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Scroll.s
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Scroll.s
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BYTES_PER_LINE: equ 256 ; screen 11
;BYTES_PER_LINE: equ 128 ; screen 5
ADDR_LAST_LINE_OF_PAGE: equ 0x8000 + (63 * 256)
; Input:
; A: number of MegaROM page for first page after first screen
InitVariablesForScroll:
; initialize variables for scrolling on last line of the next page
;ld a, 13
ld (CurrentMegaROMPage), a
ld hl, ADDR_LAST_LINE_OF_PAGE
ld (CurrentAddrLineScroll), hl
ld hl, 255 * 256
ld (CurrentVRAMAddrLineScroll), hl
; VerticalScroll: byte
xor a
ld (VerticalScroll), a
ld b, a ; data
ld c, 23 ; register #
call BIOS_WRTVDP
; VerticalScroll: word
; ld hl, 0
; ld (VerticalScroll), hl
ret
; Input:
; A: number of MegaROM page for last page of first screen
LoadFirstScreen:
; --------- Load first screen
push af
dec a
call InitVariablesForScroll
pop af
push af
; -- Load top part of first image on top 64 lines
;ld a, 14
; ld (Seg_P8000_SW), a
call Set_and_Save_MegaROM_Page
; write to VRAM bitmap area
ld hl, START_ADDR_MEGAROM_PAGE ; ImageData_14 ; RAM address (source)
ld de, NAMTBL + (0 * (256 * 64)) ; VRAM address (destiny)
ld bc, PAGE_SIZE ; ImageData_14.size ; Block length
call BIOS_LDIRVM ; Block transfer to VRAM from memory
pop af
inc a
push af
; -- Load middle part of first image on middle 64 lines
;ld a, 15
; ld (Seg_P8000_SW), a
call Set_and_Save_MegaROM_Page
; write to VRAM bitmap area
ld hl, START_ADDR_MEGAROM_PAGE ; ImageData_15 ; RAM address (source)
ld de, NAMTBL + (1 * (256 * 64)) ; VRAM address (destiny)
ld bc, PAGE_SIZE ; ImageData_15.size ; Block length
call BIOS_LDIRVM ; Block transfer to VRAM from memory
pop af
inc a
push af
; -- Load bottom part of first image on last 64 lines
;ld a, 16
; ld (Seg_P8000_SW), a
call Set_and_Save_MegaROM_Page
; write to VRAM bitmap area
ld hl, START_ADDR_MEGAROM_PAGE ; ImageData_16 ; RAM address (source)
ld de, NAMTBL + (2 * (256 * 64)) ; VRAM address (destiny)
ld bc, PAGE_SIZE ; ImageData_16.size ; Block length
call BIOS_LDIRVM ; Block transfer to VRAM from memory
pop af
ret
SCROLL_FULL_SPEED: equ 0000 0000 b
SCROLL_HALF_SPEED: equ 0000 0001 b
SCROLL_ONE_FOURTH_SPEED: equ 0000 0011 b
SCROLL_SPEED: equ SCROLL_ONE_FOURTH_SPEED
ExecuteScroll:
; speed scroll (scroll only on even frames or on all frames, or at 1/4 of frames)
ld a, (BIOS_JIFFY) ; get only low byte of JIFFY
and SCROLL_SPEED
ret nz
IFDEF DEBUG
; Start profiling a section with in a,(2ch), end with out (2ch),a. ID in A.
xor a
in a, (2ch)
ENDIF
; load next line from bitmap on the last line of virtual screen (256 lines)
; that will be the next to be shown on top of screen
ld a, (CurrentMegaROMPage)
; ld (Seg_P8000_SW), a
call Set_and_Save_MegaROM_Page
; old (slow)
; ld hl, (CurrentAddrLineScroll) ; RAM address (source)
; ld de, (CurrentVRAMAddrLineScroll) ; VRAM address (destiny)
; ld bc, 256 ; Block length
; call BIOS_LDIRVM ; Block transfer to VRAM from memory
; new (optimized) OTIR = 23 cycles/byte = 256x23 = 5888 cycles/frame ; OUTI = 18 cycles/byte = 256x18 = 4608 cycles/frame
ld a, 0000 0000 b
ld hl, (CurrentVRAMAddrLineScroll) ; VRAM address (destiny)
call SetVdp_Write
; unrolled OUTIs
ld hl, (CurrentAddrLineScroll) ; RAM address (source)
ld c, PORT_0
ld d, 8
.loopOUTI:
; 32x OUTI
call OUTI_x32
; outi outi outi outi outi outi outi outi outi outi outi outi outi outi outi outi
; outi outi outi outi outi outi outi outi outi outi outi outi outi outi outi outi
dec d
jp nz, .loopOUTI
; TODO: use VDP command to gain speed (HMMC copies data from your ram to the vram)
; info: HMMC VDP command currently is not working, check msx-tests POC
;
; ld hl, LMMM_Parameters
; call Execute_VDP_LMMM ; Logical move CPU to VRAM (copies data from your ram to the vram)
; update vars
ld de, (CurrentVRAMAddrLineScroll)
dec d ; de = de - 256
ld hl, (CurrentAddrLineScroll)
dec h ; hl = hl - 256
ld a, h
cp 0x80 - 1 ; 0x7fff
jp z, .decPage
jp .dontDecPage
.decPage:
; if (CurrentMegaROMPage == CurrentLevelLastScreen) stopScroll
ld a, (CurrentLevelLastScreen)
ld b, a
ld a, (CurrentMegaROMPage)
cp b
jp z, .stopScroll
; if (CurrentMegaROMPage == 1) stopScroll
dec a
jp z, .stopScroll
ld (CurrentMegaROMPage), a
ld hl, ADDR_LAST_LINE_OF_PAGE
.dontDecPage:
ld (CurrentAddrLineScroll), hl
ld (CurrentVRAMAddrLineScroll), de
; -------------- do vertical scroll
; VerticalScroll: word
; ld hl, (VerticalScroll)
; dec hl
; ld (VerticalScroll), hl
; ld b, l ; data
; VerticalScroll: byte
ld hl, VerticalScroll
dec (hl)
ld b, (hl) ; data
ld c, 23 ; register #
call BIOS_WRTVDP
ld hl, Screen_Y_Origin
dec (hl)
call AdjustSprites_Y
IFDEF DEBUG
; Start profiling a section with in a,(2ch), end with out (2ch),a. ID in A.
