libipa: Centralise Fixed / Floating point convertors

The rkisp1 IPA has some utility functions to convert between fixed
and floating point numbers. Move those to libipa so they're available
for use in other IPA modules too.

Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 108 insertions, 0 deletions

diff --git a/test/ipa/libipa/fixedpoint.cpp b/test/ipa/libipa/fixedpoint.cpp
new file mode 100644
index 00000000..99eb662d
--- /dev/null
+++ b/test/ipa/libipa/fixedpoint.cpp
@@ -0,0 +1,108 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2024, Paul Elder <paul.elder@ideasonboard.com>
+ *
+ * Fixed / Floating point utility tests
+ */
+
+#include <cmath>
+#include <iostream>
+#include <map>
+#include <stdint.h>
+
+#include "../src/ipa/libipa/fixedpoint.h"
+
+#include "test.h"
+
+using namespace std;
+using namespace libcamera;
+using namespace ipa;
+
+class FixedPointUtilsTest : public Test
+{
+protected:
+	/* R for real, I for integer */
+	template<unsigned int IntPrec, unsigned int FracPrec, typename I, typename R>
+	int testFixedToFloat(I input, R expected)
+	{
+		R out = fixedToFloatingPoint<IntPrec, FracPrec, R>(input);
+		R prec = 1.0 / (1 << FracPrec);
+		if (std::abs(out - expected) > prec) {
+			cerr << "Reverse conversion expected " << input
+			     << " to convert to " << expected
+			     << ", got " << out << std::endl;
+			return TestFail;
+		}
+
+		return TestPass;
+	}
+
+	template<unsigned int IntPrec, unsigned int FracPrec, typename T>
+	int testSingleFixedPoint(double input, T expected)
+	{
+		T ret = floatingToFixedPoint<IntPrec, FracPrec, T>(input);
+		if (ret != expected) {
+			cerr << "Expected " << input << " to convert to "
+			     << expected << ", got " << ret << std::endl;
+			return TestFail;
+		}
+
+		/*
+		 * The precision check is fairly arbitrary but is based on what
+		 * the rkisp1 is capable of in the crosstalk module.
+		 */
+		double f = fixedToFloatingPoint<IntPrec, FracPrec, double>(ret);
+		if (std::abs(f - input) > 0.005) {
+			cerr << "Reverse conversion expected " << ret
+			     << " to convert to " << input
+			     << ", got " << f << std::endl;
+			return TestFail;
+		}
+
+		return TestPass;
+	}
+
+	int testFixedPoint()
+	{
+		/*
+		 * The second 7.992 test is to test that unused bits don't
+		 * affect the result.
+		 */
+		std::map<double, uint16_t> testCases = {
+			{ 7.992, 0x3ff },
+			{   0.2, 0x01a },
+			{  -0.2, 0x7e6 },
+			{  -0.8, 0x79a },
+			{  -0.4, 0x7cd },
+			{  -1.4, 0x74d },
+			{    -8, 0x400 },
+			{     0, 0 },
+		};
+
+		int ret;
+		for (const auto &testCase : testCases) {
+			ret = testSingleFixedPoint<4, 7, uint16_t>(testCase.first,
+								   testCase.second);
+			if (ret != TestPass)
+				return ret;
+		}
+
+		/* Special case with a superfluous one in the unused bits */
+		ret = testFixedToFloat<4, 7, uint16_t, double>(0xbff, 7.992);
+		if (ret != TestPass)
+			return ret;
+
+		return TestPass;
+	}
+
+	int run()
+	{
+		/* fixed point conversion test */
+		if (testFixedPoint() != TestPass)
+			return TestFail;
+
+		return TestPass;
+	}
+};
+
+TEST_REGISTER(FixedPointUtilsTest)