; Pallo ; ----- ; 2006 Hannu Nuotio ; Pallo is a remake of the crap QBasic game of the same name (and author). ; Start of project: 26.8.2006 ; v.1.1 - 20.10.2006 - added joyport constants ; v.1.0 - 16.9.2006 - seems to work ; Compiles with ACME 0.91 ; # acme --cpu 6502 -f cbm -o pallo.prg pallo.a ; Type SYS 4096 to start or use crunched version. ; Known bugs: ; - If warning collides with pallo and food, pallo does not get food. ; This is done intentionally to avoid nasty coordinate check code :) ; TODO: ; - music/sfx ; - 2 player mode ; Memory map: ; $0000-$0fff : unused ; $1000-$xxxx : code ; $xxxx-$yyyy : variables (reused sprite data) ; $yyyy-$zzzz : sintable, strings, logo ; $5300-$5aff : character set ; $5b00-$5bff : sprites ; $5c00-$5ff7 : screen memory (color data) ; $6000-$7ff7 : font memory (pixel data) ; $7ff8-$7fff : sprite pointers ; $8000-$ffff : unused ; Sprites: ; 0 = $5b00 = Pallo's eyes (white) ; 1 = $5b40 = Pallo's edges (brown) ; 2 = $5bc0 = Pallo's body (green) ; 3 = $5b80 = Food (light red) ; 4 = $5b80 = Warning (dark grey) ; 5 = $5b00 = Pallo2's eyes (white) ; 6 = $5b40 = Pallo2's edges (brown) ; 7 = $5bc0 = Pallo2's body (light blue) ; Interrupt states: ; $x0 - do nothing ; $01: - update "random" numbers ; - check collisions: ; - if none, state = $02 ; - if food, state = $40 ; - if killer, state = $80 ; - if both, state = $C0 ; $02 - update sprite positions, set state = $01 ; Gameloop states: ; a = if collision goto c. read joystick, explode bomb, update sprite pos. ; b = decrease bomb & warning timeout, draw killer ; c = check which collision(s), move food & warning, erase killer, update score or end game ; Pallo movement: ; basic idea: ; X += sin(dir), Y += cos(dir) ; ; variables: ; pallo1x(h)/y = sprite coordinates (= X/Y) ; pallo1subx/y = subpixel coordinates (= x/y) ; pallo1dir = direction of movement (= dir) ; ; direction circle: ; $80 ; /--|--\ ; / 3 | 2 \ <- segment ; $C0 |---------| $40 ; \ 4 | 1 / ; \--|--/ ; $00 (dir) ; ; case dir = ; $00: Y++ ; $40: X++ ; $80: Y-- ; $C0: X-- ; ; (if dir & $3f != 0 ) case segment = ; 1: X.x += sin(dir), Y.y += cos(dir) ; 2: X.x += cos(dir), Y.y -= sin(dir) ; 3: X.x -= sin(dir), Y.y -= cos(dir) ; 4: X.x -= cos(dir), Y.y += sin(dir) ; ; sintable: ; sintable[i] = 256*sin(2*pi*i/256), i = [0,$3f] ; sin(dir) -> sintable[dir] ; cos(dir) -> sintable[$40-dir] ; --- Macros ; SpriteLine - for easy definition of sprites ; from "ddrv.a" by Marco Baye !macro SpriteLine .v { !by .v>>16, (.v>>8)&255, .v&255 } ; --- Constants joyport = $dc00 ; joystick port joypddr = $dc02 ; joystick port data direction register bombpoints = 15 ; points required to get a bomb bombtimeout = 35 ; min. time between explosions warningtimeout = 50 ; warning->killer interval ; --- Variables highscoretext = startscrtext10+12 tmp = Sprites ; last joystick state lastjoy = Sprites+1 ; interrupt state (explained above) intstate = Sprites+2 ; sprite coordinates (0=1=2=Pallo, 5=6=7=Pallo2) pallo1x = Sprites+3 pallo1xh = Sprites+4 pallo1y = Sprites+5 foodx = Sprites+6 foodxh = Sprites+7 foody = Sprites+8 warningx = Sprites+9 warningxh = Sprites+10 warningy = Sprites+11 pallo2x = Sprites+12 pallo2xh = Sprites+13 pallo2y = Sprites+14 ; pallo dir & subpixel coordinates pallo1subx = Sprites + 15 pallo1suby = Sprites + 16 pallo1dir = Sprites + 17 pallo2subx = Sprites + 18 pallo2suby = Sprites + 19 pallo2dir = Sprites + 20 ; "random" variables rnd1 = Sprites + 21 rnd2 = Sprites + 22 ; rnd[2:1] = 0..308 rnd3 = Sprites + 23 rnd4 = Sprites + 24 ; rnd[4:3] = 0..308 rnd5 = Sprites + 25 ; rnd5 = 0..182 rnd6 = Sprites + 26 ; rnd6 = 0..182 ; score & bombs bombs = Sprites + 27 ; bomb amount bombc = Sprites + 28 ; bomb counter (0..15) hscore = Sprites + 29 ; high score score = Sprites + 30 ; score ; timeouts btime = Sprites + 31 ; bomb timeout wtime = Sprites + 32 ; warning timeout ; temp char for drawbomb tmpchar = Sprites + 33 ;next variable = Sprites + 41 ; --- Main ; start of program *=$1000 mlcodeentry: ; - interrupt setup ; from "An Introduction to Programming C-64 Demos" by Puterman aka Linus Åkerlund ; http://user.tninet.se/~uxm165t/demo_programming/demo_prog/demo_prog.html ; ... + modifications ; sei ; interrupts off lda #$7f ldx #$01 sta $dc0d ; Turn off CIA 1 interrupts sta $dd0d ; Turn off CIA 2 interrupts stx $d01a ; Turn on raster interrupts lda #int ; high part of address of interrupt handler code ldy #250 ; line to trigger interrupt sta $0314 ; store in interrupt vector stx $0315 sty $d012 lda #nmi ; high part of address of NMI handler code sta $0318 ; store in NMI vector stx $0319 lda #0 sta intstate ; set interrupt state to 0 lda $dc0d ; ACK CIA 1 interrupts lda $dd0d ; ACK CIA 2 interrupts asl $d019 ; ACK VIC interrupts cli ; interrupts on ; disable bcd-mode cld ; copy character rom to $5300-$5aff ; copy sprites to $5b40-$5bfe ldx #0 ; 255 loops sei ; interrups off lda $1 and #$fb sta $1 ; character rom on - lda $d000,x ; load from char-rom sta $5300,x ; store to ram lda $d100,x ; load from char-rom sta $5400,x ; store to ram lda $d200,x ; load from char-rom sta $5500,x ; store to ram lda $d300,x ; load from char-rom sta $5600,x ; store to ram lda $d400,x ; load from char-rom sta $5700,x ; store to ram lda $d500,x ; load from char-rom sta $5800,x ; store to ram lda $d500,x ; load from char-rom sta $5900,x ; store to ram lda $d600,x ; load from char-rom sta $5a00,x ; store to ram lda Sprites,x ; load from sprites (& sine table) sta $5b00,x ; save to ram inx bne - lda $1 ora #$04 sta $1 ; character rom off asl $d019 ; ACK VIC interrupts cli ; interrupts on ; generate pallo's body sprite ldx #64 - lda $5b80,x ; a = food sprite eor $5b40,x ; a xor edges eor $5b00,x ; a xor eyes sta $5bc0,x ; save to body sprite dex bne - ; bank 1 ($4000) lda #2 sta $dd00 ; hires bitmap ; 25 rows ; file scroll = 2 ; raster compare msb = 0 ; blank lda #$2b sta $d011 ; font = "screen" = $6000 ; screen = "color" = $5c00 lda #$78 sta $d018 ; sprite block pointers ldx #108 ; -> $5b00 stx $5ff8 ; p1eyes stx $5ffd ; p2eyes inx ; -> $5b40 stx $5ff9 ; p1edge stx $5ffe ; p2edge inx ; -> $5b80 stx $5ffb ; food stx $5ffc ; warning inx ; -> $5bc0 stx $5ffa ; p1body stx $5fff ; p2body ; sprite colors lda #1 ; white sta $d027 ; p1eyes sta $d02c ; p2eyes lda #9 ; brown sta $d028 ; p1edge sta $d02d ; p2edge lda #5 ; green sta $d029 ; p1body lda #10 ; light red sta $d02a ; food lda #11 ; dark gray sta $d02b ; warning lda #14 ; light blue sta $d02e ; p2body ; misc. vic settings lda #0 sta $d020 ; border color sta $d021 ; background color sta $d01c ; sprites = hi-res lda #$10 ; sprite 4 < backgnd sta $d01b ; sprite-backgnd priority ; init random variables lda #0 sta rnd2 sta rnd4 sta rnd5 sta rnd6 ; set joyport to input lda #0 sta joypddr ; - Pre-start screen lda #0 sta hscore ; high score = 0 lda #$f0 ; fg = gray, bg = black jsr setscreencolor ; - Start screen ; clear screen ; draw logo & text ; draw highscore ; position sprites ; draw killer ; wait for fire ; startscreen: jsr clearscreen ; draw logo lda #pallologo sta logosh ; point to logo (144x88) lda #<$6000+8*2+320*1 sta logodl lda #>$6000+8*2+320*1 sta logodh ldy #11 ; y = 88/8 = 11 - ; y loop ldx #0 ; x = 0 -- ; x loop logosl = *+1 logosh = *+2 lda $0000,x ; load bitmap logodl = *+1 logodh = *+2 sta $0000,x ; store screen inx ; next x cpx #144 bne -- ; loop until x=144 clc lda #64 adc logodl sta logodl lda #1 adc logodh sta logodh ; destination += 320 clc lda #144 adc logosl sta logosl lda #0 adc logosh sta logosh ; source += 144 dey bne - ; next y ; draw text lda #startscrtext1 sta strptrh ldx #28 ldy #3 jsr printstr ; = pallo lda #startscrtext2 sta strptrh ldx #28 ldy #5 jsr printstr ; = food lda #startscrtext3 sta strptrh ldx #28 ldy #7 jsr printstr ; = warning lda #startscrtext4 sta strptrh ldx #28 ldy #9 jsr printstr ; = killer lda #startscrtext5 sta strptrh ldx #7 ldy #13 jsr printstr ; use joystick... lda #startscrtext6 sta strptrh ldx #7 ldy #14 jsr printstr ; < and > ... lda #startscrtext7 sta strptrh ldx #7 ldy #15 jsr printstr ; fire ... lda #startscrtext8 sta strptrh ldx #4 ldy #17 jsr printstr ; collect food... lda #startscrtext9 sta strptrh ldx #4 ldy #18 jsr printstr ; a bomb ... lda #startscrtext10 sta strptrh ldx #12 ldy #21 jsr printstr ; high score lda #startscrtext11 sta strptrh ldx #4 ldy #24 jsr printstr ; activate sprites lda #$1f sta $d015 ; position sprites ldx #231 lda #73 ldy #0 stx pallo1x sty pallo1xh sta pallo1y lda #89 stx foodx sty foodxh sta foody lda #105 stx warningx sty warningxh sta warningy sty pallo2x sty pallo2y sty pallo2xh ; calc & draw killer clc ldx #231-24 ldy #121-50 jsr calckiller jsr drawkiller ; update sprites lda #2 sta intstate - cmp intstate beq - ; wait for state change lda $d01f ; clear sprite-data collision lda $d01e ; clear sprite-sprite collision ; unblank screen lda #$3b sta $d011 ; wait for joystick fire jsr waitfirej ; - Entering game ; clear screen ; draw game screen & text ; position sprites ; init variables ; clear any collisions ; lda #0 sta intstate ; interrupt does nothing ; blank screen lda #$2b sta $d011 ; draw game screen & text jsr clearscreen lda #statustext sta strptrh ldx #0 ldy #0 jsr printstr jsr drawborders ; init variables & sprite positions lda #$c0 sta pallo1dir lda #0 sta warningy ; warning is offscreen sta btime sta wtime sta score sta bombs sta bombc lda #$30 ; a = char "0" sta bombstext+0 sta bombstext+1 sta scoretext+0 sta scoretext+1 sta scoretext+2 lda #2 sta intstate ; update sprites - cmp intstate beq - ; wait for state change lda $d01f ; clear sprite-data collision lda $d01e ; clear sprite-sprite collision ; unblank screen lda #$3b sta $d011 ; - Game loop ; states: ; a = if collision goto c. read joystick, update sprite pos. ; b = decrease bomb & warning