simpleMixer.h
/*
* This file is part of libsidplayfp, a SID player engine.
*
* Copyright 2011-2025 Leandro Nini <drfiemost@users.sourceforge.net>
* Copyright 2007-2010 Antti Lankila
* Copyright (C) 2000 Simon White
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef SIMPLEMIXER_H
#define SIMPLEMIXER_H
#include <vector>
#ifdef __has_include
# if __has_include(<version>)
# include <version>
# endif
#endif
#include <cstdint>
#ifdef __cpp_lib_math_constants
# include <numbers>
#endif
namespace libsidplayfp
{
class SimpleMixer
{
private:
static constexpr int_least32_t SCALE_FACTOR = 1 << 16;
#ifdef __cpp_lib_math_constants
static constexpr double SQRT_2 = std::numbers::sqrt2;
static constexpr double SQRT_3 = std::numbers::sqrt3;
#else
static constexpr double SQRT_2 = 1.41421356237;
static constexpr double SQRT_3 = 1.73205080757;
#endif
static constexpr int_least32_t SCALE[3] = {
SCALE_FACTOR, // 1 chip, no scale
static_cast<int_least32_t>((1.0 / SQRT_2) * SCALE_FACTOR), // 2 chips, scale by sqrt(2)
static_cast<int_least32_t>((1.0 / SQRT_3) * SCALE_FACTOR) // 3 chips, scale by sqrt(3)
};
private:
using mixer_func_t = int_least32_t (SimpleMixer::*)() const;
private:
std::vector<short*> m_buffers;
std::vector<int_least32_t> m_iSamples;
std::vector<mixer_func_t> m_mix;
private:
void updateParams();
/*
* Channel matrix
*
* C1
* L 1.0
* R 1.0
*
* C1 C2
* L 1.0 0.5
* R 0.5 1.0
*
* C1 C2 C3
* L 1.0 1.0 0.5
* R 0.5 1.0 1.0
*/
// Mono mixing
template <int Chips>
int_least32_t mono() const
{
int_least32_t res = 0;
for (int i = 0; i < Chips; i++)
res += m_iSamples[i];
return res * SCALE[Chips-1] / SCALE_FACTOR;
}
// Stereo mixing
int_least32_t stereo_OneChip() const { return m_iSamples[0]; }
int_least32_t stereo_ch1_TwoChips() const
{
return (m_iSamples[0] + 0.5*m_iSamples[1]) * SCALE[1] / SCALE_FACTOR;
}
int_least32_t stereo_ch2_TwoChips() const
{
return (0.5*m_iSamples[0] + m_iSamples[1]) * SCALE[1] / SCALE_FACTOR;
}
int_least32_t stereo_ch1_ThreeChips() const
{
return (m_iSamples[0] + m_iSamples[1] + 0.5*m_iSamples[2]) * SCALE[2] / SCALE_FACTOR;
}
int_least32_t stereo_ch2_ThreeChips() const
{
return (0.5*m_iSamples[0] + m_iSamples[1] + m_iSamples[2]) * SCALE[2] / SCALE_FACTOR;
}
private:
SimpleMixer() = delete;
SimpleMixer(const SimpleMixer&) = delete;
public:
SimpleMixer(bool stereo, short** buffers, int chips);
unsigned int doMix(short *buffer, unsigned int samples);
};
}
#endif // MIXER_H
libsidplayfp::SimpleMixer::doMix
unsigned int doMix(short *buffer, unsigned int samples)
Definition simpleMixer.cpp:39