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Digital-Research-Source-Code/CPM OPERATING SYSTEMS/CPM 86/CONCURRENT/CCPM-86 2.0 SOURCE/loader/lbdos.a86
Sepp J Morris 31738079c4 Upload 
Digital Research
2020-11-06 18:50:37 +01:00

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title 'CCP/M-86 Bdos Loader'
;*****************************************************************
;*****************************************************************
;** **
;** B a s i c D i s k O p e r a t i n g S y s t e m **
;** I n t e r f a c e M o d u l e **
;** **
;*****************************************************************
;*****************************************************************
;
; Copyright (c) 1983
; Digital Research
; Box 579, Pacific Grove
; California
;
; January 1983
;
;*****************************************************
;
bdosoffset equ 0000h ; offset of BDOS-86
ldroffset equ 0906h ; offset of CLDCCPM
biosoffset equ 0900h ; offset of BIOS-86
;
;******************* BDOS symbols: *******************
;
;
true equ 0ffffh
false equ not true
;
; Special 8086 symbols:
;
b equ byte ptr 0
w equ word ptr 0
;
;*****************************************************
;
; BIOS Function numbers
;
;io_const equ 0 ;console status function
;io_conin equ 1 ;console input function
;io_conout equ 2 ;console output function
;io_listst equ 3 ;list status function
;io_list equ 4 ;list output function
;io_auxin equ 5 ;aux input function
;io_auxout equ 6 ;aux output function
;io_ equ 7
;io_ equ 8
io_seldsk equ 9 ;select disk function
io_read equ 10 ;read disk function
;io_write equ 11 ;write disk function
;io_flush equ 12 ;flush buffers function
;io_ equ 13
;
; literal constants
;
enddir EQU 0ffffh ;end of directory
;
; file control block (fcb) constants
;
fcblen EQU 32 ;fcb length
;empty EQU 0e5h ;empty directory entry
recsiz EQU 128 ;record size
dirrec EQU recsiz/fcblen ;directory elts / record
dskshf EQU 2 ;log2(dirrec)
dskmsk EQU dirrec-1
fcbshf EQU 5 ;log2(fcblen)
maxext EQU 31 ;largest extent number
maxmod EQU 63 ;largest module number
namlen EQU 15 ;name length
;lstfcb EQU fcblen-1
;drv EQU 0 ;drive field
;f1 EQU 1 ;file name byte 1 to 8
;f2 EQU 2
;f3 EQU 3
;f4 EQU 4
;f5 EQU 5
;f6 EQU 6
f7 EQU 7
;f8 EQU 8
;
; reserved file indicators
;
;rofile EQU 9 ;t1' -> read/only file
;sysfil EQU 10 ;t2' -> system file
;ARCHIV EQU 11 ;t3' -> FILE HAS BEEN ARCHIVED
extnum EQU 12 ;extent number field
chksum EQU 13 ;unfilled bytes field
modnum EQU 14 ;data module number
reccnt EQU 15 ;record count field
dskmap EQU 16 ;disk map field
nxtrec EQU fcblen
;ranrec EQU nxtrec+1 ;random record field (3 bytes)
;
;
; interrupt control indicators
;
interruptbit equ 200h ; bit 9 of flag word
;
;
;**************** end of BDOS symbols ****************
;***************** BDOS entry module *****************
;
; Perform branching, error handling and special
; 8086 handling.
;
;
cseg
org ldroffset
ldr_entry:
;
org bdosoffset
os_init:
jmp user_init
os_entry:
jmp user_entry
sysdat dw 0 ;system data segment
;=========
user_init:
;=========
mov ax,cs
mov ds,ax
mov es,ax
mov ss,ax
mov sp,offset bdosstack
mov bioscs,cs
callf dword ptr iosentry
mov biosco,bios_offset+3 ;set io call to entry
xor ax,ax
push ds! mov ds,ax
mov word ptr .0380h,offset os_entry
mov .0382h,cs
pop ds
jmp ldr_entry
;
;-----------------------------------------------------
;==========
user_entry:
;==========
; User Entry Point - enter here from a INT 224
;
; REGISTER USAGE
; ENTRY EXIT
; ----- ----
; CL - Function Code AX - Copy of BX
; DX - Param BX - Return
; DS - Seg Addr CX - Error Code
; ES - Segment Return
;
; DS,SI,DI,BP preserved through call
;
; contents of users stack
; Flags
; CS
; IP <- u_stack_ss,_sp
; DS = Sysdat Segment
; u_wrkseg = user's DS
; u_retseg = user's ES
cld ! mov ax,ds ;AX = user's DS
push cs ! pop ds
mov u_retseg,es ;save user's ES
mov u_wrkseg,ax ;wipe out earlier work seg
mov bx,sp ;enable interrupt if it was on
test ss:word ptr 4[bx],interruptbit
jz bdose1
sti
bdose1:
push ds! pop es
push si! push di! push bp
call func ;chk netwrk, returns BX, ES, CX
pop bp! pop di! pop si ;setup user's environment and return
mov es,u_retseg ;restore user's ES
mov ds,u_wrkseg ;DS = user's entry DS
mov ax,bx ;parameter return BX = AX
iret ;back to user ...
