gameboy/game/text.asm

294 lines
8.7 KiB
NASM

SECTION "ram_textwriter", WRAM0
textwriter_curtext: ds 2
textwriter_posx: ds 1
textwriter_posy: ds 1
textwriter_curdelay: ds 1
textwriter_active: ds 1
textwriter_starting: ds 1
textwriter_ending: ds 1
textwriter_pausing: ds 1
SECTION "rom_textmap", ROM0,ALIGN[8]
textwriter_map:
; 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
db $44,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50 ; 0
; 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F
db $50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50,$50 ; 16
; 20 21 22 23 24 25 26 27 28 29 2A 2B 2C 2D 2E 2F
db $50,$41,$50,$45,$50,$50,$50,$43,$50,$50,$50,$50,$42,$50,$3F,$50 ; 32
; 30 31 32 33 34 35 36 37 38 39 3A 3B 3C 3D 3E 3F
db $35,$36,$37,$38,$39,$3A,$3B,$3C,$3D,$3E,$50,$50,$50,$50,$50,$40 ; 48
; 40 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F
db $50,$01,$02,$03,$04,$05,$06,$07,$08,$09,$0A,$0B,$0C,$0D,$0E,$0F ; 64
; 50 51 52 53 54 55 56 57 58 59 5A 5B 5C 5D 5E 5F
db $10,$11,$12,$13,$14,$15,$16,$17,$18,$19,$1A,$50,$50,$50,$50,$50 ; 80
; 60 61 62 63 64 65 66 67 68 69 6A 6B 6C 6D 6E 6F
db $50,$1B,$1C,$1D,$1E,$1F,$20,$21,$22,$23,$24,$25,$26,$27,$28,$29 ; 96
; 70 71 72 73 74 75 76 77 78 79 7A 7B 7C 7D 7E 7F
db $2A,$2B,$2C,$2D,$2E,$2F,$30,$31,$32,$33,$34,$50,$50,$50,$50,$50 ; 112
SECTION "TextWriter", ROM0
InitWindow:
; Fill first line in window with straight line
ld hl, (_SCRN1 + 1)
ld b, 19
ld a, $52
call Memfill
; Fill rest of the area with dark bg
call ClearWindow
; Fill last line in window with straight line
ld hl, (_SCRN1 + $61)
ld b, 19
ld a, $57
call Memfill
; Top left corner
ld hl, _SCRN1
ld [hl], $51
; Top right corner
ld hl, _SCRN1 + 19
ld [hl], $53
; Bottom Left corner
ld hl, _SCRN1 + $60
ld [hl], $56
; Bottom Right corner
ld hl, _SCRN1 + $60 + 19
ld [hl], $58
; Left line
ld hl, _SCRN1 + $20
ld [hl], $54
ld hl, _SCRN1 + $40
ld [hl], $54
; Right line
ld hl, _SCRN1 + $20 + 19
ld [hl], $55
ld hl, _SCRN1 + $40 + 19
ld [hl], $55
; Some other common memory addresses that should be filled
ld a, 0
ld [textwriter_posx], a
ld [textwriter_posy], a
ld [textwriter_ending], a
ld [textwriter_pausing], a
ld [textwriter_active], a
ld [textwriter_curdelay], a
ld [textwriter_starting], a
ret ; Return
ClearWindow:
ld hl, (_SCRN1 + $21)
ld a, $50
ld b, 18
call Memfill
ld hl, (_SCRN1 + $41)
ld b, 18
call Memfill
ret
; Start to print a string on screen
; @param de - Address source string
; @return a - garbage
; @return b - PosX on where to draw text
; @return c - PosY on where to draw text
; @return hl - Workram position for text pointer
; @return de - Memory address to source string
StartText:
ld a, 10
ld [textwriter_curdelay], a
ld a, 0
ld [textwriter_posx], a
ld [textwriter_posy], a
ld [textwriter_ending], a
ld [textwriter_pausing], a
ld a, 1
ld [textwriter_active], a
ld hl, textwriter_curtext
ld a, d
ld [hli], a
ld a, e
ld [hl], a
dec hl
ld a, 16
ld [textwriter_starting], a
call ClearWindow ; Clear it just in case
ret
; Draw text if one is currently active
DrawActiveText:
ld a, [textwriter_active] ; Check if text is currently active
and a
ret z ; If no text is active, just exit immediately
ld a, [textwriter_starting] ; Check if we're booting up the window
and a
jr z, .afterLoading ; Jump to after loading if we're not loading
; We are loading the window
ld a, [rWY] ; Get current window position
dec a ; Decrement twice (moves it slowly up)
dec a
ld [rWY], a ; Set the position back into window
ld a, [textwriter_starting]
dec a
ld [textwriter_starting], a
jr z, .afterLoading
ret
.afterLoading
ld a, [textwriter_ending] ; Check if we are ending
and a
jr z, .checkPausing ; If we are not ending, jump to check pause
; We are ending, animate the window back down
ld a, [rWY] ; Get current window position
inc a ; Increment twice
inc a
ld [rWY], a ; Set the position back into window
ld a, [textwriter_ending] ; Grab the ending guy
dec a ; Decrement it
ld [textwriter_ending], a ; Set it back
jr z, .closingAll ; If we reach zero, we can disable text renderer
ret
.closingAll
ld [textwriter_active], a
ret
.checkPausing
ld a, [textwriter_pausing] ; Check if we're in a paused state
and a
jr z, .checkDelay ; Jump to Delayer if we're not in paused state
ld b, a ; We are in pause state so store pause state in register b
ld a, [controller_newkeys] ; Check our controller
and a, PAD_A|PAD_B ; Check if we pressed either A or B
ret z ; Exit if he didn't
dec b ; Decrement B, our paused state
jr z, .continuingNextLine ; If paused state was 1 then we continue
;to render next line
; If we reach here, paused state was 2 which means we should
; end text reader
ld a, 16 ; Set a to 1
ld [textwriter_ending], a ; Mark it as we are ending
ret
.continuingNextLine
call ClearWindow
ld a, 0
ld [textwriter_pausing], a
ld [textwriter_posx], a
ld [textwriter_posy], a
jr .delayFinished
.checkDelay
; Delay writing a letter by 10 frames if no button is down
ld a, [textwriter_curdelay]
dec a
ld [textwriter_curdelay], a
jr z, .delayFinished
ld a, [controller_curkeys] ; Check our controller
and a, PAD_B
ret z ; If B button is being held, we skip any delay
.delayFinished
; Reset the curdelay
ld a, 10
ld [textwriter_curdelay], a
.startdrawtext
; Get the memory address pointing to the text currently being
; displayed. This is stored in textwriter_curtext
ld hl, textwriter_curtext ; Get the memory address of the pointer
ld d, [hl] ; Store the first byte address to d
inc hl ; Move to next byte
ld e, [hl] ; Store the next byte address to e
; We now have the current letter being drawn at [de]
; Get the current X position for the text on screen
ld hl, (_SCRN1 + $21) ; Load the top-left window position for our text
; Load the x position for current text position and
ld a, [textwriter_posx]
ld b, a
ld a, l
add b ; Add the x position
ld l, a
; Get the current Y position for the text on screen
ld a, [textwriter_posy]
and a ; Check if it's zero
jr z, .drawletter
; If not, jump forward by a whole line.
ld a, l
add a, $20
ld l, a
.drawletter
ld a, [de] ; Load the first byte in the string
ld bc, textwriter_map ; Get the map for the ASCII->Tile map
ld c, a ; Set the position of C to the ASCII byte of current character
ld a, [bc] ; Get the tile byte for the ASCII from the map
ld [hl], a ; Print the byte to the map
.checkIsEnding
ld a, [de]
and a ; Check if we reached the end
jr nz, .checkContinuing
; We have reached the end of the string, mark it
ld a, 2
ld [textwriter_pausing], a
jr .continue ; Jump straight to continue. No need to check anything
.checkContinuing
ld a, [de] ; Regrab the ascii byte we printed
cp a, $23 ; Check if it's '#'
jr nz, .checkNewline ; Jump to next check if it wasn't
ld a, 1
ld [textwriter_pausing], a
jr .continue
.checkNewline
ld a, [de] ; Regrab the ascii byte we printed
cp a, $0A ; Check if it was a new line '\n'
jr nz, .checkRepeatOnce ; Jump to checkRepeatOnce if it wasn't a new line
; The byte we printed was a new line so we increment Y position
; and reset our X position.
ld a, -1 ; Usually we'd print into first position but since we're jumping
; into continue, continue will automatically increment x for us.
ld [textwriter_posx], a
ld a, 1
ld [textwriter_posy], a ; Set our Y position to 1
ld [textwriter_curdelay], a ; Also set curdelay to 1 as well
jr .continue
.checkRepeatOnce
ld a, [bc] ; Regrab the tile we printer
; Check if we printed an empty letter
cp a, $50
jr nz, .continue
ld a, 1
ld [textwriter_curdelay], a ; Set curdelay to 1 so it immediately prints next character
.continue
; Time to update our work ram
inc de ; Increment de to next letter
; Load the position pointer of current text and update it to the next letter
ld hl, textwriter_curtext
ld a, d
ld [hli], a
ld a, e
ld [hl], a
; Update the x position in ram
ld a, [textwriter_posx]
inc a
ld [textwriter_posx], a
.exit
ld a, [textwriter_active]
ret