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Text File | 1996-12-24 | 31KB | 1,213 lines

******************************** * * * PARTB * * Machine Language Routines * * for Table.Librarian * * by James Brodsky * * * * Copyright (c) 1987 * * By Microsparc, Inc. * * * * Merlin Pro Assembler * * * ******************************** *------------------------------------ * Zero page memory locations: *------------------------------------ PTR2 EQU 0 ;general purpose pointer SHAPE1 EQU 2 ;pointer to main table END1 EQU 4 ;end of main table EFLG EQU 6 ;set if [ESC] pressed MAX EQU 7 ;max string len for input PTR EQU 6 ;general use temporary pointer PTR1 EQU 8 ;general use temporary pointer CH EQU $24 ;40 column H cursor CV EQU $25 ;V tab position A1L EQU $3C A1H EQU $3D A2L EQU $3E A2H EQU $3F A4L EQU $42 A4H EQU $43 LINNUM EQU $50 TXTTAB EQU $67 LOMEM EQU $69 ARYTAB EQU $6B STREND EQU $6D HIGHDS EQU $94 HIGHTR EQU $96 LOWTR EQU $9B DSCTMP EQU $9D PRGEND EQU $AF ERRFLG EQU $D8 SHAPE EQU $E8 ;pointer to shape table *------------------------------------ * Hardware addresses: *------------------------------------ BUFFER EQU $200 AMPV EQU $3F5 *------------------------------------ * BASIC and MONITOR routines: *------------------------------------ CHRGET EQU $B1 CHRGOT EQU $B7 MOVEUP EQU $D39A GDBUFS EQU $D539 FRMNUM EQU $DD67 CHKSTR EQU $DD6C CHKCOM EQU $DEBE SYNCHR EQU $DEC0 SYNERR EQU $DEC9 PTRGET EQU $DFE3 STRSPA EQU $E3DD MOVSTR EQU $E5E2 GETBYT EQU $E6F8 GETADR EQU $E752 CLREOL EQU $FC9C RDKEY EQU $FD0C COUT EQU $FDED COUT1 EQU $FDF0 MOVE EQU $FE2C ORG $4000 *-------------------------------------------- * * The following code is run once at $4000 * to embed the ML routines into the main * Applesoft program. * The code between INSTALL and PGMSTART * is then abandoned. * *-------------------------------------------- INSTALL ;embed code into Applesoft LDY #0 LDA PRGEND+1 LDX PRGEND STA A4H STX A4L LDA #>END LDX #<END STA A2H STX A2L LDA #>PGMSTART LDX #<PGMSTART STA A1H STX A1L JSR MOVE CLC LDA #<END-PGMSTART ADC PRGEND STA PRGEND STA LOMEM STA ARYTAB STA STREND LDA #>END-PGMSTART ADC PRGEND+1 STA PRGEND+1 STA LOMEM+1 STA ARYTAB+1 STA STREND+1 JMP $3D0 *------------------------------------------------- * * The following section of code is run once * each time the Applesoft program is loaded. * It moves the embedded ML routines to start * at $C03 and restores the Applesoft * end-of-program pointers to the end of the * Applesoft code. * The area where the ML routines were embedded * can then be used by Applesoft for * variable storage. * NOTE that if the Applesoft program is stopped * and saved after this section has been run, * the ML routines will no longer be saved * with it. * *------------------------------------------------- PGMSTART LDY #0 ;move code to page $C LDA PRGEND STA A2L SEC SBC #<END-SEGMENT STA A1L LDA PRGEND+1 STA A2H SBC #>END-SEGMENT STA A1H SEC LDA PRGEND SBC #<END-PGMSTART STA PRGEND STA LOMEM STA ARYTAB STA STREND LDA PRGEND+1 SBC #>END-PGMSTART STA PRGEND+1 STA LOMEM+1 STA ARYTAB+1 STA STREND+1 LDA #<VAREND LDX #>VAREND STA A4L STX A4H JSR MOVE ;use monitor to move code SETAMPV LDY #1 ;save old amper vector :1 LDA AMPV+1,Y STA STASH,Y DEY BPL :1 LDA #>START ;setup our amper vector LDY #<START STA AMPV+2 STY AMPV+1 LDA #$4C STA AMPV RTS ;return to BASIC after setup *---------------------------------------------------- * Program variable storage area: *---------------------------------------------------- DUM $C03 STASH DS 2 ;save old amper vector here MODE DS 1 STASH1 DS 2 ;[ESC] msg... WARNING - ; STASH1 actually extends ; over 20 bytes and overwrites ; remaining variables in this ; section. ADRSAVE1 DS 2 ;start address of shape ADREND1 DS 2 ;end address of shape LENGTH1 DS 2 ;length of shape ADRSAVE2 DS 2 ;start address of shape to move ADREND2 DS 2 ;end address of shape to move LENGTH2 DS 2 ;length of shape to move FROMNUM DS 1 ;number ofshape to move TONUM DS 1 ;number of location to move to SHAPES DS 1 ;number shapes in table COUNTER DS 1 TEMP DS 3 VAREND DEND *--------------------------------------------------- * * Start of ML code which was embedded in * Applesoft program and has been moved to its * running location. * First routine saves old Ampersand vector and * points Ampersand vector to the main * entry point, START, then exits to BASIC. * *--------------------------------------------------- SEGMENT ORG VAREND *================================================= * Entry to program - called by & vector: * Determine which routine is called and * jump to it. *================================================= START PHA JSR CHRGET ;advance TXTPTR PLA CMP #$80 ;END token BNE NOTEND * EXIT (restore old ampersand vector and pointers) EXIT LDY #1 :1 LDA STASH,Y STA AMPV+1,Y DEY BPL :1 LDA #8 ;set start of BASIC to $801 STA TXTTAB+1 LDA #0 STA TXTTAB STA ERRFLG ;kill ONERR LDY #2 :2 STA (TXTTAB),Y ;zero out first line DEY BPL :2 INC TXTTAB RTS ;end restore machine * Branch to routine called by BASIC: NOTEND CMP #$E3 ;LEN token BEQ GETLEN CMP #$A8 ;STORE token BNE :1 JMP STORE :1 CMP #$84 ;INPUT token BNE :2 JMP STRINGS :2 CMP #$83 ;DATA token BNE :3 JMP DATA :3 CMP #$85 ;DEL token BNE :4 JMP DEL :4 CMP #$D4 ;ABS token BNE :5 JMP STRIP :5 CMP #$D6 ;FRE token BNE :6 JMP MEMORY :6 JMP MEMMOV ;if not one of the above, ; see if it's "MOVE" *--------------------------------------------------------- * GETLEN (Get start and end address of a shape) * Called directly from BASIC for extract-a-shape function. * Also used by ML add and delete routines * * & LEN shapenum * returns: shape start address at PEEK (6) * shape end address at PEEK (8) *--------------------------------------------------------- GETLEN JSR GETBYT ;get number of shape to find GETLEN1 TXA ;enter here from add or delete LDX #0 ASL ;double shape # for