Issue 89 11 April, 2004
_______________________________________________________________________________
Core Warrior is a newsletter promoting the game of Corewar. Emphasis is
placed on the most active hills - currently the '94 no-pspace, '94 draft
and beginner hills. Coverage will follow wherever the action is. If you
haven't a clue what I'm talking about then check out these five-star
Internet locals for more information:
FAQs are available from:
http://www.koth.org/corewar-faq.html
http://homepages.paradise.net.nz/~anton/cw/corewar-faq.html
Web pages are at:
http://www.koth.org/ ;KOTH
http://sal.math.ualberta.ca/ ;Sal Hills
http://para.inria.fr/~doligez/corewar ;Planar
http://www.ociw.edu/~birk/corewar ;C.Birk
http://www.corewar.info/ ;Fizmo
Newbies should check the above pages for the FAQs, language specification,
guides, and tutorials. Post questions to rec.games.corewar. All new players
are infinitely welcome!
_______________________________________________________________________________
Greetings...
Redcode Frenzy News: Four rounds have taken place since last issue.
Christian Schmidt takes first place in the Extended '88 Round, while
Zul Nadzri wins the '94 Tourney Round. In the Triple Challange Round,
Joshua Hudson is victorious - and in the Big Sibling Round, Chip Wendell
claims first.
In the overall standings, Roy van Rijn retains his top spot, followed
by Christian Schmidt, still holding second place. David Houston climbs
to third, displacing Zul Nadzri down one position.
Web-News: Lukasz Grabun's homepage has moved to:
http://www.dwarfscorner.com/
Ilmari Karonen's Beginner's Guide to Redcode has moved to:
http://vyznev.net/corewar/
El Kauka has created the Absolute Beginner Hill at:
http://home.t-online.de/home/familie.kersten/johannes/
German Labarga announces the sixth of his popular mini challenges on:
http://www.estadium.ya.com/neogryzor/corewars.htm
-- John Metcalf
______________________________________________________________________________
Current Status of the KOTH.ORG '94 No Pspace Hill:
# %W/ %L/ %T Name Author Score Age
1 33/ 15/ 52 Devilstick Roy van Rijn 151.8 154
2 47/ 44/ 8 Arrow Christian Schmidt 150.5 40
3 38/ 25/ 37 Son of Vain Oversby/Pihlaja 150.2 2405
4 46/ 42/ 12 HazyLazy C 11 CS SG 149.5 49
5 38/ 27/ 35 Armadillo Lukasz Grabun 148.7 146
6 37/ 26/ 37 Gremlin van Rijn/Grabun 148.2 71
7 46/ 44/ 11 Bottomless Pit Fizmo/Roy 148.0 2
8 44/ 41/ 16 Deathstar Roy van Rijn 146.7 4
9 36/ 27/ 36 slime test 1.00 David Houston 145.0 167
10 38/ 30/ 32 Ironic Imps Roy van Rijn 145.0 365
11 37/ 29/ 34 Arctica Christian Schmidt 144.8 130
12 38/ 31/ 31 Spiritual Black Dimension Christian Schmidt 144.2 196
13 44/ 45/ 12 spell of the moon John Metcalf 143.0 9
14 40/ 39/ 21 Quirk Christian Schmidt 142.0 186
15 36/ 30/ 35 Fast Action V Christian Schmidt 141.8 5
16 35/ 29/ 36 Devilish 2 David Houston 141.7 7
17 45/ 48/ 7 Kenshin D 10 Steve Gunnell 141.1 37
18 43/ 46/ 11 Dandelion III Schmidt/Zapf 141.0 41
19 43/ 45/ 12 something strange John Metcalf 141.0 3
20 43/ 47/ 10 Filling.... Roy van Rijn 138.6 1
The hill has aged 320 since last issue, bringing it to a total age of 3159.
All but two warriors have been pushed from the hill. The survivors are
both stone/d-clear/imp - Son of Vain (which recently held the top spot, age
2401) and Ironic Imps.
Those who didn't last the duration include Reepicheep (age 1347), Hazy Test
63 (1119), Recon 2 (826), Static (344), devilish 2 (330), Squire of Silkland
(187), Hammerhead (177), Dawn 2 (166), King of Metal (160), Kenshin B test 62
(154), Soldier of Silkland (145), Damage Inc. Act II (139) and queen of the
streets (139).
