wip rlwe + some bug fixes in base2k

rlwe/src/evaluator.rs

@@ -0,0 +1,82 @@
+use crate::ciphertext::{Ciphertext, GadgetCiphertext};
+use base2k::{Module, VecZnxBig, VecZnxDft, VmpPMatOps};
+
+pub fn gadget_product_tmp_bytes(
+    module: &Module,
+    log_base2k: usize,
+    out_log_q: usize,
+    in_log_q: usize,
+    gct_rows: usize,
+    gct_log_q: usize,
+) -> usize {
+    let gct_cols: usize = (gct_log_q + log_base2k - 1) / log_base2k;
+    let in_limbs: usize = (in_log_q + log_base2k - 1) / log_base2k;
+    let out_limbs: usize = (out_log_q + log_base2k - 1) / log_base2k;
+    module.vmp_apply_dft_to_dft_tmp_bytes(out_limbs, in_limbs, gct_rows, gct_cols)
+        + 2 * module.bytes_of_vec_znx_dft(gct_cols)
+}
+
+pub fn gadget_product_inplace(
+    module: &Module,
+    a: &mut Ciphertext,
+    b: &GadgetCiphertext,
+    tmp_bytes: &mut [u8],
+) {
+    // This is safe to do because the relevant values of a are copied to a buffer before being
+    // overwritten.
+    unsafe {
+        let a_ptr: *mut Ciphertext = a;
+        gadget_product(module, a, &*a_ptr, b, tmp_bytes)
+    }
+}
+
+pub fn gadget_product(
+    module: &Module,
+    res: &mut Ciphertext,
+    a: &Ciphertext,
+    b: &GadgetCiphertext,
+    tmp_bytes: &mut [u8],
+) {
+    assert!(
+        a.log_base2k() == b.log_base2k(),
+        "invalid inputs: a.log_base2k={} != b.log_base2k={}",
+        a.log_base2k(),
+        b.log_base2k()
+    );
+
+    let log_base2k: usize = b.log_base2k();
+    let cols: usize = b.cols();
+
+    let (tmp_bytes_vmp_apply_dft, tmp_bytes) =
+        tmp_bytes.split_at_mut(module.bytes_of_vec_znx_dft(cols));
+
+    let (tmp_bytes_c1_dft, tmp_bytes_res_dft) = tmp_bytes.split_at_mut(tmp_bytes.len() >> 1);
+
+    let mut c1_dft: VecZnxDft = module.new_vec_znx_from_bytes(cols, tmp_bytes_c1_dft);
+    let mut res_dft: VecZnxDft = module.new_vec_znx_from_bytes(cols, tmp_bytes_res_dft);
+    let mut res_big: VecZnxBig = res_dft.as_vec_znx_big();
+
+    // c1_dft <- DFT(b[1])
+    module.vec_znx_dft(&mut c1_dft, a.at(1), a.limbs());
+
+    // res_dft <- DFT(c1) x GadgetCiphertext[0]
+    module.vmp_apply_dft_to_dft(&mut res_dft, &c1_dft, &b.value[0], tmp_bytes_vmp_apply_dft);
+
+    // res_big <- IDFT(DFT(c1) x GadgetCiphertext[0])
+    module.vec_znx_idft_tmp_a(&mut res_big, &mut res_dft, cols);
+
+    // res_big <- c0 + c1_dft x GadgetCiphertext[0]
+    module.vec_znx_big_add_small_inplace(&mut res_big, a.at(0), cols);
+
+    // res[0] = normalize(c0 + c1_dft x GadgetCiphertext[0])
+    module.vec_znx_big_normalize(log_base2k, res.at_mut(0), &res_big, tmp_bytes_vmp_apply_dft);
+
+    // res_dft <- DFT(c1) x GadgetCiphertext[1]
+    module.vmp_apply_dft_to_dft(&mut res_dft, &c1_dft, &b.value[1], tmp_bytes_vmp_apply_dft);
+
+    // res_big <- IDFT(DFT(c1) x GadgetCiphertext[1])
+    module.vec_znx_idft_tmp_a(&mut res_big, &mut res_dft, cols);
+
+    // res[1] = normalize(c1_dft x GadgetCiphertext[1])
+    module.vec_znx_big_normalize(log_base2k, res.at_mut(1), &res_big, tmp_bytes_vmp_apply_dft);
+}