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-rw-r--r--otautil/rangeset.cpp40
1 files changed, 40 insertions, 0 deletions
diff --git a/otautil/rangeset.cpp b/otautil/rangeset.cpp
index 532cba4a8..96955b9d0 100644
--- a/otautil/rangeset.cpp
+++ b/otautil/rangeset.cpp
@@ -103,6 +103,46 @@ void RangeSet::Clear() {
blocks_ = 0;
}
+std::vector<RangeSet> RangeSet::Split(size_t groups) const {
+ if (ranges_.empty() || groups == 0) return {};
+
+ if (blocks_ < groups) {
+ groups = blocks_;
+ }
+
+ // Evenly distribute blocks, with the first few groups possibly containing one more.
+ size_t mean = blocks_ / groups;
+ std::vector<size_t> blocks_per_group(groups, mean);
+ std::fill_n(blocks_per_group.begin(), blocks_ % groups, mean + 1);
+
+ std::vector<RangeSet> result;
+
+ // Forward iterate Ranges and fill up each group with the desired number of blocks.
+ auto it = ranges_.cbegin();
+ Range range = *it;
+ for (const auto& blocks : blocks_per_group) {
+ RangeSet buffer;
+ size_t needed = blocks;
+ while (needed > 0) {
+ size_t range_blocks = range.second - range.first;
+ if (range_blocks > needed) {
+ // Split the current range and don't advance the iterator.
+ buffer.PushBack({ range.first, range.first + needed });
+ range.first = range.first + needed;
+ break;
+ }
+ buffer.PushBack(range);
+ it++;
+ if (it != ranges_.cend()) {
+ range = *it;
+ }
+ needed -= range_blocks;
+ }
+ result.push_back(std::move(buffer));
+ }
+ return result;
+}
+
std::string RangeSet::ToString() const {
if (ranges_.empty()) {
return "";