func:
;----
cmp cl,14! jne fn1
mov si,offset bdofunc+0
jmp bdo_entry
fn1: cmp cl,15! jne fn2
mov si,offset bdofunc+3
jmp bdo_entry
fn2: cmp cl,20! jne fn3
mov si,offset bdofunc+6
jmp bdo_entry
fn3: cmp cl,26! je func26
cmp cl,32! je func32
cmp cl,44! je func44
cmp cl,51! je func51
badfunc:
mov bx,0ffffh ;return ffff for illegal function
ret
;
func26: ;set the subsequent dma address to info
;======
mov dmaad,dx ;dmaad = info
ret
func32: ;set user code
;======
mov al,dl
cmp al,0ffh
jnz setusrcode
mov bl,p_user ;interrogate user code instead
ret
setusrcode:
and al,0fh
mov p_user,al
ret ;jmp goback
func44: ;set multi-sector count
;======
mov al,dl
xor bx,bx
or al,al
jz return_not_ok
cmp al,129
jnb return_not_ok
mov u_mult_cnt,al
ret
return_not_ok:
dec bx ;BX = 0ffffh
ret
func51: ;set segment base for disk I/O
;======
mov dmabase,dx
ret
;
;*************** end BDOS entry module ***************
;**************** BDOS Disk Functions ****************
;*****************************************************
;*
;* bdos function table
;*
;*****************************************************
; structure of entry in functab
btab_addr equ word ptr 0
btab_flag equ byte ptr (btab_addr + word)
bf_getmx equ 001h ;get mxdisk queue
bf_cshell equ 002h ;conditional shell function
; bdos function table
bdofunc equ offset $
dw func14 ! db 0001b ; fxi14 equ 01h ;select disk
dw func15 ! db 0001b ; fxi15 equ 02h ;open file
dw func20 ! db 0011b ; fxi20 equ 07h ;read sequential
;========
bdoentry: ; bdos module entry point
;========
; entry: SI = offset of bdos functab entry
; DX = argument
; DS = ES = system data area
; exit: BX = return code
mov ax,word ptr p_dsk
mov word ptr seldsk,ax ;set default disk and user code
mov cx,zerolength ! xor ax,ax ;zero local variables
mov di,offset fcbdsk
rep stosb
mov info,dx ;info=dx
cmp mult_cnt,1 ! je noshell ;if mult_cnt <> 1 and
test cs:btabflag[si],bf_cshell ; func uses mult_cnt then
jnz shell ; use bdos multi sector shell
noshell:
call call_bdos
retmon:
mov bx,aret
ret
;
shell:
;-----
; entry: SI = offset of functab entry
mov shell_si,si
mov ax,dmaad! mov shell_dma,ax
mov ah,cs:btabflag[si]
call parsave33
mov shell_flag,true
mov al,mult_cnt
mult_io1:
MOV MULT_NUM,AL
push ax
mov si,shell_si
mov dx,info
call call_bdos
mov bl,byte ptr aret
or bl,bl
jz no_shell_err
mov bh,mult_cnt
pop ax
sub bh,al ;BH = # of successfull records
jmps shell03
no_shell_err:
add dmaad,80h
pop ax! dec al
jnz mult_io1
xor bx,bx
shell03:
mov aret,bx
mov ax,shell_dma! mov dmaad,ax
mov shell_flag,false
call parunsave
jmp retmon
;
call_bdos:
;---------
; entry: DX = argument
; SI = offset of bdos functab entry
call setdata ;ready to go to the function
mov savesp,sp
call cs:btab_addr[si]
bdos_return:
cmp resel,0
je retmon5
mov al,fcbdsk
mov info_fcb,al
retmon5:
cmp parcopfl,true
jne retmon6
call parunsave ;copy local vars to uda
retmon6:
ret
;
parsave33: ;copy 33 byte length FCB
;---------
mov cl,33
;jmps parsave
;
parsave: ;copy FCB from user segment to bdos segment
;-------
; entry: CL = length of FCB to save
test shell_flag,true
jnz parret
mov parcopfl,true
mov parlg,cl
xor ch,ch
mov si,info
mov di,offset info_fcb
push ds
mov ds,parametersegment
rep movsb
pop ds
parret:
ret
;
parunsave: ;copy local FCB to user segment
;---------
test shell_flag,true
jnz parret
mov cl,parlg
xor ch,ch
mov si,offset info_fcb
mov di,info
push es
mov es,parametersegment
rep movsb
pop es
ret
setlret1:
mov al,1
staret:
mov lret,al
ret
;these functions added for mpm interface
;*****************************************************
;*
;* bdos - xios interface
;*
;*****************************************************
;====== ========================
xiosif: ; xios interface routine
;====== ========================
; entry: AL = function number
; CX = argument 1
; DX = argument 2
; exit: AX = BX = output
push es
callf dword ptr iosentry
cld! pop es
ret
;======== ================================
rwxiosif: ; disk read/write xios interface
;======== ================================
; entry: AL = function number
; exit: AX = BX = output
mov dx,arecord
mov ch,byte ptr arecord+2
mov bl,curdsk
mov bh,1
xchg bh,mult_sec ;BH = multi sector count
; stack on entry to the xios
push bx ; +C | DRV | MCNT |
push track ; +C | TRACK |
push sector ; +8 | SECTOR |
push curdmabase ; +6 | DMA_SEG |
push curdma ; +4 | DMA_OFF |
; +2 | RET_SEG |
; SP+0 | RET_OFF |
callf dword ptr iosentry
add sp,10 ;remove parameters from stack
cld! push ds! pop es
ret
;*****************************************************************
;*****************************************************************
;** **
;** b a s i c d i s k o p e r a t i n g s y s t e m **
;** **
;*****************************************************************
;*****************************************************************
;***************** bdos file system ******************
; error message handlers
pererror: ;report permanent error
;--------
mov ch,1
jmps goerr
selerror: ;report select error
;--------
mov curdsk,0ffh
mov ch,4
goerr:
mov cl,0ffh
mov aret,cx ;set aret
goback:
mov sp,save_sp
jmp bdos_return
; local subroutines for bios interface
;-----------------------------------------------------
move: ;block move data
;----
; entry: CL = length of data to move
; DX = source offset
; BX = destination offset
xor ch,ch
mov si,dx
mov di,bx
rep movsb
ret
selectdisk:
;----------
; select the disk drive given in AL, and fill
; the base addresses curtrka - alloca, then fill
; the values of the disk parameter block
; entry: AL = disk to select
; exit: C flag set if no error
mov cl,al ;current disk# to cl
;lsb of dl = 0 if not yet
mov al,io_seldsk ;logged in
call xiosif ;bx filled by call
;bx = 0000 if error,
or bx,bx ;otherwise disk headers
jz ret4 ;rz - carry flag reset
add bx,8
mov si,bx
MOV di,OFFSET DPBADDR ;dx= source for move, bx=dest
mov cx,addlist ;addlist filled
rep movsb ;now fill the disk
mov si,dpbaddr ;parameter block
mov di,offset sectpt ;bx is destination
mov cx,dpblist
rep movsb ;data filled
mov cl,physhf ;convert # sectors per track
shl sectpt,cl ; from physical to logical
;set single/double map mode
mov al,byte ptr maxall+1 ;largest allocation number
or al,al
jz retselect
;if high order of maxall not
mov al,1 ;zero then use double disk map
retselect:
dec al
mov single,al ;true if single disk map mode
stc ;select disk function ok
ret4:
ret
rdbuff: ;read buffer and check if ok
;------
mov al,io_read
call rwxiosif ;current drive, track,....
