synch.c

This a framework to test new ideas in transmission technology. Actual development is a LDPC-coder in

/***************************************************************************
 *    synch.c  -  Macro for synchronisation with BS
 *                           -------------------
 *   begin                :  03/03/05
 *   authors              :  ineiti
 *   emails               :  [e-mail]
 ***************************************************************************/

/***************************************************************************
 *                                Changes
 *                                -------
 * date - name - description
 * 03/03/05 - ineiti - begin
 * 04/03/06 - ineiti - adjusted description
 *
 **************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/


/**
 *  In order to have a simple synchronisation going, this macro has been
 * written. You can call it and then wait for the synchronisation to be
 * complete, before going on with the rest of the radio.
 *
 * Usage
 * -----
 *
 *  This macro can be used either in 'polling'- or in 'callback'-mode. For
 * both modes, after you instantiated the macro with swr_sdb_instantiate_name,
 * you have to set the 'stfa_id'.
 *  For the polling-mode, you can directly set the 'synch' parameter to 1,
 * start the stfa and wait in regular intervals whether the 'status' is 1,
 * which indicates that a synchronisation has been found.
 *  In callback-mode, you have to give a pointer to a 'func' (as defined in
 * stfa.h) in 'call_synched'. After setting the 'synch' parameter to 1, you
 * can wait for 'func' to be called.
 *  In either mode, once the synchronisation is achieved, you must set the
 * 'synch' parameter to 0 before trying to add other modules to the stfa.
 *
 *  For an example, see Radio/Simple/MS/radio_ms.c
 */

#include "spc.h"
#include "stfa.h"
#include "antenna.h"


#define DBG_LVL 0


typedef struct {
  // the id of the stfa where the synch has to attach itself
  int stfa_id; // -1
  // The needed energy to consider synchronisation
  int min_energy; // 2^14
  // If a change from 0 to 1 is detected, the module attaches
  // all necessary chains to the stfa. On a change from 1 to 0,
  // all attached chains to the stfa are deleted, except the first one.
  int synch; // 0
  // A pointer to a 'func' (defined in stfa.h) that
  // is called if a synchronisation has succesfully been detected.
  func *call_synched; // NULL
}
config_t;

typedef struct {
  // 0 means not synched, 1 tells it's synched
  int status;
  // The offset of the synchronisation-signal
  int offset;
  // the synchronisation-module where the matched-filter can be
  // attached to in order to decode the synch-channel
  swr_sdb_id synch_rcv;
}
stats_t;

typedef struct {
  swr_sdb_id synch_rcv[MAX_SLOTS];
  int synching;
  int slots;
  int guard;
  int rx_gain;
  int offset;
}
private_t;


/*
 * The initialisation function, or constructor, 
 * is called the first time this module is instantiated.
 */

int spc_init( swr_sdb_t *context ) {
  // Begin system-definitions {
  config_t *config;
  stats_t *stats;
  int i;
  MOD_INC_USE_COUNT;
  if ( sizeof( private_t ) > 0 )
    context->private_data = swr_malloc( sizeof( private_t ) );
  swr_sdb_get_config_struct( context->id, (void**)&config );
  swr_sdb_get_stats_struct( context->id, (void**)&stats );
  // } End of system-definitions

  config->min_energy = 1 * ( 1 << 14 );
  config->synch = private->synching = 0;
  config->call_synched = 0;
  stats->status = 0;
  stats->synch_rcv = -1;
  for ( i=0; i<MAX_SLOTS; i++ ) {
    private->synch_rcv[i] = -1;
  }
  // Begin system-definitions
  swr_sdb_free_stats_struct( context->id, (void**)&stats );
  swr_sdb_free_config_struct( context->id, (void**)&config );
  return 0;
  // End system-definitions
}


/*
 * Every time modules from the outside change the value of a configuration parameter,
 * this function is called.
 */

int spc_reconfig( swr_sdb_t *context ) {
  // Definition of variables - don't touch
  config_t *config;
  stats_t *stats;
  swr_sdb_id stfa;
  
  int i, synch;

  swr_sdb_get_config_struct( context->id, (void**)&config );
  synch = config->synch;
  stfa  = config->stfa_id;
  swr_sdb_free_config_struct( context->id, (void**)&config );

  if ( synch == 1 ) {
    if ( !private->synching && ( stfa >= 0 ) ) {
      // Set up all the synch_rcv-modules
      private->slots = swr_sdb_get_stats_int( stfa, "slots_per_frame" );
      private->guard = swr_sdb_get_config_int( stfa, "guard_period_chips" );
      // If we have a guard-period, we can be sure to miss the synchronisation
      // signal...
      swr_sdb_set_config_int( stfa, "guard_period_chips", 0 );
      PR_DBG( 2, "Setting up %i slots for synchronising\n", private->slots );
      for ( i=0; i<private->slots; i++ ) {
        swr_chain_create( 2,
                          OLD_SPC_OUT( stfa, i ),
                          NEW_SPC_VAR( "synch_rcv", private->synch_rcv[i] ) );
      }
      private->synching = 1;
      private->rx_gain = 0;
      swr_stfa_notice_sdb( stfa, private->slots - 1, context->id );
    }
  } else if ( synch == 0 ) {
    if ( private->synching && ( stfa >= 0 ) ) {
      // Destroy all unnecessary synch-modules
      PR_DBG( 2, "Freeing %i slots of synchronising\n", private->slots );
      for ( i=1; i<private->slots; i++ ) {
        swr_sdb_destroy( private->synch_rcv[i] );
        private->synch_rcv[i] = -1;
      }
      private->synching = 0;
      
