; CP/M 2.0 disk re-definition library ; ; Copyright (c) 1979 ; Digital Research ; Box 579 ; Pacific Grove, CA ; 93950 ; ; CP/M logical disk drives are defined using the ; macros given below, where the sequence of calls ; is: ; ; disks n ; diskdef parameter-list-0 ; diskdef parameter-list-1 ; ... ; diskdef parameter-list-n ; endef ; ; where n is the number of logical disk drives attached ; to the CP/M system, and parameter-list-i defines the ; characteristics of the ith drive (i=0,1,...,n-1) ; ; each parameter-list-i takes the form ; dn,fsc,lsc,[skf],bls,dks,dir,cks,ofs,[0] ; where ; dn is the disk number 0,1,...,n-1 ; fsc is the first sector number (usually 0 or 1) ; lsc is the last sector number on a track ; skf is optional "skew factor" for sector translate ; bls is the data block size (1024,2048,...,16384) ; dks is the disk size in bls increments (word) ; dir is the number of directory elements (word) ; cks is the number of dir elements to checksum ; ofs is the number of tracks to skip (word) ; [0] is an optional 0 which forces 16K/directory entry ; ; for convenience, the form ; dn,dm ; defines disk dn as having the same characteristics as ; a previously defined disk dm. ; ; a standard four drive CP/M system is defined by ; disks 4 ; diskdef 0,1,26,6,1024,243,64,64,2 ; dsk set 0 ; rept 3 ; dsk set dsk+1 ; diskdef %dsk,0 ; endm ; endef ; ; the value of "begdat" at the end of assembly defines the ; beginning of the uninitialize ram area above the bios, ; while the value of "enddat" defines the next location ; following the end of the data area. the size of this ; area is given by the value of "datsiz" at the end of the ; assembly. note that the allocation vector will be quite ; large if a large disk size is defined with a small block ; size. ; dskhdr macro dn ;; define a single disk header list dpe&dn: dw xlt&dn,0000h ;translate table dw 0000h,0000h ;scratch area dw dirbuf,dpb&dn ;dir buff,parm block dw csv&dn,alv&dn ;check, alloc vectors endm ; disks macro nd ;; define nd disks ndisks set nd ;;for later reference dpbase equ $ ;base of disk parameter blocks ;; generate the nd elements dsknxt set 0 rept nd dskhdr %dsknxt dsknxt set dsknxt+1 endm endm ; dpbhdr macro dn dpb&dn equ $ ;disk parm block endm ; ddb macro data,comment ;; define a db statement db data comment endm ; ddw macro data,comment ;; define a dw statement dw data comment endm ; gcd macro m,n ;; greatest common divisor of m,n ;; produces value gcdn as result ;; (used in sector translate table generation) gcdm set m ;;variable for m gcdn set n ;;variable for n gcdr set 0 ;;variable for r rept 65535 gcdx set gcdm/gcdn gcdr set gcdm - gcdx*gcdn if gcdr = 0 exitm endif gcdm set gcdn gcdn set gcdr endm endm ; diskdef macro dn,fsc,lsc,skf,bls,dks,dir,cks,ofs,k16 ;; generate the set statements for later tables if nul lsc ;; current disk dn same as previous fsc dpb&dn equ dpb&fsc ;equivalent parameters als&dn equ als&fsc ;same allocation vector size css&dn equ css&fsc ;same checksum vector size xlt&dn equ xlt&fsc ;same translate table else secmax set lsc-(fsc) ;;sectors 0...secmax sectors set secmax+1 ;;number of sectors als&dn set (dks)/8 ;;size of allocation vector if ((dks) mod 8) ne 0 als&dn set als&dn+1 endif css&dn set (cks)/4 ;;number of checksum elements ;; generate the block shift value blkval set bls/128 ;;number of sectors/block blkshf set 0 ;;counts right 0's in blkval blkmsk set 0 ;;fills with 1's from right rept 16 ;;once for each bit position if blkval=1 exitm endif ;; otherwise, high order 1 not found yet blkshf set blkshf+1 blkmsk set (blkmsk shl 1) or 1 blkval set blkval/2 endm ;; generate the extent mask byte blkval set bls/1024 ;;number of kilobytes/block extmsk set 0 ;;fill from right with 1's rept 16 if blkval=1 exitm endif ;; otherwise more to shift extmsk set (extmsk shl 1) or 1 blkval set blkval/2 endm ;; may be double byte allocation if (dks) > 256 extmsk set (extmsk shr 1) endif ;; may be optional [0] in last position if not nul k16 extmsk set k16 endif ;; now generate directory reservation bit vector dirrem set dir ;;# remaining to process dirbks set bls/32 ;;number of entries per block dirblk set 0 ;;fill with 1's on each loop rept 16 if dirrem=0 exitm endif ;; not complete, iterate once again ;; shift right and add 1 high order bit dirblk set (dirblk shr 1) or 8000h if dirrem > dirbks dirrem set dirrem-dirbks else dirrem set 0 endif endm dpbhdr dn ;;generate equ $ ddw %sectors,<;sec per track> ddb %blkshf,<;block shift> ddb %blkmsk,<;block mask> ddb %extmsk,<;extnt mask> ddw %(dks)-1,<;disk size-1> ddw %(dir)-1,<;directory max> ddb %dirblk shr 8,<;alloc0> ddb %dirblk and 0ffh,<;alloc1> ddw %(cks)/4,<;check size> ddw %ofs,<;offset> ;; generate the translate table, if requested if nul skf xlt&dn equ 0 ;no xlate table else if skf = 0 xlt&dn equ 0 ;no xlate table else ;; generate the translate table nxtsec set 0 ;;next sector to fill nxtbas set 0 ;;moves by one on overflow gcd %sectors,skf ;; gcdn = gcd(sectors,skew) neltst set sectors/gcdn ;; neltst is number of elements to generate ;; before we overlap previous elements nelts set neltst ;;counter xlt&dn equ $ ;translate table rept sectors ;;once for each sector if sectors < 256 ddb %nxtsec+(fsc) else ddw %nxtsec+(fsc) endif nxtsec set nxtsec+(skf) if nxtsec >= sectors nxtsec set nxtsec-sectors endif nelts set nelts-1 if nelts = 0 nxtbas set nxtbas+1 nxtsec set nxtbas nelts set neltst endif endm endif ;;end of nul fac test endif ;;end of nul bls test endm ; defds macro lab,space lab: ds space endm ; lds macro lb,dn,val defds lb&dn,%val&dn endm ; endef macro ;; generate the necessary ram data areas begdat equ $ dirbuf: ds 128 ;directory access buffer dsknxt set 0 rept ndisks ;;once for each disk lds alv,%dsknxt,als lds csv,%dsknxt,css dsknxt set dsknxt+1 endm enddat equ $ datsiz equ $-begdat ;; db 0 at this point forces hex record endm ;