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* * *
adjust blit param<
dc.w
Init
mo v e .w
(aO),d0
0
cmp. w
#l,d
bne
skip
m o v e .w
#$50,nxln
skip:
0
lsl.w
#l,d
m o v e .w
do,nxwd
*** do the blit
6
blit,a
lea
dc.w
BitBlit
*** wait for key press, then end
move.w
#l,-(sp)
#1
trap
2
addg.l
#
,sp
. 1
0
m o v e
#
,-(sp)
trap
#1
*** Data for input is stored here
.data
dc.w
blit:
dc.w
dc.w
dc.w
dc.w
dc.l
dc.w
dc.w
dc.l
dc.w
dc.w
dc.w
dc.w
dc.w
screen:
dc.l
nxwd:
dc.w
nxln:
dc.w
dc.w
1
dc.
dc.w
dc.w
dc.w
space:
dc.w
dc.w
dc.w
alien:
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
.end
156
CHAPTER 7
init line A
?
et number of bit planes
s it monochrome?
no, leave screen width alone
yes, change screen width value
bit planes
= value to place in nxwd
* address of parameter table in a
* do Bit Blit
* call conin() to wait for key press
GEMDOS terminate command
call GEMDOS and exit
$0020
width of source image in pixels
$0017
height of source image in pixels
$0001
number of planes to blit
$0001
fg color (bit
$0000
bg color (bit
$07070707
logic ops
$0000
source x
$0000
source y
alien
base address of source image
$0002
byte offset to next word of source
$0004
source width = 4 bytes
$0002
source plane offset
$0080
destination x
$0080
destination y
$00000000
screen address goes
byte offset to next
$0008
2 for hi, 4 for med,
byte offset to next
00
0
$
a
$50 for hi, $a0 for
$0002
byte offset to next
$00000000
addr of pattern buf
$0000
byte offset to next
$0000
byte offset to next
$0000
pattern index mask
* you must reserve 24 bytes here
$
, $
, $
00 0 0
00 0 0
0000
$
, $
, $
00 0 0
00 0 0
000 0
$ 000 0 , $ 00 0 0 , $ 000 0, $0000
* image data for space creature
$0030, $0C00, $001C, $3800
$0006, $6000, $0006, $6000
$001F, $F800, $003F, $FC00
$C0FF, $FF03, $C0FF, $FF03
$E3E3, $C7C7, $7FEB, $D7FE
$3FE7, $CFFC, $03FF, $FFC0
$03FF, $FFC0, $00F8, $1F00
$00FC, $3F00, $00FF, $FF00
$0077, $EE00, $0030, $0C00
$0030, $0C00, $0030, $0C00
$0060, $0600, $00C0, $0300
$0380, $01C0
*2
1
of logic op index)
0
of logic op index)
here
word in line
8
line in planes
med and lo
plane (always
0
(
=no pattern)
line in pattern
plane in pattern
,
$0000
,
$0000
6
for lo
2
)
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