;NULLKILL
;	A program to filter nulls from text files.
; USAGE:  FILTER  d:fn.ext d:fn.ext
;		Will copy first to second, filtering as it goes.


;	Sunday   Feb 6 1983  2145
;	VERSION 1.0


        ORG 100H
;              COPY FILE 1 TO FILE 2, eliminate
;               all NULL CHARACTERS 
;

        MACLIB  SEQIO   ;SEQUENTIAL IO LIB
        MACLIB  MACRO   ;to include the print routine
BOOT    EQU     0000H   ;SYSTEM REBOOT
UCASE   EQU     5FH     ;UPPER CASE BITS
DELETE	EQU	7FH	; DELETE CHARACTER
SUPERCR	EQU	8DH	;SUPERCR or 8th bit set carriage return
SPACE	EQU	20H	; SPACE is 20H or 32 decimal
SUPERSPACE EQU	0A0H	; SPACE +7F +1
PERIOD	EQU	2EH	; PERIOD CHARACTER
SUPERPERIOD EQU	0AEH	; 2E + 7F + 1
QUESTION EQU	3FH	; QUESTION MARK
NULL	equ	00000000b ; null characters
;
;
        LXI     SP,STACK
;
;	***********************************************
	PRINT	<'Program filters NULL characters.',cr,lf>
	PRINT	<'Usually useful on TEXT files.',cr,lf>
	PRINT	<cr,lf>

;
;       *************************************************
;       DEFINE SOURCE FILE:
;               INFILE  = INPUT FILE
;               SOURCE  = INTERNAL NAME
;               (NUL)   = DEFAULT DISK
;               1       = FIRST DEFAULT NAME
;               (NUL)   = FIRST DEFAULT TYPE
;               2000    = BUFFER SIZE
        FILE    INFILE,SOURCE,,1,,2000
;
;       *************************************************
;       DEFINE DESTINATION FILE:
;               OUTFILE = OUTPUT FILE
;               DEST    = INTERNAL NAME
;               (NUL)   = DEFAULT DISK
;               2       = SECOND DEFAULT NAME
;               (NUL)   = SECOND DEFAULT TYPE
;               2000    = BUFFER SIZE
        FILE    OUTFILE,DEST,,2,,2000
;
;       *************************************
;
;       READ SOURCE FILE, TRANSLATE, WRITE DESTINATION
CYCLE:  GET     SOURCE
CYCLE1:	CPI     EOF             ;END OF FILE?
        JZ      ENDCOPY         ;SKIP TO END IF SO
;
	CPI	NULL		; is it a null?
	JZ	WASNULL		; if null, ignore it
;
;	PUT	CON
;				if you want it to print to the console, remove
;				the semicolon from above line.
	PUT	DEST		; Output the character
	JMP	CYCLE		; get another
;
;
WASNULL:
	PRINT	<'.'>		; OUTPUT A DOT TO SHOW NULL GONE
	JMP	CYCLE
;
;
NOCONV: 			;DOES NOTHING AT THE MOMENT
;       PUT     CON             ;WRITE TO CONSOLE
        PUT     DEST            ;AND TO DESTINATION FILE
	LDA	LNCNT		; GET THE LINECOUNTER
        INR     A               ;INCREMENT LINECOUNTER
        STA     LNCNT           ;STORE LINECOUNTER
        JMP     CYCLE           ;GO GET ANOTHER CHARACTER
;
;
ENDCOPY:
;	MVI	A,1AH		; GET A CONTROL Z
;        PUT     CON		; OUTPUT THE CONTROL Z
;        PUT     DEST		; PROBABLY NOT NEEDED SINCE FINIS DOES IT TOO

        FINIS   DEST            ;END OF OUTPUT
        JMP     BOOT            ;BACK TO CCP
;
SPCNT:  DB      0               ;INITIALIZE SPACECOUNTER
LNCNT:  DB      0               ;INITIALIZE LINECOUNTER
        DS      32              ;16 LEVEL STACK
STACK:
BUFFERS:
MEMSIZE EQU     BUFFERS+@NXTB   ;PROGRAM SIZE
        END