engines/common/BiquadFilter.h

/***************************************************************************
 *                                                                         *
 *   LinuxSampler - modular, streaming capable sampler                     *
 *                                                                         *
 *   Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck   *
 *   Copyright (C) 2005 Christian Schoenebeck                              *
 *                                                                         *
 *   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., 59 Temple Place, Suite 330, Boston,                 *
 *   MA  02111-1307  USA                                                   *
 ***************************************************************************/

#ifndef __LS_BIQUADFILTER_H__
#define __LS_BIQUADFILTER_H__

#include <math.h>

#include "../../common/global.h"

/// ln(2) / 2
#define LN_2_2                  0.34657359f

#ifndef LIMIT
# define LIMIT(v,l,u)           (v < l ? l : (v > u ? u : v))
#endif

namespace LinuxSampler {

    typedef float bq_t;

    /**
     * Internal parameters of the biquad filter, which are actually the
     * final parameters of the filter's transfer function. This strucure is
     * only needed when these parameters should stored outside the
     * BiquadFilter class, e.g. to save calculation time by sharing them
     * between multiple filters.
     */
    struct biquad_param_t {
        bq_t b0;
        bq_t b1;
        bq_t b2;
        bq_t a1;
        bq_t a2;
    };

    /**
     * Bi-quadratic filter
     * (adapted from lisp code by Eli Brandt, http://www.cs.cmu.edu/~eli/)
     */
    class BiquadFilter {
        protected:
            // following five variables are only used if no external biquad_param_t reference is used
            bq_t b0;
            bq_t b1;
            bq_t b2;
            bq_t a1;
            bq_t a2;
            // following four variables are used to buffer the feedback
            bq_t x1;
            bq_t x2;
            bq_t y1;
            bq_t y2;

#if __GNUC__ >= 4
            float fbc;
#else
            const static float fbc = 0.98;
#endif

            /**
             * Prevent \a f from going into denormal mode which would slow down
             * subsequent floating point calculations, we achieve that by setting
             * \a f to zero when it falls under the denormal threshold value.
             */
            inline void KillDenormal(bq_t& f) {
                // TODO: this is a generic solution for 32bit floats, should be replaced by CPU specific asm code
                f += 1e-18f;
                f -= 1e-18f;
            }
        public:
            BiquadFilter() {
                Reset();
#if __GNUC__ >= 4
                fbc = 0.98f;
#endif
            }

            void Reset() {
                x1 = 0.0f;
                x2 = 0.0f;
                y1 = 0.0f;
                y2 = 0.0f;
            }

            inline bq_t Apply(const bq_t x) {
                bq_t y;

                y = this->b0 * x + this->b1 * this->x1 + this->b2 * this->x2 +
                    this->a1 * this->y1 + this->a2 * this->y2;
                KillDenormal(y);
                this->x2 = this->x1;
                this->x1 = x;
                this->y2 = this->y1;
                this->y1 = y;

                return y;
            }

            inline bq_t Apply(biquad_param_t* param, const bq_t x) {
                bq_t y;

                y = param->b0 * x + param->b1 * this->x1 + param->b2 * this->x2 +
                    param->a1 * this->y1 + param->a2 * this->y2;
                KillDenormal(y);
                this->x2 = this->x1;
                this->x1 = x;
                this->y2 = this->y1;
                this->y1 = y;

