From 3dd5725a84f5ac71c384431ffc4929962aeaf6b2 Mon Sep 17 00:00:00 2001 From: Daniel Scally Date: Fri, 15 Nov 2024 12:25:30 +0000 Subject: 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 Reviewed-by: Kieran Bingham Reviewed-by: Laurent Pinchart --- src/ipa/libipa/fixedpoint.cpp | 42 ++++++++++++++++++++++++++++ src/ipa/libipa/fixedpoint.h | 65 +++++++++++++++++++++++++++++++++++++++++++ src/ipa/libipa/meson.build | 2 ++ 3 files changed, 109 insertions(+) create mode 100644 src/ipa/libipa/fixedpoint.cpp create mode 100644 src/ipa/libipa/fixedpoint.h (limited to 'src/ipa/libipa') diff --git a/src/ipa/libipa/fixedpoint.cpp b/src/ipa/libipa/fixedpoint.cpp new file mode 100644 index 00000000..6b698fc5 --- /dev/null +++ b/src/ipa/libipa/fixedpoint.cpp @@ -0,0 +1,42 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +/* + * Copyright (C) 2024, Paul Elder + * + * Fixed / floating point conversions + */ + +#include "fixedpoint.h" + +/** + * \file fixedpoint.h + */ + +namespace libcamera { + +namespace ipa { + +/** + * \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 */ + +} /* namespace libcamera */ diff --git a/src/ipa/libipa/fixedpoint.h b/src/ipa/libipa/fixedpoint.h new file mode 100644 index 00000000..709cf50f --- /dev/null +++ b/src/ipa/libipa/fixedpoint.h @@ -0,0 +1,65 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +/* + * Copyright (C) 2024, Paul Elder + * + * Fixed / floating point conversions + */ + +#pragma once + +#include +#include + +namespace libcamera { + +namespace ipa { + +#ifndef __DOXYGEN__ +template && + std::is_floating_point_v> * = nullptr> +#else +template +#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(static_cast(std::round(number * (1 << F)))) & mask; + + return frac; +} + +#ifndef __DOXYGEN__ +template && + std::is_integral_v> * = nullptr> +#else +template +#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(static_cast(number) << remaining_bits) >> remaining_bits; + return static_cast(t) / static_cast(1 << F); +} + +} /* namespace ipa */ + +} /* namespace libcamera */ diff --git a/src/ipa/libipa/meson.build b/src/ipa/libipa/meson.build index 93ae25da..a7f16ff6 100644 --- a/src/ipa/libipa/meson.build +++ b/src/ipa/libipa/meson.build @@ -7,6 +7,7 @@ libipa_headers = files([ 'colours.h', 'exposure_mode_helper.h', 'fc_queue.h', + 'fixedpoint.h', 'histogram.h', 'interpolator.h', 'lsc_polynomial.h', @@ -22,6 +23,7 @@ libipa_sources = files([ 'colours.cpp', 'exposure_mode_helper.cpp', 'fc_queue.cpp', + 'fixedpoint.cpp', 'histogram.cpp', 'interpolator.cpp', 'lsc_polynomial.cpp', -- cgit v1.2.1