXIT
学习啦在线学习网 MOV DI,SAVEXIT
MOVSW
MOVSW
MOVSW
MOVSW
MOVSW
MOVSW
MOV ES:[2],AX
学习啦在线学习网 SUB AX,DX
CMP AX,MAXDIF
学习啦在线学习网 JBE HAVDIF
学习啦在线学习网 MOV AX,MAXDIF
HAVDIF:
学习啦在线学习网 MOV BX,ENTRYPOINTSEG
SUB BX,AX
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
SHL AX,1
学习啦在线学习网 MOV DS,DX
MOV DS:[6],AX
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
SHL CL,1 ;Minutes to left part of byte
学习啦在线学习网 SHL CL,1
学习啦在线学习网 SHL CX,1 ;Push hours and minutes to left end
学习啦在线学习网 SHL CX,1
学习啦在线学习网 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
SHL AL,1
SHL AL,1
学习啦在线学习网 SHL AL,1
SHL AX,1
OR AL,[DAY]
RET22: RET
FOURYEARS EQU 3*365+366
READTIME:
学习啦在线学习网 ;Gets time in CX:DX. Figures new date if it has changed.
学习啦在线学习网 ;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
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
学习啦在线学习网 XOR DX,DX
MOV CX,FOURYEARS ;Number of days in 4 years
DIV CX ;Compute number of 4-year units
SHL AX,1
学习啦在线学习网 SHL AX,1
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
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?
ADD DX,200
SK:
CALL SETYEAR
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
MOV [MONTH],CL
学习啦在线学习网 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
RET23: RET
DSLIDE:
MOV AH,0
DSLIDE1:
学习啦在线学习网 LODSB ;Get count of days
学习啦在线学习网 CMP DX,AX ;See if it will fit
JB RET23 ;If not, done
SUB DX,AX
INC CX ;Count one more month/year
JMP SHORT DSLIDE1
SETYEAR:
学习啦在线学习网 ;Set year with value in CX. Adjust length of February for this year.
MOV BYTE PTR [YEAR],CL
CHKYR:
TEST CL,3 ;Check for leap year
学习啦在线学习网 MOV AL,28
学习啦在线学习网 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
YRTAB DB 200,166 ;Leap year
DB 200,165
DB 200,165
学习啦在线学习网 DB 200,165
;Days of each month
MONTAB DB 31 ;January
学习啦在线学习网 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
DB 30 ;June
DB 31 ;July
DB 31 ;August
学习啦在线学习网 DB 30 ;September
DB 31 ;October
DB 30 ;November
学习啦在线学习网 DB 31 ;December
学习啦在线学习网 GETDATE: ;Function call 42
PUSH CS
POP DS
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
学习啦在线学习网 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
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
CMP CX,119 ;Year must be less than 2100
JA RET24
学习啦在线学习网 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
CALL CHKYR ;Set Feb. up for new year
MOV AL,DH
MOV BX,OFFSET DOSGROUP:MONTAB-1
XLAT ;Look up days in month
学习啦在线学习网 CMP AL,DL
MOV AL,-1 ;Restore error flag, just in case
JB RET24 ;Error if too many days
CALL SETYEAR
MOV WORD PTR [DAY],DX ;Set both day and month
SHR CX,1
学习啦在线学习网 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]
AND CL,3
MOV SI,OFFSET DOSGROUP:YRTAB
MOV DX,AX
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
MOV SI,OFFSET DOSGROUP:MONTAB
学习啦在线学习网 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
XCHG AX,DX ;Get day count in AX
学习啦在线学习网 MOV [DAYCNT],AX
学习啦在线学习网 CALL FAR PTR BIOSSETDATE
WKDAY:
学习啦在线学习网 MOV AX,[DAYCNT]
XOR DX,DX
MOV CX,7
INC AX
学习啦在线学习网 INC AX ;First day was Tuesday
学习啦在线学习网 DIV CX ;Compute day of week
MOV [WEEKDAY],DL
XOR AL,AL ;Flag OK
学习啦在线学习网 RET25: RET
DSUM:
学习啦在线学习网 MOV AH,0
JCXZ RET25
DSUM1:
LODSB
ADD DX,AX
学习啦在线学习网 LOOP DSUM1
RET
学习啦在线学习网 GETTIME: ;Function call 44
PUSH CS
POP DS
学习啦在线学习网 CALL READTIME
学习啦在线学习网 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
学习啦在线学习网 XOR AL,AL
学习啦在线学习网 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
学习啦在线学习网 CMP CH,24 ;Check hours
JAE RET26
CMP CL,60 ;Check minutes
JAE RET26
CMP DH,60 ;Check seconds
JAE RET26
学习啦在线学习网 CMP DL,100 ;Check 1/100's
学习啦在线学习网 JAE RET26
学习啦在线学习网 CALL FAR PTR BIOSSETTIME
XOR AL,AL
RET
学习啦在线学习网 ; Default handler for division overflow trap
DIVOV:
PUSH SI
PUSH AX
MOV SI,OFFSET DOSGROUP:DIVMES
CALL OUTMES
POP AX
POP SI
学习啦在线学习网 INT 23H ;Use Ctrl-C abort on divide overflow
IRET
CODSIZ EQU $-CODSTRT ;Size of code segment
CODE ENDS
;***** DATA AREA *****
学习啦在线学习网 CONSTANTS SEGMENT BYTE
ORG 0
CONSTRT EQU $ ;Start of constants segment
IONAME:
IF NOT IBM
学习啦在线学习网 DB "PRN ","LST ","NUL ","AUX ","CON "
ENDIF
IF IBM
DB "COM1","PRN ","LPT1","NUL ","AUX ","CON "
ENDIF
DIVMES DB 13,10,"Divide overflow",13,10,"$"
CARPOS DB 0
STARTPOS DB 0
PFLAG DB 0
DIRTYDIR DB 0 ;Dirty buffer flag
学习啦在线学习网 NUMDRV DB 0 ;Number of drives
学习啦在线学习网 NUMIO DB ? ;Number of disk tables
VERFLG DB 0 ;Initialize with verify off
学习啦在线学习网 CONTPOS DW 0
DMAADD DW 80H ;User's disk transfer address (disp/seg)
DW ?
