u-boot/drivers/sound/sound.c
Simon Glass 7d92b06090 sound: Add sample rate as a parameter for square wave
At present this value is hard-coded in the function that generates a
square wave. Since sample rates vary between different hardware, it makes
more sense to have this as a parameter.

Update the function and its users.

Signed-off-by: Simon Glass <sjg@chromium.org>
2018-11-29 09:30:05 -07:00

34 lines
709 B
C

// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2012 Samsung Electronics
* R. Chandrasekar <rcsekar@samsung.com>
*/
#include <common.h>
#include <sound.h>
void sound_create_square_wave(uint sample_rate, unsigned short *data, int size,
uint freq)
{
const unsigned short amplitude = 16000; /* between 1 and 32767 */
const int period = freq ? sample_rate / freq : 0;
const int half = period / 2;
assert(freq);
/* Make sure we don't overflow our buffer */
if (size % 2)
size--;
while (size) {
int i;
for (i = 0; size && i < half; i++) {
size -= 2;
*data++ = amplitude;
}
for (i = 0; size && i < period - half; i++) {
size -= 2;
*data++ = -amplitude;
}
}
}