index STA PTR1 BCC :1 INX :1 STX PTR1+1 ;move index into PTR1 CLC LDA SHAPE ;move start address of offset to ADC PTR1 ; desired shape into PTR STA PTR LDA SHAPE+1 ADC PTR1+1 STA PTR+1 CLC LDY #0 LDA (PTR),Y ;move start address of desired ADC SHAPE ; shape into PTR1 and into PTR STA PTR1 TAX INY ;Y = 1 LDA (PTR),Y ADC SHAPE+1 STA PTR1+1 STA PTR+1 STX PTR DEY ;Y = 0 :LOOP LDA (PTR1),Y ;scan through data until BEQ :END ; zero byte found INC PTR1 BNE :LOOP INC PTR1+1 BNE :LOOP ;always :END LDY #3 :2 LDA PTR,Y STA ADRSAVE1,Y DEY BPL :2 SEC ;put lngth of shape into LENGTH1 LDA PTR1 SBC PTR STA LENGTH1 LDA PTR1+1 SBC PTR+1 STA LENGTH1+1 INC LENGTH1 BNE :3 INC LENGTH1+1 :3 RTS ;end find LEN of shape *-------------------------------------------------------- * STORE (add one shape to main table from aux table): * * & STORE shapenum AT END (add a shape) * or * & STORE shapenum AT shapenum (insert a shape) * * returns: PEEK (6) = 0 if successful * PEEK (6) = 1 if memory conflice *-------------------------------------------------------- STORE JSR GETBYT ;get number of shape to move STX FROMNUM ;save shape number JSR GETLEN1 ;get address & length of shape JSR MOVPTRS ;move to ADRSAVE2, etc. LDA #$C5 ;check for AT token JSR SYNCHR JSR SWITCH ;switch pointers for GETLEN JSR OURADR ;get params of where to add JSR UNSWITCH ;restore table pointers * Check whether there's room to add shape: CLC LDA END1 ;add length of shape to ADC LENGTH2 ; end address of table PHA LDA END1+1 ADC LENGTH2+1 STA PTR+1 PLA ;compare proposed new end addr CMP SHAPE ; with start addr of aux table LDA PTR+1 SBC SHAPE+1 BCC :OK ;continue if no collision LDA #1 STA EFLG ;else set error flag and RTS ; return without doing :OK LDA SHAPE1 ;new shape table address = STA PTR1 ; old address minus 2 SEC SBC #2 ;move new table index address STA SHAPE1 ; into SHAPE1 STA PTR ; and into PTR LDA SHAPE1+1 STA PTR1+1 ;old index address into PTR1 SBC #0 STA SHAPE1+1 STA PTR+1 LDY #0 STY A1H LDA (PTR1),Y CLC ADC #1 ;add 1 shape to number of STA (SHAPE1),Y ; shapes in table index STA SHAPES INY LDA (PTR1),Y ;move second byte of index STA (SHAPE1),Y ; down 2 addresses INY ;Y = 2 STY A1L LDX TONUM :OFFSET CLC LDA (PTR1),Y ;get shape address offset ADC A1L ;increase for new shape added STA (PTR),Y ;store it 2 bytes lower in index INY ;Y = 3 LDA (PTR1),Y ADC A1H STA (PTR),Y DEY ;Y = 2 JSR INCPTRS JSR INCPTRS DEX BNE :OFFSET BIT MODE ;ADD or INSERT? BPL :INSERT * Make new offset if shape is added at end of table: CLC LDA LENGTH1 ADC #2 STA A1L LDA LENGTH1+1 ADC #0 STA A1H LDX #1 BNE :LOOP ;branch always * Fix offsets if shape is inserted: :INSERT SEC LDA SHAPES SBC TONUM TAX CLC LDA #2 ADC LENGTH2 STA A1L LDA #0 ADC LENGTH2+1 STA A1H :LOOP CLC LDA (PTR),Y ADC A1L STA (PTR),Y INY LDA (PTR),Y ADC A1H STA (PTR),Y DEY JSR INCPTR JSR INCPTR DEX BNE :LOOP BIT MODE ;ADD or INSERT? BMI :ADDEND * Open up space to insert shape: CLC LDA ADRSAVE1 