poulpy-core 0.6.0

use poulpy_hal::layouts::{Backend, Data, Module, ScratchArena};

use crate::layouts::{
    Base2K, Degree, Dnum, Dsize, GGLWEInfos, GGLWEPreparedBackendMut, GGLWEPreparedBackendRef, GGLWEToBackendRef, GLWEInfos,
    GLWESwitchingKeyDegrees, GLWESwitchingKeyDegreesMut, LWEInfos, Rank, TorusPrecision,
    prepared::{GGLWEPrepared, GGLWEPreparedFactory, GGLWEPreparedToBackendMut, GGLWEPreparedToBackendRef},
};

/// DFT-domain (prepared) variant of a GLWE switching key.
///
/// Wraps a [`GGLWEPrepared`] with input/output degree metadata for
/// key-switching between GLWE ciphertexts. Tied to a specific backend
/// via `B: Backend`.
#[derive(PartialEq, Eq)]
pub struct GLWESwitchingKeyPrepared<D: Data, B: Backend> {
    pub(crate) key: GGLWEPrepared<D, B>,
    pub(crate) input_degree: Degree,  // Degree of sk_in
    pub(crate) output_degree: Degree, // Degree of sk_out
}

impl<D: Data, BE: Backend> GLWESwitchingKeyDegrees for GLWESwitchingKeyPrepared<D, BE> {
    fn output_degree(&self) -> &Degree {
        &self.output_degree
    }

    fn input_degree(&self) -> &Degree {
        &self.input_degree
    }
}

impl<D: Data, BE: Backend> GLWESwitchingKeyDegreesMut for GLWESwitchingKeyPrepared<D, BE> {
    fn output_degree(&mut self) -> &mut Degree {
        &mut self.output_degree
    }

    fn input_degree(&mut self) -> &mut Degree {
        &mut self.input_degree
    }
}

impl<D: Data, B: Backend> LWEInfos for GLWESwitchingKeyPrepared<D, B> {
    fn n(&self) -> Degree {
        self.key.n()
    }

    fn base2k(&self) -> Base2K {
        self.key.base2k()
    }

    fn size(&self) -> usize {
        self.key.size()
    }
}

impl<D: Data, B: Backend> GLWEInfos for GLWESwitchingKeyPrepared<D, B> {
    fn rank(&self) -> Rank {
        self.rank_out()
    }
}

impl<D: Data, B: Backend> GGLWEInfos for GLWESwitchingKeyPrepared<D, B> {
    fn rank_in(&self) -> Rank {
        self.key.rank_in()
    }

    fn rank_out(&self) -> Rank {
        self.key.rank_out()
    }

    fn dsize(&self) -> Dsize {
        self.key.dsize()
    }

    fn dnum(&self) -> Dnum {
        self.key.dnum()
    }
}

pub trait GLWESwitchingKeyPreparedFactory<B: Backend>
where
    Self: GGLWEPreparedFactory<B>,
{
    fn glwe_switching_key_prepared_alloc(
        &self,
        base2k: Base2K,
        k: TorusPrecision,
        rank_in: Rank,
        rank_out: Rank,
        dnum: Dnum,
        dsize: Dsize,
    ) -> GLWESwitchingKeyPrepared<B::OwnedBuf, B> {
        GLWESwitchingKeyPrepared::<B::OwnedBuf, B> {
            key: self.gglwe_prepared_alloc(base2k, k, rank_in, rank_out, dnum, dsize),
            input_degree: Degree(0),
            output_degree: Degree(0),
        }
    }

    fn glwe_switching_key_prepared_alloc_from_infos<A>(&self, infos: &A) -> GLWESwitchingKeyPrepared<B::OwnedBuf, B>
    where
        A: GGLWEInfos,
    {
        self.glwe_switching_key_prepared_alloc(
            infos.base2k(),
            infos.max_k(),
            infos.rank_in(),
            infos.rank_out(),
            infos.dnum(),
            infos.dsize(),
        )
    }

    fn bytes_of_glwe_key_prepared(
        &self,
        base2k: Base2K,
        k: TorusPrecision,
        rank_in: Rank,
        rank_out: Rank,
        dnum: Dnum,
        dsize: Dsize,
    ) -> usize {
        self.gglwe_prepared_bytes_of(base2k, k, rank_in, rank_out, dnum, dsize)
    }

