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 <log.h>
9 #include <sound.h>
10 
sound_create_square_wave(uint sample_rate,unsigned short * data,int size,uint freq,uint channels)11 void sound_create_square_wave(uint sample_rate, unsigned short *data, int size,
12 			      uint freq, uint channels)
13 {
14 	const unsigned short amplitude = 16000; /* between 1 and 32767 */
15 	const int period = freq ? sample_rate / freq : 0;
16 	const int half = period / 2;
17 
18 	assert(freq);
19 
20 	/* Make sure we don't overflow our buffer */
21 	if (size % 2)
22 		size--;
23 
24 	while (size) {
25 		int i, j;
26 
27 		for (i = 0; size && i < half; i++) {
28 			size -= 2;
29 			for (j = 0; j < channels; j++)
30 				*data++ = amplitude;
31 		}
32 		for (i = 0; size && i < period - half; i++) {
33 			size -= 2;
34 			for (j = 0; j < channels; j++)
35 				*data++ = -amplitude;
36 		}
37 	}
38 }
39