/** * 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 sinf(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, ALCdevice *Device, const ALeffectslot *Slot) { ALmodulatorState *state = (ALmodulatorState*)effect; 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 = cosf(F_PI*2.0f * Slot->effect.Modulator.HighPassCutoff / Device->Frequency); a = (2.0f-cw) - sqrtf(powf(2.0f-cw, 2.0f) - 1.0f); state->iirFilter.coeff = a; gain = sqrtf(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; }