System information

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
Appendix F : CP/M Disk Definition Library CP/M Operating System Manual
F-5