1 // Copyright 2014 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 // Conversion from semitones to frequency ratio.
28
29 #ifndef STMLIB_DSP_UNITS_H_
30 #define STMLIB_DSP_UNITS_H_
31
32 #include "stmlib/stmlib.h"
33 #include "stmlib/dsp/dsp.h"
34
35 namespace stmlib {
36
37 extern const float lut_pitch_ratio_high[257];
38 extern const float lut_pitch_ratio_low[257];
39
SemitonesToRatio(float semitones)40 inline float SemitonesToRatio(float semitones) {
41 float pitch = semitones + 128.0f;
42 MAKE_INTEGRAL_FRACTIONAL(pitch)
43
44 return lut_pitch_ratio_high[pitch_integral] * \
45 lut_pitch_ratio_low[static_cast<int32_t>(pitch_fractional * 256.0f)];
46 }
47
48 } // namespace stmlib
49
50 #endif // STMLIB_DSP_UNITS_H_
51