diocomp: ;check for disk errors
;-------
; entry: AL = xios return code
or al,al! jz ret4 ;rz
jmp pererror ; no
seek: ;seek the track given by arecord (actual record)
;----
mov ax,arecord ;compute track/sector
xor dx,dx
mov dl,byte ptr arecord+2
div sectpt ;dx=sector, ax=track
add ax,offsetv
MOV TRACK,ax ;save bios/xios track
MOV CL,PHYSHF
SHR dx,CL ;PHY SECTOR = SHR(LOG SECTOR,PHYSHF)
MOV SECTOR,dx ;save bios/xios sector
ret
; utility functions for file access
dmposition: ;compute disk map position for vrecord
;----------
; exit: AL = disk map position of vrecord
mov cl,blkshf ;shift count to CL
mov ch,vrecord ;current virtual record to a
shr ch,cl ;CH = shr(vrecord,blkshf)
; = vrecord/2**(sect/block)
neg cl
add cl,7 ;CL = 7 - blkshf
mov al,extval ;extent value and extmsk
;blkshf = 3,4,5,6,7
;CL = 4,3,2,1,0
;shift is 4,3,2,1,0
shl al,cl ;AL = shl(ext and extmsk,7-blkshf)
add al,ch ;add the previous
;shr(vrecord,blkshf) value
;AL is one of the following
;values, depending upon alloc
;bks blkshf
;1k 3 v/8 + extval * 16
;2k 4 v/16+ extval * 8
;4k 5 v/32+ extval * 4
;8k 6 v/64+ extval * 2
;16k 7 v/128+extval * 1
ret ;with dm$position in a
getdm: ;return disk map value from position given by cx
;-----
; entry: CX = index into disk map
; exit: BX = disk map value at position CX
mov bx,offset info_fcb+dskmap
add bx,cx ;index by asingle byte value
cmp single,0 ;single byte/map entry?
jz getdmd ;get disk map single byte
mov bl,[bx]
xor bh,bh
ret ;with bx=00bb
getdmd:
add bx,cx ;bx=.fcb(dm+1*2)
mov bx,[bx] ;return double precision value
ret
index: ;compute disk block number from current fcb
;-----
; exit: BX = disk map value for vrecord in current fcb
; Z flag set according to value in BX
call dmposition ;0...15 in register al
MOV DMINX,AL
mov cl,al
xor ch,ch
call getdm ;value to bx
mov arecord,bx
or bx,bx
ret
atran: ;compute actual record address, assuming index called
;-----
mov cl,blkshf ;shift count to reg al
mov ax,arecord
xor bh,bh
mov bl,ah
shl ax,cl
shl bx,cl
xchg ax,bx
mov al,vrecord
and al,blkmsk ;masked value in al
mov blkoff,al
or bl,al
mov arecord,bx ;arecord=bx or
;(vrecord and blkmsk)
mov byte ptr arecord+2,ah
ret
getfcb: ;set local variables from currently addressed fcb
;------
mov al,info_fcb+nxtrec
mov vrecord,al ;vrecord=fcb(nxtrec)
cmp info_fcb+reccnt,0
jne getfcb0
call get_dir_ext
mov cl,al
call set_rc
getfcb0:
mov al,info_fcb+reccnt
cmp al,81h! jb getfcb1
mov al,80h
getfcb1:
mov rcount,al ;rcount=fcb(reccnt)
mov al,extmsk ;extent mask to a
and al,info_fcb+extnum ;fcb(extnum) and extmsk
mov extval,al
ret
setfcb: ;place local values back into current fcb
;------
mov al,1
add al,vrecord
mov info_fcb+nxtrec,al ;fcb(nxtrec)=vrecord+seqio
cmp info_fcb+reccnt,80h
jnb ret41 ;dont reset if fcb(rc) > 7fh
mov al,rcount
mov info_fcb+reccnt,al ;fcb(reccnt)=rcount
ret41: ret
getdptra:
;--------
; compute the address of a directory element at
; positon dptr in the buffer
; exit: BX = buffa + dptr
mov bl,dptr
xor bh,bh
add bx,buffa ;bx = buffa + dptr
ret
rddir: ;read the current directory record
;-----
MOV ax,DCNT ;seek the record containing
MOV CL,DSKSHF! SHR ax,CL ; the current dir entry
MOV ARECORD,ax ;ARECORD = SHR(DCNT,DSKSHF)
MOV BYTE PTR ARECORD+2,0
MOV AH,3 ;LOCATE COMMAND
CALL DEBLOCK_DIR
;JMPS SETDATA
setdata: ;set data dma address
;-------
MOV ax,DMABASE
MOV CUR_DMABASE,ax
MOV ax,DMAAD
MOV CURDMA,ax
RET
endofdir: ;check if end of directory (dcnt = 0ffffh)
;--------
; exit: Z flag set if at end of directory
mov bx,offset dcnt
test_ffff:
;---------
cmp w[bx],0ffffh
ret
setenddir: ;set dcnt to the end of directory (dcnt = 0ffffh)
