ipa: rkisp1: Add a helper to convert floating-point to fixed-point

Add helper functions for converting between floating point and fixed
point numbers. Also add tests for them.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

test/ipa/meson.build

@@ -1,5 +1,7 @@
 # SPDX-License-Identifier: CC0-1.0
 
+subdir('rkisp1')
+
 ipa_test = [
     {'name': 'ipa_module_test', 'sources': ['ipa_module_test.cpp']},
     {'name': 'ipa_interface_test', 'sources': ['ipa_interface_test.cpp']},

test/ipa/rkisp1/meson.build

@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: CC0-1.0
+
+rkisp1_ipa_test = [
+    {'name': 'rkisp1-utils', 'sources': ['rkisp1-utils.cpp']},
+]
+
+foreach test : rkisp1_ipa_test
+    exe = executable(test['name'], test['sources'], libcamera_generated_ipa_headers,
+                     dependencies : libcamera_private,
+                     link_with : [libipa, test_libraries],
+                     include_directories : [libipa_includes, test_includes_internal,
+                                            '../../../src/ipa/rkisp1/'])
+
+    test(test['name'], exe, suite : 'ipa')
+endforeach

test/ipa/rkisp1/rkisp1-utils.cpp

@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2024, Paul Elder <paul.elder@ideasonboard.com>
+ *
+ * Miscellaneous utility tests
+ */
+
+#include <cmath>
+#include <iostream>
+#include <map>
+#include <stdint.h>
+
+#include "../src/ipa/rkisp1/utils.h"
+
+#include "test.h"
+
+using namespace std;
+using namespace libcamera;
+using namespace ipa::rkisp1;
+
+class RkISP1UtilsTest : public Test
+{
+protected:
+	template<unsigned int intPrec, unsigned fracPrec, typename T>
+	int testSingleFixedPoint(double input, T expected)
+	{
+		T ret = utils::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 = utils::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 },
+			{ 7.992, 0xBFF },
+			{   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;
+		}
+
+		return TestPass;
+	}
+
+	int run()
+	{
+		/* fixed point conversion test */
+		if (testFixedPoint() != TestPass)
+			return TestFail;
+
+		return TestPass;
+	}
+};
+
+TEST_REGISTER(RkISP1UtilsTest)