libsidplayfp  2.12.0
mixer.h
1 /*
2  * This file is part of libsidplayfp, a SID player engine.
3  *
4  * Copyright 2011-2023 Leandro Nini <drfiemost@users.sourceforge.net>
5  * Copyright 2007-2010 Antti Lankila
6  * Copyright (C) 2000 Simon White
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License as published by
10  * the Free Software Foundation; either version 2 of the License, or
11  * (at your option) any later version.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public License
19  * along with this program; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 
24 #ifndef MIXER_H
25 #define MIXER_H
26 
27 #include "sidcxx11.h"
28 
29 #include <stdint.h>
30 
31 #include <vector>
32 
33 namespace libsidplayfp
34 {
35 
36 class sidemu;
37 
41 class Mixer
42 {
43 private:
44  // random number generator for dithering
45  template <int MAX_VAL>
46  class randomLCG
47  {
48  static_assert((MAX_VAL != 0) && ((MAX_VAL & (MAX_VAL - 1)) == 0), "MAX_VAL must be a power of two");
49 
50  private:
51  uint32_t rand_seed;
52 
53  public:
54  randomLCG(uint32_t seed) :
55  rand_seed(seed)
56  {}
57 
58  int get()
59  {
60  rand_seed = (214013 * rand_seed + 2531011);
61  return static_cast<int>((rand_seed >> 16) & (MAX_VAL-1));
62  }
63  };
64 
65 public:
66  class badBufferSize {};
67 
68 public:
70  static constexpr unsigned int MAX_SIDS = 3;
71 
72 private:
73  static constexpr int_least32_t SCALE_FACTOR = 1 << 16;
74 
75  static constexpr double SQRT_2 = 1.41421356237;
76  static constexpr double SQRT_3 = 1.73205080757;
77 
78  static constexpr int_least32_t SCALE[3] = {
79  SCALE_FACTOR, // 1 chip, no scale
80  static_cast<int_least32_t>((1.0 / SQRT_2) * SCALE_FACTOR), // 2 chips, scale by sqrt(2)
81  static_cast<int_least32_t>((1.0 / SQRT_3) * SCALE_FACTOR) // 3 chips, scale by sqrt(3)
82  };
83 
84 private:
85  using mixer_func_t = int_least32_t (Mixer::*)() const;
86 
87  using scale_func_t = int (Mixer::*)(unsigned int);
88 
89 public:
91  static constexpr int_least32_t VOLUME_MAX = 1024;
92 
93 private:
94  std::vector<sidemu*> m_chips;
95  std::vector<short*> m_buffers;
96 
97  std::vector<int_least32_t> m_iSamples;
98  std::vector<int_least32_t> m_volume;
99 
100  std::vector<mixer_func_t> m_mix;
101  std::vector<scale_func_t> m_scale;
102 
103  int m_oldRandomValue = 0;
104  int m_fastForwardFactor = 1;
105 
106  // Mixer settings
107  short *m_sampleBuffer = nullptr;
108  uint_least32_t m_sampleCount = 0;
109  uint_least32_t m_sampleIndex = 0;
110 
111  uint_least32_t m_sampleRate = 0;
112 
113  bool m_stereo = false;
114 
115  bool m_wait = false;
116 
117  randomLCG<VOLUME_MAX> m_rand;
118 
119 private:
120  void updateParams();
121 
122  int triangularDithering()
123  {
124  const int prevValue = m_oldRandomValue;
125  m_oldRandomValue = m_rand.get();
126  return m_oldRandomValue - prevValue;
127  }
128 
129  int scale(unsigned int ch)
130  {
131  const int_least32_t sample = (this->*(m_mix[ch]))();
132  return (sample * m_volume[ch] + triangularDithering()) / VOLUME_MAX;
133  }
134 
135  int noScale(unsigned int ch)
