From b32502ea01d5a13de699d63c7ee16c68ca6a1b94 Mon Sep 17 00:00:00 2001
From: Martin Larralde <martin.larralde@embl.de>
Date: Mon, 15 May 2023 14:36:14 +0200
Subject: [PATCH] Add an unsafe constructor to create an uninitialized
`DenseMatrix`
---
lightmotif/src/dense.rs | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
diff --git a/lightmotif/src/dense.rs b/lightmotif/src/dense.rs
index 7486f64..82ca168 100644
--- a/lightmotif/src/dense.rs
+++ b/lightmotif/src/dense.rs
@@ -30,6 +30,34 @@ impl<T: Default + Copy, C: Unsigned> DenseMatrix<T, C> {
matrix
}
+ /// Create a new *uninitialized* matrix with the given number of rows.
+ pub unsafe fn uninitialized(rows: usize) -> Self {
+ // alway over-allocate columns to avoid alignment issues.
+ let c = C::USIZE.next_power_of_two();
+
+ // NOTE: this is unsafe but given that we require `T` to be
+ // copy, this should be fine, as `Copy` prevents the
+ // type to be `Dorp` as well.
+ // reserve the vector without initializing the data
+ let mut data = Vec::with_capacity((rows + 1) * c);
+ data.set_len((rows + 1) * c);
+
+ // compute offset to aligned memory
+ let mut offset = 0;
+ while data[offset..].as_ptr() as usize % c > 0 {
+ offset += 1
+ }
+
+ // record indices to each rows
+ let indices = (0..rows).into_iter().map(|i| offset + i * c).collect();
+
+ Self {
+ data,
+ indices,
+ _columns: std::marker::PhantomData,
+ }
+ }
+
/// The number of columns of the matrix.
#[inline]
pub const fn columns(&self) -> usize {
--
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