stwo-gpu-constraint-framework 2.0.0

Constraint framework for building AIR constraints with STWO-GPU
Documentation 
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use std::ops::Mul;

use num_traits::Zero;
use stwo::core::fields::m31::BaseField;
use stwo::core::fields::qm31::{SecureField, SECURE_EXTENSION_DEGREE};
use stwo::core::pcs::TreeVec;
use stwo::core::utils::offset_bit_reversed_circle_domain_index;
use stwo::core::Fraction;
use stwo::prover::backend::CpuBackend;
use stwo::prover::poly::circle::CircleEvaluation;
use stwo::prover::poly::BitReversedOrder;

use crate::logup::LogupAtRow;
use crate::{EvalAtRow, INTERACTION_TRACE_IDX};

/// Evaluates constraints at an evaluation domain points.
pub struct CpuDomainEvaluator<'a> {
    pub trace_eval: &'a TreeVec<Vec<&'a CircleEvaluation<CpuBackend, BaseField, BitReversedOrder>>>,
    pub column_index_per_interaction: Vec<usize>,
    pub row: usize,
    pub random_coeff_powers: &'a [SecureField],
    pub row_res: SecureField,
    pub constraint_index: usize,
    pub domain_log_size: u32,
    pub eval_domain_log_size: u32,
    pub logup: LogupAtRow<Self>,
}

impl<'a> CpuDomainEvaluator<'a> {
    #[allow(dead_code)]
    pub fn new(
        trace_eval: &'a TreeVec<Vec<&CircleEvaluation<CpuBackend, BaseField, BitReversedOrder>>>,
        row: usize,
        random_coeff_powers: &'a [SecureField],
        domain_log_size: u32,
        eval_log_size: u32,
        log_size: u32,
        claimed_sum: SecureField,
    ) -> Self {
        Self {
            trace_eval,
            column_index_per_interaction: vec![0; trace_eval.len()],
            row,
            random_coeff_powers,
            row_res: SecureField::zero(),
            constraint_index: 0,
            domain_log_size,
            eval_domain_log_size: eval_log_size,
            logup: LogupAtRow::new(INTERACTION_TRACE_IDX, claimed_sum, log_size),
        }
    }
}

impl EvalAtRow for CpuDomainEvaluator<'_> {
    type F = BaseField;
    type EF = SecureField;

    // TODO(spapini): Remove all boundary checks.
    fn next_interaction_mask<const N: usize>(
        &mut self,
        interaction: usize,
        offsets: [isize; N],
    ) -> [Self::F; N] {
        let col_index = self.column_index_per_interaction[interaction];
        self.column_index_per_interaction[interaction] += 1;
        offsets.map(|off| {
            // If the offset is 0, we can just return the value directly from this row.
            if off == 0 {
                let col = &self.trace_eval[interaction][col_index];
                return col[self.row];
            }
            // Otherwise, we need to look up the value at the offset.
            // Since the domain is bit-reversed circle domain ordered, we need to look up the value
            // at the bit-reversed natural order index at an offset.
            let row = offset_bit_reversed_circle_domain_index(
                self.row,
                self.domain_log_size,
                self.eval_domain_log_size,
                off,
            );
            self.trace_eval[interaction][col_index][row]
        })
    }

    fn add_constraint<G>(&mut self, constraint: G)
    where
        Self::EF: Mul<G, Output = Self::EF> + From<G>,
    {
        self.row_res += self.random_coeff_powers[self.constraint_index] * constraint;
        self.constraint_index += 1;
    }

    fn combine_ef(values: [Self::F; SECURE_EXTENSION_DEGREE]) -> Self::EF {
        SecureField::from_m31_array(values)
    }

    crate::logup_proxy!();
}