openvm_circuit_primitives/range/
mod.rs

1//! Range check for a fixed bit size via preprocessed trace.
2//!
3//! Caution: We almost always prefer to use the
4//! [VariableRangeCheckerChip](super::var_range::VariableRangeCheckerChip) instead of this chip.
5// Adapted from Valida
6
7use core::mem::size_of;
8use std::{
9    borrow::{Borrow, BorrowMut},
10    sync::atomic::AtomicU32,
11};
12
13use openvm_circuit_primitives_derive::AlignedBorrow;
14use openvm_stark_backend::{
15    interaction::InteractionBuilder,
16    p3_air::{Air, BaseAir, PairBuilder},
17    p3_field::Field,
18    p3_matrix::{dense::RowMajorMatrix, Matrix},
19    rap::{BaseAirWithPublicValues, PartitionedBaseAir},
20};
21
22mod bus;
23
24#[cfg(test)]
25pub mod tests;
26
27pub use bus::*;
28
29#[derive(Default, AlignedBorrow, Copy, Clone)]
30#[repr(C)]
31pub struct RangeCols<T> {
32    /// Number of range checks for each value
33    pub mult: T,
34}
35
36#[derive(Default, AlignedBorrow, Copy, Clone)]
37#[repr(C)]
38pub struct RangePreprocessedCols<T> {
39    /// Contains all possible values within range [0, max)
40    pub counter: T,
41}
42
43pub const NUM_RANGE_COLS: usize = size_of::<RangeCols<u8>>();
44pub const NUM_RANGE_PREPROCESSED_COLS: usize = size_of::<RangePreprocessedCols<u8>>();
45
46#[derive(Clone, Copy, Debug, derive_new::new)]
47pub struct RangeCheckerAir {
48    pub bus: RangeCheckBus,
49}
50
51impl RangeCheckerAir {
52    pub fn range_max(&self) -> u32 {
53        self.bus.range_max
54    }
55}
56
57impl<F: Field> BaseAirWithPublicValues<F> for RangeCheckerAir {}
58impl<F: Field> PartitionedBaseAir<F> for RangeCheckerAir {}
59impl<F: Field> BaseAir<F> for RangeCheckerAir {
60    fn width(&self) -> usize {
61        NUM_RANGE_COLS
62    }
63
64    fn preprocessed_trace(&self) -> Option<RowMajorMatrix<F>> {
65        // Create lookup table with all values 0..range_max
66        let column = (0..self.range_max()).map(F::from_u32).collect();
67        Some(RowMajorMatrix::new_col(column))
68    }
69}
70
71impl<AB: InteractionBuilder + PairBuilder> Air<AB> for RangeCheckerAir {
72    fn eval(&self, builder: &mut AB) {
73        let preprocessed = builder.preprocessed();
74        let prep_local = preprocessed
75            .row_slice(0)
76            .expect("window should have two elements");
77        let prep_local: &RangePreprocessedCols<AB::Var> = (*prep_local).borrow();
78        let main = builder.main();
79        let local = main.row_slice(0).expect("window should have two elements");
80        let local: &RangeCols<AB::Var> = (*local).borrow();
81        // Omit creating separate bridge.rs file for brevity
82        self.bus
83            .receive(prep_local.counter)
84            .eval(builder, local.mult);
85    }
86}
87
88pub struct RangeCheckerChip {
89    pub air: RangeCheckerAir,
90    /// Tracks multiplicity of each value in range
91    count: Vec<AtomicU32>,
92}
93
94impl RangeCheckerChip {
95    pub fn new(bus: RangeCheckBus) -> Self {
96        let mut count = vec![];
97        for _ in 0..bus.range_max {
98            count.push(AtomicU32::new(0));
99        }
100
101        Self {
102            air: RangeCheckerAir::new(bus),
103            count,
104        }
105    }
106
107    pub fn bus(&self) -> RangeCheckBus {
108        self.air.bus
109    }
110
111    pub fn range_max(&self) -> u32 {
112        self.air.range_max()
113    }
114
115    pub fn add_count(&self, val: u32) {
116        // Increment the count for this value when range checked
117        let val_atomic = &self.count[val as usize];
118        val_atomic.fetch_add(1, std::sync::atomic::Ordering::Relaxed);
119    }
120
121    pub fn generate_trace<F: Field>(&self) -> RowMajorMatrix<F> {
122        let mut rows = F::zero_vec(self.air.range_max() as usize * NUM_RANGE_COLS);
123        for (n, row) in rows.chunks_exact_mut(NUM_RANGE_COLS).enumerate() {
124            let cols: &mut RangeCols<F> = (*row).borrow_mut();
125            // Set multiplicity for each value in range
126            cols.mult = F::from_u32(self.count[n].swap(0, std::sync::atomic::Ordering::Relaxed));
127        }
128        RowMajorMatrix::new(rows, NUM_RANGE_COLS)
129    }
130}
openvm_circuit_primitives/range/mod.rs

openvm_circuit_primitives/range/
mod.rs
