10 ; BBS CRASHBUSTER, LISTING 2›20 ; BY MATTHEW RATCLIFF›30 ; (c) 1985, ANTIC PUBLISHING›40 ;›50 ;FORM: A=USR(PROG,ADR(L$),LEN(L$))›60 ;›70 RESULT =  $D4     ; RETURN # OF BAD CHARACTERS›80 TXADR =   $D6     ;SAVE STRING ADDR›90 SAVCR =   $D8     ;SAVE CHARACTER TO SEE IF CHANGED›0100     *=  $4000   ;CAN GO ANYWHERE›0110 START›0120     LDA #0      ;ZERO-OUT RESULT›0130     STA RESULT›0140     STA RESULT+1›0150     PLA         ;GET ARGS›0160     BEQ ERROR   ;DISALLOW BAD CALLS›0170     CMP #2      ;MUST BE 2›0180     BEQ AOK     ;GOOD..PROCESS IT›0190     TAX         ;BAD CALL, CLEAN UP STACK›0200 ER1 PLA ›0210     PLA ›0220     DEX ›0230     BNE ER1›0240 ERROR INC RESULT+1›0250 ;THIS WILL RETURN 256 IN CALLING›0260 ;VARIABLE, INDICATING INVALID CALL.›0270     RTS ›0280 AOK PLA ›0290     STA TXADR+1›0300     PLA ›0310     STA TXADR   ;GET STRING ADDRESS›0320     PLA ›0330     PLA         ;GET LENGTH›0340     TAY         ;USE AS INDEX›0350 LOOP›0360     LDA (TXADR),Y›0370     STA SAVCR   ;SAVE CHARACTER›0380     AND #$7F    ;DISALLOW INVERSE›0390     SEC ›0400     CMP #32     ;CHECK FOR CONTROL CARS›0410     BCS NCTL    ;NO CONTROL-GOOD›0420     CLC         ;YES, THEN ADD 64›0430     ADC #64     ;TO MAKE IT ASCII CHARACTER›0440 ;CONTROL-LETTERS & INVERSE-CONTROL-LETTERS›0450 ;BECOME EQUIVALENT VALID LETTERS.›0460 NCTL SEC ›0470     CMP #123    ;NO CHARS ABOVE CHR$(123),"z"›0480     BCC OK1›0490     SBC #64     ;TOO BIG, MAKE CTRL-";" A ";"›0500 ;ALSO TAKES CARE OF ESCAPE-CTRL EDIT KEYS›0510 OK1 CMP #96     ;NOT CTRL-PERIOD EITHER›0520     BNE ALLOK›0530     LDA #46     ;CTRL-PERIOD, MAKE IT PERIOD ONLY›0540 ALLOK STA (TXADR),Y›0550     CMP SAVCR›0560     BEQ TEST›0570     INC RESULT  ;KEEP "BAD" COUNT›0580 TEST DEY ›0590     BPL LOOP›0600     RTS         ;CLEANED UP, BACK TO BASIC›0610     .END ›