STA LOWTR ;start of block to move ADC LENGTH2 STA A4L ;destination address LDA ADRSAVE1+1 STA LOWTR+1 ADC LENGTH2+1 STA A4H LDA END1 ;end of block to move LDY END1+1 STA HIGHTR INC HIGHTR BNE :2 INY :2 STY HIGHTR+1 JSR HIGHER ;go move part of table * Move new shape into main table: LDA ADRSAVE1 ;destination address LDY ADRSAVE1+1 BNE :4 ;always :ADDEND LDX ADREND1 ;dest addr for add at end LDY ADREND1+1 INX BNE :3 INY :3 TXA :4 STA A4L STY A4H LDA ADRSAVE2 ;start address LDY ADRSAVE2+1 STA A1L STY A1H LDA ADREND2 ;end address LDY ADREND2+1 STA A2L STY A2H LDY #0 JSR MOVE :UPDATE CLC ;update end of table address LDA LENGTH2 ADC END1 STA END1 LDA LENGTH2+1 ADC END1+1 STA END1+1 LDA #0 STA EFLG ;clear error flag STOREND RTS ;end add one entry *--------------------------------------- * SUBROUTINES (used by STORE and DEL): *--------------------------------------- SWITCH LDX #1 :1 LDA SHAPE,X ;move main shape table address STA TEMP,X ; into SHAPE for GETLEN routine LDA SHAPE1,X STA SHAPE,X DEX BPL :1 RTS UNSWITCH LDX #1 :1 LDA TEMP,X STA SHAPE,X DEX BPL :1 RTS MOVPTRS LDX #5 ;save address & length :1 LDA ADRSAVE1,X STA ADRSAVE2,X DEX BPL :1 RTS OURADR LDY #0 LDA (SHAPE1),Y STA SHAPES ;number shapes in main table STY MODE JSR CHRGOT ;get loc of shape to add or DEL CMP #$80 ;END token ? BNE :1 ;no, go get a shape number STA MODE ;yes, set MODE for end (A = $80) INC MODE JSR CHRGET ;advance TXTPTR and LDA SHAPES ; use number of shapes in table TAX BNE :2 LDA END1 ;use END1 if starting new table LDY END1+1 STA ADRSAVE1 STA ADREND1 STY ADRSAVE1+1 STY ADREND1+1 LDY #0 STY LENGTH1 STY LENGTH1+1 RTS :1 JSR GETBYT :2 STX TONUM ;place to move shape to or from JMP GETLEN1 ;get move-to address and RTS INCPTRS INC PTR1 BNE INCPTR INC PTR1+1 INCPTR INC PTR BNE :1 INC PTR+1 :1 RTS *--------------------------------------------------------- * DEL (Delete one shape): * * & DEL shapenum *--------------------------------------------------------- DEL JSR SWITCH ;move main table adr into SHAPE JSR OURADR ;get info on shape to DEL JSR MOVPTRS ;save it at ADRSAVE2, etc. * Get length of segment to delete: LDX TONUM ;get info on next higher shape CPX SHAPES ; or end of table BNE :1A ;branch if not at end DEC MODE ;else set MODE negative SEC ;and use end of table info LDA END1 SBC ADRSAVE2 STA LENGTH1 LDA END1+1 SBC ADRSAVE2+1 STA LENGTH1+1 CLC BCC :1B :1A INX ;point at next higher shape JSR GETLEN1 ;get info on next higher shape SEC ;calculate length to delete LDA ADRSAVE1 SBC ADRSAVE2 STA LENGTH1 LDA ADRSAVE1+1 SBC ADRSAVE2+1 STA LENGTH1+1 :1B JSR UNSWITCH ;restore SHAPE pointer * Get address of index to last shape: LDX #0 LDA SHAPES ASL ;double # of shapes for index BCC :1 INX :1 CLC ADC SHAPE1 STA PTR TXA ADC SHAPE1+1 STA PTR+1 SEC ;(PTR1) = (PTR - 2) LDA PTR SBC #2 STA PTR1 LDA PTR+1 SBC #0 STA PTR1+1 * Calculate offset for shape deleted if not at END: LDY #0 ;subtract start of this shape CLC ; from start of next shape LDA LENGTH1 ADC #2 STA A1L LDA LENGTH1+1 ADC #0 STA A1H LDA SHAPES BIT MODE ;delete from END ? BMI :3 ;yes SEC ;calculate # of shapes above SBC TONUM ;shape to be deleted TAX ;# of shapes above into X DEX BEQ :3A ;branch if next to last * Decrement all indices above deleted shape: :LOOP SEC LDA (PTR),Y ;get original offset SBC A1L ;subtract for deleted shape STA (PTR),Y ;put back in same place INY ;then do the hi byte LDA (PTR),Y SBC A1H STA (PTR),Y DEY JSR DECPTRS JSR DECPTRS DEX BNE :LOOP ;loop if not finished * Fix offsets for shapes below deleted shape * (Subtract #2 from each offset and move each * offset up one position in table): :3A INC TONUM :3 LDX TONUM DEX :LOOP1 SEC LDA (PTR1),Y SBC #2 STA (PTR),Y INY LDA (PTR1),Y SBC #0 STA (PTR),Y DEY JSR DECPTRS JSR DECPTRS DEX BNE :LOOP1 ;loop until finished BIT MODE BMI :DECNUM ;branch if DEL at END * Move block of table down if shape deleted from middle: LDA ADRSAVE2 ;move-to address LDY ADRSAVE2+1 STA A4L STY A4H LDA ADRSAVE1 ;start of block to move LDY ADRSAVE1+1 STA A1L STY A1H LDA END1 ;end of block to move LDY END1+1 STA A2L STY A2H LDY #0 JSR MOVE ;use monitor move routine * Decrement number of shapes: :DECNUM DEC SHAPES LDA SHAPES STA (PTR),Y ;poke new # into table header INY LDA (PTR1),Y ;move next byte intact-sometimes STA (PTR),Y ; used as a type indicator * Decrease length of table: SEC LDA END1 SBC LENGTH1 STA END1 LDA END1+1 SBC LENGTH1+1 STA END1+1 * Fix start address of table: CLC LDA SHAPE1 ADC #2 STA SHAPE1 LDA SHAPE1+1 ADC #0 STA SHAPE1+1 RTS ;end DEL one shape *------------------------------- * SUBROUTINES (Used by DEL): *------------------------------- DECPTRS LDA PTR1 BNE :1 DEC PTR1+1 :1 DEC PTR1 DECPTR LDA PTR BNE :1 DEC PTR+1 :1 DEC PTR RTS *--------------------------------------------------------- * MEMORY (find how many shapes fit below hi-res page): * Enter with start address of table in $E8,E9 * end address of table in $8,9 * & FRE * returns: PEEK(6) = number of shapes that * will fit below $4000 *--------------------------------------------------------- MEMORY :1 LDA #$40 ;check at $4000 STA PTR2+1 LDY #0 STY PTR2 LDA (SHAPE),Y ;get number of shapes STA TONUM ;and save it LDA SHAPE ;move start address of table LDX SHAPE+1 ; into PTR STA PTR STX PTR+1 LDX #0 ;use X as a counter :LOOP JSR INCPTR ;point at next shape offset JSR INCPTR CLC LDA (PTR),Y ;calculate address of ADC SHAPE ; next shape in table STA PTR2 INY LDA (PTR),Y ADC SHAPE+1 DEY CMP PTR2+1 ;has hi byte reached limit? BLT :2 ;no, increment & continue BGE :3 ;yes, exit :2 INX CPX TONUM ;reached last shape ? BLT :LOOP ;no, back thru loop LDA PTR1+1 ;check end of table CMP PTR2+1 ; for collision BGE :3 ;last shape doesn't fit INX :3 DEX ;we've gone one too far STX EFLG ;mark intact valid shape RTS ;and return to caller *--------------------------------------------------------- * Jump to monitor move