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/**
* OpenAL cross platform audio library
* Copyright (C) 2009 by Chris Robinson.
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
* Or go to http://www.gnu.org/copyleft/lgpl.html
*/
#include "config.h"
#include <math.h>
#include <stdlib.h>
#include "alMain.h"
#include "alFilter.h"
#include "alAuxEffectSlot.h"
#include "alError.h"
#include "alu.h"
typedef struct ALmodulatorState {
// Must be first in all effects!
ALeffectState state;
enum {
SINUSOID,
SAWTOOTH,
SQUARE
} Waveform;
ALuint index;
ALuint step;
ALfloat Gain[MAXCHANNELS];
FILTER iirFilter;
ALfloat history[1];
} ALmodulatorState;
#define WAVEFORM_FRACBITS 16
#define WAVEFORM_FRACONE (1<<WAVEFORM_FRACBITS)
#define WAVEFORM_FRACMASK (WAVEFORM_FRACONE-1)
static __inline ALfloat Sin(ALuint index)
{
return aluSin(index * (F_PI*2.0f / WAVEFORM_FRACONE));
}
static __inline ALfloat Saw(ALuint index)
{
return index*(2.0f/WAVEFORM_FRACONE) - 1.0f;
}
static __inline ALfloat Square(ALuint index)
{
return ((index>>(WAVEFORM_FRACBITS-1))&1)*2.0f - 1.0f;
}
static __inline ALfloat hpFilter1P(FILTER *iir, ALuint offset, ALfloat input)
{
ALfloat *history = &iir->history[offset];
ALfloat a = iir->coeff;
ALfloat output = input;
output = output + (history[0]-output)*a;
history[0] = output;
return input - output;
}
#define DECL_TEMPLATE(func) \
static void Process##func(ALmodulatorState *state, ALuint SamplesToDo, \
const ALfloat *SamplesIn, ALfloat (*SamplesOut)[MAXCHANNELS]) \
{ \
const ALuint step = state->step; \
ALuint index = state->index; \
ALfloat samp; \
ALuint i, k; \
\
for(i = 0;i < SamplesToDo;i++) \
{ \
samp = SamplesIn[i]; \
\
index += step; \
index &= WAVEFORM_FRACMASK; \
samp *= func(index); \
\
samp = hpFilter1P(&state->iirFilter, 0, samp); \
\
for(k = 0;k < MAXCHANNELS;k++) \
SamplesOut[i][k] += state->Gain[k] * samp; \
} \
state->index = index; \
}
DECL_TEMPLATE(Sin)
DECL_TEMPLATE(Saw)
DECL_TEMPLATE(Square)
#undef DECL_TEMPLATE
static ALvoid ModulatorDestroy(ALeffectState *effect)
{
ALmodulatorState *state = (ALmodulatorState*)effect;
free(state);
}
static ALboolean ModulatorDeviceUpdate(ALeffectState *effect, ALCdevice *Device)
{
return AL_TRUE;
(void)effect;
(void)Device;
}
static ALvoid ModulatorUpdate(ALeffectState *effect, ALCcontext *Context, const ALeffectslot *Slot)
{
ALmodulatorState *state = (ALmodulatorState*)effect;
ALCdevice *Device = Context->Device;
ALfloat gain, cw, a = 0.0f;
ALuint index;
if(Slot->effect.Modulator.Waveform == AL_RING_MODULATOR_SINUSOID)
state->Waveform = SINUSOID;
else if(Slot->effect.Modulator.Waveform == AL_RING_MODULATOR_SAWTOOTH)
state->Waveform = SAWTOOTH;
else if(Slot->effect.Modulator.Waveform == AL_RING_MODULATOR_SQUARE)
state->Waveform = SQUARE;
state->step = fastf2u(Slot->effect.Modulator.Frequency*WAVEFORM_FRACONE /
Device->Frequency);
if(state->step == 0) state->step = 1;
cw = aluCos(F_PI*2.0f * Slot->effect.Modulator.HighPassCutoff /
Device->Frequency);
a = (2.0f-cw) - aluSqrt(aluPow(2.0f-cw, 2.0f) - 1.0f);
state->iirFilter.coeff = a;
gain = aluSqrt(1.0f/Device->NumChan);
gain *= Slot->Gain;
for(index = 0;index < MAXCHANNELS;index++)
state->Gain[index] = 0.0f;
for(index = 0;index < Device->NumChan;index++)
{
enum Channel chan = Device->Speaker2Chan[index];
state->Gain[chan] = gain;
}
}
static ALvoid ModulatorProcess(ALeffectState *effect, ALuint SamplesToDo, const ALfloat *SamplesIn, ALfloat (*SamplesOut)[MAXCHANNELS])
{
ALmodulatorState *state = (ALmodulatorState*)effect;
switch(state->Waveform)
{
case SINUSOID:
ProcessSin(state, SamplesToDo, SamplesIn, SamplesOut);
break;
case SAWTOOTH:
ProcessSaw(state, SamplesToDo, SamplesIn, SamplesOut);
break;
case SQUARE:
ProcessSquare(state, SamplesToDo, SamplesIn, SamplesOut);
break;
}
}
ALeffectState *ModulatorCreate(void)
{
ALmodulatorState *state;
state = malloc(sizeof(*state));
if(!state)
return NULL;
state->state.Destroy = ModulatorDestroy;
state->state.DeviceUpdate = ModulatorDeviceUpdate;
state->state.Update = ModulatorUpdate;
state->state.Process = ModulatorProcess;
state->index = 0;
state->step = 1;
state->iirFilter.coeff = 0.0f;
state->iirFilter.history[0] = 0.0f;
return &state->state;
}
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