engines/common/BiquadFilter.h

/***************************************************************************
 *                                                                         *
 *   LinuxSampler - modular, streaming capable sampler                     *
 *                                                                         *
 *   Copyright (C) 2003, 2004 by Benno Senoner and 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>

/// 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 a1;
        bq_t a2;
        bq_t b0;
        bq_t b1;
        bq_t b2;
    };

    /**
     * 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 a1;
            bq_t a2;
            bq_t b0;
            bq_t b1;
            bq_t b2;
            // following four variables are used to buffer the feedback
            bq_t x1;
            bq_t x2;
            bq_t y1;
            bq_t y2;

            const static float fbc = 0.98;

            /**
             * 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();
            }

            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;
            }

            // 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 */
                );
            }

            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;
            }

            // 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"
                    ::
                );
            }
    };

    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);
            }
    };

    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);
            }
    };

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