;---------
mov dcnt,enddir
ret
read_dir: ;read next directory entry
;--------
mov dx,dirmax ;in preparation for subtract
mov bx,dcnt
inc bx
mov dcnt,bx ;dcnt=dcnt+1
;continue while dirmax >= dcnt
;(dirmax-dcnt no cy)
sub dx,bx
jb setenddir ;yes, set dcnt to end
;of directory
; not at end of directory, seek next element
;cl=initialization flag
mov al,ldcnt
and al,dskmsk ;low(dcnt) and dskmsk
mov cl,fcbshf ;to multiply by fcb size
shl al,cl
;a = (low(dcnt) and dskmsk)
;shl fcbshf
mov dptr,al ;ready for next dir operation
or al,al
jnz ret71 ;return if not a new record
call rddir ;read the directory record
ret71:
ret
compext: ;compare extent# in al with that in cl
;-------
; entry: AL,CL = extent numbers to compare
; exit: Z flag set if extent numbers match
; BX,CX,DX = preserved
push cx ;save cx's original value
mov ch,extmsk
not ch ;ch has negated form of
;extent mask
and cl,ch ;low bits removed from cl
and al,ch ;low bits removed from al
sub al,cl
and al,maxext ;set flags
pop cx ;restore cx
ret
get_dir_ext:
;-----------
; compute directory extent from fcb
; scan fcb disk map backwards
; upon return dminx = 0 if no blocks are in fcb
; exit: AL = directory extent number
; BX = .fcb(extnum)
mov bx,offset info_fcb+nxtrec ;BX = .fcb(vrecord)
mov dx,1001h ;DH = disk map position (rel to 1)
;DL = no blocks switch
get_de1:
dec dh
dec bx ;decrement disk map ptr
cmp b[bx],0 ;is disk map byte non-zero ?
jne get_de2 ; yes
or dh,dh ; no - continue scan
jnz get_de1
dec dl ;DL = 0 if no blocks found
get_de2:
mov dminx,dl ;dminx = 0 if no blocks in fcb
cmp single,true ;are disk block indexes single byte ?
mov al,dh ;al = block offset in disk map
jz get_de3 ;yes
shr al,1 ;divide block offset by 2
; al = last non-zero block index in fcb (rel to 0)
; compute ext offset from last non-zero block index by
; shifting block index right 7-blkshf
get_de3:
mov cl,7
sub cl,blkshf
shr al,cl ;al = ext offset
mov ah,extmsk ;if ext offset > extmsk then
cmp ah,al ; continue scan
jb get_de1
; dir ext = (fcb ext & (~extmsk) & maxext) | ext offset
mov bx,offset info_fcb+extnum ;bx = .fcb(ext)
mov cl,[bx] ;cl = fcb extent value
not ah ;ah = ~extmsk
and ah,maxext ;ah = ah & maxext
and ah,cl ;ah = ah & fcb extent
or al,ah ;al = dir ext
ret
searchi: ;search initialization
;-------
mov bx,offset info_fcb
mov srcha,bx ;searcha = .info_fcb
mov srchl,cl ;searchl = cl
ret
search_name: ;search matching name
;-----------
mov cl,namlen
;jmps search
search: ;search for directory element at .info_fcb
;------
; entry: CL = search length
call searchi
call setenddir ;dcnt = enddir
;to start at the beginning
;(drop through to searchn)
;
searchn:
;-------
; search for the next directory element, assuming
; a previous call on search which sets searcha and searchhl
; exit: Z flag = 0 for successful searches
call read_dir ;read next dir element
call endofdir
jz srchfin
;skip to end if so
;not end of directory,
;scan for match
mov dx,srcha ;dx=beginning of user fcb
call getdptra ;bx = buffa+dptr
mov cl,srchl ;length of search to cl
xor ch,ch ;ch counts up, cl counts down
mov al,[bx] ;is fcb an xfcb ?
and al,11101111b
cmp al,[bx]
je srch_loop ;no
jmps search_n
srchfin: ;end of directory, or empty name
lret_eq_ff:
mov al,255
mov ch,al
inc ch ;zero flag set on unsuccessful
jmp staret ;searches
srchloop:
or cl,cl
jz endsearch
mov si,dx
lods al ;fcb character
and al,07fh
;scan next character if not
;chksum byte
cmp ch,chksum
jz srchok
;not the ubytes field,
;extent field
cmp ch,extnum ;may be extent field
jz srchext ;skip to search extent
cmp ch,modnum ;is field module # ?
