1use crate::{
  2    ciphertext::{Ciphertext, GadgetCiphertext, RGSWCiphertext},
  3    elem::{Elem, ElemBasics},
  4};
  5use base2k::{
  6    Infos, Module, VecZnx, VecZnxApi, VecZnxBig, VecZnxBigOps, VecZnxDft, VecZnxDftOps, VmpPMatOps,
  7};
  8use std::cmp::min;
  9
 10pub fn gadget_product_tmp_bytes(
 11    module: &Module,
 12    log_base2k: usize,
 13    out_log_q: usize,
 14    in_log_q: usize,
 15    gct_rows: usize,
 16    gct_log_q: usize,
 17) -> usize {
 18    let gct_cols: usize = (gct_log_q + log_base2k - 1) / log_base2k;
 19    let in_limbs: usize = (in_log_q + log_base2k - 1) / log_base2k;
 20    let out_limbs: usize = (out_log_q + log_base2k - 1) / log_base2k;
 21    module.vmp_apply_dft_to_dft_tmp_bytes(out_limbs, in_limbs, gct_rows, gct_cols)
 22        + 2 * module.bytes_of_vec_znx_dft(gct_cols)
 23}
 24
 25pub fn gadget_product_inplace_thread_safe<const OVERWRITE: bool, T>(
 26    module: &Module,
 27    res: &mut Elem<T>,
 28    b: &GadgetCiphertext,
 29    tmp_bytes: &mut [u8],
 30) where
 31    T: VecZnxApi + Infos,
 32{
 33    unsafe {
 34        let a_ptr: *const T = res.at(1) as *const T;
 35        gadget_product_thread_safe::<OVERWRITE, T>(module, res, &*a_ptr, b, tmp_bytes);
 36    }
 37}
 38
 39/// Evaluates the gadget product res <- a x b.
 40///
 41/// # Arguments
 42///
 43/// * `module`: backend support for operations mod (X^N + 1).
 44/// * `res`: an [Elem] to store (-cs + m * a + e, c) with res_ncols limbs.
 45/// * `a`: a [VecZnx] of a_ncols limbs.
 46/// * `b`: a [GadgetCiphertext] as a vector of (-Bs + m * 2^{-k} + E, B)
 47///       containing b_nrows [VecZnx], each of b_ncols limbs.
 48///
 49/// # Computation
 50///
 51/// res = sum[min(a_ncols, b_nrows)] decomp(a, i) * (-B[i]s + m * 2^{-k*i} + E[i], B[i])
 52///     = (cs + m * a + e, c) with min(res_limbs, b_cols) limbs.
 53pub fn gadget_product_thread_safe<const OVERWRITE: bool, T>(
 54    module: &Module,
 55    res: &mut Elem<T>,
 56    a: &T,
 57    b: &GadgetCiphertext,
 58    tmp_bytes: &mut [u8],
 59) where
 60    T: VecZnxApi + Infos,
 61{
 62    let log_base2k: usize = b.log_base2k();
 63    let rows: usize = min(b.rows(), a.limbs());
 64    let cols: usize = b.cols();
 65
 66    let bytes_vmp_apply_dft: usize =
 67        module.vmp_apply_dft_to_dft_tmp_bytes(cols, a.limbs(), rows, cols);
 68    let bytes_vec_znx_dft: usize = module.bytes_of_vec_znx_dft(cols);
 69
 70    let (tmp_bytes_vmp_apply_dft, tmp_bytes) = tmp_bytes.split_at_mut(bytes_vmp_apply_dft);
 71    let (tmp_bytes_c1_dft, tmp_bytes_res_dft) = tmp_bytes.split_at_mut(bytes_vec_znx_dft);
 72
 73    let mut c1_dft: VecZnxDft = module.new_vec_znx_dft_from_bytes(cols, tmp_bytes_c1_dft);
 74    let mut res_dft: VecZnxDft = module.new_vec_znx_dft_from_bytes(cols, tmp_bytes_res_dft);
 75    let mut res_big: VecZnxBig = res_dft.as_vec_znx_big();
 76
 77    // Alias c0 and c1 part of res_big
 78    let (tmp_bytes_res_dft_c0, tmp_bytes_res_dft_c1) =
 79        tmp_bytes_res_dft.split_at_mut(bytes_vec_znx_dft >> 1);
 80    let res_big_c0: VecZnxBig = module.new_vec_znx_big_from_bytes(cols >> 1, tmp_bytes_res_dft_c0);
 81    let mut res_big_c1: VecZnxBig =