Warriors which entered the hill since last issue and were pushed off age
100+ total 5, O--* (age 263), Dandelion II (157), B94 (141), goonie
(120) and Revenge Again (119).
Koth report: 10 warriors resided at number one for at least 10 challenges.
Most often seen there has been Devilstick (after 119 challanges), followed
by King of Metal (44), Recon 2 (34), Spiritual Black Dimension (29),
Napalm Dawn (18), O--* (16), HazyLazy C 11 (13), Arrow (12), Hazy Test 63
(11) and Ironic Imps (10).
_______________________________________________________________________________
The '94 No Pspace Hall of Fame: * indicates the warrior is still active.
Pos Name Author Age Strategy
1 Son of Vain Oversby/Pihlaja 2405 * Q^4 -> Stone/imp
2 Blacken Ian Oversby 1363 Q^2 -> Stone/imp
3 Reepicheep Grabun/Metcalf 1347 Q^4 -> Paper/stone
4 nPaper II Paul-V Khuong 1270 MiniQ^3 -> Paper
5 Uninvited John Metcalf 1130 MiniQ^3 -> Stone/imp
6 Hazy Test 63 Steve Gunnell 1119 Scanner
7 Behemot Michal Janeczek 1078 MiniQ^3 -> Bomber
8 Olivia Ben Ford 886 Q^4 -> Stone/imp
9 Recon 2 David Moore 826 Scanner
10 Keyser Soze Anton Marsden 823 Qscan -> Bomber/paper/imp
11 Quicksilver Michal Janeczek 789 Q^4 -> Stone/imp
12 Eraser II Ken Espiritu 781 Scanner
13 Inky Ian Oversby 736 Q^4 -> Paper/stone
14 Toxic Spirit Philip Thorne 685 One-shot
15 Jinx Christian Schmidt 662 Q^3 -> Scanner
16 Blade Fizmo 643 Qscan -> Scanner
17 Return of Vanquisher Lukasz Grabun 640 Q^4 -> Bomber
18 Revenge of the Papers Fizmo/Roy 605 Q^4 -> Paper
19 Jade Ben Ford 600 Q^4 -> Stone/imp
20 Firestorm John Metcalf 589 MiniQ^3 -> Paper/imp
21 Claw Fizmo 525 Qscan -> Scanner
22 G3-b David Moore 503 Twoshot
23 Thunderstrike Lukasz Grabun 484 Q^4 -> Stone/imp
24 Vanquisher Lukasz Grabun 469 Q^4 -> Bomber
25 Revival Fire P.Kline 468 Bomber
26 The Phantom Menace Anton Marsden 465 Qscan -> Paper/imp
27 The Stormkeeper Christian Schmidt 460 Q^3 -> Stone/imp
28 Positive Knife Ken Espiritu 449 Q^4 -> Stone/imp
29 Boys are Back in Town Philip Kendall 441 Scanner
= Zooom... John Metcalf 441 Scanner
31 G2-b David Moore 413 Twoshot
32 Qtest Christian Schmidt 394 Q^3 -> Paper
33 Stalker P.Kline 393 Scanner
34 Decoy Signal Ben Ford 378 Q^4 -> Paper/imp
35 Ironic Imps Roy van Rijn 365 * Q^4 -> Stone/imp
36 unheard-of Christian Schmidt 355 Q^4 -> Paper/imp
37 Hazy Lazy ... again Steve Gunnell 350 Scanner
= Dawn Roy van Rijn 350 Q^4 -> Paper/imp
39 Static Miz 344 Q^4 -> Stone/imp
40 devilish 2 David Houston 330 Q^4 -> Stone/imp
= Vain Ian Oversby 330 Q^2 -> Stone/imp
42 Omnibus John Metcalf 327 Q^2 -> Stone/imp
43 Win! David Moore 322 Scanner
44 Return of the PendragonChristian Schmidt 318 Q^4 -> Stone/imp
45 Numb Roy van Rijn 312 Q^4 -> Paper/stone
46 Hazy Lazy... Steve Gunnell 309 Scanner
47 Now you're in trouble! John Metcalf 290 Q^4 -> Stone/imp
48 Hazy Lazy ... reborn Steve Gunnell 284 Scanner
49 Candy II Lukasz Grabun 282 Q^4 -> Stone/imp
= Pixie Lukasz Grabun 282 Q^4 -> Stone/imp
There are only 2 active warriors in this extended HoF, compared to last
issue's 4. The warriors are represented by 18 Stone/imps, 13 scanners,
6 paper/imps, 4 bombers and 3 each of one-shots, papers and paper/stones.