                return y;
            }

#if CONFIG_ASM && ARCH_X86
            // expects to find input in xmm0 (xmm0 stays unmodified) and finally leaves output in xmm6
            inline void Apply4StepsSSE(biquad_param_t* param) {
                __asm__ __volatile__ (
                    "movss (%2),%%xmm4                # b0\n\t"
                    "shufps   $0x00,%%xmm4,%%xmm4     # copy b0 to other cells\n\t"
                    "mulps  %%xmm0,%%xmm4             # xmm4 = x*b0\n\t"
                    "movups (%0),%%xmm2               # load b1,b2,a1,a2\n\t"
                    "movups (%1),%%xmm5               # load x1,x2,y1,y2\n\t"
                    /* sample 0 */
                    "movaps %%xmm5,%%xmm3\n\t"
                    "mulps  %%xmm2,%%xmm5             # xmm5 = [b1,b2,a1,a2] * [x1,x2,y1,y2]\n\t"
                    "shufps $0x0a,%%xmm3,%%xmm3       # x2 = x1, y2 = y1\n\t"
                    "movss  %%xmm4,%%xmm6\n\t"
                    "addss  %%xmm5,%%xmm6\n\t"
                    "shufps $0x39,%%xmm5,%%xmm5\n\t"
                    "addss  %%xmm5,%%xmm6\n\t"
                    "shufps $0x39,%%xmm5,%%xmm5\n\t"
                    "addss  %%xmm5,%%xmm6\n\t"
                    "shufps $0x39,%%xmm5,%%xmm5\n\t"
                    "addss  %%xmm5,%%xmm6             # xmm6 = b0*x + b1*x1 + b2*x2 + a1*y1 + a2*y2\n\t"
                    /* sample 1 */
                    "shufps $0x39,%%xmm4,%%xmm4       # rotate xmm4 down 1 cell\n\t"
                    "movss  %%xmm6,%%xmm3             # y1 = y\n\t"
                    "shufps $0x4e,%%xmm3,%%xmm3       # rotate 2 cells\n\t"
                    "movss  %%xmm0,%%xmm3             # x1 = x\n\t"
                    "shufps $0x93,%%xmm6,%%xmm6       # rotate output up 1 cell\n\t"
                    "movaps %%xmm3,%%xmm5\n\t"
                    "shufps $0x39,%%xmm0,%%xmm0       # rotate input down 1 cell\n\t"
                    "mulps  %%xmm2,%%xmm5             # xmm5 = [b1,b2,a1,a2] * [x1,x2,y1,y2]\n\t"
                    "movss  %%xmm5,%%xmm6\n\t"
                    "addss  %%xmm4,%%xmm6\n\t"
                    "shufps $0x39,%%xmm5,%%xmm5\n\t"
                    "addss  %%xmm5,%%xmm6\n\t"
                    "shufps $0x39,%%xmm5,%%xmm5\n\t"
                    "addss  %%xmm5,%%xmm6\n\t"
                    "shufps $0x39,%%xmm5,%%xmm5\n\t"
                    "addss  %%xmm5,%%xmm6             # xmm6 = b0*x + b1*x1 + b2*x2 + a1*y1 + a2*y2\n\t"
                    /* sample 2 */
                    "shufps $0x0a,%%xmm3,%%xmm3       # x2 = x1, y2 = y1\n\t"
                    "shufps $0x39,%%xmm4,%%xmm4       # rotate xmm4 down 1 cell\n\t"
                    "movss  %%xmm6,%%xmm3             # y1 = y\n\t"
                    "shufps $0x4e,%%xmm3,%%xmm3       # rotate 2 cells\n\t"
                    "movss  %%xmm0,%%xmm3             # x1 = x\n\t"
                    "shufps $0x93,%%xmm6,%%xmm6       # rotate output up 1 cell\n\t"
                    "movaps %%xmm3,%%xmm5\n\t"
                    "shufps $0x39,%%xmm0,%%xmm0       # rotate input down 1 cell\n\t"
                    "mulps  %%xmm2,%%xmm5             # xmm5 = [b1,b2,a1,a2] * [x1,x2,y1,y2]\n\t"
                    "movss  %%xmm5,%%xmm6\n\t"
                    "addss  %%xmm4,%%xmm6\n\t"
                    "shufps $0x39,%%xmm5,%%xmm5\n\t"
                    "addss  %%xmm5,%%xmm6\n\t"
                    "shufps $0x39,%%xmm5,%%xmm5\n\t"
                    "addss  %%xmm5,%%xmm6\n\t"
                    "shufps $0x39,%%xmm5,%%xmm5\n\t"
                    "addss  %%xmm5,%%xmm6             # xmm6 = b0*x + b1*x1 + b2*x2 + a1*y1 + a2*y2\n\t"
                    /* sample 3 */
                    "shufps $0x0a,%%xmm3,%%xmm3       # x2 = x1, y2 = y1\n\t"
                    "shufps $0x39,%%xmm4,%%xmm4       # rotate xmm4 down 1 cell\n\t"
                    "movss  %%xmm6,%%xmm3             # y1 = y\n\t"
                    "shufps $0x4e,%%xmm3,%%xmm3       # rotate 2 cells\n\t"
                    "movss  %%xmm0,%%xmm3             # x1 = x\n\t"
                    "shufps $0x93,%%xmm6,%%xmm6       # rotate output up 1 cell\n\t"
                    "mulps  %%xmm3,%%xmm2             # xmm5 = [b1,b2,a1,a2] * [x1,x2,y1,y2]\n\t"
                    "shufps $0x39,%%xmm0,%%xmm0       # rotate input down 1 cell\n\t"
                    "movss  %%xmm2,%%xmm6\n\t"
                    "shufps $0x39,%%xmm2,%%xmm2\n\t"
                    "addss  %%xmm2,%%xmm6\n\t"
                    "shufps $0x39,%%xmm2,%%xmm2\n\t"
                    "addss  %%xmm2,%%xmm6\n\t"
                    "shufps $0x39,%%xmm2,%%xmm2\n\t"
                    "addss  %%xmm2,%%xmm6\n\t"
                    "addss  %%xmm4,%%xmm6             # xmm6 = b0*x + b1*x1 + b2*x2 + a1*y1 + a2*y2\n\t"
                    /* done */
                    "shufps $0x0a,%%xmm3,%%xmm3       # x2 = x1, y2 = y1\n\t"
                    "movss  %%xmm6,%%xmm3             # y1 = y\n\t"
                    "shufps $0x4e,%%xmm3,%%xmm3       # rotate 2 cells\n\t"
                    "movss  %%xmm0,%%xmm3             # x1 = x\n\t"
                    "shufps $0x1b,%%xmm6,%%xmm6       # swap output to correct order\n\t"
                    "shufps $0x39,%%xmm0,%%xmm0       # rotate input down 1 cell, to restore original input\n\t"
                    "movups %%xmm3,(%1)               # store x1,x2,y1,y2\n\t"
                    : /* no output */
                    : "r" (&param->b1), /* %0 - [b1,b2,a1,a2] */
                      "r" (&x1),        /* %1 - [x1,x2,y1,y2] */
                      "r" (&param->b0)  /* %2 */
                );
            }
#endif // CONFIG_ASM && ARCH_X86

            inline bq_t ApplyFB(bq_t x, const bq_t fb) {
                bq_t y;

                x += this->y1 * fb * 0.98;
                y = this->b0 * x + this->b1 * this->x1 + this->b2 * this->x2 +
                    this->a1 * this->y1 + this->a2 * this->y2;
                KillDenormal(y);
                this->x2 = this->x1;
                this->x1 = x;
                this->y2 = this->y1;
                this->y1 = y;

                return y;
            }

            inline bq_t ApplyFB(biquad_param_t* param, bq_t x, const bq_t fb) {
                bq_t y;

                x += this->y1 * fb * 0.98;
                y = param->b0 * x + param->b1 * this->x1 + param->b2 * this->x2 +
                    param->a1 * this->y1 + param->a2 * this->y2;
                KillDenormal(y);
                this->x2 = this->x1;
                this->x1 = x;
                this->y2 = this->y1;
                this->y1 = y;

