Diff: SoundWaveGenerator/SineWave.cpp

Revision:

0:1324e7d9d471

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SoundWaveGenerator/SineWave.cpp	Mon Mar 07 22:51:19 2011 +0000
@@ -0,0 +1,36 @@
+#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 / 2;
+    
+    float delta = 6.28 / (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);
+    }
+    
+    this->buffer.write(quarter, 1.0);
+    if (middle - quarter != quarter) {
+        this->buffer.write(middle - quarter, 1.0);
+    }
+    this->buffer.write(cycleLength - quarter, 0.0);
+    if (middle + quarter != cycleLength - quarter) {
+        this->buffer.write(middle + quarter, 0.0);
+    }
+}
+
+} // snd_wave_generator