18 authors hold a place in the HoF. Schmidt has most, with 8 warriors.
Grabun and Metcalf both have 6 - Gunnell, Moore, Oversby and van Rijn
4 each - Ford has 3 - Espiritu, Janeczek, Kline and Marsden have 2 each
and the remaining 6 authors, just the one warrior.
Of these redcoders, 3 have 4 different strategies in the HoF. They are
Metcalf, van Rijn and Schmidt.
How did the warriors in the HoF meet their end? Three were ;killed by
their author (Return of Vanquisher, Thunderstrike and Hazy Lazy...). The
fate of another three is shrouded in mystery - who killed Boys are Back
in Town 1.1, Zooom... and Win!?
32 of the remaining 42 met their demise at the hands of a professional
giant slayer, a redcoder with two or more HoF kills under their belt!
van Rijn has slain most, with 8 kills. Metcalf has 6 kills - Gunnell,
Labarga and Schmidt have 4 each - Grabun and Pihlaja 3 each.
Beware a warrior with 'test' in it's name, 17 HoF entries fell to one.
_______________________________________________________________________________
Current Status of the KOTH.ORG '94 Draft Hill:
# %W/ %L/ %T Name Author Score Age
1 39/ 27/ 34 Spiritual Black Dimension Christian Schmidt 150.2 35
2 31/ 14/ 55 Devilstick Roy van Rijn 147.6 26
3 39/ 33/ 28 Sunrise Zul Nadzri 146.2 45
4 35/ 25/ 40 Reepicheep Grabun/Metcalf 144.5 465
5 36/ 27/ 37 Arctica Christian Schmidt 144.2 25
6 45/ 46/ 9 Arrow Christian Schmidt 143.9 16
7 35/ 26/ 39 Devilish 2 David Houston 142.8 5
8 42/ 42/ 15 something strange John Metcalf 142.3 1
9 43/ 44/ 12 Dandelion 3 Schmidt/Zapf 142.3 19
10 34/ 26/ 41 Son of Vain Oversby/Pihlaja 141.7 436
11 41/ 41/ 18 Cyberpunk Christian Schmidt 141.5 43
12 33/ 24/ 43 Gremlin van Rijn/Grabun 141.5 21
13 36/ 31/ 33 Numb 2 Roy van Rijn 141.0 27
14 41/ 42/ 17 Return of Vanquisher PsP Lukasz Grabun 140.0 276
15 32/ 23/ 45 slime test 1.00 David Houston 139.9 13
16 34/ 28/ 38 Bitter Sweet Lukasz Grabun 139.7 258
17 31/ 23/ 45 Netpaper David Houston 139.5 67
18 42/ 44/ 15 HazyLazy C 11 CS SG 139.3 17
19 42/ 46/ 12 22% Organic Stain Remover Roy/bvowk 139.0 2
20 30/ 23/ 47 Muscle Hammer Zul Nadzri 137.9 4
After an age of 56, just 5 warriors remain on the hill from last issue.
Numb is one of those which left the hill, at an age 167.
Hand-shake alert: the new version of Sunrise and Muscle Hammer.
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The '94 Draft Hall of Fame: * indicates the warrior is still active.
