Initial Commit

code/data_colorwash.asm

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+; color data table
+; first 9 rows (40 bytes) are used for the color washer
+; on start the gradient is done by byte 40 is mirroed in byte 1, byte 39 in byte 2 etc... 
+
+color        !byte $09,$09,$02,$02,$08 
+             !byte $08,$0a,$0a,$0f,$0f 
+             !byte $07,$07,$01,$01,$01 
+             !byte $01,$01,$01,$01,$01 
+             !byte $01,$01,$01,$01,$01 
+             !byte $01,$01,$01,$07,$07 
+             !byte $0f,$0f,$0a,$0a,$08 
+             !byte $08,$02,$02,$09,$09 
+             !byte $00,$00,$00,$00,$00 
+             !byte $00
+
+color2       !byte $09,$09,$02,$02,$08 
+             !byte $08,$0a,$0a,$0f,$0f 
+             !byte $07,$07,$01,$01,$01 
+             !byte $01,$01,$01,$01,$01 
+             !byte $01,$01,$01,$01,$01 
+             !byte $01,$01,$01,$07,$07 
+             !byte $0f,$0f,$0a,$0a,$08 
+             !byte $08,$02,$02,$09,$09 
+             !byte $09

code/data_static_text.asm

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+
+; the two lines of text for color washer effect
+
+line1            !scr "    actraiser in 2013 presents...        "
+line2            !scr " example effect for dustlayer tutorials  " 
+

code/init_clear_screen.asm

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+;============================================================
+; clear screen
+; a loop instead of kernal routine to save cycles
+;============================================================
+
+init_screen      ldx #$00     ; start of loop
+                 stx $d021            ; border
+                 stx $d020            ; background
+
+clear            lda #$20     ; #$20 is the spacebar screencode
+                 sta $0400,x  ; fill four areas with 256 spacebar characters
+                 sta $0500,x 
+                 sta $0600,x 
+                 sta $06e8,x 
+                 lda #$0c     ; puts into the associated color ram dark grey ($0c)...
+                 sta $d800,x  ; and this will become color of the scroll text
+                 sta $d900,x
+                 sta $da00,x
+                 sta $dae8,x
+                 inx         
+                 bne clear   
+                 rts 

code/init_static_text.asm

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+;============================================================
+; write the two line of text to screen center
+;============================================================
+
+
+init_text  lda line1,x      ; read characters from line1 table of text...
+           sta $0590,x      ; ...and store in screen ram near the center
+           lda line2,x      ; read characters from line1 table of text...
+           sta $05e0,x      ; ...and put 2 rows below line1
+
+           inx 
+           cpx #$28         ; finished when all 40 cols of a line are processed
+           bne init_text
+           rts

code/load_resources.asm

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+; load sid music
+
+* = address_music                         ; address to load the music data
+!bin "resources/jeff_donald.sid",, $7c+2  ; remove header from sid and cut off original loading address 

code/main.asm

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+;============================================================
+;    some initialization and interrupt redirect setup
+;============================================================
+
+           sei         ; set interrupt disable flag
+            
+           jsr init_screen     ; clear the screen
+           jsr init_text       ; write lines of text
+           jsr sid_init     ; init music routine now
+
+           ldy #$7f    ; $7f = %01111111
+           sty $dc0d   ; Turn off CIAs Timer interrupts ($7f = %01111111)
+           sty $dd0d   ; Turn off CIAs Timer interrupts ($7f = %01111111)
+           lda $dc0d   ; by reading $dc0d and $dd0d we cancel all CIA-IRQs in queue/unprocessed
+           lda $dd0d   ; by reading $dc0d and $dd0d we cancel all CIA-IRQs in queue/unprocessed
+          
+           lda #$01    ; Set Interrupt Request Mask...
+           sta $d01a   ; ...we want IRQ by Rasterbeam (%00000001)
+
+           lda #<irq   ; point IRQ Vector to our custom irq routine
+           ldx #>irq 
+           sta $314    ; store in $314/$315
+           stx $315   
+
+           lda #$00    ; trigger first interrupt at row zero
+           sta $d012
+
+           cli                  ; clear interrupt disable flag
+           jmp *                ; infinite loop
+
+
+;============================================================
+;    custom interrupt routine
+;============================================================
+
+irq        dec $d019        ; acknowledge IRQ / clear register for next interrupt
+
+           jsr colwash      ; jump to color cycling routine
+           jsr play_music	  ; jump to play music routine
+
+
+           jmp $ea81        ; return to kernel interrupt routine

