xref: /openbmc/u-boot/drivers/sound/sound.c (revision 84304d48)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Copyright (C) 2012 Samsung Electronics
4  * R. Chandrasekar <rcsekar@samsung.com>
5  */
6 
7 #include <common.h>
8 #include <sound.h>
9 
10 void sound_create_square_wave(uint sample_rate, unsigned short *data, int size,
11 			      uint freq, uint channels)
12 {
13 	const unsigned short amplitude = 16000; /* between 1 and 32767 */
14 	const int period = freq ? sample_rate / freq : 0;
15 	const int half = period / 2;
16 
17 	assert(freq);
18 
19 	/* Make sure we don't overflow our buffer */
20 	if (size % 2)
21 		size--;
22 
23 	while (size) {
24 		int i, j;
25 
26 		for (i = 0; size && i < half; i++) {
27 			size -= 2;
28 			for (j = 0; j < channels; j++)
29 				*data++ = amplitude;
30 		}
31 		for (i = 0; size && i < period - half; i++) {
32 			size -= 2;
33 			for (j = 0; j < channels; j++)
34 				*data++ = -amplitude;
35 		}
36 	}
37 }
38