197 lines
8.4 KiB
C
197 lines
8.4 KiB
C
/*
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* SpanDSP - a series of DSP components for telephony
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*
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* private/v27ter_rx.h - ITU V.27ter modem receive part
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*
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* Written by Steve Underwood <steveu@coppice.org>
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*
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* Copyright (C) 2003 Steve Underwood
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*
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License version 2.1,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* $Id: v27ter_rx.h,v 1.2 2009/07/09 13:52:09 steveu Exp $
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*/
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#if !defined(_SPANDSP_PRIVATE_V27TER_RX_H_)
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#define _SPANDSP_PRIVATE_V27TER_RX_H_
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/* Target length for the equalizer is about 43 taps for 4800bps and 32 taps for 2400bps
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to deal with the worst stuff in V.56bis. */
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/*! Samples before the target position in the equalizer buffer */
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#define V27TER_EQUALIZER_PRE_LEN 16 /* This much before the real event */
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/*! Samples after the target position in the equalizer buffer */
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#define V27TER_EQUALIZER_POST_LEN 14 /* This much after the real event (must be even) */
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/*! The number of taps in the 4800bps pulse shaping/bandpass filter */
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#define V27TER_RX_4800_FILTER_STEPS 27
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/*! The number of taps in the 2400bps pulse shaping/bandpass filter */
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#define V27TER_RX_2400_FILTER_STEPS 27
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#if V27TER_RX_4800_FILTER_STEPS > V27TER_RX_2400_FILTER_STEPS
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#define V27TER_RX_FILTER_STEPS V27TER_RX_4800_FILTER_STEPS
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#else
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#define V27TER_RX_FILTER_STEPS V27TER_RX_2400_FILTER_STEPS
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#endif
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/*!
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V.27ter modem receive side descriptor. This defines the working state for a
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single instance of a V.27ter modem receiver.
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*/
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struct v27ter_rx_state_s
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{
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/*! \brief The bit rate of the modem. Valid values are 2400 and 4800. */
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int bit_rate;
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/*! \brief The callback function used to put each bit received. */
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put_bit_func_t put_bit;
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/*! \brief A user specified opaque pointer passed to the put_bit routine. */
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void *put_bit_user_data;
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/*! \brief The callback function used to report modem status changes. */
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modem_rx_status_func_t status_handler;
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/*! \brief A user specified opaque pointer passed to the status function. */
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void *status_user_data;
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/*! \brief A callback function which may be enabled to report every symbol's
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constellation position. */
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qam_report_handler_t qam_report;
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/*! \brief A user specified opaque pointer passed to the qam_report callback
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routine. */
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void *qam_user_data;
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/*! \brief The route raised cosine (RRC) pulse shaping filter buffer. */
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#if defined(SPANDSP_USE_FIXED_POINT)
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int16_t rrc_filter[V27TER_RX_FILTER_STEPS];
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#else
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float rrc_filter[V27TER_RX_FILTER_STEPS];
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#endif
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/*! \brief Current offset into the RRC pulse shaping filter buffer. */
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int rrc_filter_step;
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/*! \brief The register for the training and data scrambler. */
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unsigned int scramble_reg;
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/*! \brief A counter for the number of consecutive bits of repeating pattern through
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the scrambler. */
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int scrambler_pattern_count;
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/*! \brief The current step in the table of BC constellation positions. */
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int training_bc;
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/*! \brief TRUE if the previous trained values are to be reused. */
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int old_train;
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/*! \brief The section of the training data we are currently in. */
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int training_stage;
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/*! \brief A count of how far through the current training step we are. */
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int training_count;
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/*! \brief A measure of how much mismatch there is between the real constellation,
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and the decoded symbol positions. */
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float training_error;
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/*! \brief The value of the last signal sample, using the a simple HPF for signal power estimation. */
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int16_t last_sample;
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/*! \brief >0 if a signal above the minimum is present. It may or may not be a V.27ter signal. */
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int signal_present;
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/*! \brief Whether or not a carrier drop was detected and the signal delivery is pending. */
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int carrier_drop_pending;
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/*! \brief A count of the current consecutive samples below the carrier off threshold. */
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int low_samples;
