axmol/thirdparty/openal/core/bs2b.cpp

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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 <algorithm>
#include <cmath>
#include <iterator>
#include "bs2b.h"
#include "math_defs.h"
/* Set up all data. */
static void init(struct bs2b *bs2b)
{
float Fc_lo, Fc_hi;
float G_lo, G_hi;
float x, g;
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 = std::exp(-al::MathDefs<float>::Tau() * Fc_lo / static_cast<float>(bs2b->srate));
bs2b->b1_lo = x;
bs2b->a0_lo = G_lo * (1.0f - x) * g;
x = std::exp(-al::MathDefs<float>::Tau() * Fc_hi / static_cast<float>(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_params(struct bs2b *bs2b, int level, int srate)
{
if(srate <= 0) srate = 1;
bs2b->level = level;
bs2b->srate = srate;
init(bs2b);
} /* bs2b_set_params */
int bs2b_get_level(struct bs2b *bs2b)
{
return bs2b->level;
} /* bs2b_get_level */
int bs2b_get_srate(struct bs2b *bs2b)
{
return bs2b->srate;
} /* bs2b_get_srate */
void bs2b_clear(struct bs2b *bs2b)
{
std::fill(std::begin(bs2b->history), std::end(bs2b->history), bs2b::t_last_sample{});
} /* bs2b_clear */
void bs2b_cross_feed(struct bs2b *bs2b, float *Left, float *Right, size_t SamplesToDo)
{
const float a0_lo{bs2b->a0_lo};
const float b1_lo{bs2b->b1_lo};
const float a0_hi{bs2b->a0_hi};
const float a1_hi{bs2b->a1_hi};
const float b1_hi{bs2b->b1_hi};
float lsamples[128][2];
float rsamples[128][2];
for(size_t base{0};base < SamplesToDo;)
{
const size_t todo{std::min<size_t>(128, SamplesToDo-base)};
/* Process left input */
float z_lo{bs2b->history[0].lo};
float z_hi{bs2b->history[0].hi};
for(size_t i{0};i < todo;i++)
{
lsamples[i][0] = a0_lo*Left[i] + z_lo;
z_lo = b1_lo*lsamples[i][0];
lsamples[i][1] = a0_hi*Left[i] + z_hi;
z_hi = a1_hi*Left[i] + b1_hi*lsamples[i][1];
}
bs2b->history[0].lo = z_lo;
bs2b->history[0].hi = z_hi;
/* Process right input */
z_lo = bs2b->history[1].lo;
z_hi = bs2b->history[1].hi;
for(size_t i{0};i < todo;i++)
{
rsamples[i][0] = a0_lo*Right[i] + z_lo;
z_lo = b1_lo*rsamples[i][0];
rsamples[i][1] = a0_hi*Right[i] + z_hi;
z_hi = a1_hi*Right[i] + b1_hi*rsamples[i][1];
}
bs2b->history[1].lo = z_lo;
bs2b->history[1].hi = z_hi;
/* Crossfeed */
for(size_t i{0};i < todo;i++)
*(Left++) = lsamples[i][1] + rsamples[i][0];
for(size_t i{0};i < todo;i++)
*(Right++) = rsamples[i][1] + lsamples[i][0];
base += todo;
}
} /* bs2b_cross_feed */