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Digital-Research-Source-Code/CPM OPERATING SYSTEMS/CPM 86/CONCURRENT/CCPM-86 3.1 SOURCE/D2/FILE1.BDO
Sepp J Morris 31738079c4 Upload 
Digital Research
2020-11-06 18:50:37 +01:00

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;*****************************************************************
;*****************************************************************
;** **
;** 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 part 1 ************
; error message handlers
pererror: ;report permanent error
;--------
mov ah,1
jmps goerr
roderror: ;report read/only disk error
;--------
call discard_dir
mov ah,2
jmps goerr
roferror: ;report read/only file error
;--------
mov ah,3
jmps goerr
selerror: ;report select error
;--------
mov curdsk,0ffh
mov ah,4
goerr:
;-----
; entry: AH = error type
mov al,0ffh
mov aret,ax ;set aret
cmp error_mode,al ;if error_mode = 0ffh then
jne report_err ;report error to user
rtn_phy_errs: ;return physical error to user
if BMPM
xor al,al
xchg lock_shell,al
test al,al
JZ rtn_phy0
mov sp,lock_sp
ret
rtn_phy0:
endif
mov al,fx_intrn ;if func# = 27,31 then
cmp al,fxi27! je rtn_phy1 ; aret = 0ffffh
cmp al,fxi31! jne goback
rtn_phy1:
mov aret,0ffffh
goback:
mov sp,save_sp
jmp bdos_return
set_lret1:
;---------
mov al,1
set_lret:
;--------
mov lret,al
funcret:
;-------
ret
set_aret:
;--------
; entry: AH = extended error type
mov al,0ffh
mov aret,ax
cmp ah,3! jne set_a1
mov ah,12
set_a1:
cmp error_mode,al
je goback ;return physical & extended errors
report_err:
;----------
; entry: AH = error type
mov err_type,ah
mov al,seldsk
mov err_drv,al ;error drive
cmp error_mode,0feh ;is error mode print &
; return errors?
je rtn_phy_errs ;yes
if BMPM
mov si,rlr
or p_flag[si],pf_ctlc ;set process ^c flag
endif
if BCPM
push ds! mov ds,rlr
or ds:p_flags,pf_ctrlC
mov ds:p_ret_code,0FFFDh ;set fatal error termination code
pop ds
endif
jmps rtn_phy_errs
;-----------------------------------------------------
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
compare: ;compare strings
;-------
; entry: CL = length of strings
; BX,DX = offset of strings
; exit: Z flag set if strings match
xor ch,ch
mov si,bx
mov di,dx
repe cmps al,al
ret
seek: ;seek the track and sector given by arecord
;----
mov ax,arecord ;compute track/sector
xor dx,dx
mov dl,byte ptr arecord+2
mov cl,physhf ! xor ch,ch
jcxz seek_media
seek_shf:
shr dx,1 ;convert ARECORD from
rcr ax,1 ; logical to physical sectors
loop seek_shf
seek_media:
if PCMODE
cmp media_format,0
je seek_cpm
add ax,fatadd ! adc dx,0 ;add in record address of FAT
xchg ax,bx ;save AX
mov al,byte ptr nfats
mul byte ptr nfatrecs ;AX = number of FAT records total
add ax,bx ! adc dx,0 ;add in number of FAT records
div sectpt ;DX = sector, AX = track
jmps seek_exit
seek_cpm:
endif
div sectpt ;DX = sector, AX = track
add ax,offsetv ;add in number of system tracks
seek_exit:
MOV TRACK,ax ;save bios/xios track
MOV SECTOR,dx ;save bios/xios sector
ret
; utility functions for file access
atran: ;compute actual record address, assuming index called
;-----
mov cl,blkshf ;shift count to reg al
mov ax,arecord
mov blk_num,ax ;save for pre read check
xor bh,bh
mov bl,ah
shl ax,cl
shl bx,cl
MOV ARECORD1,ax ;save shifted block #
xchg ax,bx ; for write rand w/zero fill
mov al,vrecord
and al,blkmsk ;masked value in al
mov blk_off,al
or bl,al
mov arecord,bx ;arecord=bx or
;(vrecord and blkmsk)
mov byte ptr arecord+2,ah
ret
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
get_atts:
;--------
; get interface attributes (f5' - f8') from fcb
; zero interface attribute bits in fcb
; exit: AL = attributes f5' - f8' in high nibble
mov di,offset info_fcb+f8
mov cx,4
xor dl,dl
std ;direction from f8 to f5
