Alc/alcModulator.c

   1 /**
   2  * OpenAL cross platform audio library
   3  * Copyright (C) 2009 by Chris Robinson.
   4  * This library is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU Library General Public
   6  *  License as published by the Free Software Foundation; either
   7  *  version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  *  Library General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Library General Public
  15  *  License along with this library; if not, write to the
  16  *  Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  *  Boston, MA  02111-1307, USA.
  18  * Or go to http://www.gnu.org/copyleft/lgpl.html
  19  */
  20
  21 #include "config.h"
  22
  23 #include <math.h>
  24 #include <stdlib.h>
  25
  26 #include "alMain.h"
  27 #include "alFilter.h"
  28 #include "alAuxEffectSlot.h"
  29 #include "alError.h"
  30 #include "alu.h"
  31
  32
  33 typedef struct ALmodulatorState {
  34     // Must be first in all effects!
  35     ALeffectState state;
  36
  37     enum {
  38         SINUSOID,
  39         SAWTOOTH,
  40         SQUARE
  41     } Waveform;
  42
  43     ALuint index;
  44     ALuint step;
  45
  46     ALfloat Gain[MAXCHANNELS];
  47
  48     FILTER iirFilter;
  49     ALfloat history[1];
  50 } ALmodulatorState;
  51
  52 #define WAVEFORM_FRACBITS  16
  53 #define WAVEFORM_FRACONE   (1<<WAVEFORM_FRACBITS)
  54 #define WAVEFORM_FRACMASK  (WAVEFORM_FRACONE-1)
  55
  56 static __inline ALfloat Sin(ALuint index)
  57 {
  58     return aluSin(index * (F_PI*2.0f / WAVEFORM_FRACONE));
  59 }
  60
  61 static __inline ALfloat Saw(ALuint index)
  62 {
  63     return index*(2.0f/WAVEFORM_FRACONE) - 1.0f;
  64 }
  65
  66 static __inline ALfloat Square(ALuint index)
  67 {
  68     return ((index>>(WAVEFORM_FRACBITS-1))&1)*2.0f - 1.0f;
  69 }
  70
  71
  72 static __inline ALfloat hpFilter1P(FILTER *iir, ALuint offset, ALfloat input)
  73 {
  74     ALfloat *history = &iir->history[offset];
  75     ALfloat a = iir->coeff;
  76     ALfloat output = input;
  77
  78     output = output + (history[0]-output)*a;
  79     history[0] = output;
  80
  81     return input - output;
  82 }
  83
  84
  85 #define DECL_TEMPLATE(func)                                                   \
  86 static void Process##func(ALmodulatorState *state, ALuint SamplesToDo,        \
  87   const ALfloat *SamplesIn, ALfloat (*SamplesOut)[MAXCHANNELS])               \
  88 {                                                                             \
  89     const ALuint step = state->step;                                          \
  90     ALuint index = state->index;                                              \
  91     ALfloat samp;                                                             \
  92     ALuint i;                                                                 \
  93                                                                               \
  94     for(i = 0;i < SamplesToDo;i++)                                            \
  95     {                                                                         \
  96         samp = SamplesIn[i];                                                  \
  97                                                                               \
  98         index += step;                                                        \
  99         index &= WAVEFORM_FRACMASK;                                           \
 100         samp *= func(index);                                                  \
 101                                                                               \
 102         samp = hpFilter1P(&state->iirFilter, 0, samp);                        \
 103                                                                               \
 104         SamplesOut[i][FRONT_LEFT]   += state->Gain[FRONT_LEFT]   * samp;      \
