Memory segments relocation and exposed bugs
- Declared uninitialized segment in zero page: used assembler directives to reduce errors probability and improve code maintenance; now zeropage variables addresses are automagically computed by assembler - Added other debug messages, and rewritten some cycles for good readability and good software engineering - Fixed more uninitialized stucture bug (maybe I had some sawdust in my brain when I did this?) - Fixed concurrency bug in home screen
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299eee1257
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58
snake.asm
58
snake.asm
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@ -11,19 +11,26 @@
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; Zero page utilities
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; Zero page utilities
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; ----------------------------------------------------------------------
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; ----------------------------------------------------------------------
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SEG.U zeropage
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org $02
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; Where is the snake head in video memory? Do math to calculate address
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; Where is the snake head in video memory? Do math to calculate address
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; using pointer at $a0-$a1
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; using pointer at tileMem,tileMem+1
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tileMem = $a0
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tileMem DS 2
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; Pointer to status string ($a3-$a4)
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; Pointer to status string
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printStatusString = $a3
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printStatusString DS 2
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; Pointer to intro string ($a3-$a4)
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; Pointer to intro string
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printIntroString = $a3
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printIntroString DS 2
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; Pointer to screen position where to print intro string ($fb-$fc)
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; Pointer to screen position where to print intro string ($fb-$fc)
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introScreenStart = $fb
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introScreenStart DS 2
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#if DEBUG = 1
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; Locations $90-$FF in zeropage are used by kernal
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ECHO "End of zeropage variables. Space left: ",($90 - .)
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#endif
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SEG program
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org $801
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org $801
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. = $801 ; 10 SYS10240 ($2800) BASIC autostart
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. = $801 ; 10 SYS10240 ($2800) BASIC autostart
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BYTE #$0b,#$08,#$0a,#$00,#$9e,#$31,#$30,#$32,#$34,#$30,#$00,#$00,#$00
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BYTE #$0b,#$08,#$0a,#$00,#$9e,#$31,#$30,#$32,#$34,#$30,#$00,#$00,#$00
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@ -89,6 +96,7 @@ ST_INTRO1 = 1
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ST_PLAY = 2
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ST_PLAY = 2
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ST_OUTRO = 3
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ST_OUTRO = 3
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ST_END = 4
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ST_END = 4
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ST_PAUSE = 255
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; Screen features
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; Screen features
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SCREEN_W = 40
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SCREEN_W = 40
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@ -118,7 +126,11 @@ intro2string:
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BYTE "RETROFFICINA.GLGPROGRAMS.IT"
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BYTE "RETROFFICINA.GLGPROGRAMS.IT"
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BYTE #0
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BYTE #0
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intro3string:
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intro3string:
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#if DEBUG = 1
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BYTE "DBG RELS"
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#else
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BYTE "(C) 2018"
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BYTE "(C) 2018"
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#endif
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BYTE #0
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BYTE #0
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colorshade: ; a gradient of dark-bright-dark (40 columns)
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colorshade: ; a gradient of dark-bright-dark (40 columns)
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HEX 0b 0b 0b 0b 0b 0c 0c 0c 0c 0c 05 05 05 0d 0d 0d 0d 07 07 07 07 07 07 0d 0d 0d 0d 05 05 05 0c 0c 0c 0c 0c 0b 0b 0b 0b 0b
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HEX 0b 0b 0b 0b 0b 0c 0c 0c 0c 0c 05 05 05 0d 0d 0d 0d 07 07 07 07 07 07 0d 0d 0d 0d 05 05 05 0c 0c 0c 0c 0c 0b 0b 0b 0b 0b
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@ -194,6 +206,15 @@ start:
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; Initialize MultiColor mode
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; Initialize MultiColor mode
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jsr multicolorInit
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jsr multicolorInit
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; Zero-fill zeropage variables
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lda #$0
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ldx #$90
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zeroFillZeroPage:
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dex
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sta $0,x
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cpx #$2
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bne zeroFillZeroPage
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; Set status as first-time intro playing
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; Set status as first-time intro playing
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lda #ST_INTRO0
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lda #ST_INTRO0
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sta status
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sta status
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@ -214,6 +235,9 @@ intro0running: ; Cycle here until SPACE or `Q` is pressed
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; Intro is finished, now it's time to start the proper game
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; Intro is finished, now it's time to start the proper game
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intro0end:
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intro0end:
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; Pause everything in interrupt
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lda #ST_PAUSE
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sta status
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; Set init variables of the game
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; Set init variables of the game
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jsr fullreset
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jsr fullreset
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; Set status as game playing
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; Set status as game playing
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@ -238,15 +262,15 @@ fullreset:
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jsr multicolorOn
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jsr multicolorOn
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; Clear screen
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; Clear screen
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ldx #$ff
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ldx #$00
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lda #$20
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lda #$20
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fullresetCLS:
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fullresetCLS:
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dex
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sta $400,x
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sta $400,x
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sta $500,x
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sta $500,x
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sta $600,x
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sta $600,x
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sta $700,x
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sta $700,x
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dex
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cpx #$00
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cpx #$ff
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bne fullresetCLS
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bne fullresetCLS
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; Set overscan
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; Set overscan
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@ -277,6 +301,7 @@ upperbarLoop:
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sta irqn ; Initialize interrupt divider
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sta irqn ; Initialize interrupt divider
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lda #6
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lda #6
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sta direction ; Snake must go right
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sta direction ; Snake must go right
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; Note: these values depends on following list initialization
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lda #19
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lda #19
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sta snakeX ; Snake is at screen center width...
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sta snakeX ; Snake is at screen center width...
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lda #12
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lda #12
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@ -287,14 +312,15 @@ upperbarLoop:
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sta length ; Length of the list
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sta length ; Length of the list
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; Clear snake lists X and Y
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; Clear snake lists X and Y
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lda #$0
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ldx #$00
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ldx #$ff
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clearListLoop:
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clearListLoop:
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dex
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dex
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lda #19
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sta listX,x
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sta listX,x
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sta listY,y
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lda #12
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cpx #$0
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sta listY,x
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bne clearListLoop
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cpx #$00
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bne clearListLoop
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rts
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rts
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