get_atts_loop:
mov al,[di] ;get character
shl al,1 ;attribute bit into carry
rcr dl,1 ; then into DL
shr al,1 ;clear attribute bit
stosb ; and restore character
loop get_atts_loop ;next character
cld ;restore direction
mov al,dl
mov attributes,al ;save attributes
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
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
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
;------
xor al,al
cmp fx_intrn,fxi22 ;if func# < make then
jae setfc1
inc al ; AL=1 - sequential i/o
setfc1:
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
cmpec0: ;compute checksum
;------
; entry: BX = offset of string to checksum
; CL = number of bytes to checksum
; AL = initial value of checksum
; exit: AL = checksum value
xor ch,ch
cmpec2:
add al,[bx]
inc bx
loop cmpec2
ret ;with checksum in AL
cmpecs: ;compute checksum for current directory buffer
;------
; exit: AL = checksum value
mov bx,buffa ;current directory buffer
mov cx,4 ;# of directory in buffer
xor ah,ah ;clear checksum value
cmpec1:
push cx! xor al,al
mov cl,32 ;size of directory entry
call cmpec0
xor ah,al
pop cx
loop cmpec1
xchg al,ah ;AL = checksum value
ret
chek_fcb:
;--------
; exit: Z flag set if valid checksum
cmp high_ext,01100000b ;does high_ext = 60h
jne chksum_fcb ;no
xor al,al
mov info_fcb,al ;yes - set fcb(0) to zero
;jmps chksum_fcb
chksum_fcb: ;compute checksum for fcb
;----------
; add 1st 12 bytes of fcb + curdsk + high_ext + xfcb_readonly + bbh
; exit: Z flag set if valid checksum
if BMPM
sub al,al
mov bx,offset pd_cnt
mov cl,4
call cmpec0
add al,0bbh ;add bias
mov bx,offset info_fcb ;add 1st 12 bytes of fcb
mov cl,12
call cmpec0
inc bx ;skip extent
add al,[bx] ;add s1
add bx,3 ;skip modnum & reccnt
mov cl,16 ;checksum disk map
call cmpec0
mov bx,drvlbla
add al,2[bx] ;add in login sequence number
or al,al ;zero flag set if checksum valid
endif
if BCPM
mov bx,drvlbla
mov al,info_fcb+chksum
cmp 2[bx],al
endif
ret42: ret
if BMPM
get_cmp_mode:
;------------
; exit: AL = process compatability mode
; BX = preserved
mov si,pdaddr
mov al,p_cmod[si]
ret
cond_check_fcb:
;--------------
call get_cmp_mode
and al,10h! jnz chek_fcb ;if f4' set dont check fcb
;jmp check_fcb
endif
check_fcb:
;---------
if BMPM
mov check_fcb_ret,false
check_fcb1:
endif
call chek_fcb ;compute fcb checksum
jz ret42 ;valid if zero
if BCPM
mov dx,rlog
call test_vector
jz ret42
endif
if BMPM
and al,0fh ;is mod(chksum,16) = 0 ?
jnz check_fcb3 ;no - invalid checksum
cmp pd_cnt,0 ;is pd_cnt = 0 ?
jz check_fcb3 ;yes - invalid checksum
if PCMODE
cmp media_format,0
je $+5
jmp chk_pcfcb
endif
mov byte ptr sdcnt+1,0ffh
call chk_inv_fcb
jne check_fcb2 ;is invalid fcb
call search_name ; yes - search for directory fcb
jmps check_fcb25
check_fcb2:
mov dont_close,true
call close1 ; no - attempt partial close
check_fcb25:
mov bx,offset lret
inc b[bx]
jz check_fcb3 ;partial close or search failed
mov b[bx],0 ;zero lret
call pack_sdcnt ;look for file in lock list
mov ch,5
call search_olist
jnz check_fcb3 ;not found - invalid checksum
ret ;found - checksum ok
endif
check_fcb3:
pop bx ;discard return address
if BMPM
test check_fcb_ret,true
jnz ret45
endif
chk_media2:
mov al,10 ;10 = checksum error
jmp set_lret
if BMPM
set_chksum_fcb: ;validate fcb checksum
;--------------
call chksum_fcb ;compute fcb checksum
jz ret45 ;return if valid
sub al,info_fcb+chksum ;subtract from checksum value
neg al ;negate result
mov info_fcb+chksum,al ;restore s1
ret45: ret
reset_checksum_fcb: ;invalidate fcb checksum
;------------------
mov comp_fcb_cks,0
call chksum_fcb ;compute fcb checksum
jnz ret45 ;return if invalid
inc byte ptr info_fcb+chksum ;invalidate s1
ret
endif
if BCPM
SET_LSN:
;-------
MOV BX,DRVLBLA
MOV CL,2[BX]
