A place for talking about the Ethereum Virtual Machine on Farcaster.

is there a “magic number” solution to flipping a (uint32) number’s endianness? or is masking and shifting each byte always the best way?

cc @optimizoor

According to Hacker's Delight, it doesn't look like there's an arithmetic solution. It proposes using a rotating shift that we can emulate in the EVM by first duplicating the number to 64 bytes using MUL. This should be better than masking and shifting each byte separately. In principle this should cost 41 gas.

prev: /nook, protocol @ opensea, co-author seaport & stuff.
professional @slokh and @0xalexander fanboy

oooh this looks promising, lemme see what the opcodes work out to

I think it is:

PUSH5 0x0100000001
MUL
DUP1
PUSH1 0x08
SHR
PUSH4 0xff00ff00
AND
SWAP1
PUSH1 0x18
SHR
PUSH3 0xff00ff
AND
OR

hell yeah

a few bytes smaller than the naive way + 25 gas cheaper

ty king 👑