FreeCalypso > hg > themwi-system-sw
comparison mgw/dtmf_init.c @ 126:815e4c59162e
mgw DTMF: tone definitions and sample array generation
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Sat, 01 Oct 2022 17:09:51 -0800 |
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125:5081f2bc6f1c | 126:815e4c59162e |
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1 /* | |
2 * The code in this module executes once upon themwi-mgw startup; | |
3 * it initializes the arrays of linear PCM samples for DTMF output. | |
4 * | |
5 * The amplitudes of the two sine waves comprising each DTMF tone | |
6 * are also defined here. | |
7 */ | |
8 | |
9 #include <math.h> | |
10 #include <stdio.h> | |
11 #include <stdint.h> | |
12 #include <stdlib.h> | |
13 #include "dtmf_defs.h" | |
14 #include "int_defs.h" | |
15 | |
16 #define DTMF_AMPL_LOW_TONE 5000 | |
17 #define DTMF_AMPL_HIGH_TONE 6000 | |
18 | |
19 extern struct dtmf_desc dtmf_table[]; | |
20 | |
21 static void | |
22 init_one_dtmf(desc) | |
23 struct dtmf_desc *desc; | |
24 { | |
25 float angle_low, angle_high; | |
26 unsigned n; | |
27 int16_t *samp; | |
28 | |
29 angle_low = 0; | |
30 angle_high = 0; | |
31 samp = desc->samples; | |
32 for (n = 0; n < DTMF_MAX_FRAMES * SAMPLES_PER_FRAME; n++) { | |
33 *samp++ = sinf(angle_low) * DTMF_AMPL_LOW_TONE + | |
34 sinf(angle_high) * DTMF_AMPL_HIGH_TONE; | |
35 angle_low += desc->freq_low; | |
36 angle_high += desc->freq_high; | |
37 } | |
38 } | |
39 | |
40 dtmf_init_sample_arrays() | |
41 { | |
42 struct dtmf_desc *desc; | |
43 | |
44 for (desc = dtmf_table; desc->digit; desc++) { | |
45 desc->samples = | |
46 malloc(DTMF_MAX_FRAMES * SAMPLES_PER_FRAME * sizeof(int16_t)); | |
47 if (!desc->samples) { | |
48 perror("malloc for DTMF samples"); | |
49 exit(1); | |
50 } | |
51 init_one_dtmf(desc); | |
52 } | |
53 return 0; | |
54 } |