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/*-
* Copyright (c) 2005 Boris Mikhaylov
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include "config.h"
#include <math.h>
#include <string.h>
#include "bs2b.h"
#include "alu.h"
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif
/* Set up all data. */
static void init(struct bs2b *bs2b)
{
float Fc_lo, Fc_hi;
float G_lo, G_hi;
float x, g;
bs2b->srate = clampi(bs2b->srate, 2000, 192000);
switch(bs2b->level)
{
case BS2B_LOW_CLEVEL: /* Low crossfeed level */
Fc_lo = 360.0f;
Fc_hi = 501.0f;
G_lo = 0.398107170553497f;
G_hi = 0.205671765275719f;
break;
case BS2B_MIDDLE_CLEVEL: /* Middle crossfeed level */
Fc_lo = 500.0f;
Fc_hi = 711.0f;
G_lo = 0.459726988530872f;
G_hi = 0.228208484414988f;
break;
case BS2B_HIGH_CLEVEL: /* High crossfeed level (virtual speakers are closer to itself) */
Fc_lo = 700.0f;
Fc_hi = 1021.0f;
G_lo = 0.530884444230988f;
G_hi = 0.250105790667544f;
break;
case BS2B_LOW_ECLEVEL: /* Low easy crossfeed level */
Fc_lo = 360.0f;
Fc_hi = 494.0f;
G_lo = 0.316227766016838f;
G_hi = 0.168236228897329f;
break;
case BS2B_MIDDLE_ECLEVEL: /* Middle easy crossfeed level */
Fc_lo = 500.0f;
Fc_hi = 689.0f;
G_lo = 0.354813389233575f;
G_hi = 0.187169483835901f;
break;
default: /* High easy crossfeed level */
bs2b->level = BS2B_HIGH_ECLEVEL;
Fc_lo = 700.0f;
Fc_hi = 975.0f;
G_lo = 0.398107170553497f;
G_hi = 0.205671765275719f;
break;
} /* switch */
g = 1.0f / (1.0f - G_hi + G_lo);
/* $fc = $Fc / $s;
* $d = 1 / 2 / pi / $fc;
* $x = exp(-1 / $d);
*/
x = expf(-2.0f * F_PI * Fc_lo / bs2b->srate);
bs2b->b1_lo = x;
bs2b->a0_lo = G_lo * (1.0f - x) * g;
x = expf(-2.0f * F_PI * Fc_hi / bs2b->srate);
bs2b->b1_hi = x;
bs2b->a0_hi = (1.0f - G_hi * (1.0f - x)) * g;
bs2b->a1_hi = -x * g;
} /* init */
/* Exported functions.
* See descriptions in "bs2b.h"
*/
void bs2b_set_level(struct bs2b *bs2b, int level)
{
if(level == bs2b->level)
return;
bs2b->level = level;
init(bs2b);
} /* bs2b_set_level */
int bs2b_get_level(struct bs2b *bs2b)
{
return bs2b->level;
} /* bs2b_get_level */
void bs2b_set_srate(struct bs2b *bs2b, int srate)
{
if (srate == bs2b->srate)
return;
bs2b->srate = srate;
init(bs2b);
} /* bs2b_set_srate */
int bs2b_get_srate(struct bs2b *bs2b)
{
return bs2b->srate;
} /* bs2b_get_srate */
void bs2b_clear(struct bs2b *bs2b)
{
memset(&bs2b->last_sample, 0, sizeof(bs2b->last_sample));
} /* bs2b_clear */
extern inline void bs2b_cross_feed(struct bs2b *bs2b, float *restrict samples);
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