 105         SamplesOut[i][FRONT_RIGHT]  += state->Gain[FRONT_RIGHT]  * samp;      \
 106         SamplesOut[i][FRONT_CENTER] += state->Gain[FRONT_CENTER] * samp;      \
 107         SamplesOut[i][SIDE_LEFT]    += state->Gain[SIDE_LEFT]    * samp;      \
 108         SamplesOut[i][SIDE_RIGHT]   += state->Gain[SIDE_RIGHT]   * samp;      \
 109         SamplesOut[i][BACK_LEFT]    += state->Gain[BACK_LEFT]    * samp;      \
 110         SamplesOut[i][BACK_RIGHT]   += state->Gain[BACK_RIGHT]   * samp;      \
 111         SamplesOut[i][BACK_CENTER]  += state->Gain[BACK_CENTER]  * samp;      \
 112     }                                                                         \
 113     state->index = index;                                                     \
 114 }
 115
 116 DECL_TEMPLATE(Sin)
 117 DECL_TEMPLATE(Saw)
 118 DECL_TEMPLATE(Square)
 119
 120 #undef DECL_TEMPLATE
 121
 122
 123 static ALvoid ModulatorDestroy(ALeffectState *effect)
 124 {
 125     ALmodulatorState *state = (ALmodulatorState*)effect;
 126     free(state);
 127 }
 128
 129 static ALboolean ModulatorDeviceUpdate(ALeffectState *effect, ALCdevice *Device)
 130 {
 131     return AL_TRUE;
 132     (void)effect;
 133     (void)Device;
 134 }
 135
 136 static ALvoid ModulatorUpdate(ALeffectState *effect, ALCcontext *Context, const ALeffectslot *Slot)
 137 {
 138     ALmodulatorState *state = (ALmodulatorState*)effect;
 139     ALCdevice *Device = Context->Device;
 140     ALfloat gain, cw, a = 0.0f;
 141     ALuint index;
 142
 143     if(Slot->effect.Modulator.Waveform == AL_RING_MODULATOR_SINUSOID)
 144         state->Waveform = SINUSOID;
 145     else if(Slot->effect.Modulator.Waveform == AL_RING_MODULATOR_SAWTOOTH)
 146         state->Waveform = SAWTOOTH;
 147     else if(Slot->effect.Modulator.Waveform == AL_RING_MODULATOR_SQUARE)
 148         state->Waveform = SQUARE;
 149
 150     state->step = fastf2u(Slot->effect.Modulator.Frequency*WAVEFORM_FRACONE /
 151                           Device->Frequency);
 152     if(state->step == 0) state->step = 1;
 153
 154     cw = aluCos(F_PI*2.0f * Slot->effect.Modulator.HighPassCutoff /
 155                             Device->Frequency);
 156     a = (2.0f-cw) - aluSqrt(aluPow(2.0f-cw, 2.0f) - 1.0f);
 157     state->iirFilter.coeff = a;
 158
 159     gain = Slot->Gain;
 160     for(index = 0;index < MAXCHANNELS;index++)
 161         state->Gain[index] = 0.0f;
 162     for(index = 0;index < Device->NumChan;index++)
 163     {
 164         enum Channel chan = Device->Speaker2Chan[index];
 165         state->Gain[chan] = gain;
 166     }
 167 }
 168
 169 static ALvoid ModulatorProcess(ALeffectState *effect, ALuint SamplesToDo, const ALfloat *SamplesIn, ALfloat (*SamplesOut)[MAXCHANNELS])
 170 {
 171     ALmodulatorState *state = (ALmodulatorState*)effect;
 172
 173     switch(state->Waveform)
 174     {
 175         case SINUSOID:
 176             ProcessSin(state, SamplesToDo, SamplesIn, SamplesOut);
 177             break;
 178
 179         case SAWTOOTH:
 180             ProcessSaw(state, SamplesToDo, SamplesIn, SamplesOut);
 181             break;
 182
 183         case SQUARE:
 184             ProcessSquare(state, SamplesToDo, SamplesIn, SamplesOut);
 185             break;
 186     }
 187 }
 188
 189 ALeffectState *ModulatorCreate(void)
 190 {
 191     ALmodulatorState *state;
 192
 193     state = malloc(sizeof(*state));
 194     if(!state)
 195         return NULL;
 196
 197     state->state.Destroy = ModulatorDestroy;
 198     state->state.DeviceUpdate = ModulatorDeviceUpdate;
 199     state->state.Update = ModulatorUpdate;
 200     state->state.Process = ModulatorProcess;
 201
 202     state->index = 0;
 203     state->step = 1;
 204
 205     state->iirFilter.coeff = 0.0f;
 206     state->iirFilter.history[0] = 0.0f;
 207
 208     return &state->state;
 209 }