                return y;
            }

#if CONFIG_ASM && ARCH_X86
            // expects to find input in xmm0 (xmm0 stays unmodified) and finally leaves output in xmm7
            inline void ApplyFB4StepsSSE(biquad_param_t* param, const bq_t &fb) {
                float xs, ys;
                float t0, t1, t2, t3, t4, t5, t6, t7, t8; // temporary stack space
                __asm__ __volatile__ (
                    /* prepare input */
                    "movss  %15,%%xmm5\n\t"
                    "movss  %%xmm0,(%14)\n\t"
                    /* sample 0 */
                    "movss   %0, %%xmm3\n\t"
                    "movss   %1, %%xmm4\n\t"
                    "mulss   %%xmm4, %%xmm5\n\t"
                    "movss   %%xmm3, %2\n\t"
                    "movss   %%xmm5, %16\n\t"
                    "mulss   %%xmm3, %%xmm5\n\t"
                    "movss   %19, %%xmm2\n\t"
                    "movss   %3, %%xmm6\n\t"
                    "movss   %21, %%xmm3\n\t"
                    "addss   %%xmm5, %%xmm6\n\t"
                    "movss  %%xmm2, %%xmm5\n\t"
                    "movss   %20, %%xmm4\n\t"
                    "movss   %%xmm6, %4\n\t"
                    "mulss   %%xmm6, %%xmm5\n\t"
                    "movss   %5, %%xmm6\n\t"
                    "movss   %%xmm2, %6\n\t"
                    "movss   %%xmm4, %7\n\t"
                    "movss   %%xmm3, %%xmm2\n\t"
                    "mulss   %%xmm6, %%xmm4\n\t"
                    "mulss   %8, %%xmm2\n\t"
                    "movss   %%xmm3, %9\n\t"
                    "addss   %%xmm4, %%xmm5\n\t"
                    "movss   %18, %%xmm3\n\t"
                    "movss   %17, %%xmm4\n\t"
                    "addss   %%xmm2, %%xmm5\n\t"
                    "movss   %%xmm4, %10\n\t"
                    "movss   %%xmm3, %%xmm2\n\t"
                    "mulss   %11, %%xmm4\n\t"
                    "mulss   %12, %%xmm2\n\t"
                    "movss   %%xmm3, %13\n\t"
                    "addss   %%xmm4, %%xmm5\n\t"
                    "movss   %11, %%xmm3\n\t"
                    "movss   %4, %%xmm4\n\t"
                    "addss   %%xmm2, %%xmm5\n\t"
                    :: "m" (y1),  /* %0 */
                       "m" (fbc), /* %1 */
                       "m" (t0),  /* %2 */
                       "m" (xs),  /* %3 */
                       "m" (t7),  /* %4 */
                       "m" (x1),  /* %5 */
                       "m" (t1),  /* %6 */
                       "m" (t2),  /* %7 */
                       "m" (x2),  /* %8 */
                       "m" (t3),  /* %9 */
                       "m" (t4),  /* %10 */
                       "m" (t0),  /* %11 */
                       "m" (y2),  /* %12 */
                       "m" (t5),  /* %13 */
                       "r" (&xs),  /* %14 */
                       "m" (fb),   /* %15 */
                       "m" (ys),   /* %16 */
                       "m" (param->a1), /* %17 */
                       "m" (param->a2), /* %18 */
                       "m" (param->b0), /* %19 */
                       "m" (param->b1), /* %20 */
                       "m" (param->b2) /* %21 */
                );
                __asm__ __volatile__ (
                    "shufps $0x39,%%xmm0,%%xmm0  # rotate down one cell\n\t"
                    "movss  %%xmm5,%%xmm7\n\t"
                    ::
                );
                /* sample 1 */
                __asm__ __volatile__ (
                    "movss   %0, %%xmm4\n\t"
                    "movss   %%xmm0, %%xmm3\n\t"
                    "mulss   %%xmm5, %%xmm4\n\t"
                    "mulss   %3, %%xmm6\n\t"
                    "movss   %5, %%xmm2\n\t"
                    "addss   %%xmm4, %%xmm3\n\t"
                    "mulss   %7, %%xmm2\n\t"
                    "movss   %6, %%xmm4\n\t"
                    "movss   %%xmm3, %8\n\t"
                    "mulss   %%xmm3, %%xmm4\n\t"
                    "addss   %%xmm2, %%xmm4\n\t"
                    "movss   %9, %%xmm3\n\t"
                    "mulss   %%xmm5, %%xmm3\n\t"
                    "movss   %10, %%xmm2\n\t"
                    "addss   %%xmm6, %%xmm4\n\t"
                    "mulss   %11, %%xmm2\n\t"
                    "addss   %%xmm3, %%xmm4\n\t"
                    "addss   %%xmm2, %%xmm4\n\t"
                    :: "m" (ys),  /* %0 */
                       "m" (fbc), /* %1 */
                       "m" (xs),  /* %2 */
                       "m" (t3),  /* %3 */
                       "m" (y2),  /* %4 */
                       "m" (t2),  /* %5 */
                       "m" (t1),  /* %6 */
                       "m" (t7),  /* %7 */
                       "m" (t8),  /* %8 */
                       "m" (t4),  /* %9 */
                       "m" (t5),  /* %10 */
                       "m" (t0),  /* %11 */
                       "m" (x2),  /* %12 */
                       "m" (x1),  /* %13 */
                       "m" (y1)   /* %14 */
                );
                __asm__ __volatile__ (
                    "shufps $0x93,%%xmm7,%%xmm7  # rotate up one cell\n\t"
                    "shufps $0x39,%%xmm0,%%xmm0  # rotate down one cell\n\t"
                    "movss  %%xmm4,%%xmm7\n\t"
                    ::
                );
                /* sample 2 */
                __asm__ __volatile__ (
                    "movss   %2, %%xmm6\n\t"
                    "movss   %3, %%xmm3\n\t"
                    "mulss   %%xmm4, %%xmm6\n\t"
                    "movss   %4, %%xmm2\n\t"
                    "mulss   %9, %%xmm2\n\t"
                    "addss   %%xmm0, %%xmm6\n\t"
                    "mulss   %7, %%xmm5\n\t"
                    "mulss   %%xmm6, %%xmm3\n\t"
                    "addss   %%xmm2, %%xmm3\n\t"
                    "movss   %5, %%xmm2\n\t"
                    "mulss   %8, %%xmm2\n\t"
                    "addss   %%xmm2, %%xmm3\n\t"
                    "movss   %6, %%xmm2\n\t"
                    "mulss   %%xmm4, %%xmm2\n\t"
                    "addss   %%xmm5, %%xmm2\n\t"
                    "addss   %%xmm2, %%xmm3\n\t"
                    :: "m" (xs),  /* %0 */
                       "m" (fb),  /* %1 */
                       "m" (ys), /* %2 */
                       "m" (t1),  /* %3 */
                       "m" (t2),  /* %4 */
                       "m" (t3),  /* %5 */
                       "m" (t4),  /* %6 */
                       "m" (t5),  /* %7 */
                       "m" (t7),  /* %8 */
                       "m" (t8),  /* %9 */
                       "m" (x1),  /* %10 */
                       "m" (x2),  /* %11 */
                       "m" (y1),  /* %12 */
                       "m" (y2)   /* %13 */
                );
                __asm__ __volatile__ (
                    "shufps $0x39,%%xmm0,%%xmm0  # rotate down one cell\n\t"
                    "shufps $0x93,%%xmm7,%%xmm7  # rotate up one cell\n\t"
                    "movss  %%xmm3,%%xmm7\n\t"
                    ::
                );
                /* sample 3 */
                __asm__ __volatile__ (
                    "movss   %1, %%xmm2\n\t"
                    "mulss   %7, %%xmm4\n\t"
                    "mulss   %%xmm3, %%xmm2\n\t"
                    "movss   %3, %%xmm5\n\t"
                    "movss   %%xmm6, %11\n\t"
                    "addss   %%xmm0, %%xmm2\n\t"
                    "movss   %%xmm3, %13\n\t"
                    "mulss   %%xmm2, %%xmm5\n\t"
                    "mulss   %4, %%xmm6\n\t"
                    "movss   %%xmm2, %10\n\t"
                    "addss   %%xmm6, %%xmm5\n\t"
                    "movss   %5, %%xmm2\n\t"
                    "mulss   %9, %%xmm2\n\t"
                    "mulss   %6, %%xmm3\n\t"
                    "addss   %%xmm2, %%xmm5\n\t"
                    "addss   %%xmm3, %%xmm4\n\t"
                    "addss   %%xmm4, %%xmm5\n\t"
                    "movss   %%xmm5, %12\n\t"
                    :: "m" (xs),  /* %0 */
                       "m" (ys),  /* %1 */
                       "m" (fbc), /* %2 */
                       "m" (t1),  /* %3 */
                       "m" (t2),  /* %4 */
                       "m" (t3),  /* %5 */
                       "m" (t4),  /* %6 */
                       "m" (t5),  /* %7 */
                       "m" (t6),  /* %8 */
                       "m" (t8),  /* %9 */
                       "m" (x1),  /* %10 */
                       "m" (x2),  /* %11 */
                       "m" (y1),  /* %12 */
                       "m" (y2)   /* %13 */
                );
                __asm__ __volatile__ (
                    "shufps $0x93,%%xmm7,%%xmm7  # rotate up one cell\n\t"
                    "shufps $0x39,%%xmm0,%%xmm0  # rotate down one cell to restore original input\n\t"
                    "movss  %%xmm5,%%xmm7\n\t"
                    "shufps $0x1b,%%xmm7,%%xmm7  # swap output to correct order\n\t"
                    ::
                );
            }
#endif // CONFIG_ASM && ARCH_X86
    };

