1use poulpy_hal::{
  2    api::ScratchAvailable,
  3    layouts::{Backend, DataMut, Module, Scratch, ZnxView, ZnxViewMut, ZnxZero},
  4};
  5
  6use crate::{
  7    LWESampleExtract, ScratchTakeCore,
  8    keyswitching::GLWEKeyswitch,
  9    layouts::{GGLWEInfos, GGLWEPreparedToRef, GLWE, GLWELayout, LWE, LWEInfos, LWEToMut, LWEToRef, Rank, TorusPrecision},
 10};
 11
 12impl LWE<Vec<u8>> {
 13    pub fn keyswitch_tmp_bytes<M, R, A, K, BE: Backend>(module: &M, res_infos: &R, a_infos: &A, key_infos: &K) -> usize
 14    where
 15        R: LWEInfos,
 16        A: LWEInfos,
 17        K: GGLWEInfos,
 18        M: LWEKeySwitch<BE>,
 19    {
 20        module.lwe_keyswitch_tmp_bytes(res_infos, a_infos, key_infos)
 21    }
 22}
 23
 24impl<D: DataMut> LWE<D> {
 25    pub fn keyswitch<M, A, K, BE: Backend>(&mut self, module: &M, a: &A, ksk: &K, scratch: &mut Scratch<BE>)
 26    where
 27        A: LWEToRef,
 28        K: GGLWEPreparedToRef<BE> + GGLWEInfos,
 29        Scratch<BE>: ScratchTakeCore<BE>,
 30        M: LWEKeySwitch<BE>,
 31    {
 32        module.lwe_keyswitch(self, a, ksk, scratch);
 33    }
 34}
 35
 36impl<BE: Backend> LWEKeySwitch<BE> for Module<BE> where Self: GLWEKeyswitch<BE> + LWESampleExtract {}
 37
 38pub trait LWEKeySwitch<BE: Backend>
 39where
 40    Self: GLWEKeyswitch<BE> + LWESampleExtract,
 41{
 42    fn lwe_keyswitch_tmp_bytes<R, A, K>(&self, res_infos: &R, a_infos: &A, key_infos: &K) -> usize
 43    where
 44        R: LWEInfos,
 45        A: LWEInfos,
 46        K: GGLWEInfos,
 47    {
 48        let max_k: TorusPrecision = a_infos.k().max(res_infos.k());
 49
 50        let glwe_a_infos: GLWELayout = GLWELayout {
 51            n: self.n().into(),
 52            base2k: a_infos.base2k(),
 53            k: max_k,
 54            rank: Rank(1),
 55        };
 56
 57        let glwe_res_infos: GLWELayout = GLWELayout {
 58            n: self.n().into(),
 59            base2k: res_infos.base2k(),
 60            k: max_k,
 61            rank: Rank(1),
 62        };
 63
 64        let glwe_in: usize = GLWE::bytes_of_from_infos(&glwe_a_infos);
 65        let glwe_out: usize = GLWE::bytes_of_from_infos(&glwe_res_infos);
 66        let ks: usize = self.glwe_keyswitch_tmp_bytes(&glwe_res_infos, &glwe_a_infos, key_infos);
 67
 68        glwe_in + glwe_out + ks
 69    }
 70
 71    fn lwe_keyswitch<R, A, K>(&self, res: &mut R, a: &A, ksk: &K, scratch: &mut Scratch<BE>)
 72    where
 73        R: LWEToMut,
 74        A: LWEToRef,
 75        K: GGLWEPreparedToRef<BE> + GGLWEInfos,
 76        Scratch<BE>: ScratchTakeCore<BE>,
 77    {
 78        let res: &mut LWE<&mut [u8]> = &mut res.to_mut();
 79        let a: &LWE<&[u8]> = &a.to_ref();
 80
 81        assert!(res.n().as_usize() <= self.n());
 82        assert!(a.n().as_usize() <= self.n());
 83        assert_eq!(ksk.n(), self.n() as u32);
 84        assert!(scratch.available() >= self.lwe_keyswitch_tmp_bytes(res, a, ksk));
 85
 86        let max_k: TorusPrecision = res.k().max(a.k());
 87
 88        let a_size: usize = a.k().div_ceil(ksk.base2k()) as usize;
 89
 90        let (mut glwe_in, scratch_1) = scratch.take_glwe(&GLWELayout {
 91            n: ksk.n(),
 92            base2k: a.base2k(),
 93            k: max_k,
 94            rank: Rank(1),
 95        });
 96        glwe_in.data.zero();
 97
 98        let (mut glwe_out, scratch_1) = scratch_1.take_glwe(&GLWELayout {
 99            n: ksk.n(),
100            base2k: res.base2k(),
101            k: max_k,
102            rank: Rank(1),
103        });
104
105        let n_lwe: usize = a.n().into();
106
107        for i in 0..a_size {
108            let data_lwe: &[i64] = a.data.at(0, i);
109            glwe_in.data.at_mut(0, i)[0] = data_lwe[0];
110            glwe_in.data.at_mut(1, i)[..n_lwe].copy_from_slice(&data_lwe[1..]);
111        }
112
113        self.glwe_keyswitch(&mut glwe_out, &glwe_in, ksk, scratch_1);
114        self.lwe_sample_extract(res, &glwe_out);
115    }
116}