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;

            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;
            }

#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	schoenebeck	319	const static float fbc = 0.98;
76
77	schoenebeck	53	/**
78	schoenebeck	80	* Prevent \a f from going into denormal mode which would slow down
79			* subsequent floating point calculations, we achieve that by setting
80			* \a f to zero when it falls under the denormal threshold value.
81			*/
82			inline void KillDenormal(bq_t& f) {
83	schoenebeck	53	// TODO: this is a generic solution for 32bit floats, should be replaced by CPU specific asm code
84			f += 1e-18f;
85			f -= 1e-18f;
86			}
87			public:
88	schoenebeck	319	BiquadFilter() {
89			Reset();
90			}
91
92			void Reset() {
93	schoenebeck	53	x1 = 0.0f;
94			x2 = 0.0f;
95			y1 = 0.0f;
96			y2 = 0.0f;
97			}
98
99			inline bq_t Apply(const bq_t x) {
100			bq_t y;
101
102			y = this->b0 * x + this->b1 * this->x1 + this->b2 * this->x2 +
103			this->a1 * this->y1 + this->a2 * this->y2;
104			KillDenormal(y);
105			this->x2 = this->x1;
106			this->x1 = x;
107			this->y2 = this->y1;
108			this->y1 = y;
109
110			return y;
111			}
112
113	schoenebeck	80	inline bq_t Apply(biquad_param_t* param, const bq_t x) {
114			bq_t y;
115
116			y = param->b0 * x + param->b1 * this->x1 + param->b2 * this->x2 +
117			param->a1 * this->y1 + param->a2 * this->y2;
118			KillDenormal(y);
119			this->x2 = this->x1;
120			this->x1 = x;
121			this->y2 = this->y1;
122			this->y1 = y;
123
124			return y;
125			}
126
127	schoenebeck	617	#if CONFIG_ASM && ARCH_X86
128	schoenebeck	319	// expects to find input in xmm0 (xmm0 stays unmodified) and finally leaves output in xmm6
129			inline void Apply4StepsSSE(biquad_param_t* param) {
130			__asm__ __volatile__ (
131			"movss (%2),%%xmm4 # b0\n\t"
132			"shufps $0x00,%%xmm4,%%xmm4 # copy b0 to other cells\n\t"
133			"mulps %%xmm0,%%xmm4 # xmm4 = x*b0\n\t"
134			"movups (%0),%%xmm2 # load b1,b2,a1,a2\n\t"
135			"movups (%1),%%xmm5 # load x1,x2,y1,y2\n\t"
136			/* sample 0 */
137			"movaps %%xmm5,%%xmm3\n\t"
138			"mulps %%xmm2,%%xmm5 # xmm5 = [b1,b2,a1,a2] * [x1,x2,y1,y2]\n\t"
139			"shufps $0x0a,%%xmm3,%%xmm3 # x2 = x1, y2 = y1\n\t"
140			"movss %%xmm4,%%xmm6\n\t"
141			"addss %%xmm5,%%xmm6\n\t"
142			"shufps $0x39,%%xmm5,%%xmm5\n\t"
143			"addss %%xmm5,%%xmm6\n\t"
144			"shufps $0x39,%%xmm5,%%xmm5\n\t"
145			"addss %%xmm5,%%xmm6\n\t"
146			"shufps $0x39,%%xmm5,%%xmm5\n\t"