xor a
out (2ch), a
ENDIF
ret
.stopScroll:
call StageClearAnimation_RAM_Code
call NextLevel
ret
AdjustSprites_Y:
; adjust Y position of sprites to compensate scroll
ld hl, Player_Y
dec (hl) ; call .adjustSprite
; player shots are so fast that they don't need such a small adjust (let's save some CPU cycles!)
; ld hl, PlayerShot_0_Struct + 2
; call .adjustSprite
; ld hl, PlayerShot_1_Struct + 2
; call .adjustSprite
; ld hl, PlayerShot_2_Struct + 2
; call .adjustSprite
; TODO: if (EnemyMode == ENEMY_MODE_SMALL_ENEMIES)
ld hl, Enemy_0_Struct + 2 ; Y
dec (hl) ; call .adjustSprite
ld hl, Enemy_0_Struct + 11 ; Y1
dec (hl) ; call .adjustSprite
ld hl, Enemy_1_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, Enemy_1_Struct + 11
dec (hl) ; call .adjustSprite
ld hl, Enemy_2_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, Enemy_2_Struct + 11
dec (hl) ; call .adjustSprite
ld hl, Enemy_3_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, Enemy_3_Struct + 11
dec (hl) ; call .adjustSprite
ld hl, Enemy_4_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, Enemy_4_Struct + 11
dec (hl) ; call .adjustSprite
ld hl, Enemy_5_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, Enemy_5_Struct + 11
dec (hl) ; call .adjustSprite
ld hl, Enemy_6_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, Enemy_6_Struct + 11
dec (hl) ; call .adjustSprite
; adjust all Ys of Big Enemies
ld hl, BigEnemy_0_Struct + 2 ; Y
dec (hl) ; call .adjustSprite
ld hl, BigEnemy_0_Struct + 9 ; Y1
dec (hl) ; call .adjustSprite
ld hl, BigEnemy_0_Struct + 11 ; Y2
dec (hl) ; call .adjustSprite
ld hl, BigEnemy_0_Struct + 13 ; Y3
dec (hl) ; call .adjustSprite
ld hl, BigEnemy_0_Struct + 15 ; Y4
dec (hl) ; call .adjustSprite
ld hl, BigEnemy_0_Struct + 17 ; Y5
dec (hl) ; call .adjustSprite
ld hl, BigEnemy_0_Struct + 19 ; Y6
dec (hl) ; call .adjustSprite
ld hl, BigEnemy_1_Struct + 2 ; Y
dec (hl) ; call .adjustSprite
ld hl, BigEnemy_1_Struct + 9 ; Y1
dec (hl) ; call .adjustSprite
ld hl, BigEnemy_1_Struct + 11 ; Y2
dec (hl) ; call .adjustSprite
ld hl, BigEnemy_1_Struct + 13 ; Y3
dec (hl) ; call .adjustSprite
ld hl, BigEnemy_1_Struct + 15 ; Y4
dec (hl) ; call .adjustSprite
ld hl, BigEnemy_1_Struct + 17 ; Y5
dec (hl) ; call .adjustSprite
ld hl, BigEnemy_1_Struct + 19 ; Y6
dec (hl) ; call .adjustSprite
ld hl, EnemyShot_0_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, EnemyShot_1_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, EnemyShot_2_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, EnemyShot_3_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, EnemyShot_4_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, EnemyShot_5_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, EnemyShot_6_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, Item_0_Struct + 2
dec (hl) ; call .adjustSprite
; ld hl, Item_0_Struct + 11 ; y1 isn't used for items
; call .adjustSprite
ld hl, Item_1_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, Item_2_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, Item_3_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, Item_4_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, Item_5_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, Item_6_Struct + 2
dec (hl) ; call .adjustSprite
ld hl, GroundTarget_Sprite.Y
dec (hl) ; call .adjustSprite
ret
; .adjustSprite:
; ; CAUTION: Adjust is only working when the objects are moving on 1px or 3px increments on Y coord (don't know why)
; ; TODO: if this routine has only one instruction,
; ; substitute the call by the instruction itself saving 18 (call) + 11 (ret) = 29 cycles per object (!), aprox 900 cycles, pretty good optimization
; dec (hl)
; ; ld a, (hl)
; ; dec a
; ; ; commented out because it was causing bug
; ; ;cp 216 ; avoid value 216 (hide all sprites)
; ; ;jp nz, .continue
; ; ;ld a, 215
; ; .continue:
; ; ld (hl), a
; ret