1 files changed, 88 insertions, 0 deletions
diff --git a/src/djinterop/performance_data.cpp b/src/djinterop/performance_data.cpp
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+++ b/src/djinterop/performance_data.cpp
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+/*
+    This file is part of libdjinterop.
+
+    libdjinterop is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    libdjinterop is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with libdjinterop.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <algorithm>
+#include <cmath>
+
+#include <djinterop/djinterop.hpp>
+
+namespace djinterop
+{
+namespace enginelibrary
+{
+std::vector<beatgrid_marker> normalize_beatgrid(
+    std::vector<beatgrid_marker> beatgrid, int64_t sample_count)
+{
+    if (beatgrid.empty())
+    {
+        return beatgrid;  // Named RVO
+    }
+
+    {
+        auto last_marker_iter = std::find_if(
+            beatgrid.begin(), beatgrid.end(),
+            [sample_count](const beatgrid_marker &marker) {
+                return marker.sample_offset > sample_count;
+            });
+        if (last_marker_iter != beatgrid.end())
+        {
+            beatgrid.erase(last_marker_iter + 1, beatgrid.end());
+        }
+    }
+
+    {
+        auto after_first_marker_iter = std::find_if(
+            beatgrid.begin(), beatgrid.end(),
+            [](const beatgrid_marker &marker) {
+                return marker.sample_offset > 0;
+            });
+        if (after_first_marker_iter != beatgrid.begin())
+        {
+            beatgrid.erase(beatgrid.begin(), after_first_marker_iter - 1);
+        }
+    }
+
+    if (beatgrid.size() < 2)
+    {
+        throw std::invalid_argument{
+            "Attempted to normalize a misplaced beadgrid"};
+    }
+
+    {
+        double samples_per_beat =
+            (beatgrid[1].sample_offset - beatgrid[0].sample_offset) /
+            (beatgrid[1].index - beatgrid[0].index);
+        beatgrid[0].sample_offset -= (4 + beatgrid[0].index) * samples_per_beat;
+        beatgrid[0].index = -4;
+    }
+
+    {
+        int32_t last = static_cast<int32_t>(beatgrid.size() - 1);
+        double samples_per_beat =
+            (beatgrid[last].sample_offset - beatgrid[last - 1].sample_offset) /
+            (beatgrid[last].index - beatgrid[last - 1].index);
+        int32_t index_adjustment = static_cast<int32_t>(std::ceil(
+            (sample_count - beatgrid[last].sample_offset) / samples_per_beat));
+        beatgrid[last].sample_offset += index_adjustment * samples_per_beat;
+        beatgrid[last].index += index_adjustment;
+    }
+
+    return beatgrid;  // Named RVO
+}
+
+}  // namespace enginelibrary
+}  // namespace djinterop