first impressions of the Lego smart brick, before I do any actual tearing down: wow, I forgot how good they are at working with plastic.

[gsuberland@chaos.social]

@whitequark @ldcd @ftg hmm, seems to be hardware log2p0 and log2p1 intrinsics. weird.

[whitequark@social.treehouse.systems]

@gsuberland @ldcd @ftg what is the p0/p1?

[gsuberland@chaos.social]

@whitequark @ldcd @ftg log2p0 is plain integer log base 2 (I think with always round down behaviour?) and log2p1 is the same but add 1 after. the latter is used to calculate how many bits are needed to store a given number. I know the latter gets used in some AV compression algorithms, idk about the decompression algorithms though.

[whitequark@social.treehouse.systems]

here's the flash contents https://upload.whitequark.org/1775953651-lego_brick_00F2MZ_749DF5_W25Q16JWBY.bin

[ignaloidas@not.acu.lt]

@wren6991@types.pl @whitequark@social.treehouse.systems @gsuberland@chaos.social @ldcd@social.treehouse.systems @ftg@mastodon.radio ceil(log2(n+1)) is clz, and is somewhat often defined as such so wouldn't surprise me (I doubt it would actually have floating point log)

[whitequark@social.treehouse.systems]

@ignaloidas @gsuberland @ldcd @ftg @wren6991 i have literally never seen clz implemented that way

[ignaloidas@not.acu.lt]

@whitequark@social.treehouse.systems @gsuberland@chaos.social @ldcd@social.treehouse.systems @ftg@mastodon.radio @wren6991@types.pl jpeg xl uses the log2 way in it's spec (it took me a bit of thinking to reverse it)

(wait, now that I'm re-thinking, that's not clz but bitsize minus clz but basically same)

[wren6991@types.pl]

@ignaloidas @gsuberland @ldcd @ftg @whitequark (implements XOR instruction) Galois Field Addition Accelerator

[nicolas17@social.treehouse.systems]

@whitequark hey @zhuowei does this match anything you found in the LEGO Smart Brick app? Or does the app have a newer firmware version?

[maehw@chaos.social]

@nicolas17 @whitequark @zhuowei for everyone else who got invested now, I think you're referring to this thread: https://notnow.dev/objects/cccfc047-da57-444a-be6f-63a5a766bcf7

[wren6991@types.pl]

@whitequark cpu_top is clearly a Verilog module name lmao

[whitequark@social.treehouse.systems]

here's how the flash was mounted in its natural environment, in absence of feline predators

the SPI bus seems to be shared with something else & they're definitely using ViP

[whitequark@social.treehouse.systems]

@wren6991 yep!

[artemist@social.mildlyfunctional.gay]

@whitequark very important pad

[whitequark@social.treehouse.systems]

alright let's dump the ARC chip now

[ldcd@social.treehouse.systems]

@artemist @whitequark ️IP

[artemist@social.mildlyfunctional.gay]

@ldcd @whitequark ️️

[drwho@masto.hackers.town]

@whitequark What are you using to dump the chips?

[mlp@defcon.social]

@azonenberg @whitequark @gsuberland @ldcd @ftg
When Microchip first produced a PIC32 it was built around MIPS (I was at HI-TECH Software at the time - we had a compiler targeting it). Later they acquired Atmel and renamed the (ARM-based) SAM series "PIC32..."

[azonenberg@ioc.exchange]

@mlp @whitequark @gsuberland @ldcd @ftg yes I'm talking about their embedded controllers for laptops etc not general purposes MCUs.

Real PIC32 is mips, not the rebranded SAMs sold under the pic32 brand