drivers/sound/sound.c

   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 }