1 // Copyright 2017 Emilie Gillet.
2 //
3 // Author: Emilie Gillet (emilie.o.gillet@gmail.com)
4 //
5 // Permission is hereby granted, free of charge, to any person obtaining a copy
6 // of this software and associated documentation files (the "Software"), to deal
7 // in the Software without restriction, including without limitation the rights
8 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
9 // copies of the Software, and to permit persons to whom the Software is
10 // furnished to do so, subject to the following conditions:
11 //
12 // The above copyright notice and this permission notice shall be included in
13 // all copies or substantial portions of the Software.
14 //
15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
21 // THE SOFTWARE.
22 //
23 // See http://creativecommons.org/licenses/MIT/ for more information.
24 //
25 // -----------------------------------------------------------------------------
26 //
27 // Polynomial approximation of band-limited step for band-limited waveform
28 // synthesis.
29
30 #ifndef STMLIB_DSP_POLYBLEP_H_
31 #define STMLIB_DSP_POLYBLEP_H_
32
33 #include "stmlib/stmlib.h"
34
35 namespace stmlib {
36
ThisBlepSample(float t)37 inline float ThisBlepSample(float t) {
38 return 0.5f * t * t;
39 }
40
NextBlepSample(float t)41 inline float NextBlepSample(float t) {
42 t = 1.0f - t;
43 return -0.5f * t * t;
44 }
45
NextIntegratedBlepSample(float t)46 inline float NextIntegratedBlepSample(float t) {
47 const float t1 = 0.5f * t;
48 const float t2 = t1 * t1;
49 const float t4 = t2 * t2;
50 return 0.1875f - t1 + 1.5f * t2 - t4;
51 }
52
ThisIntegratedBlepSample(float t)53 inline float ThisIntegratedBlepSample(float t) {
54 return NextIntegratedBlepSample(1.0f - t);
55 }
56
57 } // namespace stmlib
58
59 #endif // STMLIB_DSP_POLYBLEP_H_
60