Decibels.h

/*
  ==============================================================================
    DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 
    Copyright 2022- by sonible GmbH.
 
    This file is part of VCTR - Versatile Container Templates Reconceptualized.
 
    VCTR is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License version 3
    only, as published by the Free Software Foundation.
 
    VCTR is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License version 3 for more details.
 
    You should have received a copy of the GNU Lesser General Public License
    version 3 along with VCTR.  If not, see <https://www.gnu.org/licenses/>.
  ==============================================================================
*/
 
namespace vctr::detail
{
template <is::constant C>
struct InvertedConstant
{
    static constexpr double value = 1.0 / double (C::value);
};
 
#if VCTR_USE_GCEM
template <is::constant C>
struct Log10ToLog2Constant
{
    static constexpr double value = double (C::value) / gcem::log2 (10.0);
};
 
template <is::constant C>
struct InvertedLog10ToLog2Constant
{
    static constexpr double value = gcem::log2 (10.0) / double (C::value);
};
#endif
} // namespace vctr::detail
 
namespace vctr::expressions
{
 
template <size_t extent, class SrcType, class DecibelConstant, class MinDb>
using MagToDb = ClampByConstant<extent,
                                MultiplyVecByConstant<extent,
                                                      Log10<extent, SrcType>,
                                                      DecibelConstant>,
                                MinDb,
                                DisabledConstant>;
 
template <size_t extent, class SrcType, class DecibelConstant>
using DBToMag = PowConstantBase<extent,
                                MultiplyVecByConstant<extent,
                                                      SrcType,
                                                      ::vctr::detail::InvertedConstant<DecibelConstant>>,
                                Constant<10>>;
 
#if VCTR_USE_GCEM
template <size_t extent, class SrcType, class DecibelConstant, class MinDb>
using FastMagToDb = ClampByConstant<extent,
                                    MultiplyVecByConstant<extent,
                                                          FastLog2<extent, SrcType>,
                                                          ::vctr::detail::Log10ToLog2Constant<DecibelConstant>>,
                                    MinDb,
                                    DisabledConstant>;
 
template <size_t extent, class SrcType, class DecibelConstant>
using FastDbToMag = FastExp2<extent,
                             MultiplyVecByConstant<extent,
                                                   SrcType,
                                                   ::vctr::detail::InvertedLog10ToLog2Constant<DecibelConstant>>>;
#endif
 
} // namespace vctr::expressions
 
namespace vctr
{
 
struct dBFS : Constant<20> {};
 
struct dBVoltage : Constant<20> {};
 
struct dBPower : Constant<10> {};
 
template <is::constant DecibelConstant, auto minDb = -100>
constexpr inline ExpressionChainBuilderWithRuntimeArgs<expressions::MagToDb, detail::RuntimeArgChain<std::tuple<>, std::tuple<>, std::tuple<>>, DecibelConstant, Constant<minDb>> magToDb;
 
template <is::constant DecibelConstant>
constexpr inline ExpressionChainBuilderWithRuntimeArgs<expressions::DBToMag, detail::RuntimeArgChain<std::tuple<>, std::tuple<>, std::tuple<>>, DecibelConstant> dbToMag;
 
#if VCTR_USE_GCEM
template <is::constant DecibelConstant, auto minDb = -100>
constexpr inline ExpressionChainBuilderWithRuntimeArgs<expressions::FastMagToDb, detail::RuntimeArgChain<std::tuple<>, std::tuple<>, std::tuple<>>, DecibelConstant, Constant<minDb>> fastMagToDb;
 
template <is::constant DecibelConstant>
constexpr inline ExpressionChainBuilderWithRuntimeArgs<expressions::FastDbToMag, detail::RuntimeArgChain<std::tuple<>, std::tuple<>, std::tuple<>>, DecibelConstant> fastDbToMag;
#endif
 
} // namespace vctr