Classes to produce a computed sound wave on the analog output.
Dependents: SoundWaveGeneratorTest SoundWaveGeneratorTest
SineWave.cpp@1:6864fd480178, 2011-02-08 (annotated)
- Committer:
- osmeest
- Date:
- Tue Feb 08 21:39:55 2011 +0000
- Revision:
- 1:6864fd480178
- Parent:
- 0:ed89ef772e92
Fix the Sine & Triangle wave computations which were very bad !
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
osmeest | 0:ed89ef772e92 | 1 | #include "snd_wave_generator/SineWave.h" |
osmeest | 0:ed89ef772e92 | 2 | #include <cmath> |
osmeest | 0:ed89ef772e92 | 3 | |
osmeest | 0:ed89ef772e92 | 4 | namespace snd_wave_generator { |
osmeest | 0:ed89ef772e92 | 5 | |
osmeest | 0:ed89ef772e92 | 6 | void SineWave::prepare(std::size_t sampleRate) |
osmeest | 0:ed89ef772e92 | 7 | { |
osmeest | 0:ed89ef772e92 | 8 | std::size_t cycleLength = sampleRate / this->frequency; |
osmeest | 0:ed89ef772e92 | 9 | this->buffer.resize(cycleLength); |
osmeest | 0:ed89ef772e92 | 10 | |
osmeest | 0:ed89ef772e92 | 11 | std::size_t middle = cycleLength / 2; |
osmeest | 1:6864fd480178 | 12 | std::size_t quarter = middle / 2; |
osmeest | 0:ed89ef772e92 | 13 | |
osmeest | 1:6864fd480178 | 14 | float delta = 6.28 / (float(sampleRate) / float(this->frequency)); |
osmeest | 0:ed89ef772e92 | 15 | for(std::size_t i = 0; i < quarter; ++i) { |
osmeest | 0:ed89ef772e92 | 16 | float dt = delta * i; |
osmeest | 0:ed89ef772e92 | 17 | float dv = std::sin(dt) / 2.0; |
osmeest | 0:ed89ef772e92 | 18 | float posValue = 0.5 + dv; |
osmeest | 0:ed89ef772e92 | 19 | float negValue = 0.5 - dv; |
osmeest | 0:ed89ef772e92 | 20 | this->buffer.write(i, posValue); |
osmeest | 0:ed89ef772e92 | 21 | this->buffer.write(middle - i, posValue); |
osmeest | 0:ed89ef772e92 | 22 | this->buffer.write(middle + i, negValue); |
osmeest | 0:ed89ef772e92 | 23 | this->buffer.write(cycleLength - i, negValue); |
osmeest | 0:ed89ef772e92 | 24 | } |
osmeest | 0:ed89ef772e92 | 25 | |
osmeest | 1:6864fd480178 | 26 | this->buffer.write(quarter, 1.0); |
osmeest | 0:ed89ef772e92 | 27 | if (middle - quarter != quarter) { |
osmeest | 1:6864fd480178 | 28 | this->buffer.write(middle - quarter, 1.0); |
osmeest | 0:ed89ef772e92 | 29 | } |
osmeest | 1:6864fd480178 | 30 | this->buffer.write(cycleLength - quarter, 0.0); |
osmeest | 0:ed89ef772e92 | 31 | if (middle + quarter != cycleLength - quarter) { |
osmeest | 0:ed89ef772e92 | 32 | this->buffer.write(middle + quarter, 0.0); |
osmeest | 0:ed89ef772e92 | 33 | } |
osmeest | 0:ed89ef772e92 | 34 | } |
osmeest | 0:ed89ef772e92 | 35 | |
osmeest | 0:ed89ef772e92 | 36 | } // snd_wave_generator |