;; This example shows how ;; to cut sprites where a panel is displayed. ;; Panel is displayed using Plus split screen ;; ;; sprites are cut by writing a mag value that disables them org &8000 start: ;;-------------------------------------------------- ;; STEP 1 - Unlock CPC+ additional features ;; unlock asic to gain access to asic registers di ld b,&bc ld hl,sequence ld e,17 seq: ld a,(hl) out (c),a inc hl dec e jr nz,seq ei ;; put something where main screen will be ld hl,&c000 ld e,l ld d,h inc de ld (hl),&aa ld bc,&3fff ldir ;; put something where split will be ld hl,&4000 ld e,l ld d,h inc de ld (hl),&ff ld bc,&3fff ldir ;;-------------------------------------------------- ;; STEP 2 - Setup sprite pixel data ;; ;; The ASIC has internal "RAM" used to store the sprite pixel ;; data. If you want to change the pixel data for a sprite ;; then you need to copy new data into the internal "RAM". ;; page-in asic registers to &4000-&7fff ld bc,&7fb8 out (c),c ;; write same pixel data to all sprites ld b,16 ld hl,sprite_pixel_data ;; address of sprite 0 pixel data ;; sprite 0 pixel data is in the range &4000-&4100 ld de,&4000 ;; In this loop, HL will be preserved. ;; B will count down for each sprite ;; DE will increase for each sprite write_gfx: push hl push bc ;; length of pixel data for a single sprite (16x16 = 256) ld bc,&100 ldir pop bc pop hl djnz write_gfx ;;-------------------------------------------------- ;; STEP 3 - Setup sprite palette ;; ;; The sprites use a single 15 entry sprite palette. ;; pen 0 is ALWAYS transparent. ;; ;; The sprite palette is different to the screen palette. ;; copy colours into ASIC sprite palette registers ld hl,sprite_colours ld de,&6422 ld bc,15*2 ldir ;;-------------------------------------------------- ;; STEP 4 - Setup sprite properties ;; ;; Each sprite has properties which define the x,y coordinates ;; and x,y magnification. di im 1 ;; interrupt mode 1 ld a,&c3 ld hl,interrupt1 ;; this changes as we execute interrupts ld (&0038),a ld (&0039),hl ;; set initial raster interrupt line; this will change ld a,200 ld (&6800),a ;; set screen split at line 200; this is static ld a,200 ld (&6801),a ;; screen split address; this is static ;; uses CRTC style memory addresses ld hl,&1000 ld a,h ld (&6802),a ld a,l ld (&6803),a ;; move screen up so we have space for panel ld bc,&bc07 out (c),c ld bc,&bd00+35 out (c),c ;; make space for panel (8 lines greater than normal screen) ld bc,&bc06 out (c),c ld bc,&bd00+25+8 out (c),c ei ;; setup sprite x coordinates ld hl,&6000 ;; sprite 0 register location (+0 for X) ld de,0 ;; initial x coordinate ld bc,16 ;; x coordinate increment ld a,16 ;; number of sprites to setup set_x: push af ;; write x ld (hl),e inc l ld (hl),d ;; add to get to next sprite info ld a,l add a,7 ld l,a ;; update x coordinate ex de,hl add hl,bc ex de,hl pop af dec a jr nz,set_x ld hl,&6002 ;; sprite 0 register location (+2 for Y) ld de,100 ;; initial y coordinate ld bc,16 ;; y coordinate increment ld a,16 ;; number of sprites to setup set_y: push af ;; write y ld (hl),e inc l ld (hl),d ;; add to get to next sprite info ld a,l add a,7 ld l,a ;; update y coordinate ex de,hl add hl,bc ex de,hl pop af dec a jr nz,set_y ;; we have interrupts running so we loop to see them happening. loop: jp loop ;;-------------------------------------------------- ;; this interrupt occurs at screen split location interrupt1: push af push bc push hl ;; disable all sprites to cut them at the position of the panel call