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loader.s
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loader.s
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;;;
;;; Bomb Jack Revisited
;;;
;;; 1985,2018 ops
;;;
COLUMNS = 22
ROWS = 10
PTR1 = $FB
PTR2 = $FD
LNKPRG := $C533
STXTPT := $C68E
NEWSTT := $C7AE
.include "cbm_kernal.inc"
.include "vic20.inc"
.export __LOADADDR__: absolute = 1
.segment "LOADADDR"
.addr *+2
.segment "CODE"
lda #$0A
sta CHARCOLOR
lda #>$1E00 ; set screen memory
sta $0288 ; start to $1E00
jsr CLRSCR
lda #$0C
sta VIC_CR0
lda #$2B
sta VIC_CR1
lda #$80 | COLUMNS
sta VIC_CR2
lda #(ROWS << 1) | $01
sta VIC_CR3
lda #$FC
sta VIC_CR5
lda #$97
sta VIC_CRE
lda #$E8
sta VIC_CRF
lda #$00
ldx #$0E
ldy #$10
jsr fill_pages
lda #$0A
ldx #$02
ldy #$96
jsr fill_pages
ldx #$1E ; start of screen mem
jsr fill_chars
; load loading picture
lda #$01
ldx DEVNUM
ldy #$FF
jsr SETLFS
lda #pic_end-pic
ldx #<pic
ldy #>pic
jsr SETNAM
lda #$00
jsr LOAD
; load ML routines
lda #$01
ldx DEVNUM
ldy #$FF
jsr SETLFS
lda #ml_end-ml
ldx #<ml
ldy #>ml
jsr SETNAM
lda #$00
jsr LOAD
; load character data
lda #$01
ldx DEVNUM
ldy #$00
jsr SETLFS
lda #chr_end-chr
ldx #<chr
ldy #>chr
jsr SETNAM
lda #$00 ; load temporarily
ldx #<($3C00) ; to $3C00 so it doesn't
ldy #>($3C00) ; overwrite loading picture
jsr LOAD
; load main program
lda #$01
ldx DEVNUM
ldy #$FF
jsr SETLFS
lda #main_end-main
ldx #<main
ldy #>main
jsr SETNAM
lda #$00
jsr LOAD
stx $2D
sty $2E
ldy #$00
sty $2C00
lda #<$2C01
sta $2B
lda #>$2C01
sta $2C
; copy character data to $1800 ->
sty PTR1
sty PTR2
lda #>$3C00
sta PTR1+1
lda #>$1800
sta PTR2+1
ldx #$04
@loop: lda (PTR1),y
sta (PTR2),y
iny
bne @loop
inc PTR1+1
inc PTR2+1
dex
bne @loop
jsr STXTPT
jsr LNKPRG
jmp NEWSTT
.proc fill_chars
stx PTR1+1
ldx #$00
stx PTR1
clc
@loop1: txa
ldy #$00
@loop2: sta (PTR1),y
adc #ROWS
iny
cpy #COLUMNS
bne @loop2
tya
clc
adc PTR1
sta PTR1
inx
cpx #ROWS
bne @loop1
rts
.endproc
.proc fill_pages
;; A = fill value
;; X = number of pages
;; Y = start page
sty PTR1+1
ldy #$00
sty PTR1
@loop: sta (PTR1),y
iny
bne @loop
inc PTR1+1
dex
bne @loop
rts
.endproc
pic: .byte "picture"
pic_end:
ml: .byte "ml.prg"
ml_end:
chr: .byte "chr.prg"
chr_end:
main: .byte "main.prg"
main_end: