133 lines
2.8 KiB
C++
133 lines
2.8 KiB
C++
/*
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Copyright (C) 2001 Steve Harris & Paul Davis
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef __ardour_logcurve_h__
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#define __ardour_logcurve_h__
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#include "pbd/fastlog.h"
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#include <glibmm/thread.h>
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namespace ARDOUR {
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class LogCurve {
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public:
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LogCurve (float steepness = 0.2, uint32_t len = 0) {
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l = len;
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S = steepness;
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a = log(S);
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b = 1.0f / log(1.0f + (1.0f / S));
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}
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bool operator== (const LogCurve& other) const {
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return S == other.S && l == other.l;
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}
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bool operator!= (const LogCurve& other) const {
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return S != other.S || l != other.l;
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}
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float value (float frac) const {
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return (fast_log(frac + S) - a) * b;
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}
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float value (uint32_t pos) const {
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return (fast_log(((float) pos/l) + S) - a) * b;
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}
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float invert_value (float frac) const {
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return (a - fast_log(frac + S)) * b;
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}
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float invert_value (uint32_t pos) const {
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return (a - fast_log(((float) pos/l) + S)) * b;
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}
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void fill (float *vec, uint32_t veclen, bool invert) const {
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float dx = 1.0f/veclen;
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float x;
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uint32_t i;
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if (!invert) {
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vec[0] = 0.0;
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vec[veclen-1] = 1.0;
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for (i = 1, x = 0; i < veclen - 1; x += dx, i++) {
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vec[i] = value (x);
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}
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} else {
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vec[0] = 1.0;
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vec[veclen-1] = 0.0;
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for (i = veclen-2, x = 0.0f; i > 0; x += dx, i--) {
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vec[i] = value (x);
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}
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}
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}
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float steepness() const { return S; }
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uint32_t length() const { return l; }
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void set_steepness (float steepness) {
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S = steepness;
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a = log(S);
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b = 1.0f / log(1.0f + (1.0f / S));
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}
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void set_length (uint32_t len) { l = len; }
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mutable Glib::Mutex lock;
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protected:
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float a;
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float b;
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float S;
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uint32_t l;
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};
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class LogCurveIn : public LogCurve
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{
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public:
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LogCurveIn (float steepness = 0.2, uint32_t len = 0)
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: LogCurve (steepness, len) {}
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float value (float frac) const {
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return (fast_log(frac + S) - a) * b;
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}
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float value (uint32_t pos) const {
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return (fast_log(((float) pos/l) + S) - a) * b;
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}
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};
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class LogCurveOut : public LogCurve
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{
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public:
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LogCurveOut (float steepness = 0.2, uint32_t len = 0)
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: LogCurve (steepness, len) {}
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};
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} // namespace ARDOUR
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#endif /* __ardour_logcurve_h__ */
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