Pos Name Author Age Strategy
1 Reepicheep Grabun/Metcalf 465 * Q^4 -> Paper/stone
2 Son of Vain Oversby/Pihlaja 436 * Q^4 -> Stone/imp
3 Return of Vanquisher Lukasz Grabun 276 * Q^4 -> Bomber
4 Bitter Sweet Lukasz Grabun 258 * Q^4 -> Stone/imp
5 CrazyShot 2 Christian Schmidt 249 Q^4 -> One-shot
6 Herbal Avenger Michal Janeczek 237 Scanner
7 Bustling Spirit Christian Schmidt 216 P-warrior
8 Revenge of the Papers Fizmo/Roy 204 Q^4 -> Paper
9 Uninvited John Metcalf 194 MiniQ^3 -> Stone/imp
10 Blowrag Metcalf/Schmidt 192 Q^4 -> Paper/imp
11 Incredible! John Metcalf 180 Paper/imp
12 Wallpaper Christian Schmidt 175 Q^4 -> Paper/stone
13 Mantrap Arcade Dave Hillis 170 P-warrior
14 Numb Roy van Rijn 167 Q^4 -> Paper/stone
15 PolyPap Jakub Kozisek 160 Qscan -> Paper
16 Recon 2 David Moore 156 Scanner
17 Joyful Maw Dave Hillis 143 P-warrior
18 Paperazor Christian Schmidt 141 Q^4 -> Paper
19 Sunset David Moore 138 P-warrior
20 Dawn Roy van Rijn 137 Q^4 -> Paper/imp
21 Self-Modifying Code Ben Ford 132 P-warrior
22 Combatra David Moore 131 Boot distance calculator
23 unheard-of Christian Schmidt 128 Q^4 -> Paper/imp
24 Mad Christian Schmidt 123 P-warrior
25 Microvenator Michal Janeczek 122 P-warrior
Unheard-of is the only new entry since last issue, entering the bottom of
the HoF just before it left the hill.
_______________________________________________________________________________
Current Status of the SAL Beginners Hill:
# %W/ %L/ %T Name Author Score Age
1 53.6/ 30.7/ 15.6 Studie strikes back Sascha Zapf 176.5 25
2 53.4/ 30.3/ 16.3 Shooting Star v0.262 brx 176.5 3
3 52.0/ 33.8/ 14.2 ssoBeht Sascha Zapf 170.1 16
4 52.1/ 36.0/ 11.9 Frullato LAchi 168.2 42
5 39.6/ 18.4/ 42.1 Veenah V0.8 Sascha Zapf 160.8 1
6 38.8/ 17.8/ 43.4 Paper of yesterday Sascha Zapf 159.9 77
7 39.6/ 19.5/ 40.9 Uneven Twins Sascha Zapf 159.8 29
8 48.5/ 41.9/ 9.6 Star Sascha Zapf 155.2 30
9 38.8/ 23.8/ 37.4 Fatty boy G.Labarga 153.7 83
10 45.6/ 39.5/ 14.8 French Kiss LAchi 151.7 23
11 31.9/ 20.2/ 47.9 Tom David Moore 143.7 13
12 43.3/ 45.6/ 11.1 scizzory Miz 141.0 72
13 29.2/ 18.7/ 52.2 Enigma brx 139.6 9
14 41.3/ 44.7/ 13.9 Neverland II John Metcalf 138.0 71
15 26.2/ 16.3/ 57.5 Unknown Anonymous 136.0 22
16 25.2/ 16.9/ 57.9 nGrave Ken Hubbard 133.5 34
17 28.2/ 23.1/ 48.7 Smaug Imp Ken Hubbard 133.3 39
18 28.0/ 24.8/ 47.2 test3 miz 131.2 86
19 30.8/ 49.4/ 19.8 Stoney Miz 112.2 73
20 29.8/ 52.1/ 18.1 Brimstone John Metcalf 107.4 19
21 29.2/ 60.9/ 9.8 Canizza LAchi 97.5 32
22 26.5/ 58.6/ 14.9 Repliscan Christian Schmidt 94.5 53
23 26.3/ 58.4/ 15.4 doodle brx 94.2 7
24 26.1/ 59.0/ 15.0 Sugartooth Miz 93.2 37
25 14.3/ 57.4/ 28.4 DJN Stream Ken Hubbard 71.2 27
The first four ranks are held by one-shots, followed by paper in the next
three positions. Welcome to the two newcomers, brx and LAchi, who make an
impressive debut.
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Summary of IRC Speed Redcoding Challenge Results:
# ORGANISER FIRST PLACE CORE DETAILS
-----------------------------------------------------------------------------
29 Christian Schmidt Will 'Varfar' 800 Limited Process Tiny
30 Christian Schmidt Roy van Rijn 8000 LP Multi-Warrior
31 Sascha Zapf Roy van Rijn 800 Reversing Opcodes
32 Christian Schmidt Roy van Rijn 256 Multi-Warrior, maxlength 4
33 Sascha Zapf Christian Schmidt 800 start warrior at every instr
34 Christian Schmidt David Houston 800 no }, > or DJN allowed
35 LAchi Will 'Varfar' 400w Multi-Warrior knockout
_______________________________________________________________________________
A Basic Introduction to the Anatomy of the Scanner
---------------------------------------------------
"They will gather intelligence, lay false trails and strike at their
opponents suddenly and with determination."