mov info_fcb+chksum,cl
RET
endif
setcdisk: ;set a "1" value in curdsk position of [bx]
;--------
; entry: BX = offset of vector to set
mov cl,curdsk
set_cdisk1: ;set a "1" value in cl position of [bx]
;----------
; entry: BX = offset of vector to set
; CL = position in vector to set
; exit: AX = bit set in position CL
mov ax,1 ;number to shift
shl ax,cl ;ax = mask to integrate
or [bx],ax ;[bx] = mask or rol(1,curdsk)
ret
nowrite: ;check if disk is marked read/only
;-------
; exit: Z flag reset if disk is read/only
mov dx,rodsk
test_vector: ;test current disk bit in vector
;-----------
; entry: DX = vector to test
; exit: DL = curdsk vector bit (in low order bit)
; Z flag reset if bit is on
mov cl,curdsk
test_vector1:
shr dx,cl
and dx,1
ret ;non zero if nowrite
get_dptra:
;---------
; compute the address of a directory element at
; positon dptr in the buffer
; exit: BX = buffa + dptr
; CX = preserved
mov bl,dptr
xor bh,bh
add bx,buffa ;bx = buffa + dptr
ret
ro_test:
;-------
; entry: BX = offset of fcb to test
; exit: BX = .fcb(9)
; C flag set if file is read/only
add bx,rofile ;offset to r/o bit
mov al,[bx]
rcl al,1
ret5: ret
ckrodir: ;check current directory element for read/only status
;-------
call get_dptra ;address of element
ckrofile: ;check current buff(dptr) or fcb(0) for r/o status
;--------
; entry: BX = offset of fcb to test
call ro_test
jnc ret5 ;rnc
jmp roferror
checkwrite: ;check for write protected disk
;----------
call nowrite
jz ret5 ;rz
jmp roderror
getmodnum:
;---------
; compute the address of the module number
; bring module number to accumulator
; high order bit is fwf (file write flag)
; exit: BX = offset fcb(modnum)
; AL = fcb(modnum)
mov bx,offset info_fcb+modnum
mov al,[bx]
ret ;al=fcb(modnum)
clrmodnum: ;clear the module number field for user open/make
;---------
mov info_fcb+modnum,0 ;fcb(modnum)=0
ret
clr_ext:
;-------
and info_fcb+extnum,1fh
ret
setfwf: ;set file write flag
;------
; exit: BX = .fcb(modnum)
; AL = fcb(modnum)
call getmodnum ;bx=.fcb(modnum),
;al=fcb(modnum)
;set fwf(file write flag) to 1
or al,fwfmsk
mov [bx],al ;fcb(modnum)=fcb(modnum) + 80h
;also returns non zero
;in accumulator
ret
chk_inv_fcb: ;check for invalid fcb
;-----------
mov bx,offset info_fcb+dskmap
jmps test_ffff
tst_inv_fcb: ;test for invalid fcb
;-----------
call chk_inv_fcb
jnz ret8
pop bx
mov al,9
jmp set_lret
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
ret8: ret
setenddir: ;set dcnt to the end of directory (dcnt = 0ffffh)
;---------
mov dcnt,enddir
ret
set_dcnt:
;--------
mov ax,xdcnt
and al,0fch
dec ax
mov dcnt,ax
ret
compcdr: ;return cy if cdrmax > dcnt
;-------
; exit: C flag set if current dir max > dir count
; BX = .cdrmax
; DX = dcnt
mov dx,dcnt ;dx = directory counter
mov bx,cdrmaxa ;bx=.cdrmax
cmp dx,[bx]
;condition dcnt - cdrmax
ret6: ret ;produces cy if cdrmax>dcnt
setcdr: ;if not (cdrmax > dcnt) then cdrmax = dcnt+1
;------
call compcdr
jb ret6 ;return if cdrmax > dcnt
;otherwise, bx = .cdrmax+1,
;dx = dcnt
inc dx
mov [bx],dx
ret
TST_LOG_FXS:
;-----------
; exit: Z flag set if removable and func# = 15,17,19,etc.
TEST BYTE PTR CHKSIZ+1,80H ;IS DRIVE PERMANENT?
JNZ RET6 ;YES - RET WITH Z FLAG RESET
MOV DI,OFFSET LOG_FXS ;RETURN WITH Z FLAG SET
tst_log_01:
mov cl,cs:[di] ;CS over ride on table in const area
inc di! xor ch,ch
MOV AL,fx_intrn ;IF func# = 15,17,19,etc.
push cs ! pop es
repne scas al ;ES = CS for table in const area
push ds ! pop es
RET
chk_exit_fxs:
;------------
mov bx,offset goback
push bx ;setup for error return
mov di,offset rw_fxs
call tst_log_01 ;does fx = read or write ?
jnz $+5 ; and is drive removable ?
jmp chk_media2
mov di,offset sc_fxs
call tst_log_01 ;does fx = searchn or close ?
jnz $+5 ; and is drive removable ?
