; ; Union presents a small production for Speccy.pl classic demo competition 2015 ; ; Programmed and designed by Dr Piotr - back on Amstrad after 25 years! ; Music by Ben Daglish - ripped from Masters Of Universe game (c) 1987 Gremlin Graphics ; ; Code & Graphics - copyright 2015 Union, free for noncommercial use ; Music - copyright 1987 Gremlin Graphics ; This intro features: ; - Unlimited bobs effect, using triple screen buffering, fixed point math ; - Split screen mode, with mode 0 (16 colors) in 256x148 in the upper part of the screen ; and with mode 1 (4 colors) in 400x50 ; - Overscan with 400 pixels for the scroll at the bottom of the screen ; - Raster effect on the scroll text ; - Shake screen effect, synced with music ; - No firmware calls used, pure hardware banging ; Maxam or WinAPE compatible assembler required. org &800 run &800 nolist ; screen dimensions ScreenWidth equ 128 ScreenHeight equ 148 ; screen mode 0 - 160x200 ScreenMode equ 0 ; screen bytes per pixels - calculation based on Screenmode ScreenBytesPerPixel equ ScreenMode*ScreenMode+ScreenMode+2 ; max count of chars i aa font MaxCharsInFont equ 52 ; define sprite x & y dimensions i pixels SpriteXsize equ 16 SpriteYSize equ 16 ; scroll width in bytes ScrollWidth equ 50 ; scroll height ScrollHeight equ 25 ; scroll screen mode ScrollScreenMode equ 1 ; scroll char width in pixels ScrollCharWidth equ 16 ; scroll char height in pixels ScrollCharHeight equ 25 ; deleay between changes of parameters for bobs drawing BobsDelay equ 1800 ; macro - calculate next screen lined address input and result in hl macro scr_next_line_hl bytes_per_line ld a,h ; 1 add a,8 ; 2 ld h,a ; 1 and &38 ; 2 jr nz,@scr_next_line_end ; 2 ld a,l ; 1 add a, bytes_per_line ; 2 ld l,a ; 1 ld a,h ; 1 adc a,&c0 ; 2 ld h,a ; 1 @scr_next_line_end: mend ; macro - calculate next screen lined address input and result in hl macro scr_next_line_de bytes_per_line ld a,d ; 1 add a,8 ; 2 ld d,a ; 1 and &38 ; 2 jr nz,@scr_next_line_end ; 2 ld a,e ; 1 add a, bytes_per_line ; 2 ld e,a ; 1 ld a,d ; 1 adc a,&c0 ; 2 ld d,a ; 1 @scr_next_line_end: mend ; macro - wait for vertcal refresh macro WaitVBL ld bc,&f500 @WaitVBLLoop: in a,(c) rra jr nc,@WaitVBLLoop mend ; macro - multiply 16 bit value by 8 bit value ; DE - 16 bit number to multiply by ; A - 8 bit number (multiplier) ; HL - 16 bit result macro Mul_DExA ld b,8 ld hl,0 @loop: add hl,hl rlca jr nc,@skip add hl,de @skip: djnz @loop mend ; macro - multiply 8 bit value by 8 bit value ; H,E - 8 bit numbers to multiply ; HL - 16 bit result macro Mul_HxE ld d,0 ld l,d ld b,8 @loop: add hl,hl jr nc,@skip add hl,de @skip: djnz @loop mend ; macro - get sin value from the table macro cos ld l,a ld h,0 ld de, cosTable add hl,de ld a,(hl) mend ; macro - get sin value from the table macro sin sub 64 cos mend ; macro - draw a character on screen ; b - char height, c - char width, hl- ptr to char data to draw, de - destination screen address macro DrawChar bytes_per_line @charloop: push hl push bc @lineloop: ld a,(de) inc de ld (hl),a inc hl dec c jr nz, @lineloop pop bc pop