rainbow49 by Genesis Project

screenshot added by wertstahl on 2020-09-27 22:48:37

platform :	Commodore 64 Commodore 64
type :	64b 64b
release date :	september 2020

popularity : 56%

56%

0.80

alltime top: #12502

wertstahl [Code]

added on the 2020-09-27 22:48:37 by wertstahl

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🏳️‍🌈

rulez added on the 2020-09-28 02:55:51 by DevEd

🏳️‍🌈 on the c64

rulez added on the 2020-09-28 08:53:57 by Queen_Luna

Quote:

🏳️‍🌈

rulez added on the 2020-09-28 09:30:41 by SiR

wait this isnt german flag

added on the 2020-09-28 10:12:16 by leGend

Well... At least this isn't openly named after a particular pretentious sect.

added on the 2020-09-28 10:37:39 by Tesseract

23 byte version, might or might not be rule-bending:

Code:

	* = $7c
	SEI
loop:
	LDA $D012
	AND #$E0
	TAX
	STA $D011,X
	LDY $A355,X
	SRE $A651,Y
	STA $D020
	BNE loop

Hex: 7c 00 78 ad 12 d0 29 e0 aa 9d 11 d0 bc 55 a3 5b 51 a6 8d 20 d0 d0 ec

Load normally, ignore the load error (it overwrites system variables in the zeropage which confuses the system), start with RUN.

This abuses the ROM as a source of pseudo randomness for computing the intended color from the current rasterline. Plus a few tweaks for stabilizing the timing so it does not flicker.

rulez added on the 2020-09-28 12:42:44 by Kabuto

Sizecoding and 🏳️‍🌈!

rulez added on the 2020-09-28 13:21:29 by baah

Kabuto: how did you even come up with finding that sequence in ROM for the colors and furthermore so that it makes sense in conjunction with sre?

added on the 2020-09-28 14:14:14 by wertstahl

http://dl.dataelephant.net/rainbow23.zip okay so here is kabuto`s version, which actually also autostarts, no need to run. 23 bytes with loadingbytes. i have no idea how.

added on the 2020-09-28 14:26:36 by wertstahl

🏳️‍🌈

rulez added on the 2020-09-28 14:27:02 by v3nom

Wertstahl: brute-force search that emulates a number of potential useful opcodes :-)

19-byte 🏳️‍🌈 - no more LOAD ERROR but this "waves" a bit, couldn't find a way of stabilizing this without increasing its size:

Code:

	* = $7c
	SEI
loop:
	SRE $ECBE,X
	AND $EDA9,X
	STA $D010,Y
	LAX $D012
	ASL
	TAY
	BVC loop

Hex: 7C 00 78 5F BE EC 3D A9 ED 99 10 D0 AF 12 D0 0A A8 50 F0

1st run: starts with A=$52, X=$FF, Y=$01. Will end up writing $20 to $D011 to disable the screen.

Further runs: ASL / TAY ensures that Y is always even (-> will never write $D011 again) and writes go to the border register every 32 rasterlines.

added on the 2020-09-28 15:18:13 by Kabuto

wow! 👏👏👏 for the 19b and the approach. i would have never thought of that. thats almost cheating! ;-) but then again, thats what sizecoding is all about, right? thx for the explanation!

added on the 2020-09-28 16:41:07 by wertstahl

Size coding, 🏳️‍🌈 and code golfing in a good way. Love seeing this happen :)

rulez added on the 2020-09-29 12:35:32 by alia