jmp lret_eq_ff
pop bx ;remove error return address
ret
TST_RELOG:
;---------
xor al,al
xchg relog,al
test al,al ;IF RELOG ~= 0 THEN RELOG
JZ RET6 ;CURRENT DRIVE
call curselect
jmp restart
drv_relog:
;---------
CALL curselect
xor ax,ax
MOV DCNT,ax ;SET DCNT & DPTR TO ZERO TO
MOV DPTR,al ;FORCE SEARCHES TO BEGINNING
RET ;OF DIRECTORY
if PCMODE
directio:
;--------
; Entry: CL = true if reading
; AX = number of physical records
mov mult_sec,al
push cx
call setdata
call seek
pop cx
or cl,cl ! jz wrbuff
jmps rdbuff
endif
wrbuff: ;write buffer and check condition
;------
; entry: CL = wrtype = 0 - normal write operation
; wrtype = 1 => directory write operation
; wrtype = 2 => start of new block
mov al,io_write
call rwxiosif ;current drive, track, ...
mov ah,true ;mark as a write operation
jmps diocomp ;check for i/o errors
rdbuff: ;read buffer and check if ok
;------
mov al,io_read
call rwxiosif ;current drive, track,....
diocomp0:
mov ah,false ;not a write operation
diocomp: ;check for disk errors
;-------
; entry: AL = xios return code
; AH = true if coming a from write operation
or al,al! jnz dioc
mov ff_flag,true
ret
dioc:
push ax ! push bx ;save write flag
cmp al,0ffh! je dioc01 ;has media changed
mov al,adrive ;if operation is on different drive
cmp al,seldsk ; treat error as media change
je dioc2 ; no same drive, report error
dioc01:
cmp chksiz,8000h ;is drive removable or
je dioc2 ; checksummed ?
mov dx,dlog ; yes
call test_vector ;in initialize ?
jz dioc2 ; yes - treat as perm error
call media_change
cmp fx_intrn,fxi48 ;does func# = flush buffer
je dioc0 ; yes
mov al,adrive ;is operation on
cmp al,seldsk ; different drive?
je dioc1 ; no
mov relog,0 ;no relog for different drive
dioc0:
pop bx ! pop ax
ret
dioc1:
call chk_exit_fxs
test ff_flag,true ;if not first disk operation
jz dioc15
call lret_eq_ff ; yes - return error = 0ffh
jmp goback
dioc15:
pop bx ! pop ax ;restore write flag
or ah,ah! jnz dioc3 ; if write treat as r/o error
ret
dioc2:
pop bx ! pop ax ;discard write flag
if PCMODE
push es ! mov es,uda_save
mov u_ioexerr,bh ;save extended error in UDA
pop es
endif
cmp al,2! je dioc3 ;is error read/only
jmp pererror ; no
dioc3:
jmp roderror
discard_data:
;------------
mov bx,dat_bcba
mov cl,4
jmps discard0
discard_dir: ;discard matching dir bcb's
;-----------
mov bx,dir_bcba
DISCARD: ;DISCARD BCB'S MATCHING
;-------
MOV CL,1 ;ADRIVE FOR CL BYTES
DISCARD0:
;--------
; entry: BX = bcb root address
; CL = length of bytes to match
or bx,bx ;no entries in bcb list
JZ RET7A ;RET IF ZERO
MOV BX,[BX]
DISCARD1:
PUSH CX
MOV DX,OFFSET ADRIVE ;COMPARE BCB TO ADRIVE FOR
CALL COMPARE ;CL BYTES
POP CX
JNZ DISCARD2
MOV B[BX],0FFH ;DISCARD BCB
DISCARD2:
MOV BX,12[BX] ;ADVANCE TO NEXT BCB
or bx,bx ;IS IT LAST BCB?
JNZ DISCARD1 ;NO
RET7A: RET
DEACTIVATE: ;deactivate bcb's in list
;----------
; entry: BX = bcb root address
or bx,bx ;DEACTIVATE BCB'S IN LIST BX
JZ RET7A ;BELONGING TO CURRENT PROCESS
MOV BX,[BX] ;AND DRIVE
DEACT1:
MOV AL,[BX] ;IS BCB FOR CURRENT DRIVE?
CMP AL,ADRIVE
JNZ DEACT2 ;NO
MOV AX,14[BX] ;DOES CURRENT PROCESS OWN BCB?
