Da Bootshitctor
Commented source
Written at/for Outline 2006 bootsector compo
Outline 2006, my first computer party!!! After all these years,
it finally became a reality! Yes, I'm sure you're all laughing
at me by now, but it was a wonderful experience for me! Seeing
all the people I saw on pictures on the internet in real life
was a joy and a privilege.
I knew it would be a great experience: so many people I wanted
to meet showed up at the party, all the nice conversations I
had. I only wished I had prepared more for the party, it would
have been cool to chat with people instead of bashing the
keyboard in desperation :)
Anyway, on with the main story I wanted to write here: Some
months before the party Cyclone was constantly bugging me into
entering the bootsector competition. I always answered with
stuff like: "Well, I've got no idea what to code", "If we take
into account that last year I submitted my entry right at the
deadline, then you see I had LOTS of time!".
Of course I knew from back then that he intended to win the
compo and just wanted to humiliate the rest of us with our
crappy bootsectors, but he wanted to secure his position: you
see, if there were few entries in the compo, it might have
merged with other compos, and he didn't want to take that chance
:)
Haha, stop bitching around George :) If I had wanted to avoid
merging the compo I could have easily created more bootsectors,
it usually takes only a few hours for each :) (cxt)
So the days came and went, and I still didn't have any solid
idea what to code. Then the party came, and I went there with
virtually NOTHING! However, fate had other plans for me as
you'll read below! (That is, of course, if you're still awake :)
The minute I arrived at the party place (thanks for the lift
Havoc, btw!) I met up with Grazey, Calsoft and MUG UK. Grazey
announced me that we were going to release a menu that night, so
we went to work! I was doing some code for menu #194 (the crappy
Falcon menu most of you have already seen) and Grazey was
happily hacking at the menu code for both #192C and #192D.
Calsoft with MUG were working on Cal's 2 games he was going to
release at the party (GLobotwars and BackGLash).
While talking to Cal about BackGLash he mentioned that he was a
big fan of Paul Woakes, who wrote it (who isn't anyway? :).
Immediately I grabbed the opportunity to show him Encounter on
the Atari800 emulator, which BackGLash is based on. Naturally he
was amazed by it. Anyway, because my girlfriend was getting a
bit bored, I started playing some more games on the emulator to
entertain her (hey, I try my best ;). After some games I booted
the classic H.E.R.O. and started playing. Now here's the fate
bit coming: I was still unsure about what to code at the party,
and Cyclone strolled by while playing H.E.R.O. and saw the
chunky waves that simulated the sea movement and told me
something like: "That would be a nice effect for a bootsector!"
That was it! My brain immediately went into gear! A wavy
something! Immediately I gathered some ideas and started playing
around with Turbo Assembler until next day in the afternoon!
After that lots of time was spent on debugging SH3's game,
designing some levels for BackGLash, preparing some stuff for
the D-BUG menu, chatting with people, playing both of Cal's game
on the big screen for the compo (as he couldn't do it himself
because he left early) and lots of other stuff!
So, without further ado, here's the source in all its glory. I
must also pay respect to Ziggy Stardust/Overlanders and Mcoder
for the sinus rout I used in this intro (forgot to write that in
the credits, sorry!)
;
; Da bootshitctor
; By GGN of KUA software productions/Paradize/D-BUG
; Coded at Outline 06 (03/06/06) from 11:00 to 19:59 ;)
;
; PARTY VERSION!!!!! Expect full version in about 20 years featuring overscan,
; raster scrollers and lots of other crap!
;
; Thanks: Cyclone for urging me to code it in the first place and encouragement
; Rana for tolerating with me all this time and some design input
; Defjam for faking that he liked it (although he burned me with the
; question: "is that 128 bytes?" ;)
; Grazey and Paranoid for being the first victims of this code (they
; saw previews ;)
;
OPT P+
; This little piece of code pre-shifts the graphic. Due to a slight bug,
; it does vertical movement as well, but unfortunately I was coding/testing this
; in a PC laptop and I didn't see that a glitch is produced every 16 frames :(
; Try to find the bug though!
lea pattern(PC),A0
lea 34(A0),A1
move.w #15*16-1,D7
rotloop: move.w (A0)+,D0
ror.w #1,D0
move.w D0,(A1)+
dbra D7,rotloop
; This uses XBIOS to set ST-LOW resolution and clear the screen.
clr.w -(SP)
move.l #-1,-(SP)
move.l (SP),-(SP)
move.w #5,-(SP)
trap #14
; This prints my small message on-screen.
pea message(PC)
move.w #9,-(SP)
trap #1
; And here we get the screen's pointer and store it for later use.