- A. K. DEWDNEY, Scientific American (January 1987)
Philosophy of the Scanner
-------------------------
In Corewar, a battle program will execute either one, or multiple copies of
itself. A program which is running just one copy will often lose the round
after a single successful attack against it. A program which has multiple
copies will not be beaten until each of these copies has been successfully
dealt with.
A battle program which is continually creating new copies of itself is
described as a replicator. No program can hope to attack copies of a
replicating program sufficiently fast enough to keep up with the new copies
which are constantly being spawned.
The only practical solution is to use a two stage attack. First, slow the
rate at which the replicator is producing new copies. Next, destroy all
copies of the opponent program while they are incapacitated.
The manner in which a replicator can be slowed is by making it split off
useless processes. We achive this by overwriting it with, or otherwise
forcing it to execute, SPL instructions.
Modern replicators spend approaching 50% of their time splitting off new
processes, so we will need several consecutive SPL instructions to have any
chance of being effective. The number of cycles to place these is
considerable - compared, for example, to the time taken to drop single bombs.
Before spending a substantial number of cycles, it would make sense to check
the area we are about to wipe contains an opponent, rather than empty core.
This is precisely what a scanner is designed to do:
1) look for an area of core which potentially contains an opponent,
2) attack the selected area with a stun attack to slow the opponent,
3) repeat from step 1, until an implementation determined point,
4) the end-game - change the means of attack from stun to destroy.
Let us take a closer look at each of these stages:
1 - Typical Scan Loops
----------------------
First, our scanner will look through core for a location which differs from
empty core. If we are lucky, this will contain an active copy of the
opponent. Alternatively, it may have been bombed by the opponent.
Scan loops come in a variety of speeds. The ratio of scanner size to scan
speed can make a big difference to the effectiveness of a warrior. A
small/fast scanner will find and attack a bigger/slower opponent more
frequently than that opponent finds and attacks it. It is therefore
desirable to have the lowest possible value of size/speed.
The example code in this section is labelled in a manner consistent with a
great deal of published code. Conventions used are:
* scan - the top of the scan loop, and the entry point for our examples.
Would ptr be a better entry point to the scan loops below? Why?
* ptr - the instruction holding either one or two pointers to the
location(s) to be scanned.
* inc - an instruction holding the constant 'step' in both fields, so a
single ADD instruction can update two pointers.
* step - the distance between two scanned locations. Some important
literature on 'good' scan steps is listed below in Suggested Reading.
* hop - certain scanners look at two locations which are close to each
other. When something is found, they use an attack which covers both
locations. Hop is the distance between such a pair of locations.
* start - the first location to be scanned. Often chosen to maximise the
length of time before the scanner detects itself.
Some examples of the most common forms of scan loop follow:
.5c: the simplest, with a comparatively poor size/speed ratio. Upgrade from
a .5c loop to .66c for a guaranteed improvement. Instructions with zero a &
b fields such as SPL #0,0 are invisible to the f-scan used here.
scanA ADD #step, ptrA
ptrA JMZ.F scanA, start ; scan 1 location every 2 cycles
.66c: for scanners up to length 8, .66c provides the optimal ratio. The
data at incB will usually be combined with another instruction. For example,
in Blur 2 the data is held in the SPL above the clear.
Having two scan pointers is one disadvantage of this loop. When the scan
triggers it is neccessary to either determine which pointer holds the
location to be attacked, or else attack both.
An effective variation is to change the JMP instruction to DJN, to colour
core against other scanners. Use something similar to DJN.F scanB,<-500 to
create a sequential decoy, or alternatively decrement through your scan
pointer with DJN.F scanB,@ptrB.
scanB ADD incB, ptrB
ptrB SNE start+hop, start ; scan 2 locations every 3 cycles
JMP scanB
; ...
incB DAT step, step
.75c: gives the optimal size/speed ratio for scanners between 9 and 15
instructions. The location at which something has been found is held in the
b-field of ptrC. As with the .5c scan, instructions with zero a & b fields
are invisible. If we re-enter the scan loop, the pointers need to be reset;
MOV.BA ptrC,ptrC should do the trick.
