BLI: new C++ BitVector data structure

This adds a new `blender::BitVector` data structure that was requested
a couple of times. It also replaces usages of `BLI_bitmap` in C++ code.

See the comment in `BLI_bit_vector.hh` for more details about the
advantages and disadvantages of using a bit-vector and how the new
data structure compares to `std::vector<bool>` and `BLI_bitmap`.

Differential Revision: https://developer.blender.org/D14006

1 files changed, 15 insertions, 0 deletions

diff --git a/source/blender/blenlib/BLI_index_range.hh b/source/blender/blenlib/BLI_index_range.hh
index 2b290e1ba7d..a0f129c7324 100644
--- a/source/blender/blenlib/BLI_index_range.hh
+++ b/source/blender/blenlib/BLI_index_range.hh
@@ -318,4 +318,19 @@ class IndexRange {
   Span<int64_t> as_span_internal() const;
 };
 
+struct AlignedIndexRanges {
+  IndexRange prefix;
+  IndexRange aligned;
+  IndexRange suffix;
+};
+
+/**
+ * Split a range into three parts so that the boundaries of the middle part are aligned to some
+ * power of two.
+ *
+ * This can be used when an algorithm can be optimized on aligned indices/memory. The algorithm
+ * then needs a slow path for the beginning and end, and a fast path for the aligned elements.
+ */
+AlignedIndexRanges split_index_range_by_alignment(const IndexRange range, const int64_t alignment);
+
 }  // namespace blender