136  {
137  return (this->*(m_mix[ch]))();
138  }
139 
140  /*
141  * Channel matrix
142  *
143  * C1
144  * L 1.0
145  * R 1.0
146  *
147  * C1 C2
148  * L 1.0 0.5
149  * R 0.5 1.0
150  *
151  * C1 C2 C3
152  * L 1.0 1.0 0.5
153  * R 0.5 1.0 1.0
154  */
155 
156  // Mono mixing
157  template <int Chips>
158  int_least32_t mono() const
159  {
160  int_least32_t res = 0;
161  for (int i = 0; i < Chips; i++)
162  res += m_iSamples[i];
163  return res * SCALE[Chips-1] / SCALE_FACTOR;
164  }
165 
166  // Stereo mixing
167  int_least32_t stereo_OneChip() const { return m_iSamples[0]; }
168 
169  int_least32_t stereo_ch1_TwoChips() const
170  {
171  return (m_iSamples[0] + 0.5*m_iSamples[1]) * SCALE[1] / SCALE_FACTOR;
172  }
173  int_least32_t stereo_ch2_TwoChips() const
174  {
175  return (0.5*m_iSamples[0] + m_iSamples[1]) * SCALE[1] / SCALE_FACTOR;
176  }
177 
178  int_least32_t stereo_ch1_ThreeChips() const
179  {
180  return (m_iSamples[0] + m_iSamples[1] + 0.5*m_iSamples[2]) * SCALE[2] / SCALE_FACTOR;
181  }
182  int_least32_t stereo_ch2_ThreeChips() const
183  {
184  return (0.5*m_iSamples[0] + m_iSamples[1] + m_iSamples[2]) * SCALE[2] / SCALE_FACTOR;
185  }
186 
187 public:
191  Mixer() :
192  m_rand(257254)
193  {
194  m_mix.push_back(&Mixer::mono<1>);
195  }
196 
200  void doMix();
201 
205  void clockChips();
206 
210  void resetBufs();
211 
220  void begin(short *buffer, uint_least32_t count);
221 
225  void clearSids();
226 
232  void addSid(sidemu *chip);
233 
240  sidemu* getSid(unsigned int i) const { return (i < m_chips.size()) ? m_chips[i] : nullptr; }
241 
248  bool setFastForward(int ff);
249 
256  void setVolume(int_least32_t left, int_least32_t right);
257 
263  void setStereo(bool stereo);
264 
270  void setSamplerate(uint_least32_t rate);
271 
275  bool notFinished() const { return m_sampleIndex < m_sampleCount; }
276 
280  uint_least32_t samplesGenerated() const { return m_sampleIndex; }
281 
282  /*
283  * Wait till we consume the buffer.
284  */
285  bool wait() const { return m_wait; }
286 };
287 
288 }
289 
290 #endif // MIXER_H
Definition: mixer.h:42
void addSid(sidemu *chip)
Definition: mixer.cpp:142
void resetBufs()
Definition: mixer.cpp:40
Mixer()
Definition: mixer.h:191
void clearSids()
Definition: mixer.cpp:136
bool notFinished() const
Definition: mixer.h:275
void clockChips()
Definition: mixer.cpp:34
void setStereo(bool stereo)
Definition: mixer.cpp:156
void setVolume(int_least32_t left, int_least32_t right)
Definition: mixer.cpp:182
static constexpr int_least32_t VOLUME_MAX
Maximum allowed volume, must be a power of 2.
Definition: mixer.h:91
uint_least32_t samplesGenerated() const
Definition: mixer.h:280
void setSamplerate(uint_least32_t rate)
Definition: mixer.cpp:168
void doMix()
Definition: mixer.cpp:46
void begin(short *buffer, uint_least32_t count)
Definition: mixer.cpp:102
static constexpr unsigned int MAX_SIDS
Maximum number of supported SIDs.
Definition: mixer.h:70
bool setFastForward(int ff)
Definition: mixer.cpp:173
sidemu * getSid(unsigned int i) const
Definition: mixer.h:240
Definition: sidemu.h:47