plonky2/evm/src/cpu/simple_logic/not.rs

use plonky2::field::extension::Extendable;
use plonky2::field::packed::PackedField;
use plonky2::field::types::Field;
use plonky2::hash::hash_types::RichField;
use plonky2::iop::ext_target::ExtensionTarget;
use starky::constraint_consumer::{ConstraintConsumer, RecursiveConstraintConsumer};

use crate::cpu::columns::CpuColumnsView;
use crate::cpu::stack;

const LIMB_SIZE: usize = 32;
const ALL_1_LIMB: u64 = (1 << LIMB_SIZE) - 1;

/// Evaluates constraints for NOT.
pub(crate) fn eval_packed<P: PackedField>(
    lv: &CpuColumnsView<P>,
    nv: &CpuColumnsView<P>,
    yield_constr: &mut ConstraintConsumer<P>,
) {
    // This is simple: just do output = 0xffffffff - input.
    let input = lv.mem_channels[0].value;
    let output = nv.mem_channels[0].value;
    let filter = lv.op.not_pop * lv.opcode_bits[0];
    for (input_limb, output_limb) in input.into_iter().zip(output) {
        yield_constr.constraint(
            filter * (output_limb + input_limb - P::Scalar::from_canonical_u64(ALL_1_LIMB)),
        );
    }

    // Stack constraints.
    stack::eval_packed_one(lv, nv, filter, stack::BASIC_UNARY_OP.unwrap(), yield_constr);
}

/// Circuit version of `eval_packed`.
/// Evaluates constraints for NOT.
pub(crate) fn eval_ext_circuit<F: RichField + Extendable<D>, const D: usize>(
    builder: &mut plonky2::plonk::circuit_builder::CircuitBuilder<F, D>,
    lv: &CpuColumnsView<ExtensionTarget<D>>,
    nv: &CpuColumnsView<ExtensionTarget<D>>,
    yield_constr: &mut RecursiveConstraintConsumer<F, D>,
) {
    let input = lv.mem_channels[0].value;
    let output = nv.mem_channels[0].value;
    let filter = builder.mul_extension(lv.op.not_pop, lv.opcode_bits[0]);
    for (input_limb, output_limb) in input.into_iter().zip(output) {
        let constr = builder.add_extension(output_limb, input_limb);
        let constr = builder.arithmetic_extension(
            F::ONE,
            -F::from_canonical_u64(ALL_1_LIMB),
            filter,
            constr,
            filter,
        );
        yield_constr.constraint(builder, constr);
    }

    // Stack constraints.
    stack::eval_ext_circuit_one(
        builder,
        lv,
        nv,
        filter,
        stack::BASIC_UNARY_OP.unwrap(),
        yield_constr,
    );
}