jnz $+4 ;no
and al,3fh ;yes - mask off high order bits
sub al,[bx]
and al,7fh ;mask-out flags/extent modulus
jnz searchn_jmp
jmps srchok ;matched character
srchext: ;AL = fcb character
;attempt an extent # match
push cx ;save counters
mov cl,[bx] ;directory character to c
call compext ;compare user/dir char
pop cx ;recall counters
jnz searchn_jmp ;skip if no match
srchok: ;current character matches
inc dx! inc bx
inc ch! dec cl
jmps srchloop
searchn_jmp:
jmp searchn
endsearch: ;entire name matches, return dir position
xor al,al
mov lret,al
mov ch,al
inc ch ;zero flag reset on successful
ret ;searches
check_wild: ;check for ? in file name or type
;----------
mov bx,offset info_fcb
call chk_wild
jnz ret10
mov al,9 ;extended error 9
jmp set_aret
chk_wild: ;check fcb for ? marks
;--------
; entry: BX = .fcb(0)
; exit: Z flag = 1 if ? mark found
mov cx,3f0bh ;ch = 3f, cl = 11
chk_wild1:
inc bx ;advance fcb ptr
mov al,ch
sub al,[bx]
and al,ch
jz ret10 ;rtn with z flag set if ? fnd
dec cl
jnz chk_wild1
or al,al ;rtn with z flag reset - no ?s
ret10: ret
open: ;search for the directory entry, copy to fcb
;----
call search_name
jz ret10 ;return with lret=255 if end
;not end of directory,copy fcb
opencopy:
;(referenced below to copy fcb
push bx ;bx = .fcb(modnum)
dec bx! dec bx
mov ah,[bx] ;ah = extnum
push ax ;save extnum & modnum
call getdptra
mov dx,bx ;dx = .buff(dptr)
mov bx,offset info_fcb ;bx=.fcb(0)
mov cl,nxtrec ;length of move operation
call move ;from .buff(dptr) to .fcb(0)
;note that entire fcb is
;copied, including indicators
call get_dir_ext
mov cl,al ;cl = dir_ext
pop ax! pop bx
mov [bx],al ;restore modnum
dec bx! dec bx
mov [bx],ah ;restore extnum number
; bx = .user extent#, cl = dir extent#
; if user ext < dir ext then user := 128 records
; if user ext = dir ext then user := dir records
; if user ext > dir ext then user := 0 records
set_rc:
;------
; entry: BX = .user extent #
; CL = dir extent #
xor ch,ch
mov si,offset info_fcb+reccnt
mov al,[bx] ;al = current extent
sub al,cl ;compare fcb ext to dir ext
jz set_rc2 ;fcb ext = dir ext
; actual_rc = 0, fcb(rc) = fcb(rc)
mov al,ch
jae set_rc1 ;fcb ext > dir ext
; actual_rc = 0, fcb(rc) = 0
mov al,128 ;fcb ext < dir ext
or al,[si] ; fcb(rc) = 128 | fcb(rc)
set_rc1:
mov [si],al
ret11: ret
set_rc2:
cmp b[si],al ;is fcb(rc) = 0?
jnz ret11 ;no
xor al,al ;AL = 0
mov b[si],al ;required by func 99
cmp dminx,al ;do blocks exist in fcb?
jz ret11 ;no
mov b[si],80h ;fcb(rc) = 80h
ret
restore_rc:
;----------
; if actual_rc ~= 0 then fcb(rc) = actual_rc
; entry: BX = .fcb(extnum)
mov al,info_fcb+reccnt
cmp al,81h
jb restore_rc1
and al,7fh
mov info_fcb+reccnt,al
restore_rc1:
ret
openreel:
;--------
; close the current extent, and open the next one
; if possible. rmf is true if in read mode.
; lret is set to 0 if successful
mov al,info_fcb+modnum
mov save_mod,al ;save current module #
mov bx,offset info_fcb+extnum
mov al,[bx]
mov cl,al
inc cl ;increment ext #
call comp_ext ;did we cross a dir fcb boundary ?
jnz $+5
jmp openr3 ;no
mov al,maxext
and al,cl
mov [bx],al ;update fcb extent field
jnz openr0 ;branch if in same module
; extent number overflow, go to next module
add bx,(modnum-extnum) ;bx=.fcb(modnum)
inc b[bx] ;fcb(modnum)=++1
;module number incremented,
;check for overflow
mov al,[bx]
and al,maxmod ;mask high order bits
jz openerr ;cannot overflow to 0
;otherwise, ok to continue
;with new module
openr0:
call search_name ;next extent found?
jz openerr ;end of file encountered
call opencopy
openr2:
call getfcb ;set parameters
xor al,al
mov vrecord,al
jmp staret ;lret = 0
;ret
openerr:
;-------
mov bx,offset info_fcb+extnum
mov al,save_mod
mov 2[bx],al
mov al,[bx]
dec al
and al,1fh
mov [bx],al
;cannot move to next extent
;of this file
jmp setlret1 ;lret = 1
;ret
openr3:
mov [bx],cl ;increment extent field
call get_dir_ext
mov cl,al
cmp al,[bx] ;is dir ext < fcb(ext)?
jae openr4 ;no
dec b[bx] ;decrement extent
jmp set_lret1 ;yes - reading unwritten data
openr4:
call restore_rc
call set_rc
jmps openr2
diskread: ;(may enter from seqdiskread)
;--------
;read the next record from
;the current fcb
call getfcb ;sets parameters for the read
mov al,vrecord
cmp al,rcount ;vrecord-rcount
;skip if rcount > vrecord
jb recordok
;not enough records in extent
;record count must be 128
;to continue
cmp al,128 ;vrecord = 128?
jnz diskeof ;skip if vrecord<>128
call openreel ;go to next extent if so
;now check for open ok
cmp lret,0 ;stop at eof
jnz diskeof
recordok: ;fcb addresses a record to read
call index ;error 2 if reading
;unwritten data
;(returns 1 to be compatible
;with 1.4)
;arecord=0000?
jz diskeof
call atran ;arecord now a disk address
CALL CHECK_NPRS
JC RECORDOK2
JNZ $+5
JMP READ_DEBLOCK
CALL SETDATA
call seek ;to proper track,sector
call rdbuff ;to dma address
RECORDOK2:
jmp setfcb ;replace parameter
diskeof:
jmp setlret1 ;lret = 1
;ret
CHECK_NPRS:
;----------
; DIR_CNT CONTAINS THE NUMBER OF 128 BYTE RECORDS
; TO TRANSFER DIRECTLY. THIS ROUTINE SET DIR_CNT
; WHEN INITIATING A SEQUENCE OF DIRECT PHYSICAL I/O
; OPERATIONS. DIR_CNT IS DECREMENTED EACH TIME CHECK_NPRS
; IS CALLED DURING SUCH A SEQUENCE.
; exit: ~C FLG & ~Z FLG - DIRECT PHYSICAL I/O OPERATION
; ~C FLG & Z FLG - INDIRECT(DEBLOCK) I/O OPERATION
; C FLG - NO PHYSICAL I/O OPERATION
MOV CH,blk_off ;CH = VRECORD & BLKMSK
MOV AL,DIR_CNT
CMP AL,2 ;IS DIR_CNT > 1?