It appears at first glace, if the SNE detects something through it's a-field,
the scan loop will not drop through into the attack phase. Stepping through
the code however, reveals how some simple arithmetic 'copies' the value from
the a-field of ptrC to the b-field. The scan loop can then drop through with
the b-field of ptrC pointing to whatever has been found.
scanC ADD incC, ptrC
ptrC SNE.X start, start ; scan 3 locations every 4 cycles
ADD.X incC, ptrC
JMZ.F scanC, @ptrC
; ...
incC DAT 2*step, step
.8c: ideal for scanners of more than 16 instructions, this extension to the
basic .66c loop has the same disadvantage of two scan pointers. As with it's
slower relative, changing the JMP to a DJN proves effective against other
scanners.
scanD ADD incD, ptrD
ptrD SNE start+hop, start ; scan 4 locations every 5 cycles
ADD incD, ptrD
SNE *ptrD, @ptrD
JMP scanD
; ...
incD DAT step, step
2 - Common Forms of Offense
---------------------------
Once the scanner has found something, what comes next? We hit it. We hit it
hard with a stun attack intended to bring the enemy's processes to a virtual
stand-still. There are four main types of offense to consider:
* Permanent - a.k.a. one-shots. Switch to a core-clear with one or more
SPL passes though core, beginning with the location found by the scan.
After this, the clear wipes with DAT. Simple and effective. See Scanny
Boy for an example.
* Fixed Length - switch to a fixed length attack. Afterwards, switch back
to scanning. The two most common types of fixed length attacks are SPL
carpets and special bombs (stun and incendiary for example). Take a look
at Rave and Beholder's Eye, which use these techniques.
* Variable Length - switch to a linear SPL wipe beginning at the location
where the scan detected something, continuing until it reaches empty core.
After this, switch back to scanning. This technique proves the most
effective against paper/imps. Check Mini HSA for a good example.
* Ongoing - a linear SPL wipe runs parallel to the scan. When something is
found by the scan, the pointer for the SPL wipe is adjusted to point to
the scanned location. However, the most common implementation of this
technique introduces an extra instruction to the scan loop, reducing the
speed. Blur 2 is a clear example of an ongoing attack.
The scanner needs somehow to ensure it doesn't attack itself. One way to
achieve this is to check the scan pointer isn't within a range which points
to our scanner before attacking. Other alternatives are to use a scan
pattern which avoids detecting the scanner, or using some means of hiding the
scanner from itself (reflections).
3 - The Switch
--------------
Perhaps the trickiest requirement is the need to implement a switch from the
attack to the end-game. The one-shot avoids this altogether by entering the
end-game as soon as something is found. In a traditional scanner however, we
have a choice to make:
* When our scanner detects itself either once, or a number of times, enter
the end-game. For example Mini HSA switches after 16 self-scans.
* After a number of iterations of the scan loop, drop through to the end
game. In Blur 2, there is a counter which is decremented by the scan
loop. When this reaches zero, control will pass into the end-game.
* Switch when a pre-determined location is altered by the attack. See
myZizzor for an example, which has a small decoy the scanner detects and
attacks, thus altering the checked location.
4 - The End-Game
----------------
After our scanner has completed it's main attack phase, what next? It needs
to dispose of the enemy processes we've worked so hard to stun. The two most
effective methods are:
* Clear - switch to a core-clear, which wipes core with DAT. Optionally,
the clear may wipe with SPL prior to the DAT wipe. The most often seen
type clear is the d-clear, with spiral clears also being a popular choice.
Scanners containing a spiral clear include Eggbeater, Memories, SETI and
Win!
* DAT Switch - the scan continues, bombing with DAT instead of it's previous
attack. Many of the HSA-style warriors work in this way, including Mini
HSA. Another example is the scanner from Enough is Enough!
Suggested Reading
-----------------
A selection of material discussing step sizes can be found in Push Off 07
September 1993, Core Warrior #11, and Mathematical Models for Step Sizes
(Morrell 1996). Stefan Strack provides a useful tool for finding good step
sizes, mOpt v1.2, for which there is a tutorial in Core Warrior #32.
Below are some references to a few instructive examples of scanners. These
illustrate the methods discussed above. Generally, those which function in a
similar manner are grouped together, with the most readable example in the
group listed first:
Blur 2 by Anton Marsden (CW36) - implements an ongoing attack from the scan
loop, followed up by a d-clear end-game. After reading Blur 2, continue with
Hazy Lazy, Silver Talon, Stalker, Eggbeater (CW46) and the scanner from
Enough is Enough! (CW79).
