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; 20070524 bkw: DASM source for GR.2 "LOADING..." screen.
; Object code is intended to be prepended to some other object
; file, so it uses INITAD rather than RUNAD.
; WARNING: if you modify this file such that the object code changes,
; make sure you edit cart2bin.c and correct the offset for the title
; screen text! As long as you don't change anything after the "loading"
; label, this won't be a problem.
processor 6502
include "equates.inc"
seg.u ZP
org $80
if * > $ff
echo "Zero page vars have overrun into the stack! * =", *
err
else
echo *-$80, "bytes of zero page used,", $ff-*, "remain"
endif
seg CODE
LOAD_ADDR = $6000 ; load at 24K
origin = LOAD_ADDR-6;
org origin ; make room for 6-byte header
; 2-byte Atari executable header:
byte $FF, $FF ; let DOS know it's a binary load file
; start of first segment
; 4-byte segment header:
word LOAD_ADDR ; Load address
word endbin-1 ; Last byte to load
; Rest of segment contains code and data
pagesize byte 0 ; cart2bin will fill this in with the size of
; the cart image code, in pages.
main:
; set RAMTOP to 28K, call GR.2, store "LOADING..." in screen RAM,
; then set RAMTOP back to original value.
lda RAMTOP
cmp #$C0 ; do we have 48K?
bcs ram_ok
ldx #0 ; no! print error message...
lda #9
sta ICCOM
lda #<ram_msg
sta ICBAL
lda #>ram_msg
sta ICBAH
lda #ram_msg_len
sta ICBLL
stx ICBLH
jsr CIOV
hang bcs hang ; spin forever
ram_msg byte "Need at least 48K to run this.", $9B
ram_msg_len = *-ram_msg+1
ram_ok
;sec ; carry already set by cmp above!
sbc pagesize ; adjust RAMTOP to make room for the converted cart image
pha ; save old RAMTOP value on stack
lda #$70 ; set RAMTOP to $7000 (28K). Later on we do GRAPHICS 2,
sta RAMTOP ; which will cause the DL and screen RAM to go here.
ldx #$60 ; CLOSE #6 first
lda #12 ; Command 12=CLOSE
sta ICCOM,x
jsr CIOV ; call CIO, ignore any error
;ldx #$60 ; set up IOCB #6 for CIO GRAPHICS command
lda #3 ; Command 3=OPEN
sta ICCOM,x
lda #12 ; 12=R/W access
sta ICAX1,x
lda #2 ; GR. mode 2
sta ICAX2,x
lda #<s_dev ; S: device
sta ICBAL,x
lda #>s_dev
sta ICBAH,x
lda #s_dev_len
sta ICBLL,x
lda #0
sta ICBLH,x
jsr CIOV ; call CIO
lda #5 ; POSITION 5,5
sta ROWCRS
sta COLCRS
lda #0
sta COLCRS+1
sta ICBLH,x ; PRINT #6;"LOADING...
; ldx #$60
lda #9 ; Command 9 = CIO "put record"
sta ICCOM,x
lda #<loading
sta ICBAL,x
lda #>loading
sta ICBAH,x
lda #loading_len
sta ICBLL,x
jsr CIOV ; call CIO
; ldx #$60 ; CLOSE #6
lda #12 ; Command 12=CLOSE
sta ICCOM,x
jsr CIOV ; call CIO, ignore any error
pla ; get adjusted RAMTOP value
sta RAMTOP
rts ; end of init routine, return control to DOS
s_dev byte "S:"
s_dev_len equ *-s_dev+1
; WARNING: if you change any code/data below this line, you'll probably need
; to change the offset in cart2bin.c as well.
loading byte " LOADING"
ds 6
title ds 20 ; cart2bin will fill in these 20 bytes with the filename
byte $9B ; (or title, if -t is used)
loading_len equ *-loading+1
endbin ; end of first segment
echo "Code is", *-origin+1, "bytes"
; start of second segment (which loads at INITAD, to tell DOS
; where to start running the init code loaded in segment 1)
; 4-byte segment header:
word INITAD ; load address (loading into INITAD lets our code run)
word INITAD+1 ; Last byte to load
; Segment data contains 2 bytes (the actual run address)
word main ; the 2 bytes to stuff into RUNAD
; That's all, folks!
echo "Title offset: loadscreen_bin_len - ", *-title
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