JC CHECK_NPR1 ;NO
DEC AL ;DIR_CNT = DIR_CNT - 1
MOV DIR_CNT,AL ;we are in mid-multi sector i/o
STC
ret ;RETURN WITH C FLAG SET
CHECK_NPR1:
MOV AL,PHYMSK ;CL = PHYMSK
MOV CL,AL
AND AL,CH ;AL = VRECORD & PHYMSK
;ARE WE IN MID-PHYSICAL RECORD?
JZ CHECK_NPR11 ;NO
CHECK_NPR1X:
OR CL,CL ;IS PHYMSK = 0?
JZ CHECK_NPR1Y ;YES
XOR AL,AL ;RETURN WITH Z FLAG SET & C FLAG RESET
RET
CHECK_NPR1Y:
OR AL,1 ;RESET C & Z FLAGS
RET
CHECK_NPR11:
MOV DH,CL
not DH ;DH = ~ PHYMSK
MOV AL,MULTNUM
CMP AL,2 ;IS MULT_NUM < 2?
JC CHECK_NPR1X ;YES
MOV BX,OFFSET VRECORD
MOV AH,[BX] ;AH = VRECORD
ADD AL,ah
CMP AL,80H
JC CHECK_NPR2
MOV AL,80H
CHECK_NPR2: ;AL = MIN(VRECORD + MULT_NUM,80H) = X
PUSH CX ;SAVE VRECORD & BLKMSK, PHYMSK
MOV B[BX],7FH ;VRECORD = 7F
PUSH BX! PUSH AX
MOV BL,AL ;BL = X
MOV AL,BLKMSK
MOV DL,AL
INC DL ;DL = BLKMSK + 1
not AL
AND AH,AL ;AH = VRECORD & ~BLKMSK
MOV AL,RCOUNT
AND AL,DH ;AL = RCOUNT & ~PHYMSK
CMP AL,BL ;IS AL < X?
JC CHECK_NPR23 ;YES
MOV AL,BL ;AL = MIN(VRECORD + MULT_NUM,80H) = X
CHECK_NPR23:
SUB AL,AH ;AL = AL - VRECORD & ~BLKMSK
CMP AL,DL ;IS AL < BLKMSK + 1?
JC CHECK_NPR9 ;YES
PUSH AX ;AL = MAX # OF RECORDS
CALL DMPOSITION ;COMPUTE MAXIMUM DISK POSITION
MOV CH,AL ;CH = MAX DISK POS
MOV AL,DMINX ;AL = CURRENT DISK POS
CMP AL,CH ;IS CURR POS = MAX POS?
MOV DL,AL
JZ CHECK_NPR5 ;YES
MOV CL,AL
PUSH CX ;CL = CURR POS, CH = MAX POS
MOV CH,0
CALL GET_DM ;BX = BLOCK NUMBER (CURR POS)
CHECK_NPR4:
PUSH BX
INC CX ;CURR POS = CURR POS + 1
CALL GET_DM ;GET NEXT BLOCK(CURR POS)
POP DX
INC DX
CMP BX,DX ;DOES CURR BLK = LAST BLK + 1?
JZ CHECK_NPR4 ;YES
DEC CL ;CL = INDEX OF LAST SEQ BLK
POP DX
MOV AL,DH ;AL = MAX POS
CMP AL,CL ;IS AL < LAST SEQ BLK POS
JC CHECK_NPR5 ;YES
MOV AL,CL
CHECK_NPR5: ;AL = LAST BLK POS
SUB AL,DL ;AL = AL - STARTING POS
MOV CH,AL
INC CH ;CH = # OF CONSECUTIVE BLOCKS
MOV AL,BLKMSK
INC AL ;AL = BLKMSK + 1
MUL CH ;AL = # OF CONSECUTIVE LOGICAL RECS
POP CX ;CL = MAXIMUM # OF RECORDS
XCHG AL,CL
CMP AL,CL ;IS MAX < # OF CONS. RECS?
JC CHECK_NPR9 ;YES
MOV AL,CL
CHECK_NPR9: ;AL = # OF CONSECUTIVE RECS
POP CX
POP BX
MOV [BX],CH ;RESTORE VRECORD
POP CX
MOV DH,MULT_NUM
SUB AL,CH ;AL = AL - VRECORD & blkmsk
CMP AL,DH ;IS AL < MULT_NUM
JC CHECK_NPR10 ;YES
MOV AL,DH
CHECK_NPR10: ;AL = # OF CONSECUTIVE RECS
not CL
AND AL,CL ;IF DIR_CNT = 0 THEN
JZ RET13B ;RETURN WITH Z FLAG SET, C FLAG RESET
MOV DIR_CNT,AL ;DIR_CNT = AL & ~PHYMSK
MOV CL,PHYSHF
SHR AL,CL ;AL = # OF CONSECUTIVE PHYSICAL RECS
mov mult_sec,al ;save multisector count for r/w
OR AL,1 ;RETURN WITH C AND Z FLAGS RESET
RET13B: RET
tmp_select:
;----------
; entry: DL = drive to select (0-f)
mov seldsk,dl
curselect:
;---------
mov al,seldsk
cmp al,curdsk
jne select ;don't select if seldsk = curdsk
inc al! jz select0
ret
SELECT: ;select disk in info_fcb for subsequent input or output ops
;------
cmp al,16 ! jb disk_select
select0:
jmp selerror
disk_select:
;-----------
; entry: AL = disk to select
mov adrive,al
mov curdsk,al
xor dx,dx ;dl = 1 if drive logged in
call selectdisk
jnc select0 ;carry set if select ok
ret
parsave33r:
;----------
call parsave33
;jmps reselect
reselect:
;--------
mov cl,07fh
mov bx,offset info_fcb+f7
and [bx],cl ;fcb(7) = fcb(7) & 7fh
and 1[bx],cl
and byte ptr extnum-f7[bx],1fh ;fcb(ext) = fcb(ext) & 1fh
;check current fcb to see if reselection necessary
mov resel,true ;mark possible reselect
mov al,info_fcb ;drive select code
mov fcbdsk,al ;save drive
and al,00011111b ;non zero is auto drive select
dec al ;drive code normalized to
;0...30, or 255
cmp al,0ffh
jz noselect ;auto select function,
mov seldsk,al ;save seldsk
noselect:
call curselect
;set user code
mov al,usrcode ;0...31
mov info_fcb,al
ret
compare: ;compare strings
;-------
; entry: CL = length of strings
; BX,DX = offset of strings
; exit: Z flag set if strings match
mov ch,0
mov si,bx
mov di,dx
repe cmps al,al
ret
; individual function handlers
;-----------------------------------------------------
func14: ;select disk info
;======
call tmp_select
mov al,seldsk
mov p_dsk,al
ret
func15: ;open file
;======
call parsave33r ;copy fcb from user seg.
