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dtmf.c revision 1.3 
      1 /* $NetBSD: dtmf.c,v 1.3 2013/08/11 06:31:00 dholland Exp $ */
      2 
      3 /*
      4  * Copyright (c) 2010 Jared D. McNeill <jmcneill (at) invisible.ca>
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     17  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     18  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     19  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     20  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     26  * POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #include <sys/endian.h>
     30 
     31 #include <fcntl.h>
     32 #include <math.h>
     33 #include <stdio.h>
     34 #include <stdint.h>
     35 #include <string.h>
     36 #include <stdlib.h>
     37 #include <unistd.h>
     38 
     39 #include "dtmf.h"
     40 
     41 #define	PI2	(3.14159265358979323846f * 2)
     42 
     43 static void
     44 dtmf_create(int16_t *buf, unsigned int sample_rate,
     45     unsigned short sample_length, unsigned short channels,
     46     unsigned int chanmask, float freq1, float freq2)
     47 {
     48 	int c;
     49 	unsigned i;
     50 	size_t sample_count = sample_rate * sample_length;
     51 
     52 	for (i = 0; i < sample_count; i++) {
     53 		for (c = 0; c < channels; c++) {
     54 			if ((chanmask & (1 << c)) == 0)
     55 				continue;
     56 			buf[c] = htole16(
     57 			    (sin(i * PI2 * (freq1 / sample_rate)) +
     58 			     sin(i * PI2 * (freq2 / sample_rate))) * 16383
     59 					);
     60 		}
     61 		buf += channels;
     62 	}
     63 }
     64 
     65 void
     66 dtmf_new(int16_t **buf, size_t *buflen, unsigned int sample_rate,
     67     unsigned short sample_length, unsigned short channels,
     68     unsigned int chanmask, float rate1, float rate2)
     69 {
     70 	*buflen = sample_rate * sizeof(int16_t) * sample_length * channels;
     71 	*buf = calloc(1, *buflen);
     72 	if (*buf == NULL) {
     73 		perror("calloc");
     74 		return;
     75 	}
     76 
     77 	dtmf_create(*buf, sample_rate, sample_length, channels, chanmask,
     78 	    rate1, rate2);
     79 }
     80