pasta_curves-source/examples/sha256/table16/compression/subregion_digest.rs

use super::super::{super::DIGEST_SIZE, BlockWord, CellValue16, Table16Assignment, Table16Chip};
use super::{compression_util::*, Compression, State};
use halo2::{
    arithmetic::FieldExt,
    circuit::Region,
    plonk::{Advice, Column, Error},
};

impl Compression {
    #[allow(clippy::many_single_char_names)]
    pub fn assign_digest<F: FieldExt>(
        &self,
        region: &mut Region<'_, Table16Chip<F>>,
        state: State,
    ) -> Result<[BlockWord; DIGEST_SIZE], Error> {
        let a_3 = self.extras[0];
        let a_4 = self.extras[1];
        let a_5 = self.message_schedule;
        let a_6 = self.extras[2];
        let a_7 = self.extras[3];
        let a_8 = self.extras[4];

        let (a, b, c, d, e, f, g, h) = match_state(state);

        let abcd_row = 0;
        region.assign_fixed(|| "s_digest", self.s_digest, abcd_row, || Ok(F::one()))?;
        let efgh_row = abcd_row + 2;
        region.assign_fixed(|| "s_digest", self.s_digest, efgh_row, || Ok(F::one()))?;

        // Assign digest for A, B, C, D
        self.assign_and_constrain(
            region,
            || "a_lo",
            a_3,
            abcd_row,
            &a.dense_halves.0.into(),
            &self.perm,
        )?;
        self.assign_and_constrain(
            region,
            || "a_hi",
            a_4,
            abcd_row,
            &a.dense_halves.1.into(),
            &self.perm,
        )?;
        let a = a.dense_halves.0.value.unwrap() as u32
            + (1 << 16) * (a.dense_halves.1.value.unwrap() as u32);
        region.assign_advice(|| "a", a_5, abcd_row, || Ok(F::from_u64(a as u64)))?;

        let b = self.assign_digest_word(region, abcd_row, a_6, a_7, a_8, b.dense_halves)?;
        let c = self.assign_digest_word(region, abcd_row + 1, a_3, a_4, a_5, c.dense_halves)?;
        let d = self.assign_digest_word(region, abcd_row + 1, a_6, a_7, a_8, d.dense_halves)?;

        // Assign digest for E, F, G, H
        self.assign_and_constrain(
            region,
            || "e_lo",
            a_3,
            efgh_row,
            &e.dense_halves.0.into(),
            &self.perm,
        )?;
        self.assign_and_constrain(
            region,
            || "e_hi",
            a_4,
            efgh_row,
            &e.dense_halves.1.into(),
            &self.perm,
        )?;
        let e = e.dense_halves.0.value.unwrap() as u32
            + (1 << 16) * (e.dense_halves.1.value.unwrap() as u32);
        region.assign_advice(|| "e", a_5, efgh_row, || Ok(F::from_u64(e as u64)))?;

        let f = self.assign_digest_word(region, efgh_row, a_6, a_7, a_8, f.dense_halves)?;
        let g = self.assign_digest_word(region, efgh_row + 1, a_3, a_4, a_5, g.dense_halves)?;
        let h = self.assign_digest_word(region, efgh_row + 1, a_6, a_7, a_8, h.dense_halves)?;

        Ok([
            BlockWord::new(a),
            BlockWord::new(b),
            BlockWord::new(c),
            BlockWord::new(d),
            BlockWord::new(e),
            BlockWord::new(f),
            BlockWord::new(g),
            BlockWord::new(h),
        ])
    }

    fn assign_digest_word<F: FieldExt>(
        &self,
        region: &mut Region<'_, Table16Chip<F>>,
        row: usize,
        lo_col: Column<Advice>,
        hi_col: Column<Advice>,
        word_col: Column<Advice>,
        dense_halves: (CellValue16, CellValue16),
    ) -> Result<u32, Error> {
        self.assign_and_constrain(
            region,
            || "lo",
            lo_col,
            row,
            &dense_halves.0.into(),
            &self.perm,
        )?;
        self.assign_and_constrain(
            region,
            || "hi",
            hi_col,
            row,
            &dense_halves.1.into(),
            &self.perm,
        )?;
        let val = dense_halves.0.value.unwrap() as u32
            + (1 << 16) * (dense_halves.1.value.unwrap() as u32);
        region.assign_advice(|| "word", word_col, row, || Ok(F::from_u64(val as u64)))?;

        Ok(val)
    }
}