    /** @brief Lowpass Filter
     *
     * Lowpass filter based on biquad filter implementation.
     */
    class LowpassFilter : public BiquadFilter {
        public:
            inline LowpassFilter() : BiquadFilter() {}

            inline void SetParameters(bq_t fc, bq_t bw, bq_t fs) {
                bq_t omega = 2.0 * M_PI * fc / fs;
                bq_t sn    = sin(omega);
                bq_t cs    = cos(omega);
                bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);

                const float a0r = 1.0 / (1.0 + alpha);
                this->b0 = a0r * (1.0 - cs) * 0.5;
                this->b1 = a0r * (1.0 - cs);
                this->b2 = a0r * (1.0 - cs) * 0.5;
                this->a1 = a0r * (2.0 * cs);
                this->a2 = a0r * (alpha - 1.0);
            }

            inline void SetParameters(biquad_param_t* param, bq_t fc, bq_t bw, bq_t fs) {
                bq_t omega = 2.0 * M_PI * fc / fs;
                bq_t sn    = sin(omega);
                bq_t cs    = cos(omega);
                bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);

                const float a0r = 1.0 / (1.0 + alpha);
                param->b0 = a0r * (1.0 - cs) * 0.5;
                param->b1 = a0r * (1.0 - cs);
                param->b2 = a0r * (1.0 - cs) * 0.5;
                param->a1 = a0r * (2.0 * cs);
                param->a2 = a0r * (alpha - 1.0);
            }
    };

    /** @brief Bandpass Filter
     *
     * Bandpass filter based on biquad filter implementation.
     */
    class BandpassFilter : public BiquadFilter {
        public:
            inline BandpassFilter() : BiquadFilter() {}

            inline void SetParameters(bq_t fc, bq_t bw, bq_t fs) {
                bq_t omega = 2.0 * M_PI * fc / fs;
                bq_t sn    = sin(omega);
                bq_t cs    = cos(omega);
                bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);

                const float a0r = 1.0 / (1.0 + alpha);
                this->b0 = a0r * alpha;
                this->b1 = 0.0;
                this->b2 = a0r * -alpha;
                this->a1 = a0r * (2.0 * cs);
                this->a2 = a0r * (alpha - 1.0);
            }

            inline void SetParameters(biquad_param_t* param, bq_t fc, bq_t bw, bq_t fs) {
                bq_t omega = 2.0 * M_PI * fc / fs;
                bq_t sn    = sin(omega);
                bq_t cs    = cos(omega);
                bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);

                const float a0r = 1.0 / (1.0 + alpha);
                param->b0 = a0r * alpha;
                param->b1 = 0.0;
                param->b2 = a0r * -alpha;
                param->a1 = a0r * (2.0 * cs);
                param->a2 = a0r * (alpha - 1.0);
            }
    };

    /** @brief Highpass Filter
     *
     * Highpass filter based on biquad filter implementation.
     */
    class HighpassFilter : public BiquadFilter {
        public:
            inline HighpassFilter() : BiquadFilter() {}

            inline void SetParameters(bq_t fc, bq_t bw, bq_t fs) {
                bq_t omega = 2.0 * M_PI * fc / fs;
                bq_t sn    = sin(omega);
                bq_t cs    = cos(omega);
                bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);

                const float a0r = 1.0 / (1.0 + alpha);
                this->b0 = a0r * (1.0 + cs) * 0.5;
                this->b1 = a0r * -(1.0 + cs);
                this->b2 = a0r * (1.0 + cs) * 0.5;
                this->a1 = a0r * (2.0 * cs);
                this->a2 = a0r * (alpha - 1.0);
            }

            inline void SetParameters(biquad_param_t* param, bq_t fc, bq_t bw, bq_t fs) {
                bq_t omega = 2.0 * M_PI * fc / fs;
                bq_t sn    = sin(omega);
                bq_t cs    = cos(omega);
                bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);

                const float a0r = 1.0 / (1.0 + alpha);
                param->b0 = a0r * (1.0 + cs) * 0.5;
                param->b1 = a0r * -(1.0 + cs);
                param->b2 = a0r * (1.0 + cs) * 0.5;
                param->a1 = a0r * (2.0 * cs);
                param->a2 = a0r * (alpha - 1.0);
            }
    };

