comparison projects/basic_sensor/render.cpp @ 0:8a575ba3ab52

Initial commit.

+/*
+ * render.cpp
+ *
+ *  Created on: Oct 24, 2014
+ *      Author: parallels
+ */
+
+
+#include "../../include/render.h"
+#include "../../include/Utilities.h"
+#include <rtdk.h>
+#include <cmath>
+
+float gPhase;
+float gInverseSampleRate;
+int gNumChannels;
+
+// These settings are carried over from main.cpp
+// Setting global variables is an alternative approach
+// to passing a structure to userData in initialise_render()
+
+extern int gSensorInputFrequency;
+extern int gSensorInputAmplitude;
+
+// initialise_render() is called once before the audio rendering starts.
+// Use it to perform any initialisation and allocation which is dependent
+// on the period size or sample rate.
+//
+// userData holds an opaque pointer to a data structure that was passed
+// in from the call to initAudio().
+//
+// Return true on success; returning false halts the program.
+
+bool initialise_render(int numChannels, int numMatrixFramesPerPeriod,
+					   int numAudioFramesPerPeriod, float matrixSampleRate,
+					   float audioSampleRate, void *userData)
+{
+	if(numMatrixFramesPerPeriod*2 != numAudioFramesPerPeriod) {
+		rt_printf("Error: this example needs the matrix enabled, running at half audio rate\n");
+		return false;
+	}
+
+	gNumChannels = numChannels;
+	gInverseSampleRate = 1.0 / audioSampleRate;
+	gPhase = 0.0;
+
+	return true;
+}
+
+// render() is called regularly at the highest priority by the audio engine.
+// Input and output are given from the audio hardware and the other
+// ADCs and DACs (if available). If only audio is available, numMatrixFrames
+// will be 0.
+
+void render(int numMatrixFrames, int numAudioFrames, float *audioIn, float *audioOut,
+			uint16_t *matrixIn, uint16_t *matrixOut)
+{
+	float frequency = 0;
+	float amplitude = 0;
+
+	// There are twice as many audio frames as matrix frames since audio sample rate
+	// is twice as high
+
+	for(int n = 0; n < numAudioFrames; n++) {
+		if(!(n % 2)) {
+			// Even audio samples: update frequency and amplitude from the matrix
+			frequency = map((float)matrixIn[gSensorInputFrequency], 0, MATRIX_MAX, 100, 1000);
+			amplitude = (float)matrixIn[gSensorInputAmplitude] / MATRIX_MAX;
+		}
+
+		float out = amplitude * sinf(gPhase);
+
+		for(int channel = 0; channel < gNumChannels; channel++)
+			audioOut[n * gNumChannels + channel] = out;
+
+		gPhase += 2.0 * M_PI * frequency * gInverseSampleRate;
+		if(gPhase > 2.0 * M_PI)
+			gPhase -= 2.0 * M_PI;
+	}
+}
+
+// cleanup_render() is called once at the end, after the audio has stopped.
+// Release any resources that were allocated in initialise_render().
+
+void cleanup_render()
+{
+
+}