    fn glwe_switching_key_prepared_bytes_of_from_infos<A>(&self, infos: &A) -> usize
    where
        A: GGLWEInfos,
    {
        self.bytes_of_glwe_key_prepared(
            infos.base2k(),
            infos.max_k(),
            infos.rank_in(),
            infos.rank_out(),
            infos.dnum(),
            infos.dsize(),
        )
    }

    fn glwe_switching_key_prepare_tmp_bytes<A>(&self, infos: &A) -> usize
    where
        A: GGLWEInfos,
    {
        let lvl_0: usize = self.gglwe_prepare_tmp_bytes(infos);
        lvl_0
    }

    fn glwe_switching_key_prepare<R, O>(&self, res: &mut R, other: &O, scratch: &mut ScratchArena<'_, B>)
    where
        R: GGLWEPreparedToBackendMut<B> + GLWESwitchingKeyDegreesMut,
        O: GGLWEToBackendRef<B> + GLWESwitchingKeyDegrees,
    {
        let tmp_bytes = {
            let res_infos = res.to_backend_mut();
            self.glwe_switching_key_prepare_tmp_bytes(&res_infos)
        };
        assert!(
            scratch.available() >= tmp_bytes,
            "scratch.available(): {} < GLWESwitchingKeyPreparedFactory::glwe_switching_key_prepare_tmp_bytes: {}",
            scratch.available(),
            tmp_bytes
        );
        self.gglwe_prepare(res, other, scratch);
        *res.input_degree() = *other.input_degree();
        *res.output_degree() = *other.output_degree();
    }
}

impl<B: Backend> GLWESwitchingKeyPreparedFactory<B> for Module<B> where Self: GGLWEPreparedFactory<B> {}

// module-only API: allocation/size helpers are provided by `GLWESwitchingKeyPreparedFactory` on `Module`.

// module-only API: preparation is provided by `GLWESwitchingKeyPreparedFactory` on `Module`.

pub type GLWESwitchingKeyPreparedBackendRef<'a, B> = GLWESwitchingKeyPrepared<<B as Backend>::BufRef<'a>, B>;
pub type GLWESwitchingKeyPreparedBackendMut<'a, B> = GLWESwitchingKeyPrepared<<B as Backend>::BufMut<'a>, B>;

pub trait GLWESwitchingKeyPreparedToBackendRef<B: Backend> {
    fn to_backend_ref(&self) -> GLWESwitchingKeyPreparedBackendRef<'_, B>;
}

impl<D: Data, B: Backend> GLWESwitchingKeyPreparedToBackendRef<B> for GLWESwitchingKeyPrepared<D, B>
where
    GGLWEPrepared<D, B>: GGLWEPreparedToBackendRef<B>,
{
    fn to_backend_ref(&self) -> GLWESwitchingKeyPreparedBackendRef<'_, B> {
        GLWESwitchingKeyPrepared {
            key: self.key.to_backend_ref(),
            input_degree: self.input_degree,
            output_degree: self.output_degree,
        }
    }
}

impl<D: Data, B: Backend> GGLWEPreparedToBackendRef<B> for GLWESwitchingKeyPrepared<D, B>
where
    GGLWEPrepared<D, B>: GGLWEPreparedToBackendRef<B>,
{
    fn to_backend_ref(&self) -> GGLWEPreparedBackendRef<'_, B> {
        self.key.to_backend_ref()
    }
}

impl<D: Data, B: Backend> GGLWEPreparedToBackendMut<B> for GLWESwitchingKeyPrepared<D, B>
where
    GGLWEPrepared<D, B>: GGLWEPreparedToBackendMut<B>,
{
    fn to_backend_mut(&mut self) -> GGLWEPreparedBackendMut<'_, B> {
        self.key.to_backend_mut()
    }
}

pub trait GLWESwitchingKeyPreparedToBackendMut<B: Backend> {
    fn to_backend_mut(&mut self) -> GLWESwitchingKeyPreparedBackendMut<'_, B>;
}

impl<D: Data, B: Backend> GLWESwitchingKeyPreparedToBackendMut<B> for GLWESwitchingKeyPrepared<D, B>
where
    GGLWEPrepared<D, B>: GGLWEPreparedToBackendMut<B>,
{
    fn to_backend_mut(&mut self) -> GLWESwitchingKeyPreparedBackendMut<'_, B> {
        GLWESwitchingKeyPrepared {
            key: self.key.to_backend_mut(),
            input_degree: self.input_degree,
            output_degree: self.output_degree,
        }
    }
}