2 files changed, 82 insertions, 0 deletions
diff --git a/include/libcamera/internal/delayed_controls.h b/include/libcamera/internal/delayed_controls.h
new file mode 100644
index 00000000..dc447a88
--- /dev/null
+++ b/include/libcamera/internal/delayed_controls.h
@@ -0,0 +1,81 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2020, Raspberry Pi (Trading) Ltd.
+ *
+ * delayed_controls.h - Helper to deal with controls that take effect with a delay
+ */
+#ifndef __LIBCAMERA_INTERNAL_DELAYED_CONTROLS_H__
+#define __LIBCAMERA_INTERNAL_DELAYED_CONTROLS_H__
+
+#include <stdint.h>
+#include <unordered_map>
+
+#include <libcamera/controls.h>
+
+namespace libcamera {
+
+class V4L2Device;
+
+class DelayedControls
+{
+public:
+	DelayedControls(V4L2Device *device,
+			const std::unordered_map<uint32_t, unsigned int> &delays);
+
+	void reset();
+
+	bool push(const ControlList &controls);
+	ControlList get(uint32_t sequence);
+
+	void applyControls(uint32_t sequence);
+
+private:
+	class Info : public ControlValue
+	{
+	public:
+		Info()
+			: updated(false)
+		{
+		}
+
+		Info(const ControlValue &v)
+			: ControlValue(v), updated(true)
+		{
+		}
+
+		bool updated;
+	};
+
+	/* \todo: Make the listSize configurable at instance creation time. */
+	static constexpr int listSize = 16;
+	class ControlRingBuffer : public std::array<Info, listSize>
+	{
+	public:
+		Info &operator[](unsigned int index)
+		{
+			return std::array<Info, listSize>::operator[](index % listSize);
+		}
+
+		const Info &operator[](unsigned int index) const
+		{
+			return std::array<Info, listSize>::operator[](index % listSize);
+		}
+	};
+
+	V4L2Device *device_;
+	/* \todo Evaluate if we should index on ControlId * or unsigned int */
+	std::unordered_map<const ControlId *, unsigned int> delays_;
+	unsigned int maxDelay_;
+
+	bool running_;
+	uint32_t firstSequence_;
+
+	uint32_t queueCount_;
+	uint32_t writeCount_;
+	/* \todo Evaluate if we should index on ControlId * or unsigned int */
+	std::unordered_map<const ControlId *, ControlRingBuffer> values_;
+};
+
+} /* namespace libcamera */
+
+#endif /* __LIBCAMERA_INTERNAL_DELAYED_CONTROLS_H__ */
diff --git a/include/libcamera/internal/meson.build b/include/libcamera/internal/meson.build
index 1b1bdc77..e67a359f 100644
--- a/include/libcamera/internal/meson.build
+++ b/include/libcamera/internal/meson.build
@@ -17,6 +17,7 @@ libcamera_internal_headers = files([
     'camera_sensor.h',
     'control_serializer.h',
     'control_validator.h',
+    'delayed_controls.h',
     'device_enumerator.h',
     'device_enumerator_sysfs.h',
     'device_enumerator_udev.h',