mov info_fcb+modnum,0 ;fcb(modnum)=0
call check_wild ;check for ?s in fcb
call open ;attempt to open fcb
call openx ;returns if unsuccessful
xor al,al
ret30: ret ;no - open failed
openx:
;-----
call end_of_dir ;was open successful
jz ret30 ;no
mov bx,offset info_fcb+nxtrec
cmp b[bx],0ffh
jne openxa
mov al,info_fcb+chksum
mov [bx],al
openxa:
pop bx ;discard return address
MOV CL,40H
ret
func20: ;read a file
;======
call parsave33r
jmp disk_read
;jmp goback
set_aret:
;--------
mov cl,al ;save error index
mov byte ptr aret+1,al ;aret+1 = extended errors
call lret_eq_ff
jmp goback ;return physical & extended errors
; BLOCKING/DEBLOCKING BUFFER CONTROL BLOCK (BCB) FORMAT
; +-------+-------+-------+-------+-------+-------+
; 00h | DRV | RECORD | PEND | SEQ |
; +-------+-------+-------+-------+-------+-------+
; 06h | TRACK | SECTOR | BUFFER_ADDR |
; +-------+-------+-------+-------+-------+-------+
; 0Ch | LINK | PROCESS_OFF |
; +-------+-------+-------+-------+
READ_DEBLOCK:
;------------
mov ah,1 ;AH = 1
CALL DEBLOCK_DTA
JMP SET_FCB
DEBLOCK_DIR:
;-----------
MOV CUR_DMABASE,DS ;BUFFERS IN SYSTEM DATA AREA
MOV BX,DIRBCBA
jmps DEBLOCK ;PREVIOUS LOCATE CALL
DEBLOCK_DTA:
;-----------
MOV BX,DTABCBA
MOV CUR_DMABASE,0 ;get segment from BCB
DEBLOCK: ;BDOS BLOCKING/DEBLOCKING ROUTINE
;-------
; entry: Z flag reset -> get new BCB address
; AH = 1 -> READ COMMAND
; = 2 -> WRITE COMMAND
; = 3 -> LOCATE COMMAND
; = 4 -> FLUSH COMMAND
; = 5 -> DIRECTORY UPDATE
MOV DEBLOCK_FX,AH ;SAVE DEBLOCK FX
mov cl,phymsk ;CL = PHYMSK
MOV AL,BYTE PTR ARECORD
AND AL,cl
MOV PHY_OFF,AL ;PHY_OFF = LOW(ARECORD) & PHYMSK
not cl ;CL = ~PHYMSK
and BYTE PTR ARECORD,cl ;LOW(ARECORD) = LOW(ARECORD) & ~PHYMSK
mov bx,[bx] ;GET BCB ADDRESS
MOV CURBCBA,BX ;BX = 1st curbcb
MOV ax,10[BX] ;dma address field - offset/segment
cmp cur_dmabase,0 ;if cur_dmabase <> 0, deblocking is
jne deblock0 ; for dir buf and addr is offset
mov cur_dmabase,ax ;else deblocking data buffer and
xor ax,ax ; addr is segment, offset = 0
deblock0:
MOV CURDMA,ax ;save current buffer address
CALL DEBLOCK9 ;BX=CURBCBA, DX=.ADRIVE, CL=4
cmp b[bx],0ffh! je deblock2
CALL COMPARE ;DOES BCB(0-3) = ADRIVE || ARECORD?
JZ DEBLOCK45 ;YES
DEBLOCK2:
mov bx,curbcba
mov b[bx],0ffh ;discard in case of error
MOV AL,2
CALL DEBLOCK_IO ;READ PHYSICAL RECORD
CALL DEBLOCK9 ;BX=CURBCBA, DX=.ADRIVE, CL=4
CALL MOVE
MOV B[DI],0 ;CURBCBA->BCB(4) = 0
DEBLOCK45:
xor al,al
MOV ah,PHY_OFF
shr ax,1 ;AX = phy_off * 080h
MOV SI,CURDMA
ADD SI,AX ;SI = CURDMA + PHY_OFF*80H
MOV al,DEBLOCK_FX
CMP al,3 ;IS DEBLOCK_FX = LOCATE?
