scummvm/audio/softsynth/mt32/freeverb.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * 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.
 *
 * $URL$
 * $Id$
 *
 */

// Macro for killing denormalled numbers
//
// Written by Jezar at Dreampoint, June 2000
// http://www.dreampoint.co.uk
// Based on IS_DENORMAL macro by Jon Watte
// This code is public domain

#ifndef FREEVERB_H
#define FREEVERB_H

// FIXME: Fix this really ugly hack
inline float undenormalise(void *sample) {
	if (((*(unsigned int*)sample) &  0x7f800000) == 0)
		return 0.0f;
	return *(float*)sample;
}

// Comb filter class declaration

class comb {
public:
	comb();
	void setbuffer(float *buf, int size);
	inline float process(float inp);
	void mute();
	void setdamp(float val);
	float getdamp();
	void setfeedback(float val);
	float getfeedback();
private:
	float feedback;
	float filterstore;
	float damp1;
	float damp2;
	float *buffer;
	int bufsize;
	int bufidx;
};


// Big to inline - but crucial for speed

inline float comb::process(float input) {
	float output;

	output = buffer[bufidx];
	undenormalise(&output);

	filterstore = (output * damp2) + (filterstore * damp1);
	undenormalise(&filterstore);

	buffer[bufidx] = input + (filterstore * feedback);

	if (++bufidx >= bufsize)
		bufidx = 0;

	return output;
}

// Allpass filter declaration

class allpass {
public:
	allpass();
	void setbuffer(float *buf, int size);
	inline float process(float inp);
	void mute();
	void setfeedback(float val);
	float getfeedback();
private:
	float feedback;
	float *buffer;
	int bufsize;
	int bufidx;
};


// Big to inline - but crucial for speed

inline float allpass::process(float input) {
	float output;
	float bufout;

	bufout = buffer[bufidx];
	undenormalise(&bufout);

	output = -input + bufout;
	buffer[bufidx] = input + (bufout * feedback);

	if (++bufidx >= bufsize)
		bufidx = 0;

	return output;
}


// Reverb model tuning values

const int	numcombs	= 8;
const int	numallpasses	= 4;
const float	muted		= 0;
const float	fixedgain	= 0.015f;
const float	scalewet	= 3;
const float	scaledry	= 2;
const float	scaledamp	= 0.4f;
const float	scaleroom	= 0.28f;
const float	offsetroom	= 0.7f;
const float	initialroom	= 0.5f;
const float	initialdamp	= 0.5f;
const float	initialwet	= 1 / scalewet;
const float	initialdry	= 0;
const float	initialwidth	= 1;
const float	initialmode	= 0;
const float	freezemode	= 0.5f;
const int	stereospread	= 23;

// These values assume 44.1KHz sample rate
// they will probably be OK for 48KHz sample rate
// but would need scaling for 96KHz (or other) sample rates.
// The values were obtained by listening tests.
const int combtuningL1		= 1116;
const int combtuningR1		= 1116 + stereospread;
const int combtuningL2		= 1188;
const int combtuningR2		= 1188 + stereospread;
const int combtuningL3		= 1277;
const int combtuningR3		= 1277 + stereospread;
const int combtuningL4		= 1356;
const int combtuningR4		= 1356 + stereospread;
const int combtuningL5		= 1422;
const int combtuningR5		= 1422 + stereospread;
const int combtuningL6		= 1491;
const int combtuningR6		= 1491 + stereospread;
const int combtuningL7		= 1557;
const int combtuningR7		= 1557 + stereospread;
const int combtuningL8		= 1617;
const int combtuningR8		= 1617 + stereospread;
const int allpasstuningL1	= 556;
const int allpasstuningR1	= 556 + stereospread;
const int allpasstuningL2	= 441;
const int allpasstuningR2	= 441 + stereospread;
const int allpasstuningL3	= 341;
const int allpasstuningR3	= 341 + stereospread;
const int allpasstuningL4	= 225;
const int allpasstuningR4	= 225 + stereospread;


// Reverb model declaration

class revmodel {
public:
	revmodel();
	void mute();
	void processmix(float *inputL, float *inputR, float *outputL, float *outputR, long numsamples, int skip);
	void processreplace(float *inputL, float *inputR, float *outputL, float *outputR, long numsamples, int skip);
	void setroomsize(float value);
	float getroomsize();
	void setdamp(float value);
	float getdamp();
	void setwet(float value);
	float getwet();
	void setdry(float value);
	float getdry();
	void setwidth(float value);
	float getwidth();
	void setmode(float value);
	float getmode();
private:
	void update();

	float gain;
	float roomsize, roomsize1;
	float damp, damp1;
	float wet, wet1, wet2;
	float dry;
	float width;
	float mode;

	// The following are all declared inline
	// to remove the need for dynamic allocation
	// with its subsequent error-checking messiness

	// Comb filters
	comb combL[numcombs];
	comb combR[numcombs];

	// Allpass filters
	allpass	allpassL[numallpasses];
	allpass	allpassR[numallpasses];

	// Buffers for the combs
	float bufcombL1[combtuningL1];
	float bufcombR1[combtuningR1];
	float bufcombL2[combtuningL2];
	float bufcombR2[combtuningR2];
	float bufcombL3[combtuningL3];
	float bufcombR3[combtuningR3];
	float bufcombL4[combtuningL4];
	float bufcombR4[combtuningR4];
	float bufcombL5[combtuningL5];
	float bufcombR5[combtuningR5];
	float bufcombL6[combtuningL6];
	float bufcombR6[combtuningR6];
	float bufcombL7[combtuningL7];
	float bufcombR7[combtuningR7];
	float bufcombL8[combtuningL8];
	float bufcombR8[combtuningR8];

	// Buffers for the allpasses
	float bufallpassL1[allpasstuningL1];
	float bufallpassR1[allpasstuningR1];
	float bufallpassL2[allpasstuningL2];
	float bufallpassR2[allpasstuningR2];
	float bufallpassL3[allpasstuningL3];
	float bufallpassR3[allpasstuningR3];
	float bufallpassL4[allpasstuningL4];
	float bufallpassR4[allpasstuningR4];
};

#endif