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