Add function sound_create_sine_wave().
Signed-off-by: Heinrich Schuchardt heinrich.schuchardt@canonical.com --- v2: remove stray printf() --- drivers/sound/sound.c | 37 +++++++++++++++++++++++++++++++++++++ include/sound.h | 12 ++++++++++++ 2 files changed, 49 insertions(+)
diff --git a/drivers/sound/sound.c b/drivers/sound/sound.c index c0fc50c99d..abf9bb6de2 100644 --- a/drivers/sound/sound.c +++ b/drivers/sound/sound.c @@ -8,6 +8,43 @@ #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; + + 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 *