 82        module.new_vec_znx_big_from_bytes(cols >> 1, tmp_bytes_res_dft_c1);
 83
 84    // a_dft <- DFT(a)
 85    module.vec_znx_dft(&mut c1_dft, a, a.limbs());
 86
 87    // (n x cols) <- (n x limbs=rows) x (rows x cols)
 88    // res_dft[a * (G0|G1)] <- sum[rows] DFT(a) x (DFT(G0)|DFT(G1))
 89    module.vmp_apply_dft_to_dft(&mut res_dft, &c1_dft, &b.value, tmp_bytes_vmp_apply_dft);
 90
 91    // res_big[a * (G0|G1)] <- IDFT(res_dft[a * (G0|G1)])
 92    module.vec_znx_idft_tmp_a(&mut res_big, &mut res_dft, cols);
 93
 94    // res_big <- res[0] + res_big[a*G0]
 95    module.vec_znx_big_add_small_inplace(&mut res_big, res.at(0));
 96    module.vec_znx_big_normalize(log_base2k, res.at_mut(0), &res_big_c0, tmp_bytes_c1_dft);
 97
 98    if OVERWRITE {
 99        // res[1] = normalize(res_big[a*G1])
100        module.vec_znx_big_normalize(log_base2k, res.at_mut(1), &res_big_c1, tmp_bytes_c1_dft);
101    } else {
102        // res[1] = normalize(res_big[a*G1] + res[1])
103        module.vec_znx_big_add_small_inplace(&mut res_big_c1, res.at(1));
104        module.vec_znx_big_normalize(log_base2k, res.at_mut(1), &res_big_c1, tmp_bytes_c1_dft);
105    }
106}
107
108pub fn rgsw_product_thread_safe<T>(
109    module: &Module,
110    res: &mut Elem<T>,
111    a: &Ciphertext,
112    b: &RGSWCiphertext,
113    tmp_bytes: &mut [u8],
114) where
115    T: VecZnxApi + Infos,
116{
117    let log_base2k: usize = b.log_base2k();
118    let rows: usize = a.limbs();
119    let cols: usize = b.cols();
120    let in_limbs = a.limbs();
121    let out_limbs: usize = a.limbs();
122
123    let bytes_of_vec_znx_dft = module.bytes_of_vec_znx_dft(cols);
124    let bytes_of_vmp_apply_dft_to_dft =
125        module.vmp_apply_dft_to_dft_tmp_bytes(out_limbs, in_limbs, rows, cols);
126
127    let (tmp_bytes_c0_dft, tmp_bytes) = tmp_bytes.split_at_mut(bytes_of_vec_znx_dft);
128    let (tmp_bytes_c1_dft, tmp_bytes) = tmp_bytes.split_at_mut(bytes_of_vec_znx_dft);
129    let (tmp_bytes_tmp_dft, tmp_bytes) = tmp_bytes.split_at_mut(bytes_of_vec_znx_dft);
130    let (tmp_bytes_r1_dft, tmp_bytes) = tmp_bytes.split_at_mut(bytes_of_vec_znx_dft);
131    let (tmp_bytes_r2_dft, tmp_bytes) = tmp_bytes.split_at_mut(bytes_of_vec_znx_dft);
132    let (bytes_of_vmp_apply_dft_to_dft, tmp_bytes) =
133        tmp_bytes.split_at_mut(bytes_of_vmp_apply_dft_to_dft);
134
135    let mut c0_dft: VecZnxDft = module.new_vec_znx_dft_from_bytes(cols, tmp_bytes_c0_dft);
136    let mut c1_dft: VecZnxDft = module.new_vec_znx_dft_from_bytes(cols, tmp_bytes_c1_dft);
137    let mut tmp_dft: VecZnxDft = module.new_vec_znx_dft_from_bytes(cols, tmp_bytes_tmp_dft);
138    let mut r1_dft: VecZnxDft = module.new_vec_znx_dft_from_bytes(cols, tmp_bytes_r1_dft);
139    let mut r2_dft: VecZnxDft = module.new_vec_znx_dft_from_bytes(cols, tmp_bytes_r2_dft);
140
141    // c0_dft <- DFT(a[0])
142    module.vec_znx_dft(&mut c0_dft, a.at(0), a.limbs());
143
144    // r_dft <- sum[rows] c0_dft[cols] x RGSW[0][cols]
145    module.vmp_apply_dft_to_dft(
146        &mut r1_dft,
147        &c1_dft,
148        &b.value,
149        bytes_of_vmp_apply_dft_to_dft,
150    );
151
152    // c1_dft <- DFT(a[1])
153    module.vec_znx_dft(&mut c1_dft, a.at(1), a.limbs());
154}