routine (to move down) * or to BASIC BLTU routine (to move up) * SYNTAX: * & MOVE,[old start adr],[old end adr] TO [new start adr] *--------------------------------------------------------- MEMMOV EQU * CMP #'M BEQ :1 JMP SYNERR :1 LDA #'O JSR SYNCHR LDA #'V JSR SYNCHR LDA #'E JSR SYNCHR JSR CHKCOM JSR FRMNUM ;get start address JSR GETADR :A LDA LINNUM ;LINNUM has old start address STA A1L ;store it for move down PHA ;push it for move up LDA LINNUM+1 STA A1H PHA * JSR CHKCOM ;next parameter - JSR FRMNUM ; get end address of range JSR GETADR :B LDA LINNUM STA A2L PHA LDA LINNUM+1 STA A2H PHA * LDA #$C1 ;check for "TO" token JSR SYNCHR JSR FRMNUM ;get destination address JSR GETADR LDA LINNUM STA A4L LDA LINNUM+1 STA A4H * PLA ;recover old end address STA HIGHTR+1 ; store it for MOVEUP PLA STA HIGHTR INC HIGHTR BNE :2 INC HIGHTR+1 :2 PLA ;recover old start address STA LOWTR+1 ; store it for MOVEUP PLA STA LOWTR * Decide whether move up or down: CMP LINNUM LDA LOWTR+1 SBC LINNUM+1 BCS LOWER * Move up in memory: HIGHER SEC ;get length of segment LDA HIGHTR ; to move SBC LOWTR TAY LDA HIGHTR+1 SBC LOWTR+1 TAX TYA ;low byte -> A CLC ;add length to destination addr ADC A4L STA HIGHDS TXA ADC A4H STA HIGHDS+1 JMP MOVEUP * Move down in memory: LOWER LDY #0 JMP MOVE ;monitor memory move *---------------------------------------------------- * & DATA: * Determine whether a table is a shape table * or a vector table. * Return with PEEK (6) = 1 if vector * = 0 if shape * Assumption: a vector shape (with no index) will * not have two or more non-consecutive zero bytes *---------------------------------------------------- DATA LDY #0 STY COUNTER STY MODE STY EFLG ;PEEK(6) = 0 :LOOP LDA (PTR1),Y ;get next byte BEQ :INCCTR ;branch if it's zero BIT MODE ;non-zero following zero ? BPL :LOOP1 ;no, continue INC MODE ;yes, clear MODE and continue :LOOP1 INC PTR1 BNE :1 INC PTR1+1 :1 LDA PTR1+1 ;check for end of table CMP PTR2+1 BLT :LOOP LDA PTR1 CMP PTR2 BLT :LOOP BEQ :LOOP INC EFLG ;PEEK(6) = 1 if vector table RTS ;exit to caller :INCCTR BIT MODE ;was preceding byte also 0 ? BMI :LOOP1 ;yes DEC MODE ;set MODE = #$FF INC COUNTER LDA COUNTER CMP #2 BLT :LOOP1 RTS ;PEEK(6) = 0 if shape table ;exit to caller *------------------------------------------------ * STRIP filename routine: * & ABS sexpr1,sexpr2 * returns "pure" filename in sexpr2, less * any ProDOS prefix or slot/drive parameter *------------------------------------------------ STRIP JSR PTRGET ;get name of first string STA PTR1 STY PTR1+1 LDY #0 LDA (PTR1),Y ;get length of string STA LENGTH1 TAX INY LDA (PTR1),Y ;get address of string STA PTR STA A1L INY LDA (PTR1),Y STA PTR+1 STA A1H LDY #0 STY COUNTER :LOOP LDA (PTR),Y ;get next char of string JSR INCPTR CMP #'/ ;is it a slash? BNE :CHKCOM STX LENGTH1 DEC LENGTH1 LDA PTR STA A1L LDA PTR+1 STA A1H CLC BCC :1 ;branch always :CHKCOM CMP #', ;is it a comma ? BNE :1 STX LENGTH2 SEC LDA