147			"addss %%xmm5,%%xmm6 # xmm6 = b0x + b1x1 + b2x2 + a1y1 + a2*y2\n\t"
148			/* sample 1 */
149			"shufps $0x39,%%xmm4,%%xmm4 # rotate xmm4 down 1 cell\n\t"
150			"movss %%xmm6,%%xmm3 # y1 = y\n\t"
151			"shufps $0x4e,%%xmm3,%%xmm3 # rotate 2 cells\n\t"
152			"movss %%xmm0,%%xmm3 # x1 = x\n\t"
153			"shufps $0x93,%%xmm6,%%xmm6 # rotate output up 1 cell\n\t"
154			"movaps %%xmm3,%%xmm5\n\t"
155			"shufps $0x39,%%xmm0,%%xmm0 # rotate input down 1 cell\n\t"
156			"mulps %%xmm2,%%xmm5 # xmm5 = [b1,b2,a1,a2] * [x1,x2,y1,y2]\n\t"
157			"movss %%xmm5,%%xmm6\n\t"
158			"addss %%xmm4,%%xmm6\n\t"
159			"shufps $0x39,%%xmm5,%%xmm5\n\t"
160			"addss %%xmm5,%%xmm6\n\t"
161			"shufps $0x39,%%xmm5,%%xmm5\n\t"
162			"addss %%xmm5,%%xmm6\n\t"
163			"shufps $0x39,%%xmm5,%%xmm5\n\t"
164			"addss %%xmm5,%%xmm6 # xmm6 = b0x + b1x1 + b2x2 + a1y1 + a2*y2\n\t"
165			/* sample 2 */
166			"shufps $0x0a,%%xmm3,%%xmm3 # x2 = x1, y2 = y1\n\t"
167			"shufps $0x39,%%xmm4,%%xmm4 # rotate xmm4 down 1 cell\n\t"
168			"movss %%xmm6,%%xmm3 # y1 = y\n\t"
169			"shufps $0x4e,%%xmm3,%%xmm3 # rotate 2 cells\n\t"
170			"movss %%xmm0,%%xmm3 # x1 = x\n\t"
171			"shufps $0x93,%%xmm6,%%xmm6 # rotate output up 1 cell\n\t"
172			"movaps %%xmm3,%%xmm5\n\t"
173			"shufps $0x39,%%xmm0,%%xmm0 # rotate input down 1 cell\n\t"
174			"mulps %%xmm2,%%xmm5 # xmm5 = [b1,b2,a1,a2] * [x1,x2,y1,y2]\n\t"
175			"movss %%xmm5,%%xmm6\n\t"
176			"addss %%xmm4,%%xmm6\n\t"
177			"shufps $0x39,%%xmm5,%%xmm5\n\t"
178			"addss %%xmm5,%%xmm6\n\t"
179			"shufps $0x39,%%xmm5,%%xmm5\n\t"
180			"addss %%xmm5,%%xmm6\n\t"
181			"shufps $0x39,%%xmm5,%%xmm5\n\t"
182			"addss %%xmm5,%%xmm6 # xmm6 = b0x + b1x1 + b2x2 + a1y1 + a2*y2\n\t"
183			/* sample 3 */
184			"shufps $0x0a,%%xmm3,%%xmm3 # x2 = x1, y2 = y1\n\t"
185			"shufps $0x39,%%xmm4,%%xmm4 # rotate xmm4 down 1 cell\n\t"
186			"movss %%xmm6,%%xmm3 # y1 = y\n\t"
187			"shufps $0x4e,%%xmm3,%%xmm3 # rotate 2 cells\n\t"
188			"movss %%xmm0,%%xmm3 # x1 = x\n\t"
189			"shufps $0x93,%%xmm6,%%xmm6 # rotate output up 1 cell\n\t"
190			"mulps %%xmm3,%%xmm2 # xmm5 = [b1,b2,a1,a2] * [x1,x2,y1,y2]\n\t"
191			"shufps $0x39,%%xmm0,%%xmm0 # rotate input down 1 cell\n\t"
192			"movss %%xmm2,%%xmm6\n\t"
193			"shufps $0x39,%%xmm2,%%xmm2\n\t"
194			"addss %%xmm2,%%xmm6\n\t"
195			"shufps $0x39,%%xmm2,%%xmm2\n\t"
196			"addss %%xmm2,%%xmm6\n\t"
197			"shufps $0x39,%%xmm2,%%xmm2\n\t"
198			"addss %%xmm2,%%xmm6\n\t"
199			"addss %%xmm4,%%xmm6 # xmm6 = b0x + b1x1 + b2x2 + a1y1 + a2*y2\n\t"
200			/* done */