move.w #2,-(SP)
trap #14
lea 20(SP),SP
movea.l D0,A6
; Here's the sinus generator I use in lots of programs of mine
; (by Ziggy and Mcoder)
nbsinus EQU 512
cos1 EQU 32766 ;cos(2*pi/512)
sin1 EQU 402 ;sin(2*pi/512)
genere_sinus:
lea tabsinus(PC),A0
moveq #nbsinus/4-1,D7
move.w #$7FFF,D0 ;cos(0)=1
clr.w D1 ;sin(0)=0
.loop:
move.w D0,(A0)+
move.w D1,(A0)+
move.w D0,D3
muls #cos1,D3
move.w D1,D4
muls #sin1,D4
muls #cos1,D1
muls #sin1,D0
sub.l D4,D3
add.l D0,D1
move.l D3,D0
add.l D0,D0
swap D0
add.l D1,D1
swap D1
dbra D7,.loop
lea tabsinus(PC),A0
moveq #nbsinus/4-1,D2
.loop2:
move.w (A0)+,D0
move.w (A0)+,D1
move.w D0,nbsinus*1/4*4-4+2(A0)
neg.w D0
move.w D0,nbsinus*2/4*4-4+0(A0)
move.w D0,nbsinus*3/4*4-4+2(A0)
move.w D1,nbsinus*3/4*4-4+0(A0)
neg.w D1
move.w D1,nbsinus*1/4*4-4+0(A0)
move.w D1,nbsinus*2/4*4-4+2(A0)
dbra D2,.loop2
; Here we set the palette. It's actually TOS' palette with some colours swapped
; around.
movem.l palette(pc),d0-d7
movem.l d0-7,$ffff8240.w
; Here's the main loop... What it actually does is copying plane 2 into 3, 1
; into 2 and 0 into 1 and uses plane 0 for drawing the current wave. After that
; it draws the pattern on the top of the screen. Actually the reason it's
; written like that is that because I don't swap screens at all I have to make
; sure that there are no tearing, so first I draw the sinus wave (which is at
; the bottom of the screen), and then the pattern (which is at the top of the
; screen). Dunno what happens at Falcons/TTs/Accelerated machines though :)
go: move.w phase(PC),D6 ;phase
lea 199*160(A6),A5
move.w #39,D7 ;no of blocks
lea tabsinus(PC),A1
moveq #1,D4 ;next byte's position
moveq #0,D5 ;current screen offset
wave: move.w D6,D0
lea 0(A5,D5.w),A2 ;screen address
move.w 0(A1,D0.w),D1
muls #16,D1
add.l D1,D1
swap D1
add.w #16,D1
moveq #31,D0
drawloop: subq.w #1,D1
sge (A2)
lea -160(A2),A2
dbra D0,drawloop
add.w #64,D6 ;increase phase
and.w #2047,D6
add.w D4,D5
adda.w D4,A6 ;hehe
eori.w #6,D4 ;bitplane shit
dbra D7,wave
move.w #37,-(SP)
trap #14
addq.l #2,sp
lea -160(A6),A6
lea phase(pc),a3
addi.w #64,(a3)
andi.w #2047,(a3)
move.w #32*20-1,D7
lea (-31*160)(A5),A4
lea 2(A4),A3
copystuff:
move.w 4(A4),4(A3)
move.w 2(A4),2(A3)
move.w (A4),(A3)
addq.l #8,A4
addq.l #8,A3
dbra D7,copystuff
lea 0(A6),A0
move.w counter(PC),D0
lea pattern(PC),A1
lea 0(A1,D0.w),A1
moveq #15,D0
drawpatloop0: moveq #19,D1
move.w (A1)+,D2
drawpatloop1: move.w D2,(A0)
addq.l #8,A0
dbra D1,drawpatloop1
dbra D0,drawpatloop0
lea counter(pc),a0
addi.w #32,(a0)
andi.w #511,(a0)
cmpi.b #57,$FFFFFC02.w
bne go
rts
DATA
; And here's the message that's printed on-screen.
; 1234567890123456789012345678901234567890
message: DC.B 13,10,10,10,10," Outline 2k6 - GGN/KUA/Paradize/D-BUG",0
EVEN
Our palette....
palette: dc.w $0,$f00,$f0,$700,$fff,$f00,$f0,$ff0
dc.w $f,$f0f,$ff,$555,$333,$f33,$3f3,$ff3
; Finally, the pattern sprite (designed by Rana and me :)
; Commented out is the original design.
pattern:
DC.W %100000000
DC.W %100000000
DC.W %1010000000
DC.W %1010000000
DC.W %10001000000
DC.W %10001000000
DC.W %100000100000
DC.W %100100100000
DC.W %1001000010000
DC.W %1001000010000
DC.W %10010000001000
DC.W %10010000001000
DC.W %100100000000100
DC.W %100100000000100
DC.W %1001000000000010
DC.W %1001111111111110
; DC.W %0000000100000000
; DC.W %0000000100000000
; DC.W %0000001010000000
; DC.W %0000001010000000
; DC.W %0000010001000000
; DC.W %0000010001000000
; DC.W %0000100000100000
; DC.W %0000100100100000
; DC.W %0001001010010000
; DC.W %0001001010010000
; DC.W %0010010001001000
; DC.W %0010010001001000
; DC.W %0100100000100100
; DC.W %0100100000100100
; DC.W %1001000000000010
; DC.W %1001111111111110
BSS
; This space is reserved for the pre-shifting of the sprite
DS.W 16*15
counter: DS.W 1
tabsinus: DS.B 2048
phase: DS.W 1
END
GGN for Alive, re-written 2006-07-31
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