hl scr_next_line_hl bytes_per_line djnz @charloop mend ; ---- start of the program ---- ; setup interrupt handler di im 1 ld hl,InterruptHandler ld (#0039),hl ld a,#c3 ld (#0038),a ; change stack to free area - the original location is taken by the 2nd sceen buffer ld sp,#3fff ; initialize screen address lookup table call BuildLookupTable ; initialize font character table ld hl, ScrollFont ld a,50 call InitFontCharOffsetTable ;initialize music call music_init ; set crtc vertival height (disp characters) to 26 ld bc,&bc06 out (c),c ld bc,&bd1a out (c),c ld bc,&bc07 out (c),c ld bc,&bd1f out (c),c call ClearVideoMemory ld hl,Colors ld e, 8 call SetColors WaitVBL ; enable interrupts ei ; main loop starts here Loop: ; wait for vertical blanking sync WaitVBL ld a,(UnlimitedBobsEffectEnabled) or a jr nz, init_bobs call Scroll jr loop init_bobs: ld hl,(CurrSpritePosPtr) ld a,l or h jr nz, do_bobs ld hl,SpritePos jp set_pos do_bobs WaitVBL ; get current screen buffer offset and calculate next ld a, (current_scr_offset+1) add #10 cp #40 jr nz, update_screen_offset ld a,#10 update_screen_offset: ld (current_scr_offset+1),a ; set a new hardware screen buffer offset ld bc,&bc0c out (c),c inc b out (c),a ; update sprite position call SpriteUpdatePos ld hl, (CallCnt) ld a,l or h jr nz, next ld hl,BobsDelay ld (CallCnt),hl ld hl,(CurrSpritePosPtr) inc hl inc hl inc hl inc hl inc hl ld a,(hl) or a jr nz,set_pos ld hl,SpritePos set_pos: ld (CurrSpritePosPtr),hl ld de,CurrSpritePos ld a,(hl) ld (de),a inc hl inc de ld a,(hl) ld (de),a inc hl inc de ld a,(hl) ld (CurrSpriteAngle+1),a inc hl ld a,(hl) ld (de),a inc hl inc de ld a,(hl) ld (de),a inc hl inc de ; clear 3 buffers with upper part of the screen ld a, (current_scr_offset+1) push af ld a,#10 ld (current_scr_offset+1),a ld h,ScreenHeight ld l,ScreenWidth/2 ld de,0 ld bc,0 xor a call ClearScreen ld a,#20 ld (current_scr_offset+1),a ld h,ScreenHeight ld l,ScreenWidth/2 ld de,0 ld bc,0 xor a call ClearScreen ld a,#30 ld (current_scr_offset+1),a ld h,ScreenHeight ld l,ScreenWidth/2 ld de,0 ld bc,0 xor a call ClearScreen pop af ld (current_scr_offset+1),a next: ; wait a bit ld hl,#6e0 @waitloop: dec hl ld a,l or h jr nz, @waitloop ; back to main loop jp loop ; clear screen ClearScreen: ; h,l -ysize,xsize ; bc - xstart ; de - ystart ; a - a value to fill in push af push hl call CalcScreenAddress pop de pop af ld b,d ld d,a @ClearHeightLoop: push hl ld c,e @ClearWidthLoop: ld (hl),d inc hl dec c jr nz, @ClearWidthLoop pop hl scr_next_line_hl &40 djnz @ClearHeightLoop ret ; clear screen buffers memory ClearVideoMemory: ld hl, &4000 ld de, &bfff @fill: xor a ld (hl),a inc hl dec de ld a,e or d jr nz, @fill ret ; set hardware screen address offset SetScreenAddress: ld a, (current_scr_offset+1) ld bc,&bc0c out (c),c out (c),a xor a ld bc,&bc0d out (c),c out (c),a ret CalcScreenAddress: ; de - ypos ; bc - x pos ; out- hl - current screen address sla e rl d ld hl,screen_lines_table add hl,de ; get memory offset for y coord ld e, (hl) inc hl ld d, (hl) ; account for current video screen address ex de,hl