timeout, draw killer (entry point) ; c = check which collision(s), move food & warning, erase killer, update score or end game ; state b gstateb: ; decrease bomb timeout lda btime ; a = btime (Z if 0) beq + ; skip if 0 dec btime ; btime-- ; decrease warning timeout & draw killer if timeout -> 0 + lda wtime ; a = wtime (Z if 0) beq + ; skip if 0 dec wtime ; wtime-- bne + ; skip if > 0 jsr drawkiller ; draw killer lda #0 sta warningy ; move warning offscreen + lda #1 ; next state - cmp intstate beq - ; wait for state change ; state a gstatea: ; check for collisions lda #3 bit intstate ; intstate & 3, N & V=intstate 7 & 6 bne + ; if !Z, proceed jmp gstatec ; if Z, jump to state c ; read joystick ; test fire button (falling edge) + ldy lastjoy ; y = lastjoy (for later use) lda joyport ; a = joy tax ; save to x eor lastjoy ; joy xor lastjoy stx lastjoy ; update lastjoy and #$10 ; test fire beq gstatea_p2 ; jump if no change txa ; a = joy and #$10 ; test fire bne gstatea_p2 ; jump if rising edge ; fire pressed ; check timeout and available bombs lda bombs ; a = bombs (Z if 0) beq gstatea_p2 ; jump if no bombs lda btime ; a = btime (Z if 0) bne gstatea_p2 ; jump if bomb timeout ; bomb explosion lda #1 sta $d020 ; set border white lda #0 sta intstate ; next state = 0 ; decrease bomb amount dec bombs ldy #$39 ; y = char "9" lda #$2f ; a = char "0"-1 dec bombstext+1 ; bombstext-- cmp bombstext+1 ; test BCD underflow bne + sty bombstext+1 ; save "0" to bombstext dec bombstext ; bombstext-- ; print bombs + jsr printbombs ; explode bomb lda pallo1y ; a = pallo1y sec sbc #50 ; remove sprite offset tay ; y = bomb y lda pallo1x ; a = pallo1x sec sbc #24 ; remove sprite offset tax ; x = bomb x lda pallo1xh ; a = pallo1xh sbc #0 clc beq + sec ; c = pallo1xh + jsr drawbomb ; drawbomb at x(c=msb),y lda #1 sta intstate ; next state = 1 ; set timeout lda #bombtimeout sta btime lda #0 sta $d020 ; set border black ; test left & right (use lastjoy for inertia) gstatea_p2: txa ; a = joy and #$04 ; test left bne + ; jump if not active inc pallo1dir ; pallo1dir++ inc pallo1dir ; pallo1dir++ + tya ; a = lastjoy and #$04 ; test left bne + ; jump if not active inc pallo1dir ; pallo1dir++ + txa ; a = joy and #$08 ; test right bne + ; jump if not active dec pallo1dir ; pallo1dir-- dec pallo1dir ; pallo1dir-- + tya ; a = lastjoy and #$08 ; test right bne gstatea_c ; jump if not active dec pallo1dir ; pallo1dir-- ; calculate movement & update sprite position ; check if movement is straight or from sintable gstatea_c: lda #$3f ; a = $3f bit pallo1dir ; Z = p1dir && $3f, NV = bit7&6 php ; put flags to stack lda #$3f ; a = $3f and pallo1dir ; a = p1dir & $3f bne + ; skip if !Z (sintable movement) jmp gstatea_s ; jump if Z (straight movement) ; sintable movement (flags in stack tell the segment) + tax ; x = p1dir & $3f = dir eor #$ff ; a = !a clc ; c = 0 adc #1 ; a++ and #$3f ; a = a & $3f tay ; y = $40-dir lda sintable,x ; a = sin(dir) tax ; x = sin(dir) lda sintable,y ; a = sin($40-dir) tay ; y = sin($40-dir) plp ; pull flags from stack bmi gstatea_34 ; jump if N (segment 3 or 4) bvs gstatea_2 ; jump if V (segment 2) clc ; (segment 1:x+,y+) c = 0 adc pallo1suby ; pallo1suby += sin($40-dir) sta pallo1suby ; save pallo1suby bcc + ; skip if no carry inc pallo1y ; pallo1y++ + clc ; c = 0 txa ; a = sin(dir) adc pallo1subx ; pallo1subx += sin(dir) sta pallo1subx ; save pallo1subx bcs gstatea_r ; inc x if carry jmp gstatea_f ; jump to state a finish gstatea_2: ; 2:x+,y- stx tmp ; tmp = sin(dir) lda pallo1suby ; a = pallo1suby sec ; c = 1 sbc tmp ; a = pallo1suby - sin(dir) sta pallo1suby ; save pallo1suby bcs + ; skip if carry (no borrow) dec pallo1y ; pallo1y-- + clc ; c = 0 tya ; a = sin($40-dir) adc pallo1subx ; pallo1subx += sin($40-dir) sta pallo1subx ; save pallo1subx bcs gstatea_r ; inc x if carry jmp gstatea_f ; jump to state a finish gstatea_34: ; 3 or 4 bvs gstatea_4 ; jump if V (4) sty tmp ; (3:x-,y-) tmp = sin($40-dir) lda pallo1suby ; a = pallo1suby sec ; c = 1 sbc tmp ; a = pallo1suby - sin($40-dir) sta pallo1suby ; save pallo1suby bcs + ; skip if carry (no borrow) dec pallo1y ; pallo1y-- + lda pallo1subx ; a = pallo1subx stx tmp ; tmp = sin(dir) sec ; c = 1 sbc tmp ; a = pallo1subx - sin(dir) sta pallo1subx ; save pallo1subx bcc gstatea_l ; dec x if no carry (borrow) jmp gstatea_f ; jump to state a finish gstatea_4: ; 4:x-,y+ clc ; c = 0 txa ; a = sin(dir) adc pallo1suby ; pallo1suby += sin(dir) sta pallo1suby ; save pallo1suby bcc + ; skip if no carry inc pallo1y ; pallo1y++ + lda pallo1subx ; a = pallo1subx sty tmp ; tmp = sin($40-dir) sec ; c = 1 sbc tmp ; a = pallo1subx - sin($40-dir) sta pallo1subx ; save pallo1subx bcc gstatea_l ; dec x if no carry (borrow) jmp gstatea_f ; jump to state a finish ; straight movement (pallo1) gstatea_s: plp ; pull flags from stack bmi gstatea_ul ; jump if N (up or left) bvs gstatea_r ; jump if V (right) gstatea_d: ; straight movement to down inc pallo1y ; y++ jmp gstatea_f ; jump to state a finish gstatea_r: ; straight movement to right inc pallo1x ; x++ bne gstatea_f ; jump if x!