} // namespace LinuxSampler

#endif // __LS_BIQUADFILTER_H__
1	schoenebeck	53	/***************************************************************************
2			* *
3			* LinuxSampler - modular, streaming capable sampler *
4			* *
5	schoenebeck	56	* Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck *
6	schoenebeck	617	* Copyright (C) 2005 Christian Schoenebeck *
7	schoenebeck	53	* *
8			* This program is free software; you can redistribute it and/or modify *
9			* it under the terms of the GNU General Public License as published by *
10			* the Free Software Foundation; either version 2 of the License, or *
11			* (at your option) any later version. *
12			* *
13			* This program is distributed in the hope that it will be useful, *
14			* but WITHOUT ANY WARRANTY; without even the implied warranty of *
15			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
16			* GNU General Public License for more details. *
17			* *
18			* You should have received a copy of the GNU General Public License *
19			* along with this program; if not, write to the Free Software *
20			* Foundation, Inc., 59 Temple Place, Suite 330, Boston, *
21			* MA 02111-1307 USA *
22			***************************************************************************/
23
24			#ifndef __LS_BIQUADFILTER_H__
25			#define __LS_BIQUADFILTER_H__
26
27	capela	268	#include <math.h>
28
29	schoenebeck	328	#include "../../common/global.h"
30
31	schoenebeck	53	/// ln(2) / 2
32			#define LN_2_2 0.34657359f
33
34			#ifndef LIMIT
35			# define LIMIT(v,l,u) (v < l ? l : (v > u ? u : v))
36			#endif
37
38			namespace LinuxSampler {
39
40			typedef float bq_t;
41
42			/**
43	schoenebeck	80	* Internal parameters of the biquad filter, which are actually the
44			* final parameters of the filter's transfer function. This strucure is
45			* only needed when these parameters should stored outside the
46			* BiquadFilter class, e.g. to save calculation time by sharing them
47			* between multiple filters.
48			*/
49			struct biquad_param_t {
50			bq_t b0;
51			bq_t b1;
52			bq_t b2;
53	senkov	324	bq_t a1;
54			bq_t a2;
55	schoenebeck	80	};
56
57			/**
58			* Bi-quadratic filter
59			* (adapted from lisp code by Eli Brandt, http://www.cs.cmu.edu/~eli/)
60			*/
61	schoenebeck	53	class BiquadFilter {
62			protected:
63	schoenebeck	80	// following five variables are only used if no external biquad_param_t reference is used
64	schoenebeck	53	bq_t b0;
65			bq_t b1;
66			bq_t b2;
67	senkov	324	bq_t a1;
68			bq_t a2;
69	schoenebeck	80	// following four variables are used to buffer the feedback
70	schoenebeck	53	bq_t x1;
71			bq_t x2;
72			bq_t y1;
73			bq_t y2;
74
75	persson	685	#if __GNUC__ >= 4
76			float fbc;
77			#else
78	schoenebeck	319	const static float fbc = 0.98;
79	persson	685	#endif
80	schoenebeck	319
81	schoenebeck	53	/**
82	schoenebeck	80	* Prevent \a f from going into denormal mode which would slow down
83			* subsequent floating point calculations, we achieve that by setting
84			* \a f to zero when it falls under the denormal threshold value.
85			*/
86			inline void KillDenormal(bq_t& f) {
87	schoenebeck	53	// TODO: this is a generic solution for 32bit floats, should be replaced by CPU specific asm code
88			f += 1e-18f;
89			f -= 1e-18f;
90			}
91			public:
92	schoenebeck	319	BiquadFilter() {
93			Reset();
94	persson	685	#if __GNUC__ >= 4
95			fbc = 0.98f;
96			#endif
97	schoenebeck	319	}
98
99			void Reset() {
100	schoenebeck	53	x1 = 0.0f;
101			x2 = 0.0f;
102			y1 = 0.0f;
103			y2 = 0.0f;
104			}
105
106			inline bq_t Apply(const bq_t x) {
107			bq_t y;
108
109			y = this->b0 * x + this->b1 * this->x1 + this->b2 * this->x2 +
110			this->a1 * this->y1 + this->a2 * this->y2;
111			KillDenormal(y);
112			this->x2 = this->x1;
113			this->x1 = x;
114			this->y2 = this->y1;
115			this->y1 = y;
116
117			return y;
118			}
119
120	schoenebeck	80	inline bq_t Apply(biquad_param_t* param, const bq_t x) {
121			bq_t y;
122
123			y = param->b0 * x + param->b1 * this->x1 + param->b2 * this->x2 +
124			param->a1 * this->y1 + param->a2 * this->y2;
125			KillDenormal(y);
126			this->x2 = this->x1;
127			this->x1 = x;
128			this->y2 = this->y1;
129			this->y1 = y;
130
131			return y;
132			}
133
134	schoenebeck	617	#if CONFIG_ASM && ARCH_X86
135	schoenebeck	319	// expects to find input in xmm0 (xmm0 stays unmodified) and finally leaves output in xmm6
136			inline void Apply4StepsSSE(biquad_param_t* param) {
137			__asm__ __volatile__ (
138			"movss (%2),%%xmm4 # b0\n\t"
139			"shufps $0x00,%%xmm4,%%xmm4 # copy b0 to other cells\n\t"
140			"mulps %%xmm0,%%xmm4 # xmm4 = x*b0\n\t"
141			"movups (%0),%%xmm2 # load b1,b2,a1,a2\n\t"
142			"movups (%1),%%xmm5 # load x1,x2,y1,y2\n\t"