ld de,(current_scr_offset) sla d sla d add hl,de ; calc x offset - for mode 0 divide by 2 ld a,c srl b rr c ; calc final screen memory address add hl,bc ret ; sprite related variables CurrSpriteAngle: db 0, 6 CurrSpritePos: db 96,96, 2, 2 CurrSpritePosPtr: dw 0 SpritePos: db 20,30, 6, 6, 4 db 10,10,-3, 2, 1 db 78,66, 4,-1, 4 db 44,35, 3, 2, 6 db 88,30, 4, 1, 5 db 96,96, 6, 2, 2 db 50,50, 4, 3, 3 db 0 ; update sprite position SpriteUpdatePos: ; update sprite angle ld ix,CurrSpriteAngle ld a,(ix) add (ix+1) ld (ix),a jr nc, @skip_update ; update sprite x position ld ix,CurrSpritePos ld a,(ix) add (ix+2) cp ScreenWidth-SpriteXSize jr c, @updatenext ld a,ScreenHeight-SpriteYSize @updatenext: ld (ix),a ; update sprite y position ld a,(ix+1) add (ix+3) cp ScreenHeight-SpriteYSize jr c, @updatenext2 ld a, ScreenHeight-SpriteYSize @updatenext2: ld (ix+1),a ld a,(CurrSpriteAngle) @skip_update: ; get sinus for a given angle, returns value in fp 8.8 format call sinFP ex de,hl ld a,(CurrSpritePos) ; calculate curent x position Mul_DExA push hl ; get cosinus for a given angle, returns value in fp 8.8 format ld a,(CurrSpriteAngle) call cosFP ex de,hl ld a,(CurrSpritePos+1) ; calculate curent y position Mul_DExA ex de,hl pop bc ; draw a sprite ;draw a sprite on a screen ; bc - xpos in fp 8.8 ; de - ypox in fp 8.8 DrawSpriteFP: xor a ld c,b ld e,d ld b,a ld d,a ;draw a sprite on a screen ; bc - xpos ; de - ypox DrawSprite: ; x clipping ld a,c cp 0 jp p, @ClipXNext ld c,0 jr @ClipXnext2 @ClipXnext: cp ScreenWidth-SpriteXsize jp c, @ClipXnext2 ld c,ScreenWidth-SpriteXsize @ClipXnext2: ; y clipping ld a,e cp 1 jp nc, @ClipYNext ld e,0 jr @ClipYnext2 @ClipYnext: cp ScreenHeight-SpriteYsize jp c, @ClipYnext2 ld e,ScreenHeight-SpriteYsize @ClipYnext2: ; calc target memory address for a given screen position call CalcScreenAddress ex de,hl ; de now contains destination screen memory pointer ld hl, SpriteData ld b, SpriteYSize ; draw a sprite @DrawHeightLoop: ld c, SpriteXSize/ScreenBytesPerPixel push de @DrawWidthLoop: ; get sprite data ld a,(de) ; apply sprite mask and (hl) inc hl ; copy in image data or (hl) inc hl ; write to screen ld (de),a inc de dec c jr nz, @DrawWidthLoop pop de ; calculate address of next screen line scr_next_line_de &40 djnz @DrawHeightLoop ret ; clear sprite on screen ; bc - xpos ; de - ypox ; a - a value to fill in SpriteClear: call CalcScreenAddress ld b, SpriteYSize-1 @SpriteClearHeightLoop: ld c, SpriteXSize/ScreenBytesPerPixel push hl @SpriteClearWidthLoop: ld (hl),a inc hl dec c jr nz, @SpriteClearWidthLoop pop hl scr_next_line_hl &40 djnz @SpriteClearHeightLoop ret ; scroll routines ; scroll text Scroll: ld a,(scroll_delay) or a jr z, @skip_delay dec a ld (scroll_delay),a jr @skip_write_char @skip_delay: ld hl,(current_scr_offset) call ScrollText ld a,(scroll_cnt) dec a ld (scroll_cnt),a or a jr nz,@skip_write_char call WriteChar ld a,ScrollCharWidth/4+1 ld (scroll_cnt),a @skip_write_char: ret ScrollText: ; hl - hardware screen address ; calculate final screen memory offset ld bc, #1e0e sla h sla h add hl, bc ex de, hl