LXR uboot/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
  10void 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