disable_sprites ;; next raster interrupt after panel ld a,250 ld (&6800),a ;; interrupt handler ld hl,interrupt2 ld (&0039),hl pop hl pop bc pop af ei reti ;;-------------------------------------------------- interrupt2: push af push bc push hl ;; restore sprite enables call enable_sprites ;; where panel is ld a,200 ld (&6800),a ;; back to interrupt 1 again ld hl,interrupt1 ld (&0039),hl pop hl pop bc pop af ei reti ;;-------------------------------------------------- enable_sprites: ld c,%0101 ;; x1 in X, x1 in Y, mode 2 resolution jr en_dis_sprites ;;-------------------------------------------------- disable_sprites: ld c,0 ;; disable jr en_dis_sprites ;;-------------------------------------------------- en_dis_sprites: ld hl,&6004 ;; mag for sprite 0 ld b,16 es1: ld (hl),c ;; write value into mag ld a,l ;; update pointer for next sprite mag add a,8 ld l,a djnz es1 ret ;;-------------------------------------------------- ;; - there is two bytes per colour. ;; - these are stored in a form that can be written direct ;; to the CPC+ colour palette registers (i.e. xGRB) ;; - pen 0 is always transparent and doesn't have a entry ;; in the CPC+ palette sprite_colours: defw &0111 ;; colour for sprite pen 1 defw &0222 ;; colour for sprite pen 2 defw &0333 ;; colour for sprite pen 3 defw &0444 ;; colour for sprite pen 4 defw &0555 ;; colour for sprite pen 5 defw &0666 ;; colour for sprite pen 6 defw &0777 ;; colour for sprite pen 7 defw &0888 ;; colour for sprite pen 8 defw &0999 ;; colour for sprite pen 9 defw &0aaa ;; colour for sprite pen 10 defw &0bbb ;; colour for sprite pen 11 defw &0ccc ;; colour for sprite pen 12 defw &0ddd ;; colour for sprite pen 13 defw &0eee ;; colour for sprite pen 14 defw &0fff ;; colour for sprite pen 15 ;;--------------------------------------------- ;; - there is one pixel per byte (bits 3..0 of each byte define the palette index for this pixel) ;; - these bytes are stored in a form that can be written direct to the ASIC ;; sprite pixel data sprite_pixel_data: defb &01,&02,&03,&04,&05,&06,&07,&08,&09,&0a,&0b,&0c,&0d,&0e,&0f,&01 ;; line 0 defb &01,&02,&03,&04,&05,&06,&07,&08,&09,&0a,&0b,&0c,&0d,&0e,&0f,&01 ;; line 1 defb &01,&02,&03,&04,&05,&06,&07,&08,&09,&0a,&0b,&0c,&0d,&0e,&0f,&01 ;; line 2 defb &01,&02,&03,&04,&05,&06,&07,&08,&09,&0a,&0b,&0c,&0d,&0e,&0f,&01 ;; line 3 defb &01,&02,&03,&04,&05,&06,&07,&08,&09,&0a,&0b,&0c,&0d,&0e,&0f,&01 ;; line 4 defb &01,&02,&03,&04,&05,&06,&07,&08,&09,&0a,&0b,&0c,&0d,&0e,&0f,&01 ;; line 5 defb &01,&02,&03,&04,&05,&06,&07,&08,&09,&0a,&0b,&0c,&0d,&0e,&0f,&01 ;; line 6 defb &01,&02,&03,&04,&05,&06,&07,&08,&09,&0a,&0b,&0c,&0d,&0e,&0f,&01 ;; line 7 defb &01,&02,&03,&04,&05,&06,&07,&08,&09,&0a,&0b,&0c,&0d,&0e,&0f,&01 ;; line 8 defb &01,&02,&03,&04,&05,&06,&07,&08,&09,&0a,&0b,&0c,&0d,&0e,&0f,&01 ;; line 9 defb &01,&02,&03,&04,&05,&06,&07,&08,&09,&0a,&0b,&0c,&0d,&0e,&0f,&01 ;; line 10 defb &01,&02,&03,&04,&05,&06,&07,&08,&09,&0a,&0b,&0c,&0d,&0e,&0f,&01 ;; line 11 defb &01,&02,&03,&04,&05,&06,&07,&08,&09,&0a,&0b,&0c,&0d,&0e,&0f,&01 ;; line 12 defb &01,&02,&03,&04,&05,&06,&07,&08,&09,&0a,&0b,&0c,&0d,&0e,&0f,&01 ;; line 13 defb &01,&02,&03,&04,&05,&06,&07,&08,&09,&0a,&0b,&0c,&0d,&0e,&0f,&01 ;; line 14 defb &01,&02,&03,&04,&05,&06,&07,&08,&09,&0a,&0b,&0c,&0d,&0e,&0f,&01 ;; line 15 ;;---------------------------------------------------------- ;; this is the sequence to unlock the ASIC extra features sequence: defb &ff,&00,&ff,&77,&b3,&51,&a8,&d4,&62,&39,&9c,&46,&2b,&15,&8a,&cd,&ee end start