143			/* sample 0 */
144			"movaps %%xmm5,%%xmm3\n\t"
145			"mulps %%xmm2,%%xmm5 # xmm5 = [b1,b2,a1,a2] * [x1,x2,y1,y2]\n\t"
146			"shufps $0x0a,%%xmm3,%%xmm3 # x2 = x1, y2 = y1\n\t"
147			"movss %%xmm4,%%xmm6\n\t"
148			"addss %%xmm5,%%xmm6\n\t"
149			"shufps $0x39,%%xmm5,%%xmm5\n\t"
150			"addss %%xmm5,%%xmm6\n\t"
151			"shufps $0x39,%%xmm5,%%xmm5\n\t"
152			"addss %%xmm5,%%xmm6\n\t"
153			"shufps $0x39,%%xmm5,%%xmm5\n\t"
154			"addss %%xmm5,%%xmm6 # xmm6 = b0x + b1x1 + b2x2 + a1y1 + a2*y2\n\t"
155			/* sample 1 */
156			"shufps $0x39,%%xmm4,%%xmm4 # rotate xmm4 down 1 cell\n\t"
157			"movss %%xmm6,%%xmm3 # y1 = y\n\t"
158			"shufps $0x4e,%%xmm3,%%xmm3 # rotate 2 cells\n\t"
159			"movss %%xmm0,%%xmm3 # x1 = x\n\t"
160			"shufps $0x93,%%xmm6,%%xmm6 # rotate output up 1 cell\n\t"
161			"movaps %%xmm3,%%xmm5\n\t"
162			"shufps $0x39,%%xmm0,%%xmm0 # rotate input down 1 cell\n\t"
163			"mulps %%xmm2,%%xmm5 # xmm5 = [b1,b2,a1,a2] * [x1,x2,y1,y2]\n\t"
164			"movss %%xmm5,%%xmm6\n\t"
165			"addss %%xmm4,%%xmm6\n\t"
166			"shufps $0x39,%%xmm5,%%xmm5\n\t"
167			"addss %%xmm5,%%xmm6\n\t"
168			"shufps $0x39,%%xmm5,%%xmm5\n\t"
169			"addss %%xmm5,%%xmm6\n\t"
170			"shufps $0x39,%%xmm5,%%xmm5\n\t"
171			"addss %%xmm5,%%xmm6 # xmm6 = b0x + b1x1 + b2x2 + a1y1 + a2*y2\n\t"
172			/* sample 2 */
173			"shufps $0x0a,%%xmm3,%%xmm3 # x2 = x1, y2 = y1\n\t"
174			"shufps $0x39,%%xmm4,%%xmm4 # rotate xmm4 down 1 cell\n\t"
175			"movss %%xmm6,%%xmm3 # y1 = y\n\t"
176			"shufps $0x4e,%%xmm3,%%xmm3 # rotate 2 cells\n\t"
177			"movss %%xmm0,%%xmm3 # x1 = x\n\t"
178			"shufps $0x93,%%xmm6,%%xmm6 # rotate output up 1 cell\n\t"
179			"movaps %%xmm3,%%xmm5\n\t"
180			"shufps $0x39,%%xmm0,%%xmm0 # rotate input down 1 cell\n\t"
181			"mulps %%xmm2,%%xmm5 # xmm5 = [b1,b2,a1,a2] * [x1,x2,y1,y2]\n\t"
182			"movss %%xmm5,%%xmm6\n\t"
183			"addss %%xmm4,%%xmm6\n\t"
184			"shufps $0x39,%%xmm5,%%xmm5\n\t"
185			"addss %%xmm5,%%xmm6\n\t"
186			"shufps $0x39,%%xmm5,%%xmm5\n\t"
187			"addss %%xmm5,%%xmm6\n\t"
188			"shufps $0x39,%%xmm5,%%xmm5\n\t"
189			"addss %%xmm5,%%xmm6 # xmm6 = b0x + b1x1 + b2x2 + a1y1 + a2*y2\n\t"
190			/* sample 3 */
191			"shufps $0x0a,%%xmm3,%%xmm3 # x2 = x1, y2 = y1\n\t"
192			"shufps $0x39,%%xmm4,%%xmm4 # rotate xmm4 down 1 cell\n\t"
193			"movss %%xmm6,%%xmm3 # y1 = y\n\t"
194			"shufps $0x4e,%%xmm3,%%xmm3 # rotate 2 cells\n\t"
195			"movss %%xmm0,%%xmm3 # x1 = x\n\t"
196			"shufps $0x93,%%xmm6,%%xmm6 # rotate output up 1 cell\n\t"
197			"mulps %%xmm3,%%xmm2 # xmm5 = [b1,b2,a1,a2] * [x1,x2,y1,y2]\n\t"
198			"shufps $0x39,%%xmm0,%%xmm0 # rotate input down 1 cell\n\t"
199			"movss %%xmm2,%%xmm6\n\t"
200			"shufps $0x39,%%xmm2,%%xmm2\n\t"
201			"addss %%xmm2,%%xmm6\n\t"
202			"shufps $0x39,%%xmm2,%%xmm2\n\t"
203			"addss %%xmm2,%%xmm6\n\t"
204			"shufps $0x39,%%xmm2,%%xmm2\n\t"
205			"addss %%xmm2,%%xmm6\n\t"
206			"addss %%xmm4,%%xmm6 # xmm6 = b0x + b1x1 + b2x2 + a1y1 + a2*y2\n\t"
207			/* done */
208			"shufps $0x0a,%%xmm3,%%xmm3 # x2 = x1, y2 = y1\n\t"
209			"movss %%xmm6,%%xmm3 # y1 = y\n\t"
210			"shufps $0x4e,%%xmm3,%%xmm3 # rotate 2 cells\n\t"
211			"movss %%xmm0,%%xmm3 # x1 = x\n\t"
212			"shufps $0x1b,%%xmm6,%%xmm6 # swap output to correct order\n\t"
213			"shufps $0x39,%%xmm0,%%xmm0 # rotate input down 1 cell, to restore original input\n\t"
214			"movups %%xmm3,(%1) # store x1,x2,y1,y2\n\t"
215			: /* no output */
216			: "r" (&param->b1), /* %0 - [b1,b2,a1,a2] */
217			"r" (&x1), /* %1 - [x1,x2,y1,y2] */
218			"r" (&param->b0) /* %2 */
219			);
220			}
221	schoenebeck	617	#endif // CONFIG_ASM && ARCH_X86
222	schoenebeck	319
223	schoenebeck	53	inline bq_t ApplyFB(bq_t x, const bq_t fb) {
224			bq_t y;
225
226			x += this->y1 * fb * 0.98;
227			y = this->b0 * x + this->b1 * this->x1 + this->b2 * this->x2 +
228			this->a1 * this->y1 + this->a2 * this->y2;
229			KillDenormal(y);
230			this->x2 = this->x1;
231			this->x1 = x;
232			this->y2 = this->y1;
233			this->y1 = y;
234
235			return y;
236			}
237	schoenebeck	80
238			inline bq_t ApplyFB(biquad_param_t* param, bq_t x, const bq_t fb) {
239			bq_t y;
240
241			x += this->y1 * fb * 0.98;
242			y = param->b0 * x + param->b1 * this->x1 + param->b2 * this->x2 +
243			param->a1 * this->y1 + param->a2 * this->y2;
244			KillDenormal(y);
245			this->x2 = this->x1;
246			this->x1 = x;
247			this->y2 = this->y1;
248			this->y1 = y;
249
250			return y;
251			}
252	schoenebeck	319
253	schoenebeck	617	#if CONFIG_ASM && ARCH_X86
254	schoenebeck	319	// expects to find input in xmm0 (xmm0 stays unmodified) and finally leaves output in xmm7
255			inline void ApplyFB4StepsSSE(biquad_param_t* param, const bq_t &fb) {
256			float xs, ys;
257			float t0, t1, t2, t3, t4, t5, t6, t7, t8; // temporary stack space