      // Write the synchronisation-offset to the STFA
      swr_sdb_set_config_int( stfa, "guard_period_chips", private->guard );
      swr_sdb_set_config_int( stfa, "offset_chips_rcv", private->offset );
      swr_sdb_set_config_int( private->synch_rcv[0], "stfa_id", stfa );
      swr_sdb_get_stats_struct( context->id, (void**)&stats );
      stats->synch_rcv = private->synch_rcv[0];
      swr_sdb_free_stats_struct( context->id, (void**)&stats );
      swr_stfa_notice_sdb( stfa, private->slots - 1, -1 );
    }
  }

  return 0;
}


int spc_send( swr_sdb_t *context ) {
  config_t *config;
  stats_t *stats;
  int max_slot, max_en, max_pos, i, en;
  func *call = NULL;
  swr_sdb_get_config_struct( context->id, (void**)&config );
  swr_sdb_get_stats_struct( context->id, (void**)&stats );

  if ( private->synching ) {
    PR_DBG( 4, "Searching for synchronisation\n" );
    max_slot = -1;
    max_en = 0;
    max_pos = 0;
    for ( i=0; i<private->slots; i++ ) {
      en = swr_sdb_get_stats_int( private->synch_rcv[i], "synch_amp" );
      if ( en > max_en ) {
        max_slot = i;
        max_en = en;
        max_pos = swr_sdb_get_stats_int( private->synch_rcv[i], "synch_pos" );
      }
    }

    // Check that we have enough energy from the basestation
    if ( max_en < config->min_energy ) {
      private->rx_gain += 1;
      PR_DBG( 3, "Max_en: %i, Increasing rx-gain to: %i\n",
              max_en, private->rx_gain );
      if ( private->rx_gain > 1024 ) {
        PR_DBG( 0, "Rx-gain too high, restarting...\n" );
        private->rx_gain = 0;
      }
      //swr_sdb_set_config_int( config->stfa_id, "amp_rx_if", private->rx_gain );
      swr_ant_set_gains( 0, (double)private->rx_gain, 0 );
    } else {
      // Save the offset, and set the status to 'synched'
      private->offset = max_slot *
                        swr_sdb_get_stats_int( config->stfa_id, "blocks_per_slot" ) *
                        DAQ_DMA_BLOCK_SIZE_SAMPLES / DAQ_SAMPLES_PER_CHIP + max_pos;
      PR_DBG( 2, "Top pos: %i at slot %i with energy %i -> offset %i\n",
              max_pos, max_slot, max_en, private->offset );
      stats->status = 1;
      stats->offset = private->offset;
      call = config->call_synched;
      config->synch = 0;
    }
  } else {
    PR_DBG( 0, "There should be no msg while not synching!\n" );
  }

  swr_sdb_free_stats_struct( context->id, (void**)&stats );
  swr_sdb_free_config_struct( context->id, (void**)&config );

  // If we have a call-back function, let's call it...
  if ( call ) {
    spc_reconfig( context );
    call( SUBS_MSG_OK, NULL, context->id );
  }
  return 0;
}


/*
 * This is the `destructor'.
 */
int spc_finalize( swr_sdb_t *context ) {
  int i;

  PR_DBG( 2, "Deleting synch\n" );
  // Delete all remaining synchs
  for ( i=0; i<MAX_SLOTS; i++ ) {
    if ( private->synch_rcv[i] >= 0 ) {
      swr_sdb_destroy( private->synch_rcv[i] );
    }
  }
  if ( sizeof( private_t ) > 0 )
    swr_free( private );
  MOD_DEC_USE_COUNT;
  PR_DBG( 2, "Finished deleting synch\n" );
  return 0;
}


/*
 * This function is called upon "insmod" and is used to register the
 * different parts of the module to the SPM.
 */
swr_spc_id_t cdb_id;
int spc_module_init(void) {
  swr_spc_desc_t *desc;

  /**
   * Get a description-part from SPM
   * Give the following parameters:
   * Input-ports, output-ports, config-params, stat-params
   */
  desc = swr_spc_get_new_desc( 0, 0, 4, 3 );
  if ( !desc ) {
    PR_DBG( 0, "Can't initialise the module. This is BAD!\n" );
    return -1;
  }

  /**
   * Define the different parts of config and stats. You have to define
   * them in the same order as they appear in the structures. The names
   * can be freely chosen.
   *
   * UM_CONFIG_{INT,DOUBLE,STRING128,POINTER}( "name" );
   * UM_STATS_{INT,DOUBLE,STRING128,POINTER,BLOCK}( "name" );
   */
  UM_CONFIG_INT( "stfa_id" );
  UM_CONFIG_INT( "min_energy" );
  UM_CONFIG_INT( "synch" );
  UM_CONFIG_POINTER( "call_synched" );
  UM_STATS_INT( "status" );
  UM_STATS_INT( "offset" );
  UM_STATS_INT( "synch_rcv" );

  // Initialise the callback-functions. Delete the ones you don't use
  desc->fn_init              = spc_init;
  desc->fn_reconfigure       = spc_reconfig;
  desc->fn_process_data      = spc_send;
  desc->fn_finalize          = spc_finalize;

  // And register the module in the SPM. Change the name!
  cdb_id = swr_cdb_register_spc( &desc, "macro_synch" );
  if ( cdb_id == SWR_SPM_INVALID_ID ) {
    swr_spc_free_desc( desc );
    PR_DBG( 0, "Couldn't register the module!\n" );
    return 1;
  }
  PR_DBG( 4, "Ready\n" );
  return 0;
}


/*
 * This is called upon rmmod
 */
void spc_module_exit( void ) {
  PR_DBG( 2, "Freeing id: %i\n", cdb_id );
  if ( swr_cdb_unregister_spc( cdb_id ) < 0 ) {
    PR_DBG( 0, "Still in use somewhere\n" );
  }
}


module_init( spc_module_init );
module_exit( spc_module_exit );