1 /***************************************************/
2 /*! \class ReedTable
3 \brief STK reed table class.
4
5 This class implements a simple one breakpoint,
6 non-linear reed function, as described by
7 Smith (1986). This function is based on a
8 memoryless non-linear spring model of the reed
9 (the reed mass is ignored) which saturates when
10 the reed collides with the mouthpiece facing.
11
12 See McIntyre, Schumacher, & Woodhouse (1983),
13 Smith (1986), Hirschman, Cook, Scavone, and
14 others for more information.
15
16 by Perry R. Cook and Gary P. Scavone, 1995 - 2005.
17 */
18 /***************************************************/
19
20 #include "ReedTable.h"
21
22 using namespace Nyq;
23
ReedTable()24 ReedTable :: ReedTable()
25 {
26 offset_ = (StkFloat) 0.6; // Offset is a bias, related to reed rest position.
27 slope_ = (StkFloat) -0.8; // Slope corresponds loosely to reed stiffness.
28 }
29
~ReedTable()30 ReedTable :: ~ReedTable()
31 {
32 }
33
setOffset(StkFloat offset)34 void ReedTable :: setOffset(StkFloat offset)
35 {
36 offset_ = offset;
37 }
38
setSlope(StkFloat slope)39 void ReedTable :: setSlope(StkFloat slope)
40 {
41 slope_ = slope;
42 }
43
computeSample(StkFloat input)44 StkFloat ReedTable :: computeSample(StkFloat input)
45 {
46 // The input is differential pressure across the reed.
47 lastOutput_ = offset_ + (slope_ * input);
48
49 // If output is > 1, the reed has slammed shut and the
50 // reflection function value saturates at 1.0.
51 if (lastOutput_ > 1.0) lastOutput_ = (StkFloat) 1.0;
52
53 // This is nearly impossible in a physical system, but
54 // a reflection function value of -1.0 corresponds to
55 // an open end (and no discontinuity in bore profile).
56 if (lastOutput_ < -1.0) lastOutput_ = (StkFloat) -1.0;
57 return lastOutput_;
58 }
59
60