学习啦在线学习网 ENDMEM DW ?
MAXSEC DW 0
BUFFER DW ?
BUFSECNO DW 0
BUFDRVNO DB -1
DIRTYBUF DB 0
BUFDRVBP DW ?
学习啦在线学习网 DIRBUFID DW -1
学习啦在线学习网 DAY DB 0
MONTH DB 0
YEAR DW 0
DAYCNT DW -1
WEEKDAY DB 0
CURDRV DB 0 ;Default to drive A
学习啦在线学习网 DRVTAB DW 0 ;Address of start of DPBs
DOSLEN EQU CODSIZ+($-CONSTRT) ;Size of CODE + CONSTANTS segments
CONSTANTS ENDS
学习啦在线学习网 DATA SEGMENT WORD
; Init code overlaps with data area below
ORG 0
学习啦在线学习网 INBUF DB 128 DUP (?)
CONBUF DB 131 DUP (?) ;The rest of INBUF and console buffer
LASTENT DW ?
学习啦在线学习网 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 (?)
NAME3 DB 12 DUP (?)
学习啦在线学习网 EXTFCB DB ?
学习啦在线学习网 ;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 ?
学习啦在线学习网 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
学习啦在线学习网 READOP DB ?
THISDRV DB ?
EVEN
FCB DW ? ;Address of user FCB
学习啦在线学习网 NEXTADD DW ?
学习啦在线学习网 RECPOS DB 4 DUP (?)
RECCNT DW ?
学习啦在线学习网 LASTPOS DW ?
CLUSNUM DW ?
学习啦在线学习网 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 ?
学习啦在线学习网 DB 80H DUP (?) ;Stack space
IOSTACK LABEL BYTE
学习啦在线学习网 DB 80H DUP (?)
学习啦在线学习网 DSKSTACK LABEL BYTE
IF DSKTEST
NSS DW ?
学习啦在线学习网 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
MOV ES:[DMAADD+2],DX
学习啦在线学习网 MOV SI,[DRVTAB] ;Address of first DPB
学习啦在线学习网 MOV AL,-1
MOV CL,[NUMIO] ;Number of DPBs
FLGFAT:
MOV DI,ES:[SI.FAT] ;get pointer to FAT
学习啦在线学习网 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
MOV AX,[ENDMEM]
学习啦在线学习网 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
学习啦在线学习网 MOV ES:[ENDMEM],DX
学习啦在线学习网 LODSB ;Get no. of drives & no. of I/O drivers
学习啦在线学习网 MOV ES:[NUMIO],AL
MOV DI,OFFSET DOSGROUP:MEMSTRT
PERDRV:
MOV BP,DI
学习啦在线学习网 MOV AL,ES:[DRVCNT]
STOSB ;DEVNUM
LODSB ;Physical unit no.