CMP AX,RLR
JNZ DEACT2 ;NO
MOV WORD PTR 14[BX],0 ;DEACTIVATE BCB
mov al,fx_intrn
cmp al,fxi48! je deact11 ;IS func# = flush or free drive ?
cmp al,fxi39! jne deact2
deact11:
MOV B[BX],0FFH ;yes - DISCARD BCB
DEACT2:
MOV BX,12[BX] ;ADVANCE TO NEXT BCB
or bx,bx
JNZ DEACT1
RET
; BLOCKING/DEBLOCKING BUFFER CONTROL BLOCK (BCB) FORMAT
; +-------+-------+-------+-------+-------+-------+
; 00h | DRV | RECORD | PEND | SEQ |
; +-------+-------+-------+-------+-------+-------+
; 06h | TRACK | SECTOR | BUFFER_ADDR |
; +-------+-------+-------+-------+-------+-------+
; 0Ch | LINK | PROCESS_OFF |
; +-------+-------+-------+-------+
GET_BCBA: ; get buffer control block address
;--------
; entry: BX = .bcb list root
; exit: BX = .bcb SEQ,LINK,PD fields updated
MOV ROOT_BCBA,BX
mov di,bx
sub di,12 ;DI = last bcb (previous curbcb)
mov bx,[bx] ;BX = 1st curbcb
cmp word ptr 12[bx],0 ;IS THERE ONLY 1 BCB IN BCB LIST?
jnz $+5 ;YES
jmp get_bcb35
xor ax,ax
MOV EMPTY_BCBA,ax
mov p_last_bcba,ax
MOV P_BCB_CNT,al
GET_BCB1:
CMP B[BX],0FFH ;IS CURBCB DISCARDED?
je get_bcb10 ;yes
mov ax,14[bx]
or ax,ax ;IS BCB INACTIVE?
JNZ get_bcb11 ;NO
MOV SI,EMPTY_BCBA
OR SI,SI ;IS EMPTY_BCBA = 0?
JZ get_bcb10 ;YES - SAVE INACTIVE BCB ADDR
MOV SI,12[SI]
CMP B[SI],0FFH ;is empty_bcb a discarded bcb?
JZ get_bcb12 ;yes - DONT SAVE INACTIVE BCB ADDR
GET_BCB10:
MOV EMPTY_BCBA,di ;EMPTY_BCBA = LAST_BCBA
mov byte ptr 5[bx],0 ;reset sequence counter
JMPS get_bcb12
GET_BCB11:
CMP AX,RLR ;DOES CURRENT PROCESS OWN BCB?
jne get_bcb12 ;NO
INC P_BCB_CNT ;P_BCB_CNT = P_BCB_CNT + 1
MOV P_LAST_BCBA,di
GET_BCB12:
MOV CUR_BCBA,BX
push di
CALL DEBLOCK9 ;BX=CURBCBA, DX=.ADRIVE, CL=4
CALL COMPARE ;DOES CURBCB(0-3) = ADRIVE || ARECORD
pop di
mov bx,cur_bcba
JNZ get_bcb15 ;NO
mov al,5[bx]
cmp al,0ffh! je get_bcb14 ;does bcb(5) = 0ffh? (not seq)
mov ah,phy_off
CMP al,ah! JZ GET_BCB14 ;DOES BCB(5) = PHY_OFF? (same record)
INC al ;INCR BCB SEQUENCE
CMP AL,ah! JZ GET_BCB13 ;DOES BCB(5)+1 = PHY_OFF? (next record)
mov al,0ffh ;no - mark bcb as not seg
GET_BCB13:
mov 5[bx],al
GET_BCB14:
JMP GET_BCB3 ;MOVE CUR BCB TO HEAD OF BCB LIST
GET_BCB15:
mov ax,14[bx]
cmp ax,rlr ;DOES CURRENT PROCESS OWN BCB?
JNZ GET_BCB17 ;NO
mov al,adrive
cmp al,[bx]! jne get_bcb17 ;does the drive match?
MOV AL,phymsk
or al,al! jz get_bcb17 ;does phymsk = 0?
CMP AL,5[bx] ;DOES BCB(5) = PHYMSK?
jne GET_BCB17 ;NO
MOV byte ptr 5[BX],0 ;yes - seq bcb - bcb(5) = 0
; move bcb to end of list
cmp word ptr 12[bx],0 ;IS CUR BCB ALREADY AT END OF LIST?
JZ GET_BCB2 ;YES
DEC P_BCB_CNT
xor ax,ax ;BCB(LINK) = 0
xchg ax,12[bx] ;remove cur bcb from bcb list
mov 12[di],ax
xchg ax,bx ;place cur bcb at end of bcb list
GET_BCB16:
mov si,bx
mov bx,12[si]
or bx,bx! jnz get_bcb16
mov 12[si],ax
jmps get_bcb18
GET_BCB17:
cmp word ptr 12[bx],0 ;is bcb at end of list
je get_bcb2 ; yes
mov di,bx ;DI = new last bcb
GET_BCB18:
mov bx,12[di] ;BX = new cur bcb
JMP GET_BCB1
GET_BCB2: ;END OF BCB SCAN - NO MATCH
MOV si,EMPTY_BCBA ;WAS A DISCARDED OR INACTIVE BCB
or si,si ;FOUND?
jz GET_BCB25 ;NO
mov di,si ;LAST_BCBA = EMPTY_BCBA
GET_BCB25:
MOV SI,ROOT_BCBA ;IS THE NUMBER OF BCB'S OWNED
MOV AL,P_BCB_CNT ;BY THIS PROCESS GREATER THAN
CMP AL,2[SI] ;THE MAXIMUM SET BY GENSYS?
