openvm_native_recursion/
utils.rs

1use openvm_native_compiler::ir::{Builder, CanSelect, Config, Felt, MemVariable, Var};
2use openvm_stark_backend::p3_field::{
3    coset::TwoAdicMultiplicativeCoset, PrimeCharacteristicRing, TwoAdicField,
4};
5use openvm_stark_sdk::config::FriParameters;
6
7use crate::fri::{types::FriConfigVariable, TwoAdicMultiplicativeCosetVariable};
8
9pub fn const_fri_config<C: Config>(
10    builder: &mut Builder<C>,
11    params: &FriParameters,
12) -> FriConfigVariable<C> {
13    let two_adicity = C::F::TWO_ADICITY;
14    let generators = builder.array(two_adicity + 1);
15    let subgroups = builder.array(two_adicity + 1);
16    for i in 0..=C::F::TWO_ADICITY {
17        let constant_generator = C::F::two_adic_generator(i);
18        builder.set(&generators, i, constant_generator);
19
20        let constant_domain = TwoAdicMultiplicativeCoset::new(C::F::ONE, i).unwrap();
21        let domain_value: TwoAdicMultiplicativeCosetVariable<_> = builder.constant(constant_domain);
22        // ATTENTION: here must use `builder.set_value`. `builder.set` will convert `Usize::Const`
23        // to `Usize::Var` because it calls `builder.eval`.
24        builder.set_value(&subgroups, i, domain_value);
25    }
26    FriConfigVariable {
27        log_blowup: params.log_blowup,
28        blowup: 1 << params.log_blowup,
29        log_final_poly_len: params.log_final_poly_len,
30        num_queries: params.num_queries,
31        commit_proof_of_work_bits: params.commit_proof_of_work_bits,
32        query_proof_of_work_bits: params.query_proof_of_work_bits,
33        subgroups,
34        generators,
35    }
36}
37
38/// Reference: <https://github.com/Plonky3/Plonky3/blob/622375885320ac6bf3c338001760ed8f2230e3cb/field/src/helpers.rs#L136>
39pub fn reduce_32<C: Config>(builder: &mut Builder<C>, vals: &[Felt<C::F>]) -> Var<C::N> {
40    let mut power = C::N::ONE;
41    let result: Var<C::N> = builder.eval(C::N::ZERO);
42    for val in vals.iter() {
43        let val = builder.cast_felt_to_var(*val);
44        builder.assign(&result, result + val * power);
45        power *= C::N::from_usize(1usize << 32);
46    }
47    result
48}
49
50/// Reference: <https://github.com/Plonky3/Plonky3/blob/622375885320ac6bf3c338001760ed8f2230e3cb/field/src/helpers.rs#L149>
51pub fn split_32<C: Config>(builder: &mut Builder<C>, val: Var<C::N>, n: usize) -> Vec<Felt<C::F>> {
52    let felts = builder.var_to_64bits_f_circuit(val);
53    assert!(n <= felts.len());
54    felts[0..n].to_vec()
55}
56
57/// Eval two expressions, return in the reversed order if cond == 1. Otherwise, return in the
58/// original order. This is a helper function for optimal performance.
59pub fn cond_eval<C: Config, V: MemVariable<C, Expression: Clone> + CanSelect<C>>(
60    builder: &mut Builder<C>,
61    cond: Var<C::N>,
62    v1: impl Into<V::Expression>,
63    v2: impl Into<V::Expression>,
64) -> [V; 2] {
65    let a: V;
66    let b: V;
67    if builder.flags.static_only {
68        let v1: V = builder.eval(v1.into());
69        let v2: V = builder.eval(v2.into());
70        a = V::select(builder, cond, v2.clone(), v1.clone());
71        b = V::select(builder, cond, v1, v2);
72    } else {
73        let v1 = v1.into();
74        let v2 = v2.into();
75        a = builder.uninit();
76        b = builder.uninit();
77        builder.if_eq(cond, C::N::ONE).then_or_else(
78            |builder| {
79                builder.assign(&a, v2.clone());
80                builder.assign(&b, v1.clone());
81            },
82            |builder| {
83                builder.assign(&a, v1.clone());
84                builder.assign(&b, v2.clone());
85            },
86        );
87    }
88    [a, b]
89}
openvm_native_recursion/utils.rs

openvm_native_recursion/
utils.rs
