;File:    DIRSIZE.ASM
;
;         DIRSIZE - Display directory size.
;         Count the number of occupied slots
;         in the disk directory.
;
5000      ORG 100H
DRS:      LXI H,0             ;Present COUNT = 0
5005      SHLD COUNT
5010      LXI D,BUFF          ;Set buffer address
5015      MVI C,1AH
5020      CALL 5
;
5025      MVI C,11H           ;Find first occurence
5030      LXI D,FCB
5035      CALL 5
5040      CPI 0FFH
5045      JZ DRS2             ;If done
;
DRS1:     CALL AEC            ;Advance entry count
5050      MVI C,12h           ;Find next occurence
5055      CALL 5
5060      CPI 0FFH
5065      JNZ DRS1            ;If not done
;
;         Display the resulting count.
;
DRS2:     CALL ALN            ;CR,LF
5070      LHLD COUNT
5075      CALL DHW            ;Display hex word
5080      LXI D,DRSA          ;"entries used"
5080      CALL MSG
5085      JMP 0000
;
;         AEC - Advance Entry Count.
;
AEC:      LHLD COUNT
5090      INX H
5095      SHLD COUNT
6000      RET
;
DRSA:     DB      ' directory entries are currently'
6005      DB      ' occupied (value in hex).$'
COUNT:    DW      0
FCB:      DB      0,'???????????',0,0,0,0
6010      DS      20
;
;         DHW-DISPLAY HEX WORD.
;         DISPLAY FOUR HEX DIGITS
;         ENTRY HL=WORD TO BE DISPLAYED
;
DHW:      PUSH H
2710      MOV A,H              ;DISPLAY HIGH BYTE
2720      CALL DHB
2730      POP H
Š2740      MOV A,L             ;Display low byte
;
;         DHB - Display Hex Byte.
;         Display two hex digits.
;         Entry   A = byte to be displayed
;
DHB:      PUSH PSW
3000      RRC ! RRC ! RRC ! RRC
3100      CALL DHD            ;display hex digit
3200      POP PSW
;
;         DHD - Display Hex Digit.
;         Entry   A,low 4 bits = digit
;
DHD:      ANI 0FH
3300      CPI 10
3400      JNC DHD1            ;If not 0 through 9
;
3500      ADI '0'
3600      JMP DCH
;
DHD1:     ADI 'A'-10          ;Create "A,B,C,D,E, or F"
;
;         DCH - Display one character.
;         Entry   A = ASCII encoded char
;
DCH:      MOV E,A
3800      MVI C,2
3900      CALL 5
4100      RET
;
;         ALN - Advance to new line.
;         Issue CR,LF
;
ALN:      MVI A,0DH          ;carriage-return
4500      CALL DCH
4505      MVI A,0AH           ;line-feed
4600      CALL DCH
4700      RET 
;
;         FCC - Filter out Control Codes.
;         Entry   A = ASCII code
;         Exit    B = ASCII graphic char
;                 A = 'up-arrow' if control-code
;                   = blank, if graphic
;
FCC:      CPI 20H
1700      JNC FCC1            ;If not control code
;
;         We have a control-code.
;         Return 'up-arrow' in A; graphic in B.
;
1800      ADI 40H
1900      MOV B,A
2000      MVI A,5EH           ;up-arrow
Š2100      RET
;
;         We have a graphic character.
;         Return blank in A; graphic in B.
;
FCC1:     MOV B,A
2200      MVI A,20H           ;blank
2300      RET
;
;         MSG - Issue Message to Console.
;         Entry   DE = message address
;
MSG:      MVI C,9
2400      CALL 5
2500      RET
;
;         RCC - Read a Console Character.
;         Exit    A = character
;
RCC:      MVI C,1
2600      CALL 5
2700      RET          
          ORG  200H
BUFF      EQU  $