201			"shufps $0x0a,%%xmm3,%%xmm3 # x2 = x1, y2 = y1\n\t"
202			"movss %%xmm6,%%xmm3 # y1 = y\n\t"
203			"shufps $0x4e,%%xmm3,%%xmm3 # rotate 2 cells\n\t"
204			"movss %%xmm0,%%xmm3 # x1 = x\n\t"
205			"shufps $0x1b,%%xmm6,%%xmm6 # swap output to correct order\n\t"
206			"shufps $0x39,%%xmm0,%%xmm0 # rotate input down 1 cell, to restore original input\n\t"
207			"movups %%xmm3,(%1) # store x1,x2,y1,y2\n\t"
208			: /* no output */
209			: "r" (&param->b1), /* %0 - [b1,b2,a1,a2] */
210			"r" (&x1), /* %1 - [x1,x2,y1,y2] */
211			"r" (&param->b0) /* %2 */
212			);
213			}
214	schoenebeck	617	#endif // CONFIG_ASM && ARCH_X86
215	schoenebeck	319
216	schoenebeck	53	inline bq_t ApplyFB(bq_t x, const bq_t fb) {
217			bq_t y;
218
219			x += this->y1 * fb * 0.98;
220			y = this->b0 * x + this->b1 * this->x1 + this->b2 * this->x2 +
221			this->a1 * this->y1 + this->a2 * this->y2;
222			KillDenormal(y);
223			this->x2 = this->x1;
224			this->x1 = x;
225			this->y2 = this->y1;
226			this->y1 = y;
227
228			return y;
229			}
230	schoenebeck	80
231			inline bq_t ApplyFB(biquad_param_t* param, bq_t x, const bq_t fb) {
232			bq_t y;
233
234			x += this->y1 * fb * 0.98;
235			y = param->b0 * x + param->b1 * this->x1 + param->b2 * this->x2 +
236			param->a1 * this->y1 + param->a2 * this->y2;
237			KillDenormal(y);
238			this->x2 = this->x1;
239			this->x1 = x;
240			this->y2 = this->y1;
241			this->y1 = y;
242
243			return y;
244			}
245	schoenebeck	319
246	schoenebeck	617	#if CONFIG_ASM && ARCH_X86
247	schoenebeck	319	// expects to find input in xmm0 (xmm0 stays unmodified) and finally leaves output in xmm7
248			inline void ApplyFB4StepsSSE(biquad_param_t* param, const bq_t &fb) {
249			float xs, ys;
250			float t0, t1, t2, t3, t4, t5, t6, t7, t8; // temporary stack space
251			__asm__ __volatile__ (
252			/* prepare input */
253			"movss %15,%%xmm5\n\t"
254			"movss %%xmm0,(%14)\n\t"
255			/* sample 0 */
256			"movss %0, %%xmm3\n\t"
257			"movss %1, %%xmm4\n\t"
258			"mulss %%xmm4, %%xmm5\n\t"
259			"movss %%xmm3, %2\n\t"
260			"movss %%xmm5, %16\n\t"
261			"mulss %%xmm3, %%xmm5\n\t"
262			"movss %19, %%xmm2\n\t"
263			"movss %3, %%xmm6\n\t"
264			"movss %21, %%xmm3\n\t"
265			"addss %%xmm5, %%xmm6\n\t"
266			"movss %%xmm2, %%xmm5\n\t"
267			"movss %20, %%xmm4\n\t"
268			"movss %%xmm6, %4\n\t"
269			"mulss %%xmm6, %%xmm5\n\t"
270			"movss %5, %%xmm6\n\t"
271			"movss %%xmm2, %6\n\t"
272			"movss %%xmm4, %7\n\t"
273			"movss %%xmm3, %%xmm2\n\t"
274			"mulss %%xmm6, %%xmm4\n\t"