=0 ("carry"=0) inc pallo1xh ; x++ (msb) jmp gstatea_f ; jump to state a finish gstatea_ul: ; straight, up or left bvs gstatea_l ; jump if V (left) gstatea_u: ; straight movement to up dec pallo1y ; y-- jmp gstatea_f ; jump to state a finish gstatea_l: ; straight movement to left dec pallo1x ; x-- lda #$ff ; a = $ff (for "carry" test) cmp pallo1x ; test "carry" bne gstatea_f ; jump if x!=$ff ("carry"=0) dec pallo1xh ; x-- (msb) jmp gstatea_f ; jump to state a finish gstatea_f: lda #2 ; next state - cmp intstate beq - ; wait for state change jmp gstateb ; back to state b ; state c - a collision happened gstatec: ; N->killer, V->food, NV->both php ; save flags bvs + ; skip if food collision jmp gstatec_k ; jump if not food collision ; food collision ; increase score + inc score ; score++ lda #$3a ; a = char "9"+1 ldy #$30 ; y = char "0" inc scoretext+2 ; scoretext++ cmp scoretext+2 ; test BCD overflow bne + sty scoretext+2 ; save "0" to scoretext inc scoretext+1 ; scoretext++ cmp scoretext+1 ; test BCD overflow bne + sty scoretext+1 ; save "0" to scoretext inc scoretext ; scoretext++ ; print score + jsr printscore ; increase bomb couter inc bombc ; bomb counter ++ lda #bombpoints ; a = bombpoints cmp bombc ; if bomb counter != bombpoints, bne ++ ; jump ; give a bomb to player lda #0 sta bombc ; reset bomb counter inc bombs ; bombs++ lda #$3a ; a = char "9"+1 ldy #$30 ; y = char "0" inc bombstext+1 ; bombstext++ cmp bombstext+1 ; test BCD overflow bne + sty bombstext+1 ; save "0" to bombstext inc bombstext ; bombstext++ ; print bombs + jsr printbombs ; if warning timeout>0 draw killer ++ lda wtime ; a = wtime (Z if 0) beq + ; skip if Z jsr drawkiller ; move food & warning + clc lda rnd1 ; a = rnd1 adc #25 ; add sprite x offset + 1 sta foodx ; save to food x lda #0 ; a = 0 adc rnd2 ; add msb + c sta foodxh ; save to food x msb clc ; c = 0 lda rnd5 ; a = rnd5 adc #59 ; add sprite y offset + 9 sta foody ; save to food y clc lda rnd3 ; a = rnd3 adc #25 ; add sprite x offset + 1 sta warningx ; save to warning x lda #0 ; a = 0 adc rnd4 ; add msb + c sta warningxh ; save to warning x msb clc ; c = 0 lda rnd6 ; a = rnd6 adc #59 ; add sprite y offset + 9 sta warningy ; save to warning y ; calc & erase killer below food lda rnd5 ; a = rnd5 clc adc #9 ; a += 9 tay ; y = rnd5 + 9 ldx rnd1 ; x = rnd1 inx ; x++ (Z if 255->0) beq + lda rnd2 ; a = rnd2 clc beq ++ + sec ; c = rnd[1:2] msb ++ jsr calckiller ; calc killer at x(c=msb),y jsr erasekiller ; erase killer under food ; calc killer lda rnd6 ; a = rnd6 clc adc #9 ; a += 9 tay ; y = rnd6 + 9 ldx rnd3 ; x = rnd3 inx ; x++ (Z if 255->0) beq + lda rnd4 ; a = rnd4 clc beq ++ + sec ; c = rnd[3:4] msb ++ jsr calckiller ; calc killer at x(c=msb),y ; set warning timeout + lda #warningtimeout ; a = warningtimeout sta wtime ; set timeout gstatec_k: ; test killer plp ; restore flags bpl gstatec_f ; jump if not killer collision ; killer collision ; set state to 0 lda #0 sta intstate ; interrupt does nothing lda #2 sta $d020 ; set border red ; check score and highscore lda hscore ; a = high score cmp score ; check if score>highscore bcs ++ ; jump if not ; print high score lda #gothighscoretext sta strptrh ldx #16 ldy #0 jsr printstr ; update highscore lda score sta hscore lda scoretext+0 sta highscoretext+0 lda scoretext+1 sta highscoretext+1 lda scoretext+2 sta highscoretext+2 jmp +++ ; jump ; print game over ++ lda #gameovertext sta strptrh ldx #16 ldy #0 jsr printstr ; wait for fire (falling edge) +++ jsr waitfirej lda #0 sta $d020 ; set border black ; blank screen lda #$2b sta $d011 ; goto start screen jmp startscreen gstatec_f: lda #2 sta intstate ; next state = 2 - cmp intstate beq - ; wait for state change lda $d01f ; clear sprite-data collision lda $d01e ; clear sprite-sprite collision lda #2 sta intstate ; next state = 2 jmp gstatea ; back to state a, read joystick ; --- Interrupt routines ; - IRQ ; Interrupt states: ; $x0 - do nothing ; $01 - update random numbers ; - check collisions: ; - if none, state = $02 ; - if food, state = $40 ; - if killer, state = $80 ; - if both, state = $c0 ; $02 - update sprite positions, set state = $01 ; int: lda #$0f ; a = $f and intstate ; a = intstate & $f bne + jmp int_return ; if state = $x0, return + cmp #2 bne + jmp int_sprites ; if state = 2, update sprites ; state $01: update "random" numbers + clc lda #13 adc rnd1 sta rnd1 bcc + inc rnd2 ; rnd[1:2] += 13 + clc lda #23 adc rnd3 sta rnd3 bcc + inc rnd4 ; rnd[3:4] += 23 + inc rnd5 ; rnd5 ++ clc lda #29 adc rnd6 ; rnd6 += 29 sta rnd6 ; set numbers within limits ; rnd[1:2] = 0..306 lda rnd2 beq + ; jump if msb = 0 lda rnd1 sec sbc #<306 ; a = rnd1-306 (lsb) bcc + ; jump if