Initial Vectorail GC format library

include/gc/EventStream.hpp

@@ -0,0 +1,46 @@
+#ifndef OPENROLLER_GC_EVENTSTREAM_HPP
+#define OPENROLLER_GC_EVENTSTREAM_HPP
+
+#include <cstddef>
+#include <cstdint>
+#include <string>
+#include <vector>
+
+namespace gc {
+
+struct GameEvent {
+    uint16_t id = 0;
+    float timestamp = 0.0f;
+    uint16_t a = 0;  // unknown (often 0)
+    uint32_t type = 0;
+    float value = 0.0f;
+    uint16_t b = 0;  // unknown (often 0)
+};
+
+struct EventStreamDecodeResult {
+    size_t recordSize = 16;     // 16 or 12 (for now)
+    int alignment = 0;          // best alignment within [0,recordSize-1]
+    size_t eventCount = 0;      // decoded event count at best alignment (bounded)
+    double padZeroRatio = 0.0;  // fraction of padding fields that are zero (0..1)
+    int score = 0;              // heuristic score for ranking
+};
+
+EventStreamDecodeResult TryDecodeEventStream(const std::vector<uint8_t>& bytes, size_t start, size_t end);
+
+// Like TryDecodeEventStream, but forces recordSize=12 or 16.
+EventStreamDecodeResult TryDecodeEventStreamFixed(const std::vector<uint8_t>& bytes, size_t start, size_t end, size_t recordSize);
+
+// Decodes using a fixed record size (big endian).
+// recordSize=16: u16 id, f32 timestamp, u16 a, u16 type, f32 value, u16 b
+// recordSize=12: f32 timestamp, u32 type, f32 value
+bool DecodeEventStream(
+    const std::vector<uint8_t>& bytes,
+    size_t start,
+    size_t end,
+    size_t recordSize,
+    std::vector<GameEvent>* out,
+    std::string* err);
+
+} // namespace gc
+
+#endif