275			"mulss %8, %%xmm2\n\t"
276			"movss %%xmm3, %9\n\t"
277			"addss %%xmm4, %%xmm5\n\t"
278			"movss %18, %%xmm3\n\t"
279			"movss %17, %%xmm4\n\t"
280			"addss %%xmm2, %%xmm5\n\t"
281			"movss %%xmm4, %10\n\t"
282			"movss %%xmm3, %%xmm2\n\t"
283			"mulss %11, %%xmm4\n\t"
284			"mulss %12, %%xmm2\n\t"
285			"movss %%xmm3, %13\n\t"
286			"addss %%xmm4, %%xmm5\n\t"
287			"movss %11, %%xmm3\n\t"
288			"movss %4, %%xmm4\n\t"
289			"addss %%xmm2, %%xmm5\n\t"
290			:: "m" (y1), /* %0 */
291			"m" (fbc), /* %1 */
292			"m" (t0), /* %2 */
293			"m" (xs), /* %3 */
294			"m" (t7), /* %4 */
295			"m" (x1), /* %5 */
296			"m" (t1), /* %6 */
297			"m" (t2), /* %7 */
298			"m" (x2), /* %8 */
299			"m" (t3), /* %9 */
300			"m" (t4), /* %10 */
301			"m" (t0), /* %11 */
302			"m" (y2), /* %12 */
303			"m" (t5), /* %13 */
304			"r" (&xs), /* %14 */
305			"m" (fb), /* %15 */
306			"m" (ys), /* %16 */
307			"m" (param->a1), /* %17 */
308			"m" (param->a2), /* %18 */
309			"m" (param->b0), /* %19 */
310			"m" (param->b1), /* %20 */
311			"m" (param->b2) /* %21 */
312			);
313			__asm__ __volatile__ (
314			"shufps $0x39,%%xmm0,%%xmm0 # rotate down one cell\n\t"
315			"movss %%xmm5,%%xmm7\n\t"
316			::
317			);
318			/* sample 1 */
319			__asm__ __volatile__ (
320			"movss %0, %%xmm4\n\t"
321			"movss %%xmm0, %%xmm3\n\t"
322			"mulss %%xmm5, %%xmm4\n\t"
323			"mulss %3, %%xmm6\n\t"
324			"movss %5, %%xmm2\n\t"
325			"addss %%xmm4, %%xmm3\n\t"
326			"mulss %7, %%xmm2\n\t"
327			"movss %6, %%xmm4\n\t"
328			"movss %%xmm3, %8\n\t"
329			"mulss %%xmm3, %%xmm4\n\t"
330			"addss %%xmm2, %%xmm4\n\t"
331			"movss %9, %%xmm3\n\t"
332			"mulss %%xmm5, %%xmm3\n\t"
333			"movss %10, %%xmm2\n\t"
334			"addss %%xmm6, %%xmm4\n\t"
335			"mulss %11, %%xmm2\n\t"
336			"addss %%xmm3, %%xmm4\n\t"
337			"addss %%xmm2, %%xmm4\n\t"
338			:: "m" (ys), /* %0 */
339			"m" (fbc), /* %1 */
340			"m" (xs), /* %2 */
341			"m" (t3), /* %3 */
342			"m" (y2), /* %4 */
343			"m" (t2), /* %5 */
344			"m" (t1), /* %6 */
345			"m" (t7), /* %7 */
346			"m" (t8), /* %8 */
347			"m" (t4), /* %9 */
348			"m" (t5), /* %10 */
349			"m" (t0), /* %11 */
350			"m" (x2), /* %12 */
351			"m" (x1), /* %13 */
352			"m" (y1) /* %14 */
353			);
354			__asm__ __volatile__ (
355			"shufps $0x93,%%xmm7,%%xmm7 # rotate up one cell\n\t"
356			"shufps $0x39,%%xmm0,%%xmm0 # rotate down one cell\n\t"
357			"movss %%xmm4,%%xmm7\n\t"
358			::
359			);
360			/* sample 2 */
361			__asm__ __volatile__ (
362			"movss %2, %%xmm6\n\t"