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/*! \brief A highest magnitude sample seen. */
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int16_t high_sample;
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/*! \brief The position of the current symbol in the constellation, used for
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differential decoding. */
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int constellation_state;
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/*! \brief The current phase of the carrier (i.e. the DDS parameter). */
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uint32_t carrier_phase;
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/*! \brief The update rate for the phase of the carrier (i.e. the DDS increment). */
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int32_t carrier_phase_rate;
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/*! \brief The carrier update rate saved for reuse when using short training. */
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int32_t carrier_phase_rate_save;
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#if defined(SPANDSP_USE_FIXED_POINTx)
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/*! \brief The proportional part of the carrier tracking filter. */
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float carrier_track_p;
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/*! \brief The integral part of the carrier tracking filter. */
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float carrier_track_i;
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#else
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/*! \brief The proportional part of the carrier tracking filter. */
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float carrier_track_p;
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/*! \brief The integral part of the carrier tracking filter. */
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float carrier_track_i;
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#endif
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/*! \brief A power meter, to measure the HPF'ed signal power in the channel. */
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power_meter_t power;
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/*! \brief The power meter level at which carrier on is declared. */
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int32_t carrier_on_power;
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/*! \brief The power meter level at which carrier off is declared. */
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int32_t carrier_off_power;
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/*! \brief Current read offset into the equalizer buffer. */
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int eq_step;
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/*! \brief Current write offset into the equalizer buffer. */
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int eq_put_step;
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/*! \brief Symbol counter to the next equalizer update. */
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int eq_skip;
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/*! \brief The current half of the baud. */
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int baud_half;
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#if defined(SPANDSP_USE_FIXED_POINT)
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/*! \brief The scaling factor accessed by the AGC algorithm. */
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int16_t agc_scaling;
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/*! \brief The previous value of agc_scaling, needed to reuse old training. */
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int16_t agc_scaling_save;
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/*! \brief The current delta factor for updating the equalizer coefficients. */
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float eq_delta;
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/*! \brief The adaptive equalizer coefficients. */
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/*complexi16_t*/ complexf_t eq_coeff[V27TER_EQUALIZER_PRE_LEN + 1 + V27TER_EQUALIZER_POST_LEN];
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/*! \brief A saved set of adaptive equalizer coefficients for use after restarts. */
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/*complexi16_t*/ complexf_t eq_coeff_save[V27TER_EQUALIZER_PRE_LEN + 1 + V27TER_EQUALIZER_POST_LEN];
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/*! \brief The equalizer signal buffer. */
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/*complexi16_t*/ complexf_t eq_buf[V27TER_EQUALIZER_PRE_LEN + 1 + V27TER_EQUALIZER_POST_LEN];
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#else
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/*! \brief The scaling factor accessed by the AGC algorithm. */
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float agc_scaling;
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/*! \brief The previous value of agc_scaling, needed to reuse old training. */
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float agc_scaling_save;
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/*! \brief The current delta factor for updating the equalizer coefficients. */
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float eq_delta;
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/*! \brief The adaptive equalizer coefficients. */
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complexf_t eq_coeff[V27TER_EQUALIZER_PRE_LEN + 1 + V27TER_EQUALIZER_POST_LEN];
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/*! \brief A saved set of adaptive equalizer coefficients for use after restarts. */
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complexf_t eq_coeff_save[V27TER_EQUALIZER_PRE_LEN + 1 + V27TER_EQUALIZER_POST_LEN];
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/*! \brief The equalizer signal buffer. */
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complexf_t eq_buf[V27TER_EQUALIZER_PRE_LEN + 1 + V27TER_EQUALIZER_POST_LEN];
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#endif
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/*! \brief Integration variable for damping the Gardner algorithm tests. */
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int gardner_integrate;
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/*! \brief Current step size of Gardner algorithm integration. */
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int gardner_step;
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/*! \brief The total symbol timing correction since the carrier came up.
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This is only for performance analysis purposes. */
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int total_baud_timing_correction;
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/*! \brief Starting phase angles for the coarse carrier aquisition step. */
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int32_t start_angles[2];
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/*! \brief History list of phase angles for the coarse carrier aquisition step. */
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int32_t angles[16];
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/*! \brief Error and flow logging control */
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logging_state_t logging;
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};
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#endif
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/*- End of file ------------------------------------------------------------*/
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