1 files changed, 99 insertions, 0 deletions
diff --git a/src/zencore/profiling/counterstrace.cpp b/src/zencore/profiling/counterstrace.cpp
new file mode 100644
index 000000000..63e8a2dd3
--- /dev/null
+++ b/src/zencore/profiling/counterstrace.cpp
@@ -0,0 +1,99 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+
+#include <zencore/profiling/counterstrace.h>
+
+#if ZEN_WITH_TRACE
+
+#	include <zencore/timer.h>
+#	include <zencore/trace.h>
+
+#	include <atomic>
+#	include <cstring>
+
+namespace {
+
+// Wire-compatible with UE's CountersTrace events (Counters.Spec /
+// SetValueInt / SetValueFloat). Channel name matches UE so users can mix &
+// match analyzers.
+UE_TRACE_CHANNEL_DEFINE(CountersChannel)
+
+UE_TRACE_EVENT_BEGIN(Counters, Spec, NoSync | Important)
+	UE_TRACE_EVENT_FIELD(uint16_t, Id)
+	UE_TRACE_EVENT_FIELD(uint8_t, Type)
+	UE_TRACE_EVENT_FIELD(uint8_t, DisplayHint)
+	UE_TRACE_EVENT_FIELD(UE::Trace::AnsiString, Name)
+UE_TRACE_EVENT_END()
+
+UE_TRACE_EVENT_BEGIN(Counters, SetValueInt)
+	UE_TRACE_EVENT_FIELD(uint64_t, Cycle)
+	UE_TRACE_EVENT_FIELD(int64_t, Value)
+	UE_TRACE_EVENT_FIELD(uint16_t, CounterId)
+UE_TRACE_EVENT_END()
+
+UE_TRACE_EVENT_BEGIN(Counters, SetValueFloat)
+	UE_TRACE_EVENT_FIELD(uint64_t, Cycle)
+	UE_TRACE_EVENT_FIELD(double, Value)
+	UE_TRACE_EVENT_FIELD(uint16_t, CounterId)
+UE_TRACE_EVENT_END()
+
+}  // namespace
+
+namespace zen::counters_detail {
+
+uint16_t
+OutputInitCounter(const char* Name, TraceCounterType Type, TraceCounterDisplayHint Hint)
+{
+	if (!UE_TRACE_CHANNELEXPR_IS_ENABLED(CountersChannel) || Name == nullptr)
+	{
+		return 0;
+	}
+
+	// Counter ids are uint16; tourist's analyzer truncates anyway. Wrapping
+	// past 0xFFFF would re-use ids, so we cap allocation -- in practice no
+	// real-world trace uses anywhere near 65k distinct counters.
+	static std::atomic<uint32_t> g_NextId{0};
+	uint32_t					 Allocated = g_NextId.fetch_add(1, std::memory_order_relaxed) + 1;
+	if (Allocated > 0xFFFFu)
+	{
+		return 0;
+	}
+	uint16_t Id = uint16_t(Allocated);
+
+	uint16_t NameLen = uint16_t(std::strlen(Name));
+	UE_TRACE_LOG(Counters, Spec, CountersChannel, NameLen * sizeof(char))
+		<< Spec.Id(Id) << Spec.Type(uint8_t(Type)) << Spec.DisplayHint(uint8_t(Hint)) << Spec.Name(Name, NameLen);
+
+	return Id;
+}
+
+void
+OutputSetValueInt(uint16_t Id, int64_t Value)
+{
+	if (Id == 0 || !UE_TRACE_CHANNELEXPR_IS_ENABLED(CountersChannel))
+	{
+		return;
+	}
+	UE_TRACE_LOG(Counters, SetValueInt, CountersChannel)
+		<< SetValueInt.Cycle(zen::GetHifreqTimerValue()) << SetValueInt.Value(Value) << SetValueInt.CounterId(Id);
+}
+
+void
+OutputSetValueFloat(uint16_t Id, double Value)
+{
+	if (Id == 0 || !UE_TRACE_CHANNELEXPR_IS_ENABLED(CountersChannel))
+	{
+		return;
+	}
+	UE_TRACE_LOG(Counters, SetValueFloat, CountersChannel)
+		<< SetValueFloat.Cycle(zen::GetHifreqTimerValue()) << SetValueFloat.Value(Value) << SetValueFloat.CounterId(Id);
+}
+
+bool
+IsCountersChannelEnabled()
+{
+	return UE_TRACE_CHANNELEXPR_IS_ENABLED(CountersChannel);
+}
+
+}  // namespace zen::counters_detail
+
+#endif	// ZEN_WITH_TRACE