ld b, ScrollHeight @scroll_loop: ld a,b push de ld h,d ld l,e inc hl ld bc, ScrollWidth*2 ldir ld b,a pop de scr_next_line_de ScrollWidth*2 djnz @scroll_loop ret ; restart scroll text RestartScrollText: ld hl, scroll_text ld (scrolltext_ptr), hl WriteChar: ; get a char from text scroll, check if reached end ld hl, (scrolltext_ptr) ld a, (hl) or a jr z, RestartScrollText inc hl ld (scrolltext_ptr), hl cp 1 jr nz, @write_skip_delay ld a, (hl) inc hl ld (scrolltext_ptr), hl ld (scroll_delay), a ld a,64 @write_skip_delay: cp 2 jr nz, @write_skip_trigger_bobs ; copy scroll area to remaining 2 screen buffers ld hl,#c000 ld de,#4000 ld bc,#3fff ldir ld hl,#c000 ld de,#8000 ld bc,#3fff ldir ld hl,BobsDelay ld (CallCnt),hl ld (UnlimitedBobsEffectEnabled),a ret @write_skip_trigger_bobs: cp 32 jr nz, @write_skip_space add 32 jr @skip @write_skip_space: cp 63 jr nc, @skip add 16+26 @skip: ; calculate offset to the char in the font sub 64 sla a ld de,0 ld e,a ld hl, charoffset_table add hl,de ld e,(hl) inc hl ld d,(hl) ; calculate final screen memory offset ld hl,(current_scr_offset) sla h sla h ld bc,#1e0e+96 add hl,bc ld b, ScrollCharHeight ld c, 4 ; draw a char ; DrawChar ScrollWidth*2 ;DrawChar: ; b - char height, hl-char data to draw, de - destination address charloop: push hl ld a,(de) inc de ld (hl),a inc hl ld a,(de) inc de ld (hl),a inc hl ld a,(de) inc de ld (hl),a inc hl ld a,(de) inc de ld (hl),a pop hl scr_next_line_hl ScrollWidth*2 djnz charloop ret ; initialize table, containing font offsets for each character ; hl - new font data ; a - number of chars InitFontCharOffsetTable: push af ld e, (hl) inc hl ld a, (hl) inc hl push hl ld h,a Mul_HxE push hl pop bc pop hl pop af ld de,charoffset_table @fonttableloop: ex de,hl ld (hl), e inc hl ld (hl), d inc hl ex de,hl add hl,bc dec a or a jr nz, @fonttableloop ret ; screen related variables ; current screen offset in crtc values current_scr_offset: dw &3000 scroll_delay: db 0 scroll_cnt db 4 scrolltext_ptr; dw scroll_text scroll_text: db ' FIRST ',1,120 db ' THERE WAS GFORCE ',1,100 db ' NOW ',1,100 db ' AFTER 25 YEARS ',1,120 db ' WE ARE BACK ',1,140 db ' UNION PRESENTS ',1,240 db ' A PRODUCTION FOR SPECCY PL 2O15 CLASSIC DEMO COMPETITION ' db ' PROGRAM GRAPHICS AND DESIGN BY DR PIOTR ' db ' UNLIMITED BOBS ',2,0 db 'MUSIC BY BEN DAGLISH RIPPED FROM MASTERS OF UNIVERSE GAME BY GREMLIN GRAPHICS',2,0 ; interupt im 1 handler routine, called every 300th of second InterruptHandler: di ; store used registers on the stack push af push bc push de push hl push ix ; find if an interrupt was triggered in vertical blanking ld b,&f5 in a,(c) rra jr nc,@UpdateIntCnt ; if so, reset interrupt counter xor a jr @SkipCnt @UpdateIntCnt: ld a,(IntCnt) inc a @skipcnt: ; handle various operations depending on screen vertical position ld (IntCnt),a or a jr nz, @next1 ; change video mode to 0 ld bc,&7f8c out (c),c ; set screen size to 256 pixels (32 crtc chars) ld bc,&bc01 out (c),c ld bc,&bd20 out (c),c ld bc,&bc02 out (c),c ld bc,&bd2a out (c),c ; on every 50th of second call music player call music_play