code/setup_symbols.asm

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+address_music = $1000 ; loading address for sid tune
+sid_init = $1000      ; init routine for music
+sid_play = $1006      ; play music routine

code/sub_colorwash.asm

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+;============================================================
+; color washer routine
+;============================================================
+
+
+; during the control of the color washing routine, 
+; we take the byte, which is at color+00 and then 
+; we place it at color+$28, then we call a continuous loop 
+; which makes the data table cycle by subtracting each piece of data in the data table by one
+; and read the calculations 40 times ($28). Therefore the data table pulls each byte of data. 
+; Also inside our loop, the colors are read from the data table and put into color RAM, 
+; which starts at $D800.
+
+colwash    lda color+$00      ; load first color
+           sta color+$28      ; store in column 40 ($28 = #40) - this resets the table for the next color cycle
+           sta $d9df,x
+           ldx #$00           ; init loop
+cycle1     lda color+$01,x    ; CYCLE iterates once(!) by moving color by 1 in table
+           sta color+$00,x 
+           lda color,x        ; load current color
+           sta $d990,x        ; put into color ram for one of the 40 positions
+           inx                ; inc iterator
+           cpx #$28           ; have we done 40 iterations yet?
+           bne cycle1         ; if no, continue
+
+colwash2   lda color2+$28     ; load last color
+           sta color2+$00     ; store in column 00 this resets the table for the next color cycle
+           ldx #$28
+cycle2     lda color2-$01,x   ; CYCLE iterates once(!) by moving color by 1 in table in reverse order
+           sta color2+$00,x 
+           lda color2,x       ; load current color
+           sta $d9df,x        ; put into color ram for one of the 40 positions
+           dex                ; decrease iterator
+           bne cycle2         ; if x not zero yet, continue
+
+           rts                ; return 

code/sub_music.asm

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+;============================================================
+; play music directive
+;============================================================
+
+play_music jsr sid_play
+		   rts

index.asm

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+;============================================================
+; Example Project for C64 Tutorials from 
+; Code by actraiser/Dustlayer
+; Music: Ikari Intro by Laxity
+;
+; Simple Colorwash effect with a SID playing
+;
+; http://www.dustlayer.com
+; 
+;============================================================
+
+;============================================================
+; index file which loads all source code and resources files
+;============================================================
+
+;============================================================
+;    specify output file
+;============================================================
+
+!cpu 6502
+!to "build/hello_world.prg",cbm    ; output file
+
+;============================================================
+; BASIC loader with start address $c000
+;============================================================
+
+* = $0801                               ; BASIC start address (#2049)
+!byte $0d,$08,$dc,$07,$9e,$20,$34,$39   ; BASIC loader to start at $c000...
+!byte $31,$35,$32,$00,$00,$00           ; puts BASIC line 2012 SYS 49152
+* = $c000     				            ; start address for 6502 code
+
+;============================================================
+;  Main routine with IRQ setup and custom IRQ routine
+;============================================================
+
+!source "code/main.asm"
+
+;============================================================
+;    setup and init symbols we use in the code
+;============================================================
+
+!source "code/setup_symbols.asm"
+
+;============================================================
+; tables and strings of data 
+;============================================================
+
+!source "code/data_static_text.asm"
+!source "code/data_colorwash.asm"
+
+;============================================================
+; one-time initialization routines
+;============================================================
+
+!source "code/init_clear_screen.asm"
+!source "code/init_static_text.asm"
+
+;============================================================
+;    subroutines called during custom IRQ
+;============================================================
+
+!source "code/sub_colorwash.asm"
+!source "code/sub_music.asm"
+
+;============================================================
+; load resource files (for this small intro its just the sid)
+;============================================================
+
+!source "code/load_resources.asm"