Mercurial > hg > audiostuff
view spandsp-0.0.3/spandsp-0.0.3/src/power_meter.c @ 5:f762bf195c4b
import spandsp-0.0.3
author | Peter Meerwald <pmeerw@cosy.sbg.ac.at> |
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date | Fri, 25 Jun 2010 16:00:21 +0200 |
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/* * SpanDSP - a series of DSP components for telephony * * power_meter.c * * Written by Steve Underwood <steveu@coppice.org> * * Copyright (C) 2003 Steve Underwood * * All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2, as * published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * * $Id: power_meter.c,v 1.18 2006/11/19 14:07:25 steveu Exp $ */ /*! \file */ #ifdef HAVE_CONFIG_H #include <config.h> #endif #include <inttypes.h> #include <stdlib.h> #include <stdio.h> #include <fcntl.h> #include <string.h> #include <float.h> #if defined(HAVE_TGMATH_H) #include <tgmath.h> #endif #if defined(HAVE_MATH_H) #include <math.h> #endif #include <assert.h> #include "spandsp/telephony.h" #include "spandsp/power_meter.h" power_meter_t *power_meter_init(power_meter_t *s, int shift) { if (s == NULL) return NULL; s->shift = shift; s->reading = 0; return s; } /*- End of function --------------------------------------------------------*/ power_meter_t *power_meter_damping(power_meter_t *s, int shift) { s->shift = shift; return s; } /*- End of function --------------------------------------------------------*/ int32_t power_meter_update(power_meter_t *s, int16_t amp) { s->reading += ((amp*amp - s->reading) >> s->shift); return s->reading; } /*- End of function --------------------------------------------------------*/ int32_t power_meter_level_dbm0(float level) { float l; level -= DBM0_MAX_POWER; if (level > 0.0) level = 0.0; l = powf(10.0f, level/10.0f)*(32767.0f*32767.0f); return (int32_t) l; } /*- End of function --------------------------------------------------------*/ int32_t power_meter_level_dbov(float level) { float l; if (level > 0.0) level = 0.0; l = powf(10.0f, level/10.0f)*(32767.0f*32767.0f); return (int32_t) l; } /*- End of function --------------------------------------------------------*/ float power_meter_dbm0(power_meter_t *s) { if (s->reading <= 0) return FLT_MIN; /* This is based on A-law, but u-law is only 0.03dB different, so don't worry. */ return log10f((float) s->reading/(32767.0f*32767.0f))*10.0f + DBM0_MAX_POWER; } /*- End of function --------------------------------------------------------*/ float power_meter_dbov(power_meter_t *s) { if (s->reading <= 0) return FLT_MIN; return log10f((float) s->reading/(32767.0f*32767.0f))*10.0f; } /*- End of function --------------------------------------------------------*/ /*- End of file ------------------------------------------------------------*/