1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31

use ark_ff::Field;
use o1_utils::FieldHelpers;

use super::{variables::Variables, WitnessCell};

/// Witness cell copied from bits of another witness cell
pub struct CopyBitsCell {
    row: usize,
    col: usize,
    start: usize, // inclusive
    end: usize,   // exclusive
}

impl CopyBitsCell {
    /// Create witness cell copied from bits [start, end) of the witness cell at position (row, col)
    pub fn create(row: usize, col: usize, start: usize, end: usize) -> Box<CopyBitsCell> {
        Box::new(CopyBitsCell {
            row,
            col,
            start,
            end,
        })
    }
}

impl<F: Field, const W: usize> WitnessCell<F, F, W> for CopyBitsCell {
    fn value(&self, witness: &mut [Vec<F>; W], _variables: &Variables<F>, _index: usize) -> F {
        F::from_bits(&witness[self.col][self.row].to_bits()[self.start..self.end])
            .expect("failed to deserialize field bits for copy bits cell")
    }
}