ld hl,(CallCnt) ld a,l or h jr z,IntExit dec hl ld (CallCnt),hl jp ShakeEffect @next1: cp #3 jr nz,@next2 jr IntExit @next2: cp #4 jr nz,IntExit ld bc,#bc02 out (c),c ld bc,#bd2a out (c),c ; in lower part of the screenm change the screen mode to 1 ld bc,&7f8d out (c),c ; set overscan width = 400 pixels (50 crtc chars) ld bc,&bc01 out (c),c ld bc,&bd32 out (c),c ld bc,&bc02 out (c),c ld bc,&bd33 out (c),c ld bc,&7f00 ld a,#54 out (c),c out (c),a ; call raster effect jr RasterEffect IntExit: ; reset colors to default after raster effect ld hl,Colors ld e, 8 call SetColors ; restore registers from stack pop ix pop hl pop de pop bc pop af ; return from interrupt ei reti ; this keeps track of the section of the screen we are currenty in IntCnt: db 0 CallCnt: dw 0 ShakeEffectEnabled: db 0 RasterEffectEnabled: db 1 UnlimitedBobsEffectEnabled: db 0 ; various effects called from interrupt routine ; Raster effect - make stripes on the scroll font RasterEffect: ; check if raster effect is enabled ld a, (RasterEffectEnabled) or a jr z, IntExit defs 19,0 ld b,12 @raster_effect_loop: push bc ; set colors to a color from the table ld hl,RasterColorsTable ld bc,&7f01 out (c),c ld a,4 @raster_effect_loop2: outi ; nops to exactly sync to the next raster line defs 54,0 inc b dec a jr nz,@raster_effect_loop2 ; move colors in the table to get the moving raster effect ld hl,RasterColorsTable+1 ld de,RasterColorsTable ld a,(de) ld bc,12 ldir ld (RasterColorsTable+12),a defs 20,0 pop bc djnz @raster_effect_loop jp IntExit RasterColorsTable: db #5c,#4c,#4e,#4a,#4b,#4a,#4e,#4c,#54,#54,#54,#54,#54 ; shake effect - shakes the screen by changing position of horizontal sync. pulse ShakeEffect: ; check if the effect is enabled ld a,(ShakeEffectEnabled) or a jp z, IntExit ; wait a bit ld b,20 @wait_loop: djnz @wait_loop ld hl,(WavePtr) ld b,5 @shake_loop: push bc ; change the position of horizontal sync. pulse crtc register ld bc,#bc02 out (c),c inc b ld a,(hl) inc hl sub #3 out (c),a pop bc djnz @shake_loop ; change the offset to the table to get the moving shake effect ld hl,(WavePtr) inc hl ld a, (ShakeCnt) dec a jr nz,@shake_skip ; reset table offsets and counters xor a ld (ShakeEffectEnabled),a ld a,28 ld hl, waves @shake_skip: ld (ShakeCnt),a ld (WavePtr),hl shake_reset: jp IntExit ShakeCnt: db 28 WavePtr: dw waves waves: db 42,43,44,45,46,47,48,49,48,47,46,45,44,43,42,43,44,45,46,47,48,49 db 45,44,43,42,43,44 db 45,46,47,48,49,49,49,48,47,46,45,44,43,42,43,44,45,45 ; get sinus value from the table - also available as a macro sin: sub 64 ; get cosinus value from the table - also available as a macro cos: ld l,a ld h,0 ld de, CosTable add hl,de ld a,(hl) ret ; get sin value from the table in fixed point 8.8 sinFP: sub 64 ; get cossin value from the table in fixed point 8.8 cosFP: ld l,a ld h,0 ld de, CosTable add hl,de ld a,(hl) add 64 ld l,a rla ; sbc a,a ; ld h,a ld h,0 ; add hl, hl add hl, hl ret ; 256 values of cosinus, kept between -64,64 range - calculated as cos(2*PI*a/256)/64 CosTable: defb 64, 64, 64, 64, 64, 64, 63, 63 defb 63, 62, 62, 62, 61, 61, 