Activate custom gates in JS and add rangeCheck64 gadget #179
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mitschabaude
changed the title
| @@ -20,6 +20,41 @@ use std::path::Path; | |||
| use std::sync::Arc; | |||
| use wasm_bindgen::prelude::*; | |||
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| pub struct SimpleFeatureFlags { | |||
| pub range_check0: bool, | |||
| pub range_check1: bool, | |||
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Just a clarifying question for me: what does range_check1 correspond to? range_check0 is the 64 bit range check; what is the other one?
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Here's how I understand it (@jspada would know the full details):
range_check0 actually has space for up to 88 bits (for the 64-bit check we set the upper two 12-bit limbs to constant zero). However, when used in the 88-bit mode it doesn't fully constrain all limbs by itself and needs to "collaborate" with subsequent gates.
The main objective for both range check gates was to enable a 3x88-bit check (used in foreign field arithmetic, supports bigint sizes up to 264 = 3 * 88 bits). The range_check1 gate is what is needed together with two range_check0 gates and one Zero gate to collaboratively do this 3*88 bit check.
Note that that's 264 bits of range check in 4 gates, which is 264 / 4 = 66 bits per gate on average. So the collaborative approach gives you a 2 bit edge over the single gate version here 😅 Just doing 4 64-bit range checks separately would have only given us 256 bit checks which would've been to small for important use cases in foreign field multiplication.
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companion of o1-labs/o1js#1176, see PR description there