LENGTH1 SBC LENGTH2 TAX CLC BCC :END :1 DEX BNE :LOOP LDX LENGTH1 :END STX LENGTH2 LDA #$0D ;RETURN STA BUFFER,X DEX LDY #0 :LUP LDA (A1L),Y STA BUFFER,Y INY DEX CPX #$FF BNE :LUP JSR CHKCOM ;read a comma JSR PTRGET ;get adr of second variable LDX LENGTH2 JMP EXIT1 *------------------------------------------------------ * STRING input routine: * & INPUT sexpr [,aexpr] * optional second parameter limits length of input. * if length is defined, routine also writes * them on text page 2 * returns: string input in sexpr * PEEK(6) = 1 if user pressed [ESC] else =0 * [DELETE] key works like backspace *------------------------------------------------------ STRINGS JSR PTRGET ;get name of variable JSR CHKSTR ;make sure it's a string LDY #0 STY MODE LDX #19 ;store pgm's [ESC] prompt :1B LDA $7D7,X STA STASH1,X DEX BPL :1B LDA #$FE STA MAX ;default max input length JSR CHRGOT ;end of input params? BEQ :1 ;yes, branch JSR CHKCOM JSR GETBYT ;get max allowable length INX STX MAX DEC MODE ;MODE = #$FF LDA #$60 STA $B72 :1 LDX #$00 ;zero X reg STX EFLG ;zero ESC flag JSR RDKEY ;get first char input CMP #$8D ;[RETURN] ? BEQ :ADDINP ;yes, process it PHA ;else save it JSR CLREOL ;and clear line on screen PLA JMP :INPUT1 * :NOTCR JSR COUT ;print character BIT MODE BPL :1A STA $B72,X ;print also on page 2 CPX MAX BGE :1A LDA #$60 ;flashing space STA $B73,X ; as a cursor on page 2 :1A INX CPX MAX ;buffer full? BLT :INPUT ;no, go get more input :BCKSPC TXA ;full buffer or back arrow key BEQ :INPUT ;branch if at beginning JSR ERASE ;erase one character BNE :INPUT ;branch if not at beginning JSR FIXPRMPT ;else restore [ESC] prompt :INPUT JSR RDKEY :INPUT1 CMP #$9B ;[ESC] ? BNE :4 ;no, continue CPX #0 ;at beginning of input? BEQ :3 ;yes, set flag and return JSR FIXPRMPT ;no, restore [ESC] message and :2 JSR ERASE ; erase to beginning of input BNE :2 BEQ :INPUT :3 INC EFLG ;set ESC flag and BNE :CR ; return to BASIC :4 CMP #$88 ;[<--] BEQ :BCKSPC CMP #$FF ;[DELETE] BEQ :BCKSPC CMP #$8D ;[RETURN] BEQ :ADDINP CMP #$A0 ;reject CONTROL characters BLT :INPUT CPX #0 BNE :ADDINP JSR OURPRMPT ;display [ESC] message :ADDINP STA BUFFER,X CMP #$8D BNE :NOTCR :CR LDA #$8D JSR COUT :EXIT LDY EFLG ;DON'T CHANGE STRING BEQ EXIT1 ; IF EXITING VIA [ESC] RTS EXIT1 LDY #$00 TXA STA ($83),Y STA $1E INY LDA #$00 STA ($83),Y INY LDA #$02 STA ($83),Y JSR GDBUFS LDA $1E JSR STRSPA LDY #$02 :LOOP LDA DSCTMP,Y STA ($83),Y DEY BPL :LOOP LDX #$00 LDY #$02 LDA DSCTMP JMP MOVSTR ERASE LDA #$88 JSR COUT1 LDA #$A0 ;print " "; JSR COUT1 BIT MODE BPL :6 STA $B72,X LDA #$60 STA $B71,X :6 LDA #$88 JSR COUT1 DEX RTS ;end erase one char OURPRMPT LDY #20 ;print "ERASE ENTRY" PHA ;save entered char :LOOP LDA PRMPT,Y STA $7D7,Y STA $BD7,Y DEY BPL :LOOP PLA RTS FIXPRMPT LDY #19 ;restore pgm's [ESC] prompt PHA :LOOP LDA STASH1,Y STA $7D7,Y STA $BD7,Y DEY BPL :LOOP PLA RTS PRMPT ASC "ERASE ENTRY" ASC " " ;10 spaces HEX 000000 ORG END