JNZ DEBLOCK6 ;NO
MOV BUFFA,SI ;YES
RET
DEBLOCK6:
MOV CX,40H ;transfer 40h words
MOV DI,DMAAD
mov ax,dmabase
mov dx,cur_dmabase
push ds! push es
mov ds,dx ;setup source segment
mov es,ax ;setup destination segment
rep movsw ;transfer data
pop es! pop ds
RET
DEBLOCK9: ;SETUP FOR MOVE OR COMPARE
MOV BX,CURBCBA
MOV DX,OFFSET ADRIVE
MOV CL,4
RET
DEBLOCK_IO:
;----------
; entry: AL = 0 -> SEEK ONLY
; = 1 -> WRITE
; = 2 -> READ
PUSH AX
CALL SEEK
POP AX
DEC AL
JS deblk_io2
; JNZ deblk_io1
; mov cl,1
; JMP WRBUFF
;deblk_io1:
CALL RDBUFF
deblk_io2:
mov si,offset track
mov di,curbcba
add di,6 ;MOVE TRACK & SECTOR
mov cx,2 ;TO BCB
rep movsw
ret
endcode equ offset $
;*************** end bdos file system ****************
;****************** BDOS data area *******************
;
;
dseg
; Variables in data segment:
org endcode
iosentry rw 0
biosco dw biosoffset ;offset and
bioscs dw 0 ;segment for callf to BIOS
;
;*****************************************************
;
;*****************************************************
;*
;* bdos file system data area
;*
;*****************************************************
; variables in data segment:
;
;the following variables are set to zero upon entry to file system
fcbdsk db 0 ;disk named in fcb
parcopfl db 0 ;true if parameter block copied
aret dw 0 ;adr value to return
lret equ byte ptr aret ;low(aret)
resel db 0 ;reselection flag
DIR_CNT DB 0 ;DIRECT I/O COUNT
MULT_NUM DB 0 ;MULTI-SECTOR COUNT used in bdos
zerolength equ (offset $)-(offset fcbdsk)
mult_sec db 1 ;multi sector count passed to xios
BLK_OFF DB 0 ;RECORD OFFSET WITHIN BLOCK
;
DEBLOCK_FX DB 0 ;DEBLOCK FUNCTION #
PHY_OFF DB 0 ;RECORD OFFSET WITHIN PHYSICAL RECORD
CURBCBA DW 0 ;CURRENT BCB OFFSET
TRACK DW 0 ;BCB RECORD'S TRACK
SECTOR DW 0 ;BCB RECORD'S SECTOR
; seldsk,usrcode are initialized as a pair
p_dsk db 0 ;selected disk num
p_user db 0 ;curr user num
;info dw 0 ;info adr
srcha dw 0 ;search adr
;the following variable order is critical
;variables copied from uda for mp/m x
;variables included in fcb checksum for mp/m and cp/m x
;variables used to access system lock list for mp/m x
;dmaad dw 0 ;dma offset 1
;dmabase dw 0 ;dma base 2
;srchl db 0 ;search len 4
;dcnt dw 0 ;directory counter 7
;dblk dw 0 ;directory block 8 ?? - not used - ??
u_mult_cnt rb 0
mult_cnt db 1 ;bdos multi-sector cnt 10
;df_password rb 8 ;process default pw 11
;high_ext db 0 ;fcb high extent bits 2
;xfcb_read_only db 0 ;xfcb read only flag 3
curdsk db 0ffh ;current disk 4 1
org ((offset $) + 1) and 0fffeh
; curtrka - alloca are set upon disk select
; (data must be adjacent)
;cdrmaxa dw 0 ;ptr to cur dir max val
;drvlbla dw 0 ;drive label data byte addr
buffa dw 0 ;ptr to dir dma addr
dpbaddr dw 0 ;curr disk param block addr
checka dw 0 ;curr checksum vector addr
alloca dw 0 ;curr alloc vector addr
DIRBCBA DW 0 ;DIRECTORY BUFFER CONTROL BLOCK ADDR
DTABCBA dw 0 ;DATA BUFFER CONTROL BLOCK ADDR
addlist equ 10 ;"$-buffa" = addr list size
; sectpt - offset obtained from disk parm block at dpbaddr
; (data must be adjacent)
sectpt dw 0 ;sectors per track
blkshf db 0 ;block shift factor
blkmsk db 0 ;block mask
extmsk db 0 ;extent mask
maxall dw 0 ;max alloc num
dirmax dw 0 ;max dir num
dirblk dw 0 ;reserved alloc bits for dir
chksiz dw 0 ;size of checksum vector
offsetv dw 0 ;offset tracks at beginning
PHYSHF DB 0 ;PHYSICAL RECORD SHIFT FACTOR
PHYMSK DB 0 ;PHYSICAL RECORD MASK
endlist rs 0 ;end of list
dpblist equ (offset endlist)-(offset sectpt)
;size
; local variables
save_mod db 0 ;open_reel module save field
dminx db 0 ;local for diskwrite
single db 0 ;set true if single byte
;alloc map
rcount db 0 ;record count in curr fcb
extval db 0 ;extent num and extmsk
vrecord db 0 ;curr virtual record
ADRIVE DB 0 ;CURRENT DISK - must preceed arecord
arecord dw 0 ;curr actual record
db 0 ;curr actual record high byte
CUR_DMABASE DW 0
CUR_DMA DW 0
; local variables for directory access
dptr db 0 ;directory pointer 0,1,2,3
; shell variables
shell_si dw 0 ;bdos command offset
shell_dma dw 0 ;dmaad save area
shell_flag db 0 ;parsave shell flag
; special 8086 variables:
u_retseg dw 0 ;user return segment
parlg db 0 ;len of parameter block
; bdos stack switch variables and stack
; used for all bdos disk functions
org ((offset $) + 1) and 0fffeh
; 69 word bdos stack
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch
bdosstack rw 0
save_sp rw 1
; local buffer area:
info_fcb rb 0;40 ;local user FCB
db 'COPYRIGHT(C)1983,'
db 'DIGITAL RESEARCH(01/26/83)'
db 'XXXX-0000-654321'
;
info dw 0 ;information address
;
u_wrkseg rw 0
parametersegment dw 0 ;user parameter segment
;
;
dmaad dw 0 ;user DMA address
dmabase dw 0 ;user DMA base
seldsk db 0 ;current user disk
usrcode db 0 ;current user number
dcnt dw 0 ;directory index
ldcnt equ byte ptr dcnt ;low(dcnt)
srchl db 0 ;search length
;
;
db 0 ;end of this data area
;***************** end BDOS data area ****************
;******************** end of BDOS ********************
end
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