HAL 9000 by Justin Kao (CW50) - an alternative means of implementing an
ongoing attack, or scan directed clear.
Mini HSA from Electric Head by Anton Marsden (CW59) - provides an excellent
introduction to the workings of HSA. Scanning continues into the end-game,
with the SPL wipe becoming a DAT wipe. Also, check He Scans Alone, Mischief
(CW80) and Razor.
Beholder's Eye v1.7 by W. Mintardjo - an easy to read spl/jmp bomber.
Continue reading with Iron Gate (CW19), Harmony II and Memories (CW19).
myZizzor by Magnus Paulsson - performs a variable length attack, followed by
a SPL / DAT clear.
Origin of Storms by John Metcalf (CW86) - a variable length attack realized
in the scan loop, followed by the ever-present d-clear.
Rave 4.1 by Stefan Strack - a good example of a .66c scan with a fixed length
SPL carpet. Also, you should take a look at SETI. Next study Win! and
Recon 2, two warriors based on the same concept, employing an abundance of
effective techniques.
Scanny Boy by David van Dam (CW29) - drops straight through from the scan
loop into the end-game's SPL / DAT clear and provides a good example of a
one-shot. See also Tiny BiShot 2.0, The Bloodhound, G2 and Phantasm 50.
_______________________________________________________________________________
Extra Extra - Dandelion II by Christian Schmidt and Sascha Zapf
Blur-style scanners, such as The Machine, Hazy Lazy, etc. make an
interesting all-round scanner. They should be more effective against paper
than a one-shot due to targetting more real copies in a smaller amount of
time. The typical end-game strategy is a d-clear which performs better
against stone/imps, as it is harder to hit (3 instructions in the clearing
stage only 1 of which is vulnerable to DAT bombs). However, Blur-style
scanner can't handle paper/imps well and often loose significantly against
them.
We decided to change this aspect and tried to create a Blur-style scanner
which is able to beat paper/imps as well. To do this we had to change the
end-game strategy, because modifying the scan loop won't help the situation.
We figured out that we obtain best results if we use a more complex anti-imp
clear (found in Forgotten Scanner, one of Moore's one-shots) instead of a
d-clear. Due to the larger size compared with a d-clear the complete code
would be much more vulnerable. It would be more frequently found by
scanners and more often hit by stones.
Separating the clear from the scanning code led to an improved overall
performance. After optimizing the scan step and the gap between the scan
section and the core-clear we finally added a decoy to fool one-shots.
Compared to other Blur-style scanners, Dandelion II has a shorter scanning
phase. This is long enough to slow down papers significantly, but short
enough to give the clear sufficient time to kill all remaining imps.
Below is a comparison between Dandelion II and three other Blur-style
scanners:
Against paper/imps:
Name |Decoy Signal| RotF Copy | Blowrag | Overall
| W L T Pts| W L T Pts| W L T Pts|
-----------------+------------+-------------+------------+---------
Dandelion II |49 20 31 179|45 25 30 166|32 40 28 124| 469
zooom... |11 47 42 74|11 38 51 85|13 25 62 101| 260
Hazy Lazy | 9 45 46 74| 8 43 49 72|24 38 38 111| 257
Herbal Avenger | 7 45 48 69| 9 36 55 83|14 28 58 100| 252
Against stone/imps:
Name | Son of Vain| Hammerhead | Uninvited | Overall
| W L T Pts| W L T Pts| W L T Pts|
-----------------+------------+-------------+------------+---------
Hazy Lazy |36 37 27 136|40 39 21 140|41 49 10 134| 410
Herbal Avenger |26 40 33 111|30 44 26 116|38 48 14 128| 355
Dandelion II |26 44 30 108|37 48 15 126|24 64 12 83| 317
zooom... |17 54 29 81|36 44 20 128|29 59 12 99| 308
It is clearly seen that Dandelion II scores really nice against paper/imps
while it looses some stone/imp resistance. Okay, without further ado here
is the code:
;redcode-94nop
;name Dandelion II
;author Schmidt/Zapf
;strategy blurish scanner TNG
;strategy decoymaker added
;assert CORESIZE == 8000
sSep equ 8
sOff equ 5753
sStep equ 7212
cOff equ 602
inc nop #sStep, sStep
cptr mov clear, }6727
sgate mov clear, >cptr
scan seq sOff+sSep, sOff
mov.b scan, cptr
add inc, scan
jmn sgate, @sgate
jmp clear
for 17
dat 0, 0
rof
gap equ 26
gate dat 4009+cOff, {gap+cOff
jumper jmp 4009, gap
dat 0, 0
dat 0, 0
jmp 7684, <2667
clear spl #4007, gap
mov @switch, >gate
mov jumper, }gate
switch djn clear+1, {clear
for 28
dat 0, 0
rof
dplace equ (inc+2453)
decoy mov <dplace+0, {dplace+2
mov <dplace+3, {dplace+5
mov <dplace+6, {dplace+8
mov <dplace+9, {dplace+11
djn.f scan, <dplace+13
end decoy
_______________________________________________________________________________
Extra Extra Extra - Something Strange by John Metcalf
Something Strange is another addition to the ever-growing category of
Blur-like scanners. The code demonstrates two techniques:
* the use of a pre-scan,
* the inclusion of DJN decrements in a Blur loop.