258			__asm__ __volatile__ (
259			/* prepare input */
260			"movss %15,%%xmm5\n\t"
261			"movss %%xmm0,(%14)\n\t"
262			/* sample 0 */
263			"movss %0, %%xmm3\n\t"
264			"movss %1, %%xmm4\n\t"
265			"mulss %%xmm4, %%xmm5\n\t"
266			"movss %%xmm3, %2\n\t"
267			"movss %%xmm5, %16\n\t"
268			"mulss %%xmm3, %%xmm5\n\t"
269			"movss %19, %%xmm2\n\t"
270			"movss %3, %%xmm6\n\t"
271			"movss %21, %%xmm3\n\t"
272			"addss %%xmm5, %%xmm6\n\t"
273			"movss %%xmm2, %%xmm5\n\t"
274			"movss %20, %%xmm4\n\t"
275			"movss %%xmm6, %4\n\t"
276			"mulss %%xmm6, %%xmm5\n\t"
277			"movss %5, %%xmm6\n\t"
278			"movss %%xmm2, %6\n\t"
279			"movss %%xmm4, %7\n\t"
280			"movss %%xmm3, %%xmm2\n\t"
281			"mulss %%xmm6, %%xmm4\n\t"
282			"mulss %8, %%xmm2\n\t"
283			"movss %%xmm3, %9\n\t"
284			"addss %%xmm4, %%xmm5\n\t"
285			"movss %18, %%xmm3\n\t"
286			"movss %17, %%xmm4\n\t"
287			"addss %%xmm2, %%xmm5\n\t"
288			"movss %%xmm4, %10\n\t"
289			"movss %%xmm3, %%xmm2\n\t"
290			"mulss %11, %%xmm4\n\t"
291			"mulss %12, %%xmm2\n\t"
292			"movss %%xmm3, %13\n\t"
293			"addss %%xmm4, %%xmm5\n\t"
294			"movss %11, %%xmm3\n\t"
295			"movss %4, %%xmm4\n\t"
296			"addss %%xmm2, %%xmm5\n\t"
297			:: "m" (y1), /* %0 */
298			"m" (fbc), /* %1 */
299			"m" (t0), /* %2 */
300			"m" (xs), /* %3 */
301			"m" (t7), /* %4 */
302			"m" (x1), /* %5 */
303			"m" (t1), /* %6 */
304			"m" (t2), /* %7 */
305			"m" (x2), /* %8 */
306			"m" (t3), /* %9 */
307			"m" (t4), /* %10 */
308			"m" (t0), /* %11 */
309			"m" (y2), /* %12 */
310			"m" (t5), /* %13 */
311			"r" (&xs), /* %14 */
312			"m" (fb), /* %15 */
313			"m" (ys), /* %16 */
314			"m" (param->a1), /* %17 */
315			"m" (param->a2), /* %18 */
316			"m" (param->b0), /* %19 */
317			"m" (param->b1), /* %20 */
318			"m" (param->b2) /* %21 */
319			);
320			__asm__ __volatile__ (
321			"shufps $0x39,%%xmm0,%%xmm0 # rotate down one cell\n\t"
322			"movss %%xmm5,%%xmm7\n\t"
323			::
324			);
325			/* sample 1 */
326			__asm__ __volatile__ (
327			"movss %0, %%xmm4\n\t"
328			"movss %%xmm0, %%xmm3\n\t"
329			"mulss %%xmm5, %%xmm4\n\t"
330			"mulss %3, %%xmm6\n\t"
331			"movss %5, %%xmm2\n\t"
332			"addss %%xmm4, %%xmm3\n\t"
333			"mulss %7, %%xmm2\n\t"
334			"movss %6, %%xmm4\n\t"
335			"movss %%xmm3, %8\n\t"
336			"mulss %%xmm3, %%xmm4\n\t"
337			"addss %%xmm2, %%xmm4\n\t"
338			"movss %9, %%xmm3\n\t"
339			"mulss %%xmm5, %%xmm3\n\t"
340			"movss %10, %%xmm2\n\t"
341			"addss %%xmm6, %%xmm4\n\t"
342			"mulss %11, %%xmm2\n\t"
343			"addss %%xmm3, %%xmm4\n\t"
344			"addss %%xmm2, %%xmm4\n\t"
345			:: "m" (ys), /* %0 */
346			"m" (fbc), /* %1 */
347			"m" (xs), /* %2 */
348			"m" (t3), /* %3 */
349			"m" (y2), /* %4 */
350			"m" (t2), /* %5 */
351			"m" (t1), /* %6 */
352			"m" (t7), /* %7 */
353			"m" (t8), /* %8 */
354			"m" (t4), /* %9 */
355			"m" (t5), /* %10 */
356			"m" (t0), /* %11 */
357			"m" (x2), /* %12 */
358			"m" (x1), /* %13 */
359			"m" (y1) /* %14 */
360			);
361			__asm__ __volatile__ (
362			"shufps $0x93,%%xmm7,%%xmm7 # rotate up one cell\n\t"
363			"shufps $0x39,%%xmm0,%%xmm0 # rotate down one cell\n\t"
364			"movss %%xmm4,%%xmm7\n\t"
365			::
366			);
367			/* sample 2 */
368			__asm__ __volatile__ (
369			"movss %2, %%xmm6\n\t"
370			"movss %3, %%xmm3\n\t"
371			"mulss %%xmm4, %%xmm6\n\t"
372			"movss %4, %%xmm2\n\t"
373			"mulss %9, %%xmm2\n\t"
374			"addss %%xmm0, %%xmm6\n\t"
375			"mulss %7, %%xmm5\n\t"
376			"mulss %%xmm6, %%xmm3\n\t"
377			"addss %%xmm2, %%xmm3\n\t"
378			"movss %5, %%xmm2\n\t"
379			"mulss %8, %%xmm2\n\t"
380			"addss %%xmm2, %%xmm3\n\t"
381			"movss %6, %%xmm2\n\t"
382			"mulss %%xmm4, %%xmm2\n\t"
383			"addss %%xmm5, %%xmm2\n\t"
384			"addss %%xmm2, %%xmm3\n\t"
385			:: "m" (xs), /* %0 */
386			"m" (fb), /* %1 */
387			"m" (ys), /* %2 */
388			"m" (t1), /* %3 */
389			"m" (t2), /* %4 */
390			"m" (t3), /* %5 */
391			"m" (t4), /* %6 */
392			"m" (t5), /* %7 */
393			"m" (t7), /* %8 */
394			"m" (t8), /* %9 */
395			"m" (x1), /* %10 */
396			"m" (x2), /* %11 */
397			"m" (y1), /* %12 */
398			"m" (y2) /* %13 */
399			);
400			__asm__ __volatile__ (
401			"shufps $0x39,%%xmm0,%%xmm0 # rotate down one cell\n\t"
402			"shufps $0x93,%%xmm7,%%xmm7 # rotate up one cell\n\t"
403			"movss %%xmm3,%%xmm7\n\t"
404			::
405			);
406			/* sample 3 */
407			__asm__ __volatile__ (
408			"movss %1, %%xmm2\n\t"
409			"mulss %7, %%xmm4\n\t"
410			"mulss %%xmm3, %%xmm2\n\t"
411			"movss %3, %%xmm5\n\t"
412			"movss %%xmm6, %11\n\t"
413			"addss %%xmm0, %%xmm2\n\t"
414			"movss %%xmm3, %13\n\t"
415			"mulss %%xmm2, %%xmm5\n\t"
416			"mulss %4, %%xmm6\n\t"
417			"movss %%xmm2, %10\n\t"
418			"addss %%xmm6, %%xmm5\n\t"
419			"movss %5, %%xmm2\n\t"
420			"mulss %9, %%xmm2\n\t"