60, 60 defb 59, 59, 58, 57, 56, 56, 55, 54 defb 53, 52, 51, 50, 49, 48, 47, 46 defb 45, 44, 43, 42, 41, 39, 38, 37 defb 36, 34, 33, 32, 30, 29, 27, 26 defb 24, 23, 22, 20, 19, 17, 16, 14 defb 12, 11, 9, 8, 6, 5, 3, 2 defb 0, -2, -3, -5, -6, -8, -9,-11 defb -12,-14,-16,-17,-19,-20,-22,-23 defb -24,-26,-27,-29,-30,-32,-33,-34 defb -36,-37,-38,-39,-41,-42,-43,-44 defb -45,-46,-47,-48,-49,-50,-51,-52 defb -53,-54,-55,-56,-56,-57,-58,-59 defb -59,-60,-60,-61,-61,-62,-62,-62 defb -63,-63,-63,-64,-64,-64,-64,-64 defb -64,-64,-64,-64,-64,-64,-63,-63 defb -63,-62,-62,-62,-61,-61,-60,-60 defb -59,-59,-58,-57,-56,-56,-55,-54 defb -53,-52,-51,-50,-49,-48,-47,-46 defb -45,-44,-43,-42,-41,-39,-38,-37 defb -36,-34,-33,-32,-30,-29,-27,-26 defb -24,-23,-22,-20,-19,-17,-16,-14 defb -12,-11, -9, -8, -6, -5, -3, -2 defb 0, 2, 3, 5, 6, 8, 9, 11 defb 12, 14, 16, 17, 19, 20, 22, 23 defb 24, 26, 27, 29, 30, 32, 33, 34 defb 36, 37, 38, 39, 41, 42, 43, 44 defb 45, 46, 47, 48, 49, 50, 51, 52 defb 53, 54, 55, 56, 56, 57, 58, 59 defb 59, 60, 60, 61, 61, 62, 62, 62 defb 63, 63, 63, 64, 64, 64, 64, 64 ;16x16 SpriteData: defb &FF,&00,&FF,&00,&FF,&00,&00,&0C,&00,&0C,&FF,&00,&FF,&00,&FF,&00; line 0 defb &FF,&00,&FF,&00,&00,&0C,&00,&00,&00,&00,&00,&0C,&FF,&00,&FF,&00; line 1 defb &FF,&00,&AA,&04,&00,&78,&00,&E4,&00,&C0,&00,&C0,&55,&08,&FF,&00; line 2 defb &FF,&00,&00,&1C,&00,&F0,&00,&A0,&00,&30,&00,&30,&00,&84,&FF,&00; line 3 defb &AA,&04,&00,&D8,&00,&F0,&00,&40,&00,&30,&00,&30,&00,&60,&55,&08; line 4 defb &AA,&04,&00,&78,&00,&E4,&00,&90,&00,&30,&00,&30,&00,&60,&55,&08; line 5 defb &00,&4C,&00,&78,&00,&A0,&00,&30,&00,&30,&00,&30,&00,&C0,&00,&04; line 6 defb &00,&08,&00,&78,&00,&A0,&00,&30,&00,&30,&00,&60,&00,&00,&00,&8C; line 7 defb &00,&08,&00,&44,&00,&C8,&00,&30,&00,&30,&00,&80,&00,&00,&00,&8C; line 8 defb &00,&08,&00,&C0,&00,&90,&00,&60,&00,&C0,&00,&00,&00,&44,&00,&8C; line 9 defb &AA,&04,&00,&C0,&00,&30,&00,&C0,&00,&80,&00,&44,&00,&6C,&55,&08; line 10 defb &AA,&04,&00,&40,&00,&90,&00,&C0,&00,&00,&00,&9C,&00,&B4,&55,&08; line 11 defb &FF,&00,&00,&08,&00,&C0,&00,&80,&00,&00,&00,&78,&00,&A4,&FF,&00; line 12 defb &FF,&00,&AA,&04,&00,&40,&00,&80,&00,&00,&00,&3C,&55,&08,&FF,&00; line 13 defb &FF,&00,&FF,&00,&00,&0C,&00,&00,&00,&00,&00,&0C,&FF,&00,&FF,&00; line 14 defb &FF,&00,&FF,&00,&FF,&00,&00,&0C,&00,&0C,&FF,&00,&FF,&00,&FF,&00; line 15 ; a table of pointers to screen memory lines screen_lines_table: ds 200*2,0 SetColors: ; hl - color table of hardware values ; e - number of colors to set ld bc,&7f00 @loop: ld a,(hl) inc hl out (c),c out (c),a inc c dec e jr nz, @loop ld bc,&7f10 ld a,(hl) out (c),c out (c),a ret Colors: db #57,#55,#54,#5f,#44,#4b,#5b,#54,#57 ; include music player and data read "MastersOfUniverseMusic.asm" ; build screen lines lookup tables BuildLookupTable: ld de,&0000 ld b,200 ld hl, screen_lines_table build_table_loop: ld (hl),e inc hl ld (hl),d inc hl scr_next_line_de &40 dec b jr nz,build_table_loop ret ; table of character offsets in a font charoffset_table: ds MaxCharsInFont*2,0 ; include compiled fonts ScrollFont: incbin "ScrollFont.bin"