Add function sound_create_sine_wave().
Signed-off-by: Heinrich Schuchardt <heinrich.schucha...@canonical.com>
---
drivers/sound/sound.c | 39 +++++++++++++++++++++++++++++++++++++++
include/sound.h | 12 ++++++++++++
2 files changed, 51 insertions(+)
diff --git a/drivers/sound/sound.c b/drivers/sound/sound.c
index c0fc50c99d..10551f1e45 100644
--- a/drivers/sound/sound.c
+++ b/drivers/sound/sound.c
@@ -8,6 +8,45 @@
#include <log.h>
#include <sound.h>
+/* Amplitude between 1 and 32767 */
+#define AMP 16384
+#define AMP2PI ((int)(6.28318530718 * AMP))
+
+void sound_create_sine_wave(uint sample_rate, unsigned short *data, int size,
+ uint freq, uint channels)
+{
+ int v, x = 0, y = AMP;
+
+ printf("%d\n", AMP2PI);
+
+ if (freq >= 0 && freq < sample_rate / 8) {
+ v = (AMP2PI * freq) / sample_rate;
+ /* tan(x) = x + x^3/3 + ... */
+ v += ((v * v) / AMP * v) / (3 * AMP);
+ } else {
+ v = 0;
+ }
+
+ for (int i = 0; i < size - (2 * channels - 1);) {
+ int s, dx, dy;
+
+ dx = (v * y) / AMP;
+ dy = -((v * x) / AMP);
+ x += dx;
+ y += dy;
+
+ /* Normalize radius: (1+x)^2 ~ 1+2x, for small x */
+ s = AMP * AMP - x * x - y * y;
+ s /= 2 * AMP;
+ s += AMP;
+ x = (s * x) / AMP;
+ y = (s * y) / AMP;
+
+ for (int j = 0; size && j < channels; ++j, i += 2)
+ *data++ = x;
+ }
+}
+
void sound_create_square_wave(uint sample_rate, unsigned short *data, int size,
uint freq, uint channels)
{
diff --git a/include/sound.h b/include/sound.h
index dab9ea186e..cf9c3e8fb7 100644
--- a/include/sound.h
+++ b/include/sound.h
@@ -34,6 +34,18 @@ struct sound_uc_priv {
int setup_done;
};
+/**
+ * Generates sine wave sound data for 1 second
+ *
+ * @sample_rate: Sample rate in Hz
+ * @data: data buffer pointer
+ * @size: size of the buffer in bytes
+ * @freq: frequency of the wave
+ * @channels: Number of channels to use
+ */
+void sound_create_sine_wave(uint sample_rate, unsigned short *data, int size,
+ uint freq, uint channels);
+
/**
* Generates square wave sound data for 1 second
*
--
2.37.2
