1
LINE
DW
1
LINE MODE (line draw)
BIT# BLTCONO BLTCON l
15 START3 0
14 START2 0
13 START 1 0
12
START0 0
11 1
0
10 0 0
09
1 0
08
1 0
07
LF7 0
06 LF6
SIGN
05 LF5 OVF
04 LF4 SUD
03 LF3 SUL
02
LF2
AUL
0 1 LF1 SING
00 LFO LINE(= 1)
START3-0
Starting point of line (0 thru 15 hex)
LF7-0
Logic function minterm select lines
should be preloaded with
4A
in order
to select the equation
D
=
(AC
+
ABC).
Since
A
contains a single bit true
(8000), most bits will pass the C field
unchanged (not
A
and C), but one bit
will invert the C Field and combine
it
with texture (A and
B
and not C). The
A
bit is automatically moved across
the word by the hardware.
LINE
Line mode control bit (set to 1)
SIGN Sign flag
OVF Word overflow flag
SING
Single bit per horiz. line
for use with subsequent Area Fill
SUD
Sometimes Up or Down
(
=
AUD*)
SUL Sometimes Up or Left
AUL
Always Up or Left
The
3
bits above select the Octant for line draw:
OCT SUD SUL
AUL
-
0
1
1
0
1
0
0 1
2
0 1
1
3
1
1 1
4 1 0
1
5
0
1
0
6 0 0 0
7
0
0 0
Blitter
start
and size (Window, width height)
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