363			"movss %3, %%xmm3\n\t"
364			"mulss %%xmm4, %%xmm6\n\t"
365			"movss %4, %%xmm2\n\t"
366			"mulss %9, %%xmm2\n\t"
367			"addss %%xmm0, %%xmm6\n\t"
368			"mulss %7, %%xmm5\n\t"
369			"mulss %%xmm6, %%xmm3\n\t"
370			"addss %%xmm2, %%xmm3\n\t"
371			"movss %5, %%xmm2\n\t"
372			"mulss %8, %%xmm2\n\t"
373			"addss %%xmm2, %%xmm3\n\t"
374			"movss %6, %%xmm2\n\t"
375			"mulss %%xmm4, %%xmm2\n\t"
376			"addss %%xmm5, %%xmm2\n\t"
377			"addss %%xmm2, %%xmm3\n\t"
378			:: "m" (xs), /* %0 */
379			"m" (fb), /* %1 */
380			"m" (ys), /* %2 */
381			"m" (t1), /* %3 */
382			"m" (t2), /* %4 */
383			"m" (t3), /* %5 */
384			"m" (t4), /* %6 */
385			"m" (t5), /* %7 */
386			"m" (t7), /* %8 */
387			"m" (t8), /* %9 */
388			"m" (x1), /* %10 */
389			"m" (x2), /* %11 */
390			"m" (y1), /* %12 */
391			"m" (y2) /* %13 */
392			);
393			__asm__ __volatile__ (
394			"shufps $0x39,%%xmm0,%%xmm0 # rotate down one cell\n\t"
395			"shufps $0x93,%%xmm7,%%xmm7 # rotate up one cell\n\t"
396			"movss %%xmm3,%%xmm7\n\t"
397			::
398			);
399			/* sample 3 */
400			__asm__ __volatile__ (
401			"movss %1, %%xmm2\n\t"
402			"mulss %7, %%xmm4\n\t"
403			"mulss %%xmm3, %%xmm2\n\t"
404			"movss %3, %%xmm5\n\t"
405			"movss %%xmm6, %11\n\t"
406			"addss %%xmm0, %%xmm2\n\t"
407			"movss %%xmm3, %13\n\t"
408			"mulss %%xmm2, %%xmm5\n\t"
409			"mulss %4, %%xmm6\n\t"
410			"movss %%xmm2, %10\n\t"
411			"addss %%xmm6, %%xmm5\n\t"
412			"movss %5, %%xmm2\n\t"
413			"mulss %9, %%xmm2\n\t"
414			"mulss %6, %%xmm3\n\t"
415			"addss %%xmm2, %%xmm5\n\t"
416			"addss %%xmm3, %%xmm4\n\t"
417			"addss %%xmm4, %%xmm5\n\t"
418			"movss %%xmm5, %12\n\t"
419			:: "m" (xs), /* %0 */
420			"m" (ys), /* %1 */
421			"m" (fbc), /* %2 */
422			"m" (t1), /* %3 */
423			"m" (t2), /* %4 */
424			"m" (t3), /* %5 */
425			"m" (t4), /* %6 */
426			"m" (t5), /* %7 */
427			"m" (t6), /* %8 */
428			"m" (t8), /* %9 */
429			"m" (x1), /* %10 */
430			"m" (x2), /* %11 */
431			"m" (y1), /* %12 */
432			"m" (y2) /* %13 */
433			);
434			__asm__ __volatile__ (
435			"shufps $0x93,%%xmm7,%%xmm7 # rotate up one cell\n\t"
436			"shufps $0x39,%%xmm0,%%xmm0 # rotate down one cell to restore original input\n\t"
437			"movss %%xmm5,%%xmm7\n\t"
438			"shufps $0x1b,%%xmm7,%%xmm7 # swap output to correct order\n\t"
439			::
440			);
441			}
442	schoenebeck	617	#endif // CONFIG_ASM && ARCH_X86
443	schoenebeck	53	};
444
445	schoenebeck	563	/** @brief Lowpass Filter
446			*
447			* Lowpass filter based on biquad filter implementation.