The advantage of the pre-scan used here is two-fold. It is faster than the
main scan loop, which loses some of it's time to wiping. Also, the scan
pattern used performs better in the early cycles of the game.
In most Blur-like scanners the SPL wipe is active within the scan loop,
wiping and wasting precious cycles even before something is discovered.
Zooom (CW70) demonstrated a trick using self-modifying code in which the
SPL wipe is inactive until the scan finds something. Using a pre-scan
achieves similar results.
When Blur-like scan loops look at more than one location, these locations
tend to be close to each other, typically 4-8 cells apart. This avoids the
need to determine which of the scanned locations contains something. This
forms a poor scan pattern against any opponent larger than the 4-8 cell gap.
Something Strange's pre-scan uses the same scan step as the main scan loop.
However, the pre-scan doesn't need to scan locations close to each other,
and can be given a much better pattern:
pre-scan pattern : step*1, step*2, step*3, step*4, step*5
main-scan pattern : step*1, step*1+hop, step*2, step*2+hop, step*3
With the addition of an extra line of code, it was possible to add a DJN.F
attack to the main scan loop. This currently decrements through the scan
pointer.
Decrementing through the scan pointer appears to be more successful than
beginning a decrement stream where something is discovered and working back
through core, while the SPL wipe moves forward.
Some questions about general Blur-like scanners to consider:
Could a Blur-like scanner with a faster scan loop be effective? Perhaps
one could be built from the .75c or .8c loops.
Would it be worth adding a couple of lines logic to the basic scanner to
achieve a better scan pattern in the main scan loop?
Are there any special considerations when choosing a step for a Blur-like
scanner?
Anyway, here's the code:
;redcode-94nop
;name something strange
;author John Metcalf
;strategy tonight something strange stalks the core
;strategy .8c pre-scan -> .5c scan / .25c wipe -> d-clear
;assert CORESIZE == 8000
ORG ptrD
step EQU 230 ; (or 3470, 5110)
hop EQU 5 ; gap
sbmb EQU incB
cptr MOV.B ptrB, #-3196 ; adjust the wipe pointer
scanB MOV sbmb, >cptr ; SPL wipe from the scan loop
SUB incB, ptrB
ptrB SNE ptrD+hop-step, ptrD
DJN.F scanB, @ptrB
JMN cptr, ptrB ; scan until we detect our SNE
gate EQU ptrB
incB SPL #-step, <-step ; a typical d-clear
clear MOV dbmb, >gate
DJN.F clear, >gate
dbmb DAT <2667, 8
FOR 72
DAT 0,0
ROF
first EQU (ptrB+step)
incD DAT step*2, step*2
DAT 0, 0
scanD ADD incD, ptrD ; .8c pre-scan
ptrD SNE first+step, first
ADD incD, ptrD
SNE *ptrD, @ptrD
DJN.F scanD, @ptrD
ADD ptrD, ptrB ; adjust pointer in main scan
JMP ptrB, <ptrB+2-step
END
_______________________________________________________________________________
Questions? Concerns? Comments? Complaints? Mail them to people who
care. Beppe Bezzi <giuseppe.bezzi@galactica.it>, Philip Kendall
<pak21@cam.ac.uk>, Anton Marsden <anton@paradise.net.nz>, John Metcalf
<grumpy3039@hotmail.com> and Christian Schmidt <fizmo_master@yahoo.com>
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