ipa: libipa: Add ExposureModeHelper

Add a helper for managing exposure modes and splitting exposure times
into shutter and gain values.

Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

1 files changed, 53 insertions, 0 deletions

diff --git a/src/ipa/libipa/exposure_mode_helper.h b/src/ipa/libipa/exposure_mode_helper.h
new file mode 100644
index 00000000..0ffc164e
--- /dev/null
+++ b/src/ipa/libipa/exposure_mode_helper.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024, Paul Elder <paul.elder@ideasonboard.com>
+ *
+ * exposure_mode_helper.h - Helper class that performs computations relating to exposure
+ */
+
+#pragma once
+
+#include <tuple>
+#include <utility>
+#include <vector>
+
+#include <libcamera/base/span.h>
+#include <libcamera/base/utils.h>
+
+namespace libcamera {
+
+namespace ipa {
+
+class ExposureModeHelper
+{
+public:
+	ExposureModeHelper(const Span<std::pair<utils::Duration, double>> stages);
+	~ExposureModeHelper() = default;
+
+	void setLimits(utils::Duration minShutter, utils::Duration maxShutter,
+		       double minGain, double maxGain);
+
+	std::tuple<utils::Duration, double, double>
+	splitExposure(utils::Duration exposure) const;
+
+	utils::Duration minShutter() const { return minShutter_; }
+	utils::Duration maxShutter() const { return maxShutter_; }
+	double minGain() const { return minGain_; }
+	double maxGain() const { return maxGain_; }
+
+private:
+	utils::Duration clampShutter(utils::Duration shutter) const;
+	double clampGain(double gain) const;
+
+	std::vector<utils::Duration> shutters_;
+	std::vector<double> gains_;
+
+	utils::Duration minShutter_;
+	utils::Duration maxShutter_;
+	double minGain_;
+	double maxGain_;
+};
+
+} /* namespace ipa */
+
+} /* namespace libcamera */