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kimchi/circuits/witness/
copy_shift_cell.rs

1use super::{variables::Variables, WitnessCell};
2use alloc::{boxed::Box, vec::Vec};
3use ark_ff::Field;
4
5/// Witness cell copied from another cell and shifted
6pub struct CopyShiftCell {
7    row: usize,
8    col: usize,
9    shift: u64,
10}
11
12impl CopyShiftCell {
13    /// Create witness cell copied from the witness cell at position (row, col) and then scaled by 2^shift
14    pub fn create(row: usize, col: usize, shift: u64) -> Box<CopyShiftCell> {
15        Box::new(CopyShiftCell { row, col, shift })
16    }
17}
18
19impl<F: Field, const W: usize> WitnessCell<F, F, W> for CopyShiftCell {
20    fn value(&self, witness: &mut [Vec<F>; W], _variables: &Variables<F>, _index: usize) -> F {
21        F::from(2u32).pow([self.shift]) * witness[self.col][self.row]
22    }
23}