BIP-0440: clarify wordspan costs
BIP-0441: update wordspan costs and fix OP_RIGHT
Apply BIP-0440 wordspan notation to numeric and bitvector costs.
Define OP_RIGHT as rightmost-byte extraction with bounded copying cost.
Clarify OP_UPSHIFT, CLTV/CSV, and final success-check costs.
- Apply BIP-0440 wordspan notation to numeric and bitvector costs.
- Define OP_RIGHT as rightmost-byte extraction with bounded copying cost.
- Clarify OP_UPSHIFT, CLTV/CSV, and final success-check costs.
347 | @@ -331,6 +348,7 @@ Work in progress: 348 | 349 | ==Changelog== 350 | 351 | +* 0.2.1: 2026-06-15: define wordspan notation and clarify byte-length versus word-span costs.
It may not matter, but in both changelog additions in this pull, the date is two weeks ago.
Thanks for reviewing!
I don't think the changes are substantial enough to provide value for the mailing list, the OP_RIGHT definition was simply a mistake it seems, it now corresponds to the historical and the more natural semantics. I would give some time for @rustyrussell to take a look at the diff, but otherwise fine from my side.
Are you still waiting for @rustyrussell to take a look, or is this ready to go?
Well he seems to be unresponsive so good to merge from my side.
I don't see any obvious errors in this change.
Are you waiting for review from anyone, or do you plan to send a mail list post to discuss?
692 | 693 | -We increase the length of B here to the next word boundary, using 694 | -"((length(B) + 7) / 8) * 8", as the multiplication below makes the 695 | -difference of that from the simple "length(B)" significant. 696 | +We increase the operand lengths to the next word boundary for the word-span 697 | +loops, using <code>wordspan(n)</code> from [[bip-0440.mediawiki|BIP440]], as
Nano-consistency-nit: BIP440 speaks of <code>wordspan(X)</code>, while this line calls it <code>wordspan(n)</code>.
LGTM, the wordspan notation looks very helpful.
Given the triviality of the nit I commented on, I’ll merge this PR in a couple days if there is no update, but if you want to fix it or something else, please feel free to update.