rnd[1:2]<306 sta rnd1 ; rnd1 -= 306 (lsb) lda #0 sta rnd2 ; rnd[1:2] = rnd[1:2] mod 306 ; rnd[3:4] = 0..306 + lda rnd4 beq + ; jump if msb = 0 lda rnd3 sec sbc #<306 ; a = rnd3-306 (lsb) bcc + ; jump if rnd[3:4]<306 sta rnd3 ; rnd3 -= 306 (lsb) lda #0 sta rnd4 ; rnd[3:4] = rnd[3:4] mod 306 ; rnd5 = 0..180 + lda rnd5 sec sbc #180 ; a = rnd5-180 bcc + ; jump if rnd5<180 sta rnd5 ; rnd5 = rnd5 mod 180 ; rnd6 = 0..180 + lda rnd6 sec sbc #180 ; a = rnd6-180 bcc + ; jump if rnd6<180 sta rnd6 ; rnd6 = rnd6 mod 180 ; state $01: check collisions + ldy #$00 ; next state = $00 lda $d01e ; sprite-sprite collision tax ; save to x and #$08 ; test food beq ++ ; skip if no collision ; test pallo txa ; a = sprite-sprite collision and #$07 ; test pallo collision beq ++ ; skip if no collision ; test warning (ignore if food+pallo+warning) txa ; a = sprite-sprite collision and #$10 ; test warning collision bne ++ ; skip if collision ldy #$40 ; next state = $40 ++ lda $d01f ; sprite-data collision and #$07 ; test pallo beq + ; skip if no collision tya ; a = next state ora #$80 ; next state |= $80 tay ; y = next state + cpy #$00 ; if next state = 0 bne + ; jump if collisions ldy #$02 ; next state = $02 + sty intstate ; set next state jmp int_return ; return ; state $02: update sprites int_sprites: ; pallo ldx pallo1x lda pallo1y stx $d000 sta $d001 stx $d002 sta $d003 stx $d004 sta $d005 ; food ldx foodx lda foody stx $d006 sta $d007 ; warning ldx warningx lda warningy stx $d008 sta $d009 ; pallo2 ;ldx pallo2x ;lda pallo2y ;stx $d00a ;sta $d00b ;stx $d00c ;sta $d00d ;stx $d00e ;sta $d00f ; sprite pos msbs lda #0 ;ora pallo2xh ;asl ;ora pallo2xh ;asl ;ora pallo2xh ;asl ora warningxh asl ora foodxh asl ora pallo1xh asl ora pallo1xh asl ora pallo1xh sta $d010 ; sprite pos msbs dec intstate ; next state = $01 int_return: asl $d019 ; ACK interrupt (to re-enable it) pla tay pla tax pla ; pop y,x and a from stack rti ; return ; - NMI ; nmi: rti ; return ; --- Subroutines ; - clearscreen ; clearscreen: ldx #0 ; 256 loops lda #0 ; clear - sta $6000,x sta $6100,x sta $6200,x sta $6300,x sta $6400,x sta $6500,x sta $6600,x sta $6700,x sta $6800,x sta $6900,x sta $6a00,x sta $6b00,x sta $6c00,x sta $6d00,x sta $6e00,x sta $6f00,x sta $7000,x sta $7100,x sta $7200,x sta $7300,x sta $7400,x sta $7500,x sta $7600,x sta $7700,x sta $7800,x sta $7900,x sta $7a00,x sta $7b00,x sta $7c00,x sta $7d00,x sta $7e00,x sta $7ee8,x inx bne - rts ; return ; - setscreencolor ; parameters: ; a = screen color (0xfb, f/b=fore/background) ; setscreencolor: ldx #0 ; 256 loops - sta $5c00,x sta $5d00,x sta $5e00,x sta $5ee8,x inx bne - rts ; return ; - drawbowders ; drawborders: ; left & right edge ldx #0 ; 8 loops -- lda #$61 sta drawbordersl+1 lda #$62 sta drawbordersr+1 lda #$40 sta drawbordersl lda #$78 ; left dest. = (0,1) sta drawbordersr ; right dest.= (39,1) ldy #24 ; 24 loops - lda #$80 ; left edge drawbordersl=*+1 sta $0000,x ; save to dest. lda #$01 ; right edge drawbordersr=*+1 sta $0000,x ; save to dest. clc lda #$40 adc drawbordersl sta drawbordersl lda #1 adc drawbordersl+1 sta drawbordersl+1 ; left dest. += 320 clc lda #$40 adc drawbordersr sta drawbordersr lda #1 adc drawbordersr+1 sta drawbordersr+1 ; right dest. += 320 dey bne - inx cpx #8 bne -- ; top & bottom edge lda #$61 sta drawborderst+1 lda #$7e sta drawbordersb+1 lda #$40 sta drawborderst lda #$07 ; top dest. = (0,1) sta drawbordersb ; bottom dest.= (0,23) ldx #40 ; 40 loops - lda #$ff ; line drawborderst=*+1 sta $0000 ; save to dest. drawbordersb=*+1 sta $0000 ; save to dest. clc lda #8 adc drawborderst sta drawborderst lda #0 adc drawborderst+1 sta drawborderst+1 ; left dest. += 8 clc lda #$8 adc drawbordersb sta drawbordersb lda #0 adc drawbordersb+1 sta drawbordersb+1 ; bottom dest. += 8 dex bne - rts ; return ; - waitfirej ; returns: ; lastjoy ; waitfirej: lda joyport ; a = joy sta lastjoy ; update lastjoy - lda joyport ; a = joy tax ; save to x eor lastjoy ; joy xor lastjoy stx lastjoy ; update lastjoy and #$10 ; test fire beq - ; jump if no change txa ; a = joy and #$10 ; test fire bne - ; jump if rising edge rts ; - drawbomb ; parameters: ; x = x-coordinate, c = msb ; y = y-coordinate ; drawbomb: ; get tx&ty text coords from x,y ; tx-=3, ty-=3 ; ex=tx+6+1, ey=ty+6+1 (end coord+1) ; check limits: ; x: <0 -> 0, >39 -> 39 ; y: <1 -> 1, >24 -> 24 txa ; a = x-coord. ror ; c->bit7 lsr lsr ; a = x/8, c = "0.5" adc #-3 ; a = a-3 + c (round) bpl + ; jump if a>0 clc ; c = 0 adc #7 ; a+=7 sta drawbombex ; store x end coord lda #0 ; a = 0 sta drawbombtx ; store x start coord jmp ++ ; jump to y coord conversion + sta drawbombtx ; store x start coord clc ; c = 0 adc #7 ; a+=7 cmp #40 ; check if a>40 bcc + ; jump if a<=40 lda #40 ; a = 40 + sta drawbombex ; store to x end address ++ tya ; a = y-coord. lsr lsr lsr ; a = y/8, c = "0.5" adc #-3 ; a = a-3 + c (round) bpl + ; jump if a>0 clc ; c = 0 adc #7 ; a+=7 sta drawbombey ; store y end coord lda #1 ; a = 1 sta drawbombty ; store y start coord jmp ++ ; jump + bne + ; jump if a!