JC GET_BCB26 ;NO
MOV di,P_LAST_BCBA ;USE THE LAST BCB OWNED BY THE
GET_BCB26: ;CURRENT PROCESS
mov bx,12[di]
mov al,phy_off
mov 5[bx],al ;sequence field = phy_off
GET_BCB3:
MOV SI,ROOT_BCBA ;PUT CURBCB ON HEAD OF BCB LIST
MOV AX,[SI]
cmp ax,bx ;is cur bcb at head of bcb list
je get_bcb35 ;yes
xchg ax,12[bx]
mov 12[di],ax
MOV [SI],BX
GET_BCB35:
MOV AX,RLR ;SET THE BCB PROCESS FIELD
MOV 14[BX],AX
RET
;
; unallocated block entry structure
;
; +-----+-----+-----+-----+-----+-----+
; | LINK | BLOCK | DRV | HWM |
; +-----+-----+-----+-----+-----+-----+
;
; LINK - link to next entry or 0 if end of list
; BLOCK - allocation block number
; DRV - drive number or 0FFh if not valid
; HWM - high water mark of sectors written to block
;
ua_link equ word ptr 0
ua_block equ word ptr 2
ua_drv equ byte ptr 4
ua_hwm equ byte ptr 5
ua_setup: ;set up unallocated block entry in list
;--------
; entry: DX = block number
; exit: DX = block number
mov bx,offset ua_lroot ;get unallocated list root
ua_in1:
mov di,bx ;save last entry address
mov bx,ua_link[bx]
cmp ua_link[bx],0 ;loop to end of list
jne ua_in1
mov al,adrive ;initialize entry values
mov ua_drv[bx],al
mov ua_block[bx],dx
xor ax,ax
mov ua_hwm[bx],al
mov ua_link[di],ax ;zero link of last entry
mov ax,bx
xchg ua_lroot,ax ;place entry at beginning of list
mov ua_link[bx],ax
ret
ua_discard: ;invalidates entrys for the current disk
;----------
; entry: none
mov al,adrive ;get current disk
mov bx,offset ua_lroot
ua_fl1:
mov bx,ua_link[bx]
cmp ua_drv[bx],al
jne ua_fl2
mov ua_drv[bx],0ffh
ua_fl2:
cmp ua_link[bx],0 ;loop to end of list
jne ua_fl1
ret
ua_preread: ;check if pre read is required
;----------
; entry: CL = vrecord number & blkmsk
; exit: C flag set if pre read required
if PCMODE
test media_format,0FFh
jz ua_cpm ;if media format is PCDOS
cmp pc_pre_read,1 ; and PC_PRE_READ is non-zero
cmc ; set carry flag (pre read is required)
ret
ua_cpm:
endif
mov al,adrive
mov bx,offset ua_lroot
mov dx,blk_num ;DX = block number
ua_pr0:
mov bx,ua_link[bx]
cmp ua_drv[bx],al ;if ua_drv = curdsk
jne ua_pr2 ; and ua_block = block# then
cmp ua_block[bx],dx ; check high water mark
jne ua_pr2
cmp cl,ua_hwm[bx] ;if ua_hwm <= cl then
jb ua_pr1
mov al,phymsk
mov ah,al! not ah
and cl,ah! inc al ; compute next physical offset
add al,cl ; save new high water mark
mov ua_hwm[bx],al ; and return with carry reset
ua_pr1:
ret ; else return with carry set
ua_pr2:
cmp ua_link[bx],0
jne ua_pr0
stc ;return with carry set
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,cur_bcba
add di,6 ;MOVE TRACK & SECTOR
mov cx,2 ;TO BCB
rep movsw
ret
if PCMODE
dblockio:
;--------
; Entry: CL = true if reading
; CH = true if preread is required on write
mov ah,1
test cl,cl ! jnz dblockio_1
inc ah
dblockio_1: ;AH = 1 - reading, 2 - writing
mov pc_pre_read,ch ;setup pre read condition
jmp deblock_dta
endif
READ_DEBLOCK:
;------------
mov ah,1 ;AH = 1
CALL DEBLOCK_DTA
JMP SETFCB
DEBLOCK_DIR:
;-----------
MOV CUR_dma_seg,DS ;BUFFERS IN SYSTEM DATA AREA
MOV BX,DIR_BCBA
CMP AH,5 ;IS FX = DIRECTORY UPDATE?
JNZ DEBLOCK ;NO
MOV BX,CUR_BCBA ;YES - CUR_BCBA KNOWN FROM
jmps DEBLOCK ;PREVIOUS LOCATE CALL
DEBLOCK_DTA:
;-----------
MOV BX,DAT_BCBA
MOV CUR_dma_seg,0 ;get segment from BCB
CMP AH,4 ;IS FX = FLUSH?
