*BASIC
AUTO
REM > Z/FREE
REM Z80 Source code for FREE.COM
REM v0.01 28-Nov-88 JGH: Initial version
:
DIM mcode% &800:start%=&100
BDOS=5
:
FOR P=0 TO 1
O%=mcode%:P%=start%
[OPT P*3+4
LD C,25:CALL BDOS:\ PUSH AF:  :\ Read current drive
:
LD C,27:CALL BDOS:PUSH HL     :\ Get allocation table address
LD C,31:CALL BDOS             :\ Get disk parameter block address
INC HL:INC HL:LD A,(HL)       :\ A=BlockSHift
LD DE,3:ADD HL,DE             :\ HL=>DiskSizeMax
LD E,(HL):INC HL:LD D,(HL)    :\ DE=DiskSizeMax
POP IX:PUSH DE:PUSH AF:LD HL,0:\ Save size, zero total
\ IX=> alloc, A=acc, B=8 loop, C=byte, DE=DSM, HL=size
:
.Loop0
LD B,8:LD C,(IX+0)            :\ Set up inner loop, get byte
.Loop1
SLA C:JR NC,BitZero:INC HL    :\ Inc total if bit set
.BitZero
DEC DE:LD A,D:AND E:JR Z,TotalCounted
DJNZ Loop1:INC IX:JR Loop0
:
.TotalCounted
POP AF:POP DE                 :\ A=BSH, DE=DSM
EX DE,HL:AND A:SBC HL,DE      :\ DE=used, HL=free
DEC A
.Loop3
SLA E:RL D:SLA L:RL H         :\ Shift DE and HL left
DEC A:JR NZ,Loop3
:
PUSH DE:CALL PrNumbers
LD DE,StrFree:CALL PrString
POP HL:CALL PrNumbers
LD DE,StrUsed:CALL PrString
:
\ pops
RET
:
.PrNumbers
LD (Total+1),HL:SLA L:RL H    :\ Store, convert to 128-byte sector count
LD A,H:CALL PrHex:LD A,L:CALL PrHex:\  Print sector total
LD DE,StrSectors:CALL PrString
LD A,ASC" ":LD (Lead),A
LD C,&F:LD DE,&4240:CALL PrDec
:
CALL PrComma
LD C,&1:LD DE,&86A0:CALL PrDec
LD DE,10000:CALL PrDec0
LD DE,1000:CALL PrDec0
:
CALL PrComma
LD DE,100:CALL PrDec0
LD DE,10:CALL PrDec0
LD A,(Total):CALL PrNybble
LD DE,StrBytes
:
.PrString
LD C,9:JP BDOS
:
.PrHex
PUSH AF:RRA:RRA:RRA:RRA
CALL PrNybble:POP AF
:
.PrNybble
AND 15:CP 10
JR C,P%+4:ADD A,7
ADD A,ASC"0"
.OUTCHR
PUSH HL
LD E,A:LD C,2:CALL BDOS
POP HL:RET
:
.PrDec0
LD C,0
.PrDec
LD B,&FF
LD A,(Total+2):LD HL,(Total) 
.DecLoop
INC B:€ A:SBC HL,DE:SBC A,C
JR NC,DecLoop
ADD HL,DE:ADC A,C
LD (Total+2),A:LD (Total),HL
LD A,B:€ A:JR Z,PrZero
LD A,ASC"0":LD (Lead),A
LD A,B:JP PrNybble
.PrZero
LD A,(Lead):JP OUTCHR
:
.PrComma
LD A,(Lead):CP ASC" ":JR Z,OUTCHR
LD A,ASC",":JP OUTCHR
:
RET
:
.Lead
DEFM " "
:
.Total
DEFB 0:DEFW 0
:
.StrSectors
DEFM " Sectors = $"
:
.StrBytes
DEFM " Bytes $"
.StrFree
DEFM "Free":DEFB 13:DEFB 10:DEFM "$"
.StrUsed
DEFM "Used":DEFB 13:DEFB 10:DEFM "$"
:
]NEXT
A$="*SAVE FREE.COM "+STR$~mcode%+" "+STR$~O%
PRINT A$