This commit is contained in:
Jean-Philippe Bossuat
2025-10-26 16:32:22 +01:00
parent 98208d5e67
commit 881483d1bb
11 changed files with 173 additions and 140 deletions

View File

@@ -1,9 +1,9 @@
use crate::{
api::{
ModuleN, ScratchTakeBasic, SvpApplyDftToDft, SvpPPolAlloc, SvpPPolBytesOf, SvpPrepare, VecZnxDftAddScaledInplace,
VecZnxDftBytesOf,
VecZnxDftBytesOf, VecZnxDftZero,
},
layouts::{Backend, Module, Scratch, VecZnxDftToMut, VecZnxDftToRef, VecZnxToRef, ZnxInfos, ZnxZero},
layouts::{Backend, Module, Scratch, VecZnxDftToMut, VecZnxDftToRef, VecZnxToRef, ZnxInfos},
};
impl<BE: Backend> Convolution<BE> for Module<BE>
@@ -15,7 +15,8 @@ where
+ SvpPrepare<BE>
+ SvpPPolBytesOf
+ VecZnxDftBytesOf
+ VecZnxDftAddScaledInplace<BE>,
+ VecZnxDftAddScaledInplace<BE>
+ VecZnxDftZero<BE>,
Scratch<BE>: ScratchTakeBasic,
{
}
@@ -29,46 +30,15 @@ where
+ SvpPrepare<BE>
+ SvpPPolBytesOf
+ VecZnxDftBytesOf
+ VecZnxDftAddScaledInplace<BE>,
+ VecZnxDftAddScaledInplace<BE>
+ VecZnxDftZero<BE>,
Scratch<BE>: ScratchTakeBasic,
{
fn convolution_tmp_bytes(&self, res_size: usize) -> usize {
self.bytes_of_svp_ppol(1) + self.bytes_of_vec_znx_dft(1, res_size)
fn convolution_tmp_bytes(&self, b_size: usize) -> usize {
self.bytes_of_svp_ppol(1) + self.bytes_of_vec_znx_dft(1, b_size)
}
/// Evaluates a bivariate convolution over Z[X, Y] / (X^N + 1) where Y = 2^-K
/// and scales the result by 2^{res_scale * K}
///
/// # Example
/// a = [a00, a10, a20, a30] = (a00 * 2^-K + a01 * 2^-2K) + (a10 * 2^-K + a11 * 2^-2K) * X ...
/// [a01, a11, a21, a31]
///
/// b = [b00, b10, b20, b30] = (b00 * 2^-K + b01 * 2^-2K) + (b10 * 2^-K + b11 * 2^-2K) * X ...
/// [b01, b11, b21, b31]
///
/// If res_scale = 0:
/// res = [ 0, 0, 0, 0] = (r01 * 2^-2K + r02 * 2^-3K + r03 * 2^-4K + r04 * 2^-5K) + ...
/// [r01, r11, r21, r31]
/// [r02, r12, r22, r32]
/// [r03, r13, r23, r33]
/// [r04, r14, r24, r34]
///
/// If res_scale = 1:
/// res = [r01, r11, r21, r31] = (r01 * 2^-K + r02 * 2^-2K + r03 * 2^-3K + r04 * 2^-4K + r05 * 2^-5K) + ...
/// [r02, r12, r22, r32]
/// [r03, r13, r23, r33]
/// [r04, r14, r24, r34]
/// [r05, r15, r25, r35]
///
/// If res_scale = -1:
/// res = [ 0, 0, 0, 0] = (r01 * 2^-3K + r02 * 2^-4K + r03 * 2^-5K) + ...
/// [ 0, 0, 0, 0]
/// [r01, r11, r21, r31]
/// [r02, r12, r22, r32]
/// [r03, r13, r23, r33]
///
/// If res.size() < a.size() + b.size() + 1 + res_scale, result is truncated accordingly in the Y dimension.
