halo2/src/gadget/sha256/table16/message_schedule.rs

use std::convert::TryInto;

use super::{
    super::BLOCK_SIZE, BlockWord, CellValue16, SpreadInputs, Table16Assignment, Table16Chip, ROUNDS,
};
use crate::{
    arithmetic::FieldExt,
    circuit::{Cell, Layouter},
    plonk::{Advice, Column, ConstraintSystem, Error, Fixed, Permutation},
};

// mod schedule_gates;
mod schedule_util;
// mod subregion1;
// mod subregion2;
// mod subregion3;

// use schedule_gates::ScheduleGate;

#[derive(Clone, Debug)]
pub(super) struct MessageWord {
    var: Cell,
    value: Option<u32>,
}

#[derive(Clone, Debug)]
pub(super) struct MessageSchedule {
    lookup: SpreadInputs,
    message_schedule: Column<Advice>,
    extras: [Column<Advice>; 6],

    /// Construct a word using reduce_4.
    s_word: Column<Fixed>,
    /// Decomposition gate for W_0, W_62, W_63.
    s_decompose_0: Column<Fixed>,
    /// Decomposition gate for W_[1..14]
    s_decompose_1: Column<Fixed>,
    /// Decomposition gate for W_[14..49]
    s_decompose_2: Column<Fixed>,
    /// Decomposition gate for W_[49..62]
    s_decompose_3: Column<Fixed>,
    /// sigma_0 gate for W_[1..14]
    s_lower_sigma_0: Column<Fixed>,
    /// sigma_1 gate for W_[49..62]
    s_lower_sigma_1: Column<Fixed>,
    /// sigma_0_v2 gate for W_[14..49]
    s_lower_sigma_0_v2: Column<Fixed>,
    /// sigma_1_v2 gate for W_[14..49]
    s_lower_sigma_1_v2: Column<Fixed>,
    perm: Permutation,
}

impl MessageSchedule {
    /// Configures the message schedule.
    ///
    /// `message_schedule` is the column into which the message schedule will be placed.
    /// The caller must create appropriate permutations in order to load schedule words
    /// into the compression rounds.
    ///
    /// `extras` contains columns that the message schedule will only use for internal
    /// gates, and will not place any constraints on (such as lookup constraints) outside
    /// itself.
    pub(super) fn configure<F: FieldExt>(
        meta: &mut ConstraintSystem<F>,
        lookup: SpreadInputs,
        message_schedule: Column<Advice>,
        extras: [Column<Advice>; 6],
        perm: Permutation,
    ) -> Self {
        // Create fixed columns for the selectors we will require.
        let s_word = meta.fixed_column();
        let s_decompose_0 = meta.fixed_column();
        let s_decompose_1 = meta.fixed_column();
        let s_decompose_2 = meta.fixed_column();
        let s_decompose_3 = meta.fixed_column();
        let s_lower_sigma_0 = meta.fixed_column();
        let s_lower_sigma_1 = meta.fixed_column();
        let s_lower_sigma_0_v2 = meta.fixed_column();
        let s_lower_sigma_1_v2 = meta.fixed_column();

        // TODO: Create gates

        MessageSchedule {
            lookup,
            message_schedule,
            extras,
            s_word,
            s_decompose_0,
            s_decompose_1,
            s_decompose_2,
            s_decompose_3,
            s_lower_sigma_0,
            s_lower_sigma_1,
            s_lower_sigma_0_v2,
            s_lower_sigma_1_v2,
            perm,
        }
    }

    pub(super) fn process<F: FieldExt>(
        &self,
        layouter: &mut impl Layouter<Table16Chip<F>>,
        input: [BlockWord; BLOCK_SIZE],
    ) -> Result<([MessageWord; ROUNDS], [(CellValue16, CellValue16); ROUNDS]), Error> {
        let mut w = Vec::<MessageWord>::with_capacity(ROUNDS);
        let mut w_halves = Vec::<(CellValue16, CellValue16)>::with_capacity(ROUNDS);

        layouter.assign_region(
            || "process message block",
            |region| {
                let region = std::cell::RefCell::new(region);

                // TODO: Assign cells

                Ok(())
            },
        )?;

        Ok((w.try_into().unwrap(), w_halves.try_into().unwrap()))
    }
}