421			"mulss %6, %%xmm3\n\t"
422			"addss %%xmm2, %%xmm5\n\t"
423			"addss %%xmm3, %%xmm4\n\t"
424			"addss %%xmm4, %%xmm5\n\t"
425			"movss %%xmm5, %12\n\t"
426			:: "m" (xs), /* %0 */
427			"m" (ys), /* %1 */
428			"m" (fbc), /* %2 */
429			"m" (t1), /* %3 */
430			"m" (t2), /* %4 */
431			"m" (t3), /* %5 */
432			"m" (t4), /* %6 */
433			"m" (t5), /* %7 */
434			"m" (t6), /* %8 */
435			"m" (t8), /* %9 */
436			"m" (x1), /* %10 */
437			"m" (x2), /* %11 */
438			"m" (y1), /* %12 */
439			"m" (y2) /* %13 */
440			);
441			__asm__ __volatile__ (
442			"shufps $0x93,%%xmm7,%%xmm7 # rotate up one cell\n\t"
443			"shufps $0x39,%%xmm0,%%xmm0 # rotate down one cell to restore original input\n\t"
444			"movss %%xmm5,%%xmm7\n\t"
445			"shufps $0x1b,%%xmm7,%%xmm7 # swap output to correct order\n\t"
446			::
447			);
448			}
449	schoenebeck	617	#endif // CONFIG_ASM && ARCH_X86
450	schoenebeck	53	};
451
452	schoenebeck	563	/** @brief Lowpass Filter
453			*
454			* Lowpass filter based on biquad filter implementation.
455			*/
456	schoenebeck	53	class LowpassFilter : public BiquadFilter {
457			public:
458			inline LowpassFilter() : BiquadFilter() {}
459
460			inline void SetParameters(bq_t fc, bq_t bw, bq_t fs) {
461			bq_t omega = 2.0 * M_PI * fc / fs;
462			bq_t sn = sin(omega);
463			bq_t cs = cos(omega);
464			bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);
465
466			const float a0r = 1.0 / (1.0 + alpha);
467			this->b0 = a0r * (1.0 - cs) * 0.5;
468			this->b1 = a0r * (1.0 - cs);
469			this->b2 = a0r * (1.0 - cs) * 0.5;
470			this->a1 = a0r * (2.0 * cs);
471			this->a2 = a0r * (alpha - 1.0);
472			}
473	schoenebeck	80
474			inline void SetParameters(biquad_param_t* param, bq_t fc, bq_t bw, bq_t fs) {
475			bq_t omega = 2.0 * M_PI * fc / fs;
476			bq_t sn = sin(omega);
477			bq_t cs = cos(omega);
478			bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);
479
480			const float a0r = 1.0 / (1.0 + alpha);
481			param->b0 = a0r * (1.0 - cs) * 0.5;
482			param->b1 = a0r * (1.0 - cs);
483			param->b2 = a0r * (1.0 - cs) * 0.5;
484			param->a1 = a0r * (2.0 * cs);
485			param->a2 = a0r * (alpha - 1.0);
486			}
487	schoenebeck	53	};
488
489	schoenebeck	563	/** @brief Bandpass Filter
490			*
491			* Bandpass filter based on biquad filter implementation.
492			*/
493	schoenebeck	53	class BandpassFilter : public BiquadFilter {
494			public:
495			inline BandpassFilter() : BiquadFilter() {}
496
497			inline void SetParameters(bq_t fc, bq_t bw, bq_t fs) {
498			bq_t omega = 2.0 * M_PI * fc / fs;
499			bq_t sn = sin(omega);
500			bq_t cs = cos(omega);
501			bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);
502
503			const float a0r = 1.0 / (1.0 + alpha);
504			this->b0 = a0r * alpha;
505			this->b1 = 0.0;
506			this->b2 = a0r * -alpha;
507			this->a1 = a0r * (2.0 * cs);
508			this->a2 = a0r * (alpha - 1.0);
509			}
510	schoenebeck	80
511			inline void SetParameters(biquad_param_t* param, bq_t fc, bq_t bw, bq_t fs) {
512			bq_t omega = 2.0 * M_PI * fc / fs;
513			bq_t sn = sin(omega);
514			bq_t cs = cos(omega);
515			bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);
516
517			const float a0r = 1.0 / (1.0 + alpha);
518			param->b0 = a0r * alpha;
519			param->b1 = 0.0;
520			param->b2 = a0r * -alpha;
521			param->a1 = a0r * (2.0 * cs);
522			param->a2 = a0r * (alpha - 1.0);
523			}
524	schoenebeck	53	};
525
526	schoenebeck	563	/** @brief Highpass Filter
527			*
528			* Highpass filter based on biquad filter implementation.
529			*/
530	schoenebeck	53	class HighpassFilter : public BiquadFilter {
531			public:
532			inline HighpassFilter() : BiquadFilter() {}
533
534			inline void SetParameters(bq_t fc, bq_t bw, bq_t fs) {
535			bq_t omega = 2.0 * M_PI * fc / fs;
536			bq_t sn = sin(omega);
537			bq_t cs = cos(omega);
538			bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);
539
540			const float a0r = 1.0 / (1.0 + alpha);
541			this->b0 = a0r * (1.0 + cs) * 0.5;
542			this->b1 = a0r * -(1.0 + cs);
543			this->b2 = a0r * (1.0 + cs) * 0.5;
544			this->a1 = a0r * (2.0 * cs);
545			this->a2 = a0r * (alpha - 1.0);
546			}
547	schoenebeck	80
548			inline void SetParameters(biquad_param_t* param, bq_t fc, bq_t bw, bq_t fs) {
549			bq_t omega = 2.0 * M_PI * fc / fs;
550			bq_t sn = sin(omega);
551			bq_t cs = cos(omega);
552			bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);
553
554			const float a0r = 1.0 / (1.0 + alpha);
555			param->b0 = a0r * (1.0 + cs) * 0.5;
556			param->b1 = a0r * -(1.0 + cs);
557			param->b2 = a0r * (1.0 + cs) * 0.5;
558			param->a1 = a0r * (2.0 * cs);
559			param->a2 = a0r * (alpha - 1.0);
560			}
561	schoenebeck	53	};
562
563			} // namespace LinuxSampler
564
565			#endif // __LS_BIQUADFILTER_H__