fn convolution<R, A, B>(&self, res: &mut R, res_scale: i64, a: &A, b: &B, scratch: &mut Scratch<BE>)
fn bivariate_convolution_full<R, A, B>(&self, k: i64, res: &mut R, a: &A, b: &B, scratch: &mut Scratch<BE>)
where
R: VecZnxDftToMut<BE>,
A: VecZnxToRef,
@@ -78,32 +48,99 @@ where
let a: &crate::layouts::VecZnx<&[u8]> = &a.to_ref();
let b: &crate::layouts::VecZnxDft<&[u8], BE> = &b.to_ref();
assert!(res.cols() >= a.cols() + b.cols() - 1);
let res_cols: usize = res.cols();
let a_cols: usize = a.cols();
let b_cols: usize = b.cols();
res.zero();
assert!(res_cols >= a_cols + b_cols - 1);
let (mut ppol, scratch_1) = scratch.take_svp_ppol(self, 1);
let (mut res_tmp, _) = scratch_1.take_vec_znx_dft(self, 1, res.size());
for a_col in 0..a.cols() {
for a_limb in 0..a.size() {
// Prepares the j-th limb of the i-th col of A
self.svp_prepare(&mut ppol, 0, &a.as_scalar_znx_ref(a_col, a_limb), 0);
for b_col in 0..b.cols() {
// Multiplies with the i-th col of B
self.svp_apply_dft_to_dft(&mut res_tmp, 0, &ppol, 0, b, b_col);
// Adds on the [a_col + b_col] of res, scaled by 2^{-(a_limb + 1) * Base2K}
self.vec_znx_dft_add_scaled_inplace(
res,
a_col + b_col,
&res_tmp,
0,
-(1 + a_limb as i64) + res_scale,
);
}
for res_col in 0..res_cols {
let a_min: usize = res_col.saturating_sub(b_cols - 1);
let a_max: usize = res_col.min(a_cols - 1);
self.bivariate_convolution_single(k, res, res_col, a, a_min, b, res_col - a_min, scratch);
for a_col in a_min + 1..a_max + 1 {
self.bivariate_convolution_single_add(k, res, res_col, a, a_col, b, res_col - a_col, scratch);
}
}
}
/// Evaluates a bivariate convolution over Z[X, Y] / (X^N + 1) where Y = 2^-K over the
/// selected columsn and stores the result on the selected column, scaled by 2^{k * Base2K}
///
/// # Example
/// a = [a00, a10, a20, a30] = (a00 * 2^-K + a01 * 2^-2K) + (a10 * 2^-K + a11 * 2^-2K) * X ...
/// [a01, a11, a21, a31]
///
/// b = [b00, b10, b20, b30] = (b00 * 2^-K + b01 * 2^-2K) + (b10 * 2^-K + b11 * 2^-2K) * X ...
/// [b01, b11, b21, b31]
///
/// If k = 0:
/// res = [ 0, 0, 0, 0] = (r01 * 2^-2K + r02 * 2^-3K + r03 * 2^-4K + r04 * 2^-5K) + ...
/// [r01, r11, r21, r31]
/// [r02, r12, r22, r32]
/// [r03, r13, r23, r33]
/// [r04, r14, r24, r34]
///
/// If k = 1:
/// res = [r01, r11, r21, r31] = (r01 * 2^-K + r02 * 2^-2K + r03 * 2^-3K + r04 * 2^-4K + r05 * 2^-5K) + ...
/// [r02, r12, r22, r32]
/// [r03, r13, r23, r33]
/// [r04, r14, r24, r34]
/// [r05, r15, r25, r35]
///
/// If k = -1:
/// res = [ 0, 0, 0, 0] = (r01 * 2^-3K + r02 * 2^-4K + r03 * 2^-5K) + ...
/// [ 0, 0, 0, 0]
/// [r01, r11, r21, r31]
/// [r02, r12, r22, r32]
/// [r03, r13, r23, r33]
///
/// If res.size() < a.size() + b.size() + 1 + k, result is truncated accordingly in the Y dimension.
fn bivariate_convolution_single_add<R, A, B>(
&self,
k: i64,
res: &mut R,
res_col: usize,
a: &A,
a_col: usize,
b: &B,
b_col: usize,
scratch: &mut Scratch<BE>,
) where
R: VecZnxDftToMut<BE>,
A: VecZnxToRef,
B: VecZnxDftToRef<BE>,
{
let res: &mut crate::layouts::VecZnxDft<&mut [u8], BE> = &mut res.to_mut();
let a: &crate::layouts::VecZnx<&[u8]> = &a.to_ref();
let b: &crate::layouts::VecZnxDft<&[u8], BE> = &b.to_ref();
let (mut ppol, scratch_1) = scratch.take_svp_ppol(self, 1);
let (mut res_tmp, _) = scratch_1.take_vec_znx_dft(self, 1, b.size());
for a_limb in 0..a.size() {
self.svp_prepare(&mut ppol, 0, &a.as_scalar_znx_ref(a_col, a_limb), 0);
self.svp_apply_dft_to_dft(&mut res_tmp, 0, &ppol, 0, b, b_col);
self.vec_znx_dft_add_scaled_inplace(res, res_col, &res_tmp, 0, -(1 + a_limb as i64) + k);
}
}
fn bivariate_convolution_single<R, A, B>(
&self,
k: i64,
res: &mut R,
res_col: usize,
a: &A,
a_col: usize,
b: &B,
b_col: usize,
scratch: &mut Scratch<BE>,
) where
R: VecZnxDftToMut<BE>,
A: VecZnxToRef,
B: VecZnxDftToRef<BE>,
{
self.vec_znx_dft_zero(res, res_col);
self.bivariate_convolution_single_add(k, res, res_col, a, a_col, b, b_col, scratch);
}
}