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comparison spandsp-0.0.3/spandsp-0.0.3/src/power_meter.c @ 5:f762bf195c4b

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import spandsp-0.0.3
author Peter Meerwald <pmeerw@cosy.sbg.ac.at>
date Fri, 25 Jun 2010 16:00:21 +0200
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4:26cd8f1ef0b1 5:f762bf195c4b
1 /*
2 * SpanDSP - a series of DSP components for telephony
3 *
4 * power_meter.c
5 *
6 * Written by Steve Underwood <steveu@coppice.org>
7 *
8 * Copyright (C) 2003 Steve Underwood
9 *
10 * All rights reserved.
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License version 2, as
14 * published by the Free Software Foundation.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 *
25 * $Id: power_meter.c,v 1.18 2006/11/19 14:07:25 steveu Exp $
26 */
27
28 /*! \file */
29
30 #ifdef HAVE_CONFIG_H
31 #include <config.h>
32 #endif
33
34 #include <inttypes.h>
35 #include <stdlib.h>
36 #include <stdio.h>
37 #include <fcntl.h>
38 #include <string.h>
39 #include <float.h>
40 #if defined(HAVE_TGMATH_H)
41 #include <tgmath.h>
42 #endif
43 #if defined(HAVE_MATH_H)
44 #include <math.h>
45 #endif
46 #include <assert.h>
47
48 #include "spandsp/telephony.h"
49 #include "spandsp/power_meter.h"
50
51 power_meter_t *power_meter_init(power_meter_t *s, int shift)
52 {
53 if (s == NULL)
54 return NULL;
55 s->shift = shift;
56 s->reading = 0;
57 return s;
58 }
59 /*- End of function --------------------------------------------------------*/
60
61 power_meter_t *power_meter_damping(power_meter_t *s, int shift)
62 {
63 s->shift = shift;
64 return s;
65 }
66 /*- End of function --------------------------------------------------------*/
67
68 int32_t power_meter_update(power_meter_t *s, int16_t amp)
69 {
70 s->reading += ((amp*amp - s->reading) >> s->shift);
71 return s->reading;
72 }
73 /*- End of function --------------------------------------------------------*/
74
75 int32_t power_meter_level_dbm0(float level)
76 {
77 float l;
78
79 level -= DBM0_MAX_POWER;
80 if (level > 0.0)
81 level = 0.0;
82 l = powf(10.0f, level/10.0f)*(32767.0f*32767.0f);
83 return (int32_t) l;
84 }
85 /*- End of function --------------------------------------------------------*/
86
87 int32_t power_meter_level_dbov(float level)
88 {
89 float l;
90
91 if (level > 0.0)
92 level = 0.0;
93 l = powf(10.0f, level/10.0f)*(32767.0f*32767.0f);
94 return (int32_t) l;
95 }
96 /*- End of function --------------------------------------------------------*/
97
98 float power_meter_dbm0(power_meter_t *s)
99 {
100 if (s->reading <= 0)
101 return FLT_MIN;
102 /* This is based on A-law, but u-law is only 0.03dB different, so don't worry. */
103 return log10f((float) s->reading/(32767.0f*32767.0f))*10.0f + DBM0_MAX_POWER;
104 }
105 /*- End of function --------------------------------------------------------*/
106
107 float power_meter_dbov(power_meter_t *s)
108 {
109 if (s->reading <= 0)
110 return FLT_MIN;
111 return log10f((float) s->reading/(32767.0f*32767.0f))*10.0f;
112 }
113 /*- End of function --------------------------------------------------------*/
114 /*- End of file ------------------------------------------------------------*/

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