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|
; this file needs to be assembled with:
; cl65 -o newtitle.xex -t none newtitle.s
; It contains only an init routine, no run address.
.include "atari.inc"
; location sound code will look at to see whether sound
; is disabled (0 = enabled, !0 = disabled). If you
; change this here, change it in sounds.h also!
sound_disabled = $06ff
; where our screen was loaded (see newtitle.pl)
screendata = $9000
; homebrew atari xex header
.word $ffff
.word version
.word end-1
; needs to be above the BSS (see taipan.map). we'll place it right at
; the end of screendata.
.org $a800
version:
.incbin "ver.dat"
help:
.incbin "help.dat"
helphitbl:
.byte >version
.byte >help
.byte >(help+32)
.byte >(help+64)
.byte >(help+96)
.byte 0
helplotbl:
.byte <version
.byte <help
.byte <(help+32)
.byte <(help+64)
.byte <(help+96)
.byte 0
helpshowing = FR1
; N<space> or FF (inverse)
sounddisp = help + 78
colorchoices:
.byte $c0,$10,$00
colorcount = (*-colorchoices)-1
textchoices:
.byte $0c,$0e,$0a
textcount = (*-textchoices)-1
; executable code here
start:
; setup color registers
lda colorchoices
sta COLOR2 ; text bg
lda textchoices
sta COLOR1 ; text fg
; turn off screen, in case vblank happens while we work
lda #0
sta FR0
sta SDMCTL
; build our display list
; TODO, for now it's hardcoded (see 'dlist' below)
; wait for the next frame, to avoid graphics glitching
jsr wait1jiffy
; setup our display list
lda SDLSTL
sta FR0
lda SDLSTH
sta FR0+1
lda #<dlist
sta SDLSTL
lda #>dlist
sta SDLSTH
; switch to narrow playfield, enable screen
lda #$21
sta SDMCTL
; clear any keypress that happened during loading
lda #$ff
sta CH
ldx #0 ; X = index into bg color choices
ldy #0 ; Y = index into text color choices
; wait for user to press a key
wait4key:
lda colorchoices,x
sta COLOR2
lda textchoices,y
sta COLOR1
lda CH
cmp #$ff
beq wait4key
cmp #28 ; Escape key
bne not_esc
; show next line of help
showhelp:
stx FR1+1
ldx helpshowing
inx
loadhelp:
lda helphitbl,x
bne helpok
ldx #0
beq loadhelp
helpok:
sta help_lms+1
lda helplotbl,x
sta help_lms
stx helpshowing
ldx FR1+1
clc
bcc x_ok
not_esc:
cmp #62 ; S key
bne not_s
jsr enable_disable_sound
clc
bcc showhelp
not_s:
cmp #21 ; B key
bne not_b
dex
bpl x_ok
ldx #colorcount
bne x_ok
not_b:
cmp #45 ; T key
bne keyok
dey
bpl x_ok
ldy #textcount
x_ok:
lda #$ff
sta CH
bne wait4key
keyok:
; eat the keypress
lda #$ff
sta CH
rts ; return to DOS (which loads the rest of the game)
wait1jiffy:
lda RTCLOK+2
wait:
cmp RTCLOK+2
beq wait
rts
enable_disable_sound:
lda #2
sta helpshowing
lda sound_disabled
eor #$01
sta sound_disabled
beq now_on
lda #166 ; inverse F screen code
sta sounddisp
sta sounddisp+1
rts
now_on:
lda #174 ; inverse N screen code
sta sounddisp
lda #128 ; inverse space screen code
sta sounddisp+1
rts
; display list here
dlist:
.byte $70 ; 24 scanlines of blanks
.byte $70
.byte $70
; .byte $30 ; 4 more since image is only 184 lines tall
.byte $0f | $40 ; LMS, BASIC mode 8
.word screendata
.repeat 127
.byte $0f ; 127 more scanlines of mode 8
.endrepeat
.byte $0f | $40 ; Hit 4K boundary, LMS again
.word screendata+$1000
.repeat 55
.byte $0f ; 55 more scanlines of mode 8
.endrepeat
; .byte $30 ; blank 4 lines to match GR.8 (does it even matter?)
.byte $02 | $40 ; LMS, 1 line of GR.0 for the version
help_lms:
.word version
.byte $41 ; JVB, jump & wait for vblank
.word dlist
end:
.word INITAD
.word INITAD+1
.word start
|
