143 lines
2.6 KiB
NASM
143 lines
2.6 KiB
NASM
; load new level on the screen
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statusLevelTitle SUBROUTINE
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jsr clearScreen
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.back:
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; Print "Next Level"
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lda #<levelIntroString
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sta printIntroString
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lda #>levelIntroString
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sta printIntroString + 1
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lda #$00
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sta introScreenStart
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lda #$04
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sta introScreenStart + 1
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jsr printIntro
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; Print level Title
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lda levelPointer
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sta printIntroString
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lda levelPointer + 1
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sta printIntroString + 1
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lda #$e2
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sta introScreenStart
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lda #$05
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sta introScreenStart + 1
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jsr printIntro
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; advance level pointer, based on title string length
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iny
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tya
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tax
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lda #levelPointer
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sta nextPointerPointer
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jsr nextPointer
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; wait
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lda #ST_LEVEL_LOAD
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sta delayStatus
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lda #ST_DELAY
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sta status
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rts
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statusLevelLoad SUBROUTINE
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; Upper bar -- fill with spaces, color yellow
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ldx #39
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upperbarLoop:
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lda #$0
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sta $400,x
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lda #7
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sta $d800,x
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dex
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cpx #$ff
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bne upperbarLoop
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; Set upper bar text
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lda #<scoreString
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sta printStatusString
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lda #>scoreString
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sta printStatusString + 1
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jsr printStatus
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; initialize video pointer with first video memory address
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; (skip first line, used for the status bar)
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ldy #39
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sty levelVideoPointer
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ldy #$04
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sty levelVideoPointer + 1
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ldy #39
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sty levelColorPointer
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ldy #$d8
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sty levelColorPointer + 1
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; Level data is compressed with RLE. Array example:
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; +---+---+---+---+--..--+---+---+
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; | T | N | T | N | .. | 0 | 0 |
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; +---+---+---+---+--..--+---+---+
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; T tile char
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; N count (how many repeated tile chars)
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; 0 end of level
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writeLevelLoop:
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; read `T`
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ldy #0
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lda (levelPointer),y
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sta levelT
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; read `N`
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iny
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lda (levelPointer),y
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sta levelN
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; increment array pointer
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iny
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tya
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tax
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lda #levelPointer
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sta nextPointerPointer
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jsr nextPointer
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; check for array end
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lda levelN
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cmp #0
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beq writeLevelEnd
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; retrieve `N` and put in Y
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ldy levelN
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; unpack char from RLE to the screen
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writeLevelElement:
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lda levelT
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sta (levelVideoPointer),y
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; tiles colors can be found in an array
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; position in array = tile value - $60
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sec
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sbc #$60
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tax
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lda tilesColors,x
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sta (levelColorPointer),y
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dey
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bne writeLevelElement
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; increment dest video memory pointer
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lda #levelVideoPointer
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sta nextPointerPointer
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ldx levelN
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jsr nextPointer
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lda #levelColorPointer
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sta nextPointerPointer
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ldx levelN
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jsr nextPointer
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jmp writeLevelLoop
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writeLevelEnd:
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lda #ST_PLAY
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sta status
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rts
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