=0 lda #1 ; a = 1 + sta drawbombty ; store y start coord clc ; c = 0 adc #7 ; a+=7 cmp #25 ; check if a>25 bcc + ; jump if a<=25 lda #25 ; a = 25 + sta drawbombey ; store to y end address ; bombdest = ty*320+tx*8 ++ lda drawbombty ; a = ty sta bombdesth ; bombdesth = "256*ty" lda #0 ; a=0 lsr bombdesth ; bombdesth = "128*ty", c=lsb ror ; c->a,msb lsr bombdesth ; bombdesth = "64*ty", c=lsb ror ; bombdesth:a = 64*ty sta bombdestl ; bombdest = 64*ty lda drawbombty ; a = ty adc bombdesth ; a = ty+bombdesth sta bombdesth ; bombdest = 320*y ; tmp=8*tx lda #0 ; a=0 ldx drawbombtx ; x = tx stx tmp ; tmp = tx asl tmp ; tmp = 2*tx, c=msb rol ; c->a,lsb asl tmp ; tmp = 4*tx, c=msb rol asl tmp ; tmp = 8*tx, c=msb rol ; a:tmp = 8*tx ; bomdest = $6000+320*ty+8*tx adc bombdesth ; a = bombdesth + "tmph" sta bombdesth ; charyh = a lda tmp ; a = tmp clc ; c = 0 adc bombdestl ; a = bombdestl + tmp sta bombdestl ; bombdestl = a sta bombdest2l ; bombdest2l = a lda #$60 ; a = $60 (screenmem msb) adc bombdesth ; a = $60+bombdesth+c sta bombdesth ; bombdest = $6000 + 320*ty + 8*tx sta bombdest2h ; bombdest2 = $6000 + 320*ty + 8*tx ; for y=ty..ey drawbombyloop: ldx #0 ; reset dest x offset lda drawbombtx ; a = bomb x offset sta drawbombx ; reset bomb x offset ; for x=tx..ex drawbombxloop: ; make char to print: ; char = $00 ; if x=0 , set $80 all ; if x=39, set $01 all ; if y=1 , or $ff first ; if y=24, or $ff last drawbombx=*+1 ldy #$00 ; y = bomb x coord lda #$00 ; bomb char line = 0 cpy #0 ; check if bomb is at left edge bne + ; jump if not ora #$80 ; don't erase left edge + cpy #39 ; check if bomb is at right edge bne + ; jump if not ora #$01 ; don't erase right edge + sta tmpchar+0 ; create char sta tmpchar+1 sta tmpchar+2 sta tmpchar+3 sta tmpchar+4 sta tmpchar+5 sta tmpchar+6 sta tmpchar+7 drawbombty=*+1 ldy #$00 ; y = bomb y coord cpy #1 ; check if bomb is at top edge bne + ; jump if not lda #$ff ; dont erase top edge sta tmpchar+0 + cpy #24 ; check if bomb is at bottom edge bne + ; jump if not lda #$ff ; dont erase bottom edge sta tmpchar+7 + ldy #0 ; reset char line counter ; printchar - and version - lda tmpchar,y ; a = char line y bombdestl=*+1 bombdesth=*+2 and $0000,x ; a &= screen mem bombdest2l=*+1 bombdest2h=*+2 sta $0000,x ; screen mem = a inx ; x++ iny ; y++ cpy #8 ; check if y = 8 bne - ; jump if not ; next x inc drawbombx ; bomb x ++ lda drawbombx ; a = bomb x drawbombex=*+1 cmp #$00 ; check if bomb x = end bomb x bne drawbombxloop ; if not, next x ; next y inc drawbombty ; bomb y ++ lda drawbombty ; a = bomb y drawbombey=*+1 cmp #$00 ; check if bomb y = end bomb y beq drawbomb_f ; if it is, jump to end ; dest+=320 clc lda #64 adc bombdestl sta bombdestl sta bombdest2l lda #1 adc bombdesth sta bombdesth sta bombdest2h ; ...destination += 320 jmp drawbombyloop drawbomb_f: rts ; return drawbombtx !by 0 ; start bomb x variable ; - calckiller ; parameters: ; x = x-coordinate, c = msb ; y = y-coordinate ; returns: ; ktemp = killer data ; kloc(l:h) = killer location ; kloc2(l:h) = killer location ; calckiller: ; x&7 -> shifts txa ; a = x (c = msb) and #7 ; a = x&7 sta kxoff ; kxoff = x&7 ; x&$f8 -> x-coordinate txa ; a = x (c = msb) ror ; c->a,msb; a = x/2 and #$fc ; a = (x/2)&$fc tax ; x = (x/2)&$fc ; y&7 -> line offset tya ; a = y and #7 ; a = y&7 sta kyoff ; kyoff = y&7 ; (y/8)*320 -> y-coordinate tya ; a = y lsr lsr lsr ; a = y/8 tay ; y = y/8 sty kloch ; kloch = "256*y" lda #0 ; a=0 lsr kloch ; kloch = "128*y", c=lsb ror ; c->a,msb lsr kloch ; kloch = "64*y", c=lsb ror ; kloch:a = 64*y/8 sta klocl ; kloc = 64*y/8 tya ; a = y/8 adc kloch ; a = y/8+kloch sta kloch ; kloc = 320*y/8 ; kloc = $6000+320*(y/8)+8*(x/8) txa ; a = (x/2)&$fc asl ; a = (x/8)*8, c = msb tax ; x = (x/8)*8 lda #0 ; a = 0 adc kloch ; a = kloch + c sta kloch ; kloc = 320*y/8 + msb((x/8)*8), c = 0 txa ; a = lsb((x/8)*8) adc klocl ; a += klocl sta klocl ; klocl = 320*y/8 + lsb((x/8)*8), c = msb sta kloc2l ; kloc2l = 320*y/8 + lsb((x/8)*8), c = msb lda #$60 ; a = $60 (screenmem msb) adc kloch ; a = $60+kloch+c sta kloch ; kloc = $6000+320*(y/8)+8*(x/8) sta kloc2h ; kloc2 = $6000+320*(y/8)+8*(x/8) ; clear ktemp ldx #48 ; 48 loops lda #0 ; clear - dex sta ktemp,x bne - ; copy from kdata to ktemp with y offset kyoff=*+1 ; y offset ldy #0 ; y = destination ldx #0 ; x = source - lda kdata,x ; a = row 1, line x sta ktemp,y ; ktemp line y = a lda kdata+16,x ; a = row 2, line x sta ktemp+8,y ; ktemp line y = a inx ; x++ iny ; y++ cpy #8 ; if y = 8 then y = 24 bne + ldy #24 ; (see ktemp comments) + cpx #9 ; loop until source line = 9 bne - ; shift ktemp by x offset lda kxoff ; load x offset beq ++ ; if x offset = 0, skip shifting ldx kyoff ; line counter = y offset ldy #9 ; 9 loops -- tya ; a = loop counter kxoff = *+1 ldy #0 ; y = x offset - clc ; c = 0 ror ktemp,x ; 0->ktemp(left) >>1->c ror ktemp+8,x ; c->ktemp(mid) >>1->c ror ktemp+16,x ; c->ktemp(right)>>1->c dey ; loop for offset times bne - inx ; x++ cpx #8 ; if x = 8 then x = 24 bne + ldx #24 ; (see ktemp comments) + tay ; y = loop counter dey ; y-- bne -- ++ rts ; return ; - drawkiller ; parameters: ; kloc = kloc2 = location to print killer ; kdata = killer data to print ; notes: ; if x > 308, this "leaks" into the next line ; (or sprite pointers), but they are just OR'd with 0 ; drawkiller: ldx #0 ; 48 loops - lda ktemp,x ; a = killer temp data klocl=*+1 kloch=*+2 ora $0000,x ; a |= screen data kloc2l=*+1 kloc2h=*+2 sta $0000,x ; screen data = a inx ; x++ cpx #24 ; if x=24 (4. char)... bne + clc lda #40 adc klocl sta klocl sta kloc2l lda #1 adc kloch sta kloch sta kloc2h ; ...destination += 320-24 + cpx #48 ; loop while x < 48 bne - rts ; return ; - erasekiller ; parameters: ; kloc = kloc2 = location to print killer ; kdata = killer data to print ; notes: ; if x > 308, this "leaks" into the next line ; (or sprite pointers), but they are just AND'd with 1 ; erasekiller: ; copy locations from drawkiller lda klocl sta flocl lda kloch sta floch lda kloc2l sta floc2l lda kloc2h sta floc2h ldx #0 ; 48 loops - lda ktemp,x ; a = killer temp data eor #$ff ; invert a flocl=*+1 floch=*+2 and $0000,x ; a &= screen data floc2l=*+1 floc2h=*+2 sta $0000,x ; screen data = a inx ; x++ cpx #24 ; if x=24 (4. char)... bne + clc lda #40 adc flocl sta flocl sta floc2l lda #1 adc floch sta floch sta floc2h ; ...destination += 320-24 + cpx #48 ; loop while x < 48 bne - rts ; return ; - printscore ; uses: printstrnocalc ; printscore: lda #>$6000+8*7 sta charyh lda #<$6000+8*7 sta charyl lda #>scoretext sta strptrh lda #$6000+8*38 sta charyh lda #<$6000+8*38 sta charyl lda #>bombstext sta strptrh lda # string to print ; assumptions: ; x = 0..39, y = 0..24 ; uses: ; printchar (chary(l:h),charxl) ; ; - printstrnocalc ; parameters: ; chary -> where to print (320*y+8*x) ; strptr(l:h) -> string to print ; assumptions: ; x = 0..39, y = 0..24 ; uses: ; printchar (chary(l:h),charxl) ; printstr: ;chary=320*y=256*y+64*y sty charyh ; charyh = "256*y" lda #0 ; a=0 lsr charyh ; charyh = "128*y", c=lsb ror ; c->a,msb lsr charyh ; charyh = "64*y", c=lsb ror ; charyh:a = 64*y sta charyl ; chary = 64*y tya ; a = y adc charyh ; a = y+charyh sta charyh ; chary = 320*y ;charx=8*x lda #0 ; a=0 stx charxl ; charxl = x asl charxl ; charxl = 2*x, c=msb rol ; c->a,lsb asl charxl ; charxl = 4*x, c=msb rol asl charxl ; charxl = 8*x, c=msb rol ; a:charxl = 8*x ; chary=$6000+320*y+8*x adc charyh ; a = charyh + "charxh" sta charyh ; charyh = a lda charxl ; a = charxl clc ; c = 0 adc charyl ; a = charyl + charxl sta charyl ; charyl = a lda #$60 ; a = $60 (screenmem msb) adc charyh ; a = $60+charyh+c sta charyh ; chary = $6000 + 320*y + 8*x printstrnocalc: ; chary is set ldy #0 ; y = 0 - ; char loop strptrl=*+1 strptrh=*+2 lda $0000,y ; a = char at strptr+y beq + ; if char = 0, leave jsr printchar ; print a to chary iny ; y++, -> next char lda #8 clc adc charyl ; a = charyl+8, c=msb sta charyl lda #0 adc charyh ; a = 0 +charyh+c sta charyh ; chary->next x-pos. jmp - + rts ; return ; - printchar ; parameters: ; chary = where to print (320*y+8*x) ; a = char (-> charxl=$5300+char*8) ; printchar: sta charxl ; charxl = char lda #0 asl charxl ; charxl = 2*x, c=msb rol ; c->a,lsb asl charxl ; charxl = 4*x, c=msb rol asl charxl ; charxl = 8*x, c=msb rol ; a:charxl = 8*x, tmp = 0 adc #$53 ; a:charxl = $5300+char*8 sta charxh ldx #7 ; 8 lines - ; line loop charxl=*+1 charxh=*+2 lda $0000,x ; load from char-rom charyl=*+1 charyh=*+2 sta $0000,x ; store to screen dex ; next line bpl - rts ; return ; --- Sprites ; ...reused as variables Sprites ; eyes (white) ; 765432107654321076543210 +SpriteLine %........................ ;1 +SpriteLine %........................ ;2 +SpriteLine %........................ ;3 +SpriteLine %........................ ;4 +SpriteLine %..#.#.#.#............... ;5 +SpriteLine %........................ ;6 +SpriteLine %........................ ;7 +SpriteLine %........................ ;8 +SpriteLine %........................ ;9 +SpriteLine %........................ ;10 +SpriteLine %........................ ;11 +SpriteLine %........................ ;12 +SpriteLine %........................ ;13 +SpriteLine %........................ ;14 +SpriteLine %........................ ;15 +SpriteLine %........................ ;16 +SpriteLine %........................ ;17 +SpriteLine %........................ ;18 +SpriteLine %........................ ;19 +SpriteLine %........................ ;20 +SpriteLine %........................ ;21 !byte 0 ; edges, mouth, eyes (brown) ; 765432107654321076543210 +SpriteLine %...#####................ ;1 +SpriteLine %..#.....#............... ;2 +SpriteLine %##.