STOSB ;DRVNUM
CMP AL,15
JA BADINIT
CBW ;Index into FAT size table
SHL AX,1
学习啦在线学习网 ADD AX,OFFSET DOSGROUP:FATSIZTAB
XCHG BX,AX
学习啦在线学习网 LODSW ;Pointer to DPT
PUSH SI
MOV SI,AX
LODSW
STOSW ;SECSIZ
MOV DX,AX
CMP AX,ES:[MAXSEC]
JBE NOTMAX
学习啦在线学习网 MOV ES:[MAXSEC],AX
NOTMAX:
LODSB
DEC AL
学习啦在线学习网 STOSB ;CLUSMSK
JZ HAVSHFT
CBW
FIGSHFT:
INC AH
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)
学习啦在线学习网 MOVSB ;FATCNT
学习啦在线学习网 MOVSW ;MAXENT
MOV AX,DX ;SECSIZ again
MOV CL,5
学习啦在线学习网 SHR AX,CL
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)
FNDFATSIZ:
学习啦在线学习网 MOV AL,1
MOV DX,1
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
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
学习啦在线学习网 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]
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
MOV ES:[BP.MAXCLUS],CX
学习啦在线学习网 MOV AX,BX ;Pointer into FAT size table
STOSW ;Allocate space for FAT pointer
MOV AL,ES:[BP.FATSIZ]
XOR AH,AH
学习啦在线学习网 MUL ES:[BP.SECSIZ]
CMP AX,ES:[BX] ;Bigger than already allocated
学习啦在线学习网 JBE SMFAT
MOV ES:[BX],AX
SMFAT:
POP SI ;Restore pointer to init. table
学习啦在线学习网 MOV AL,ES:[DRVCNT]
INC AL
MOV ES:[DRVCNT],AL
CMP AL,ES:[NUMIO]
学习啦在线学习网 JAE CONTINIT
学习啦在线学习网 JMP PERDRV
BADINITJ:
JMP BADINIT
学习啦在线学习网 CONTINIT:
PUSH CS
POP DS
;Calculate true address of buffers, FATs, free space
MOV BP,[MAXSEC]
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
MOV [DRVTAB],AX ;Start of DPBs
学习啦在线学习网 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
MOV SI,OFFSET DOSGROUP:FATSIZTAB
学习啦在线学习网 MOV DI,SI
MOV CX,16
学习啦在线学习网 TOTFATSIZ:
INC BP ;Add one for Dirty byte
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
学习啦在线学习网 CMP AX,BP ;If size was zero done
学习啦在线学习网 LOOPNZ TOTFATSIZ
MOV AL,15
SUB AL,CL ;Compute number of FATs used
学习啦在线学习网 MOV [NUMDRV],AL
XOR AX,AX ;Set zero flag
REPZ SCASW ;Make sure all other entries are zero
学习啦在线学习网 JNZ BADINITJ
学习啦在线学习网 ADD BP,15 ;True start of free space
学习啦在线学习网 MOV CL,4
学习啦在线学习网 SHR BP,CL ;First free segment
学习啦在线学习网 MOV DX,CS
学习啦在线学习网 ADD DX,BP
MOV BX,0FH
学习啦在线学习网 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
学习啦在线学习网 MEMSCAN:
INC CX
JZ SETEND
MOV DS,CX
学习啦在线学习网 MOV AL,[BX]
NOT AL
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
MOV DX,CS ;Program segment
ENDIF
IF NOT HIGHMEM
MOV BP,CS
ENDIF
学习啦在线学习网 ; 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
学习啦在线学习网 MOV ES,BP
学习啦在线学习网 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
MOV ES,AX
MOV DI,INTBASE
MOV AX,OFFSET DOSGROUP:QUIT
STOSW ;Set abort address--displacement
MOV AX,BP
学习啦在线学习网 MOV BYTE PTR DS:[ENTRYPOINT],LONGJUMP
学习啦在线学习网 MOV WORD PTR DS:[ENTRYPOINT+1],OFFSET DOSGROUP:ENTRY
MOV WORD PTR DS:[ENTRYPOINT+3],AX
学习啦在线学习网 MOV WORD PTR DS:[0],OFFSET DOSGROUP:DIVOV ;Set default divide trap address
MOV DS:[2],AX
学习啦在线学习网 MOV CX,9
REP STOSW ;Set 5 segments (skip 2 between each)
MOV WORD PTR DS:[INTBASE+4],OFFSET DOSGROUP:COMMAND
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
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
学习啦在线学习网 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
学习啦在线学习网 XCHG AX,CX
MOV DI,OFFSET DOSGROUP:MEMSTRT.FAT
FATPOINT:
MOV SI,WORD PTR [DI] ;Get address within FAT address table
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
学习啦在线学习网 JBE MOVJMP ;Are we moving to higher or lower memory?
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:
MOV ES,BP
JMP MOVFAT
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]
学习啦在线学习网 ADD AX,ES:[BP.DIRSEC]
FIGMAX:
;AX has equivalent of FIRREC
学习啦在线学习网 SUB AX,ES:[BP.DSKSIZ]
NEG AX
MOV CL,ES:[BP.CLUSSHFT]
学习啦在线学习网 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
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:
学习啦在线学习网 DB 13,10,"INIT TABLE BAD",13,10,"$"
FATSIZTAB:
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
学习啦在线学习网 ADJFAC EQU DIRBUF-MEMSTRT
学习啦在线学习网 DATA ENDS
END
看了“DOS操作系统源码相关资料知识”还想看：
5.操作系统发展简史