Classes to produce a computed sound wave on the analog output.
Dependents: SoundWaveGeneratorTest SoundWaveGeneratorTest
Diff: SineWave.cpp
- Revision:
- 0:ed89ef772e92
- Child:
- 1:6864fd480178
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/SineWave.cpp Mon Jan 24 22:44:39 2011 +0000 @@ -0,0 +1,34 @@ +#include "snd_wave_generator/SineWave.h" +#include <cmath> + +namespace snd_wave_generator { + +void SineWave::prepare(std::size_t sampleRate) +{ + std::size_t cycleLength = sampleRate / this->frequency; + this->buffer.resize(cycleLength); + + std::size_t middle = cycleLength / 2; + std::size_t quarter = middle / 4; + + float delta = 3.14 / (2.0 * float(sampleRate) / float(this->frequency)); + for(std::size_t i = 0; i < quarter; ++i) { + float dt = delta * i; + float dv = std::sin(dt) / 2.0; + float posValue = 0.5 + dv; + float negValue = 0.5 - dv; + this->buffer.write(i, posValue); + this->buffer.write(middle - i, posValue); + this->buffer.write(middle + i, negValue); + this->buffer.write(cycleLength - i, negValue); + } + + if (middle - quarter != quarter) { + this->buffer.write(quarter, 1.0); + } + if (middle + quarter != cycleLength - quarter) { + this->buffer.write(middle + quarter, 0.0); + } +} + +} // snd_wave_generator