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(unsigned short *data, int size, uint32_t freq) 11 { 12 const int sample = 48000; 13 const unsigned short amplitude = 16000; /* between 1 and 32767 */ 14 const int period = freq ? sample / 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; 25 for (i = 0; size && i < half; i++) { 26 size -= 2; 27 *data++ = amplitude; 28 *data++ = amplitude; 29 } 30 for (i = 0; size && i < period - half; i++) { 31 size -= 2; 32 *data++ = -amplitude; 33 *data++ = -amplitude; 34 } 35 } 36 } 37