JNZ DEBLOCK ;NO
DEBLOCK_FLUSH:
;-------------
MOV BX,[BX]
MOV TRACK,0FFFFH
DEBLOCK_FLUSH0:
MOV AL,ADRIVE
CMP AL,[BX] ;DOES BCB(0) = ADRIVE?
JNZ DEBLOCK_FLUSH1 ;NO
TEST BYTE PTR 4[BX],0FFH ;IS BUFFER WRITE PENDING?
JZ DEBLOCK_FLUSH1 ;NO
MOV ax,14[BX] ;IS BCB OWNED BY CALLING PROCESS?
CMP ax,RLR
JNZ DEBLOCK_FLUSH1 ;NO
MOV AX,6[BX] ;IS BCB(6) < TRACK?
CMP AX,TRACK
JNC DEBLOCK_FLUSH1 ;NO
MOV TRACK,AX ;YES - TRACK = BCB(6)
MOV SECTOR,BX ;SECTOR = .BCB
DEBLOCK_FLUSH1:
mov bx,12[bx]
or bx,bx
JNZ DEBLOCK_FLUSH0
CMP TRACK,0FFFFH ;WAS A DIRTY BCB FOUND?
JNZ $+3 ;YES
RET
MOV BX,SECTOR ;FLUSH THE BCB'S BUFFER
xor al,al ;set z flag
MOV AH,4
mov cur_dma_seg,0 ;get segment from BCB
CALL DEBLOCK
MOV BX,DAT_BCBA
jmps DEBLOCK_FLUSH
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
lahf ;save Z flag
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
sahf
JZ $+5 ;IF DEBLOCK CALLED WITH Z FLAG RESET
CALL GET_BCBA ;THEN GET BCB ADDRESS
MOV CUR_BCBA,BX
MOV ax,10[BX] ;dma address field - offset/segment
cmp cur_dma_seg,0 ;if cur_dma_seg <> 0, deblocking is
jne deblock0 ; for dir buf and addr is offset
mov cur_dma_seg,ax ;else deblocking data buffer and
xor ax,ax ; addr is segment, offset = 0
deblock0:
MOV CUR_DMA,ax ;save current buffer address
mov al,deblock_fx
cmp al,3! jne deblock01 ;if (deblock func = locate)
xor ah,ah ; and (must read dir = true)
xchg rd_dir_flag,ah ; force sector read from disk
test ah,0f0h ; to verify media has not changed
jnz deblock25
deblock01:
CALL DEBLOCK9 ;BX=CUR_BCBA, DX=.ADRIVE, CL=4
cmp b[bx],0ffh! je deblock2
CMP al,4 ;IS DEBLOCK_FX >=4?
JNC DEBLOCK1 ;YES
CALL COMPARE ;DOES BCB(0-3) = ADRIVE || ARECORD?
JZ DEBLOCK45 ;YES
DEBLOCK1:
CMP al,5 ;IS DEBLOCK_FX = DIR UPDATE?
JZ DEBLOCK15 ;YES
TEST BYTE PTR 4[BX],0FFH ;IS BCB(4) WRITE PENDING FLAG SET?
JZ DEBLOCK2 ;NO
DEBLOCK15:
MOV BYTE PTR 4[BX],0 ;WRITE BCB BUFFER
PUSH WORD PTR ADRIVE ;SAVE ADRIVE & ARECORD(0)
PUSH WORD PTR ARECORD+1 ;SAVE ARECORD(1,2)
mov ax,2[bx]
mov word ptr arecord+1,ax
mov ax,[bx]
mov word ptr adrive,ax ;ADRIVE || ARECORD = CURBCB(0-3)
MOV BYTE PTR [BX],0FFH ;DISCARD BUFFER IN CASE WRITE FAILS
cmp curdsk,al
je $+5
call disk_select1
mov al,1
jnz $+5
CALL DEBLOCK_IO ;write buffer if drive logged in
CALL DEBLOCK9 ;RESTORE BCB PREFIX
CALL MOVE
POP WORD PTR ARECORD+1 ;RESTORE ARECORD(1,2)
POP WORD PTR ADRIVE ;RESTORE ADRIVE & ARECORD(0)
CALL CURSELECT
DEBLOCK2:
MOV al,DEBLOCK_FX ;DOES DEBLOCK_FX = DIR UPDATE OR FLUSH
CMP al,4
JC $+3
RET ;YES
CMP al,2 ;DOES DEBLOCK_FX = WRITE?