448			*/
449	schoenebeck	53	class LowpassFilter : public BiquadFilter {
450			public:
451			inline LowpassFilter() : BiquadFilter() {}
452
453			inline void SetParameters(bq_t fc, bq_t bw, bq_t fs) {
454			bq_t omega = 2.0 * M_PI * fc / fs;
455			bq_t sn = sin(omega);
456			bq_t cs = cos(omega);
457			bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);
458
459			const float a0r = 1.0 / (1.0 + alpha);
460			this->b0 = a0r * (1.0 - cs) * 0.5;
461			this->b1 = a0r * (1.0 - cs);
462			this->b2 = a0r * (1.0 - cs) * 0.5;
463			this->a1 = a0r * (2.0 * cs);
464			this->a2 = a0r * (alpha - 1.0);
465			}
466	schoenebeck	80
467			inline void SetParameters(biquad_param_t* param, bq_t fc, bq_t bw, bq_t fs) {
468			bq_t omega = 2.0 * M_PI * fc / fs;
469			bq_t sn = sin(omega);
470			bq_t cs = cos(omega);
471			bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);
472
473			const float a0r = 1.0 / (1.0 + alpha);
474			param->b0 = a0r * (1.0 - cs) * 0.5;
475			param->b1 = a0r * (1.0 - cs);
476			param->b2 = a0r * (1.0 - cs) * 0.5;
477			param->a1 = a0r * (2.0 * cs);
478			param->a2 = a0r * (alpha - 1.0);
479			}
480	schoenebeck	53	};
481
482	schoenebeck	563	/** @brief Bandpass Filter
483			*
484			* Bandpass filter based on biquad filter implementation.
485			*/
486	schoenebeck	53	class BandpassFilter : public BiquadFilter {
487			public:
488			inline BandpassFilter() : BiquadFilter() {}
489
490			inline void SetParameters(bq_t fc, bq_t bw, bq_t fs) {
491			bq_t omega = 2.0 * M_PI * fc / fs;
492			bq_t sn = sin(omega);
493			bq_t cs = cos(omega);
494			bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);
495
496			const float a0r = 1.0 / (1.0 + alpha);
497			this->b0 = a0r * alpha;
498			this->b1 = 0.0;
499			this->b2 = a0r * -alpha;
500			this->a1 = a0r * (2.0 * cs);
501			this->a2 = a0r * (alpha - 1.0);
502			}
503	schoenebeck	80
504			inline void SetParameters(biquad_param_t* param, bq_t fc, bq_t bw, bq_t fs) {
505			bq_t omega = 2.0 * M_PI * fc / fs;
506			bq_t sn = sin(omega);
507			bq_t cs = cos(omega);
508			bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);
509
510			const float a0r = 1.0 / (1.0 + alpha);
511			param->b0 = a0r * alpha;
512			param->b1 = 0.0;
513			param->b2 = a0r * -alpha;
514			param->a1 = a0r * (2.0 * cs);
515			param->a2 = a0r * (alpha - 1.0);
516			}
517	schoenebeck	53	};
518
519	schoenebeck	563	/** @brief Highpass Filter
520			*
521			* Highpass filter based on biquad filter implementation.
522			*/
523	schoenebeck	53	class HighpassFilter : public BiquadFilter {
524			public:
525			inline HighpassFilter() : BiquadFilter() {}
526
527			inline void SetParameters(bq_t fc, bq_t bw, bq_t fs) {
528			bq_t omega = 2.0 * M_PI * fc / fs;
529			bq_t sn = sin(omega);
530			bq_t cs = cos(omega);
531			bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);
532
533			const float a0r = 1.0 / (1.0 + alpha);
534			this->b0 = a0r * (1.0 + cs) * 0.5;
535			this->b1 = a0r * -(1.0 + cs);
536			this->b2 = a0r * (1.0 + cs) * 0.5;
537			this->a1 = a0r * (2.0 * cs);
538			this->a2 = a0r * (alpha - 1.0);
539			}
540	schoenebeck	80
541			inline void SetParameters(biquad_param_t* param, bq_t fc, bq_t bw, bq_t fs) {
542			bq_t omega = 2.0 * M_PI * fc / fs;
543			bq_t sn = sin(omega);
544			bq_t cs = cos(omega);
545			bq_t alpha = sn * sinh(M_LN2 / 2.0 * bw * omega / sn);
546
547			const float a0r = 1.0 / (1.0 + alpha);
548			param->b0 = a0r * (1.0 + cs) * 0.5;
549			param->b1 = a0r * -(1.0 + cs);
550			param->b2 = a0r * (1.0 + cs) * 0.5;
551			param->a1 = a0r * (2.0 * cs);
552			param->a2 = a0r * (alpha - 1.0);
553			}
554	schoenebeck	53	};
555
556			} // namespace LinuxSampler
557
558			#endif // __LS_BIQUADFILTER_H__