[PATCH v5] ipa: rkisp1: Add a helper to convert floating-point to fixed-point
Paul Elder
paul.elder at ideasonboard.com
Fri May 31 08:51:21 CEST 2024
Add helper functions for converting between floating point and fixed
point numbers. Also add tests for them.
Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
Reviewed-by: Stefan Klug <stefan.klug at ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
---
Changes in v5:
- fix test comments
- add documentation for the actual parameters (only template parameters
were documented previously)
Changes in v4:
- relax the test case floating point precision
- optimize the fixed -> floating point converter
Changes in v3:
- (used to be "libcamera: utils: Add a helper to convert floating-point to fixed-point")
- move the everything from libcamera global utils to the rkisp1 ipa
Changes in v2:
- added the reverse conversion function (fixed -> floating)
- added tests
- make the conversion code cleaner
---
src/ipa/rkisp1/meson.build | 1 +
src/ipa/rkisp1/utils.cpp | 42 +++++++++++++++
src/ipa/rkisp1/utils.h | 66 ++++++++++++++++++++++++
test/ipa/meson.build | 2 +
test/ipa/rkisp1/meson.build | 15 ++++++
test/ipa/rkisp1/rkisp1-utils.cpp | 87 ++++++++++++++++++++++++++++++++
6 files changed, 213 insertions(+)
create mode 100644 src/ipa/rkisp1/utils.cpp
create mode 100644 src/ipa/rkisp1/utils.h
create mode 100644 test/ipa/rkisp1/meson.build
create mode 100644 test/ipa/rkisp1/rkisp1-utils.cpp
diff --git a/src/ipa/rkisp1/meson.build b/src/ipa/rkisp1/meson.build
index e813da53a..cf05cdb27 100644
--- a/src/ipa/rkisp1/meson.build
+++ b/src/ipa/rkisp1/meson.build
@@ -8,6 +8,7 @@ ipa_name = 'ipa_rkisp1'
rkisp1_ipa_sources = files([
'ipa_context.cpp',
'rkisp1.cpp',
+ 'utils.cpp',
])
rkisp1_ipa_sources += rkisp1_ipa_algorithms
diff --git a/src/ipa/rkisp1/utils.cpp b/src/ipa/rkisp1/utils.cpp
new file mode 100644
index 000000000..960ec64e9
--- /dev/null
+++ b/src/ipa/rkisp1/utils.cpp
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024, Paul Elder <paul.elder at ideasonboard.com>
+ *
+ * Miscellaneous utility functions specific to rkisp1
+ */
+
+#include "utils.h"
+
+/**
+ * \file utils.h
+ */
+
+namespace libcamera {
+
+namespace ipa::rkisp1::utils {
+
+/**
+ * \fn R floatingToFixedPoint(T number)
+ * \brief Convert a floating point number to a fixed-point representation
+ * \tparam I Bit width of the integer part of the fixed-point
+ * \tparam F Bit width of the fractional part of the fixed-point
+ * \tparam R Return type of the fixed-point representation
+ * \tparam T Input type of the floating point representation
+ * \param number The floating point number to convert to fixed point
+ * \return The converted value
+ */
+
+/**
+ * \fn R fixedToFloatingPoint(T number)
+ * \brief Convert a fixed-point number to a floating point representation
+ * \tparam I Bit width of the integer part of the fixed-point
+ * \tparam F Bit width of the fractional part of the fixed-point
+ * \tparam R Return type of the floating point representation
+ * \tparam T Input type of the fixed-point representation
+ * \param number The fixed point number to convert to floating point
+ * \return The converted value
+ */
+
+} /* namespace ipa::rkisp1::utils */
+
+} /* namespace libcamera */
diff --git a/src/ipa/rkisp1/utils.h b/src/ipa/rkisp1/utils.h
new file mode 100644
index 000000000..450f22442
--- /dev/null
+++ b/src/ipa/rkisp1/utils.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2024, Paul Elder <paul.elder at ideasonboard.com>
+ *
+ * Miscellaneous utility functions specific to rkisp1
+ */
+
+#pragma once
+
+#include <cmath>
+#include <limits>
+#include <type_traits>
+
+namespace libcamera {
+
+namespace ipa::rkisp1::utils {
+
+#ifndef __DOXYGEN__
+template<unsigned int I, unsigned int F, typename R, typename T,
+ std::enable_if_t<std::is_integral_v<R> &&
+ std::is_floating_point_v<T>> * = nullptr>
+#else
+template<unsigned int I, unsigned int F, typename R, typename T>
+#endif
+constexpr R floatingToFixedPoint(T number)
+{
+ static_assert(sizeof(int) >= sizeof(R));
+ static_assert(I + F <= sizeof(R) * 8);
+
+ /*
+ * The intermediate cast to int is needed on arm platforms to properly
+ * cast negative values. See
+ * https://embeddeduse.com/2013/08/25/casting-a-negative-float-to-an-unsigned-int/
+ */
+ R mask = (1 << (F + I)) - 1;
+ R frac = static_cast<R>(static_cast<int>(std::round(number * (1 << F)))) & mask;
+
+ return frac;
+}
+
+#ifndef __DOXYGEN__
+template<unsigned int I, unsigned int F, typename R, typename T,
+ std::enable_if_t<std::is_floating_point_v<R> &&
+ std::is_integral_v<T>> * = nullptr>
+#else
+template<unsigned int I, unsigned int F, typename R, typename T>
+#endif
+constexpr R fixedToFloatingPoint(T number)
+{
+ static_assert(sizeof(int) >= sizeof(T));
+ static_assert(I + F <= sizeof(T) * 8);
+
+ /*
+ * Recreate the upper bits in case of a negative number by shifting the sign
+ * bit from the fixed point to the first bit of the unsigned and then right shifting
+ * by the same amount which keeps the sign bit in place.
+ * This can be optimized by the compiler quite well.
+ */
+ int remaining_bits = sizeof(int) * 8 - (I + F);
+ int t = static_cast<int>(static_cast<unsigned>(number) << remaining_bits) >> remaining_bits;
+ return static_cast<R>(t) / static_cast<R>(1 << F);
+}
+
+} /* namespace ipa::rkisp1::utils */
+
+} /* namespace libcamera */
diff --git a/test/ipa/meson.build b/test/ipa/meson.build
index 180b0da0a..dc956284c 100644
--- a/test/ipa/meson.build
+++ b/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']},
diff --git a/test/ipa/rkisp1/meson.build b/test/ipa/rkisp1/meson.build
new file mode 100644
index 000000000..5ffc5dd60
--- /dev/null
+++ b/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
diff --git a/test/ipa/rkisp1/rkisp1-utils.cpp b/test/ipa/rkisp1/rkisp1-utils.cpp
new file mode 100644
index 000000000..ed6f44e9b
--- /dev/null
+++ b/test/ipa/rkisp1/rkisp1-utils.cpp
@@ -0,0 +1,87 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2024, Paul Elder <paul.elder at ideasonboard.com>
+ *
+ * Miscellaneous utility tests
+ */
+
+#include <cmath>
+#include <iostream>
+#include <map>
+
+#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)
--
2.39.2
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