JNZ DEBLOCK25 ;NO
MOV cl,BLK_OFF
call ua_preread ;is preread required?
jc DEBLOCK25 ; yes
XOR AL,AL
CALL DEBLOCK_IO ;SEEK ONLY
JMPS DEBLOCK4
DEBLOCK25:
mov bx,cur_bcba
mov b[bx],0ffh ;discard in case of error
MOV AL,2
CALL DEBLOCK_IO ;READ PHYSICAL RECORD
DEBLOCK4:
CALL DEBLOCK9 ;BX=CUR_BCBA, DX=.ADRIVE, CL=4
CALL MOVE
MOV B[DI],0 ;CUR_BCBA->BCB(4) = 0
DEBLOCK45:
xor al,al
MOV ah,PHY_OFF
shr ax,1 ;AX = phy_off * 080h
MOV SI,CUR_DMA
ADD SI,AX ;SI = CUR_DMA + 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,dma_ofst
CMP al,1 ;IS DEBLOCK_FX = READ?
mov ax,dma_seg
mov dx,cur_dma_seg
push ds! push es
je DEBLOCK7 ; yes
MOV BYTE PTR 4[BX],0FFH ; no - write
xchg di,si ;exchange dma offsets
xchg ax,dx ;exchange dma segments
DEBLOCK7:
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,CUR_BCBA
MOV DX,OFFSET ADRIVE
MOV CL,4
RETD1:
RET
read_dir:
;--------
call rdir
test relog,0ffh
jz retd1
call chk_exit_fxs
CALL TST_RELOG ;RELOG IN DRIVE
;JMP RDDIR ;READ DIR REC ZERO & 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 drec,ax
MOV ARECORD,ax ;ARECORD = SHR(DCNT,DSKSHF)
MOV BYTE PTR ARECORD+2,0
MOV AH,3 ;LOCATE COMMAND
JMPS WRDIR0
if PCMODE
rd_pcdir:
;--------
; Exit: AX = offset of directory entry
; = 0 if end of directory
call read_dir
call endofdir
jnz rd_pcdir1
xor ax,ax
ret
rd_pcdir1:
call get_dptra
mov ax,bx
ret
endif
wrdir: ;write the current directory entry, set checksum
;-----
call checkwrite ;verify disk is read/write
MOV AH,5 ;DIRECTORY UPDATE CODE
CALL WRDIR0
mov cl,true
JMP CHECKSUM ;initialize entry
WRDIR0:
CALL DEBLOCK_DIR
;JMPS SETDATA
setdata: ;set data dma address
;-------
MOV ax,dma_seg
MOV CUR_dma_seg,ax
MOV ax,dma_ofst
MOV CUR_DMA,ax
RET
rdir: ;read next directory entry
;----
; entry: CL = true if initializing
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
jnb $+5 ; no
jmp setenddir ; yes, set dcnt to end
; of directory
; not at end of directory, seek next element
;cl=initialization flag
mov al,ldcnt
and al,dskmsk ;low(dcnt) and dskmsk
push cx
mov cl,fcbshf ;to multiply by fcb size
shl al,cl
pop cx
;a = (low(dcnt) and dskmsk)
;shl fcbshf
mov dptr,al ;ready for next dir operation
test rd_dir_flag,true ;if must read or locate dir
jnz rddir2 ; read next directory record
or al,al ;else
jnz ret71 ; return if not a new record
RDDIR2:
push cx ;save initialization flag cl
call rddir ;read the directory record
pop cx ;recall initialization flag
test relog,0ffh
jnz ret71
;jmps checksum ;checksum the directory element
checksum:
;--------
; compute current checksum record and update the
; directory element if cl=true, or check for = if not
; drec < chksiz?
; entry: CL = true update checksum
; = false if check for equal
mov dx,drec
mov bx,chksiz
and bh,7fh ;remove permanent drive bit
sub dx,bx
jae ret7 ;skip checksum if past
;checksum vector size
;drec < chksiz, so continue
push cx ;save init flag
call cmpecs ;check sum value to al
mov bx,drec ;value of arecord
add bx,checka ;bx=.check(arecord)
pop cx ;recall true or false to cl
inc cl ;true produces zero flag
jz initcs
if BMPM
inc cl ;0feh produces zero flag
jz test_dir_cs
endif
;not initializing, compare
cmp al,[bx] ;compute$cs=check(arecord)?
jz ret7 ;no message if ok
CALL NOWRITE
JNZ RET7 ;RETURN IF ALREADY READ/ONLY
media_change:
mov bx,dat_bcba
call discard
if BMPM
call flush_file0 ;flush files
endif
mov al,0ffh
MOV RELOG,al
mov hashl,al
mov bx,offset rlog
call setcdisk
; mov cl,curdsk ;ax is setup in setcdisk
; mov ax,1
; shl ax,cl
jmp reset_37x
if BMPM
test_dir_cs:
cmp al,[bx] ;compute_cs=check(arecord)
jz ret7
jmp flush_files
endif
initcs:
;initializing the checksum
mov [bx],al
ret7: ret
;********** end bdos file system part 1 **********

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