133 lines
3.6 KiB
C
133 lines
3.6 KiB
C
/*-
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* Copyright (c) 2005 Boris Mikhaylov
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include "config.h"
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#include <math.h>
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#include <string.h>
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#include "bs2b.h"
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#include "alu.h"
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/* Set up all data. */
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static void init(struct bs2b *bs2b)
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{
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float Fc_lo, Fc_hi;
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float G_lo, G_hi;
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float x, g;
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switch(bs2b->level)
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{
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case BS2B_LOW_CLEVEL: /* Low crossfeed level */
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Fc_lo = 360.0f;
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Fc_hi = 501.0f;
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G_lo = 0.398107170553497f;
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G_hi = 0.205671765275719f;
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break;
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case BS2B_MIDDLE_CLEVEL: /* Middle crossfeed level */
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Fc_lo = 500.0f;
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Fc_hi = 711.0f;
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G_lo = 0.459726988530872f;
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G_hi = 0.228208484414988f;
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break;
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case BS2B_HIGH_CLEVEL: /* High crossfeed level (virtual speakers are closer to itself) */
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Fc_lo = 700.0f;
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Fc_hi = 1021.0f;
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G_lo = 0.530884444230988f;
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G_hi = 0.250105790667544f;
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break;
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case BS2B_LOW_ECLEVEL: /* Low easy crossfeed level */
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Fc_lo = 360.0f;
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Fc_hi = 494.0f;
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G_lo = 0.316227766016838f;
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G_hi = 0.168236228897329f;
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break;
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case BS2B_MIDDLE_ECLEVEL: /* Middle easy crossfeed level */
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Fc_lo = 500.0f;
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Fc_hi = 689.0f;
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G_lo = 0.354813389233575f;
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G_hi = 0.187169483835901f;
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break;
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default: /* High easy crossfeed level */
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bs2b->level = BS2B_HIGH_ECLEVEL;
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Fc_lo = 700.0f;
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Fc_hi = 975.0f;
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G_lo = 0.398107170553497f;
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G_hi = 0.205671765275719f;
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break;
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} /* switch */
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g = 1.0f / (1.0f - G_hi + G_lo);
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/* $fc = $Fc / $s;
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* $d = 1 / 2 / pi / $fc;
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* $x = exp(-1 / $d);
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*/
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x = expf(-2.0f * F_PI * Fc_lo / bs2b->srate);
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bs2b->b1_lo = x;
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bs2b->a0_lo = G_lo * (1.0f - x) * g;
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x = expf(-2.0f * F_PI * Fc_hi / bs2b->srate);
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bs2b->b1_hi = x;
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bs2b->a0_hi = (1.0f - G_hi * (1.0f - x)) * g;
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bs2b->a1_hi = -x * g;
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} /* init */
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/* Exported functions.
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* See descriptions in "bs2b.h"
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*/
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void bs2b_set_params(struct bs2b *bs2b, int level, int srate)
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{
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if(srate <= 0) srate = 1;
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bs2b->level = level;
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bs2b->srate = srate;
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init(bs2b);
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} /* bs2b_set_params */
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int bs2b_get_level(struct bs2b *bs2b)
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{
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return bs2b->level;
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} /* bs2b_get_level */
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int bs2b_get_srate(struct bs2b *bs2b)
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{
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return bs2b->srate;
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} /* bs2b_get_srate */
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void bs2b_clear(struct bs2b *bs2b)
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{
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memset(&bs2b->last_sample, 0, sizeof(bs2b->last_sample));
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} /* bs2b_clear */
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extern inline void bs2b_cross_feed(struct bs2b *bs2b, float *restrict samples);
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