#...#.##............. ;3 +SpriteLine %#...#.#...#............. ;4 +SpriteLine %#..#...#..#............. ;5 +SpriteLine %#.........#............. ;6 +SpriteLine %##.#####.##............. ;7 +SpriteLine %..#.....#............... ;8 +SpriteLine %...#####................ ;9 +SpriteLine %........................ ;10 +SpriteLine %........................ ;11 +SpriteLine %........................ ;12 +SpriteLine %........................ ;13 +SpriteLine %........................ ;14 +SpriteLine %........................ ;15 +SpriteLine %........................ ;16 +SpriteLine %........................ ;17 +SpriteLine %........................ ;18 +SpriteLine %........................ ;19 +SpriteLine %........................ ;20 +SpriteLine %........................ ;21 !byte 0 ; ball (food, warning) ; 765432107654321076543210 +SpriteLine %...#####................ ;1 +SpriteLine %..#######............... ;2 +SpriteLine %###########............. ;3 +SpriteLine %###########............. ;4 +SpriteLine %###########............. ;5 +SpriteLine %###########............. ;6 +SpriteLine %###########............. ;7 +SpriteLine %..#######............... ;8 +SpriteLine %...#####................ ;9 +SpriteLine %........................ ;10 +SpriteLine %........................ ;11 +SpriteLine %........................ ;12 +SpriteLine %........................ ;13 +SpriteLine %........................ ;14 +SpriteLine %........................ ;15 +SpriteLine %........................ ;16 +SpriteLine %........................ ;17 +SpriteLine %........................ ;18 +SpriteLine %........................ ;19 +SpriteLine %........................ ;20 +SpriteLine %........................ ;21 !byte 0 ; pallo's body = ball xor eyes xor edges ; --- Sintable ; 256*sin(2*pi*i/256), i = [0,63] sintable !byte $00,$06,$0c,$12,$19,$1f,$25,$2b,$31,$38,$3e,$44,$4a,$50,$56,$5c !byte $61,$67,$6d,$73,$78,$7e,$83,$88,$8e,$93,$98,$9d,$a2,$a7,$ab,$b0 !byte $b5,$b9,$bd,$c1,$c5,$c9,$cd,$d1,$d4,$d8,$db,$de,$e1,$e4,$e7,$ea !byte $ec,$ee,$f1,$f3,$f4,$f6,$f8,$f9,$fb,$fc,$fd,$fe,$fe,$ff,$ff,$ff ; --- Strings !ct scr ; C64 screencode ; |---------0---------0---------0--------| statustext !tx "score: 000 pallo bombs: 00",0 scoretext !tx "000",0 ; x offset 7 bombstext !tx "00",0 ; x offset 38 gameovertext !tx "game over.",0 gothighscoretext !tx "highscore!",0 startscrtext1 !tx "= pallo",0 startscrtext2 !tx "= food",0 startscrtext3 !tx "= warning",0 startscrtext4 !tx "= killer",0 startscrtext5 !tx "use joystick in port 2",0 startscrtext6 !tx "< and > .... rotate pallo",0 startscrtext7 !tx "fire ....... explode bomb",0 startscrtext8 !tx "collect food, avoid collisions.",0 startscrtext9 !tx "a bomb is given every 15 points.",0 startscrtext10 !tx "high score: 000",0 startscrtext11 !tx "by hannu nuotio for c64cgc 2006",0 ; --- Bitmaps pallologo ; 144x88, 1bpp logo !bin "logo.b" ; --- Killer data ; A killer occupies 2x2 chars. ; Initial data organisation: (read by drawkiller) ; l r left right ; 7654321076543210 ; 0 16 ...#####........ ; 1 17 ..#######....... ; 2 18 ###########..... ; 3 19 ###########..... ; 4 20 ###########..... ; 5 21 ###########..... ; 6 22 ###########..... ; 7 23 -> ..#######....... top ; 8 24 ...#####........ bottom ; 9 25 ................ ; 10 26 ................ ; 11 27 ................ ; 12 28 ................ ; 13 29 ................ ; 14 30 ................ ; 15 31 ................ kdata ;76543210 !by %...##### ; left !by %..###### ; 1 !by %######## ; 2 !by %######## ; 3 !by %######## ; 4 !by %######## ; 5 !by %######## ; 6 !by %..###### ; 7 !by %...##### ; 8 !by %........ ; 9 !by %........ ; 10 !by %........ ; 11 !by %........ ; 12 !by %........ ; 13 !by %........ ; 14 !by %........ ; 15 !by %........ ; right !by %#....... !by %###..... !by %###..... !by %###..... !by %###..... !by %###..... !by %#....... !by %........ !by %........ !by %........ !by %........ !by %........ !by %........ !by %........ !by %........ ; A shifted killer occupies at most 3x2 chars. ; Final data organisation: (by drawkiller) ; l m r left middle right ; 765432107654321076543210 ; 0 8 16 ...#####................ ; 1 9 17 ..#######............... ; 2 10 18 ###########............. ; 3 11 19 ###########............. ; 4 12 20 ###########............. ; 5 13 21 ###########............. ; 6 14 22 ###########............. ; 7 15 23 -> ..#######............... top ; 24 32 40 ...#####................ bottom ; 25 33 41 ........................ ; 26 34 42 ........................ ; 27 35 43 ........................ ; 28 36 44 ........................ ; 29 37 45 ........................ ; 30 38 46 ........................ ; 31 39 47 ........................ ; ; shift down by (y mod 8) steps (apply offset) ; shift right by (x mod 8) steps (ror loop) ; draw with drawkiller (or-version of printchar) ktemp = * ; shifted version (48 bytes)