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; As of 3cbd137, the xex build will run in 40K. This stuff no longer
; checks for 48K or tries to disable the BASIC cart. With 40K free, we
; get 360 bytes for the stack, which is less than the linker config's
; 512 byte stack... but we never use anywhere near the full amount.
; We still do a GR.0 here, because the taipan.c code expects it to
; have been set up, and because some loaders (e.g. fenders) don't
; do it for us.
; Memcheck needs to do this:
;1. Do a GRAPHICS 0
;2. If RAMTOP >=$A0, go to step 6
;3. Print "need 40K" message
;4. Wait for a keypress
;5. Exit to DOS (without loading the rest of the file)
;6. Exit via RTS, so the rest of the game will load.
;At no point do we look at RAMSIZ, since it can't be trusted under SDX.
;Note that when we reach step 6, RAMTOP is always $C0 (either it was,
;or we set it to that).
; cl65 -o checkmem.xex -t none checkmem.s
.include "atari.inc"
.macpack atari
start = $0600 ; use page 6 for now
; homebrew XEX header
.word $ffff
.word start
.word end-1
.org start
msg:
scrcode "Need at least 40K"
msglen = * - msg - 1
S: .byte "S:",0
init:
;1. Do a GRAPHICS 0
jsr gr_0
;2. If RAMTOP is >=$A0, go to step 5.
lda RAMTOP
cmp #$a0
bcc memerr
;5. Exit via RTS, so the rest of the game will load.
rts
;3. Print a "need 40K" message
memerr:
lda #<msg
sta FR0
lda #>msg
sta FR0+1
ldy #msglen
msgloop:
lda (FR0),y
sta (SAVMSC),y
dey
bpl msgloop
;4. Wait for a keypress
sty CH ; y == $ff at this point, clear keyboard
; ...wait for a keystroke...
wait4key:
cpy CH
beq wait4key
sty CH ; clear the key so DOS menu won't see it.
;5. Exit to DOS (without loading the rest of the file)
jmp (DOSVEC)
gr_0:
ldx #6*$10 ; CLOSE #6
lda #CLOSE
sta ICCOM,x
jsr CIOV
; GRAPHICS 0
ldx #6*$10 ; IOCB #6
lda #OPEN
sta ICCOM,x
lda #$1c ; $c = read/write
sta ICAX1,x
lda #0 ; aux2 byte zero
sta ICAX2,x
lda #<S
sta ICBAL,x
lda #>S
sta ICBAH,x
jsr CIOV
; save display list pointer where taipan.c's main() can find it.
; this is done ASAP after the CIO call, to avoid saving the DL
; after SpartaDOS's TDLINE has had a chance to modify it.
; we use FRE because the menu code in newtitle.s trashes FR0 and FR1.
lda SDLSTL
sta FRE
lda SDLSTH
sta FRE+1
rts
end:
.word INITAD
.word INITAD+1
.word init
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