snr_send.c

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

/***************************************************************************
 *    snr_send.c  -  Send a prepared slot for SNR-measurememtn
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   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.                                   *
 *                                                                         *
 ***************************************************************************/


/**
 * This module expects some random input that is then modulated
 * using QPSK modulation so that the noise can be mesured.
 */

#include "spc.h"


#define DBG_LVL 0


typedef struct {
  // The amplitude of the generated QPSK-signal
  int amplitude; // 32767
  // The QPSK-type, 0->in the corner, 1->on the axes
  int type; // 0
}
config_t;

typedef struct {
  // ADD HERE, int, double or char[128]
}
stats_t;

typedef struct {
  int amplitude;
  int type;
}
private_t;


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

int send_init( swr_sdb_t *context ) {
  // Begin system-definitions {
  config_t *config;
  stats_t *stats;
  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->amplitude = 32767;
  config->type = 0;

  // 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
}


/*
 * To configure the inputs
 * this is called when the output-sizes change.
 */
int send_configure_inputs( swr_sdb_t *context ) {
  // Definition of variables - don't touch
  config_t *config;
  swr_sdb_get_config_struct( context->id, (void**)&config );

  size_in(0) = ( size_out(0) * 2 + 7 ) / 8;

  // Definition - don't touch
  swr_sdb_free_config_struct( context->id, (void**)&config );
  return 0;
}


/*
 * To configure the outputs
 * this is called when the input-sizes change
 */
int send_configure_outputs( swr_sdb_t *context ) {
  // Definition of variables - don't touch
  config_t *config;
  swr_sdb_get_config_struct( context->id, (void**)&config );

  size_out(0) = size_in(0) * 4;

  // Definition - don't touch
  swr_sdb_free_config_struct( context->id, (void**)&config );
  return 0;
}


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

int send_reconfig( swr_sdb_t *context ) {
  // Definition of variables - don't touch
  config_t *config;
  swr_sdb_get_config_struct( context->id, (void**)&config );

  private->amplitude = config->amplitude;
  private->type = config->type;

  // Definition - don't touch
  swr_sdb_free_config_struct( context->id, (void**)&config );
  return 0;
}


/*
 * This is the function that implements the `main method' of the class
 * Every class has got just ONE method/working-mode.
 */
int send_pdata( swr_sdb_t *context ) {
  // Definition of variables - don't touch
  stats_t *stats;
  int i, amp;
  U8 *in;
  SYMBOL_COMPLEX *out;

  in = buffer_in(0);
  out = buffer_out(0);

  // Fill the slot with random QPSK symbols

  for ( i=0; i<size_out(0); i++ ) {
    switch( private->type ) {
    case 0:
      // The amplitude in this case is
      // Sqrt( Re^2 + Im^2 ) and thus the
      // desired amplitude has to be divided by
      // sqrt(2)
      amp = private->amplitude / sqrt( 2 );
      out[i].real = ( 2 * ( *in & 1 ) - 1 ) * amp;
      *in = *in >> 1;
      out[i].imag = ( 2 * ( *in & 1 ) - 1 ) * amp;
      *in = *in >> 1;
      break;
    case 1:
      amp = private->amplitude;
      if ( *in & 1 ) {
        *in = *in >> 1;
        out[i].real = ( 2 * ( *in & 1 ) - 1 ) * amp;
        out[i].imag = 0;
      } else {
        *in = *in >> 1;
        out[i].imag = ( 2 * ( *in & 1 ) - 1 ) * amp;
        out[i].real = 0;
      }
      *in = *in >> 1;
      break;
    }
    // Get the next input-byte of random
    if ( i && !( i % 4 ) ) {
      in++;
    }
    PR_DBG( 4, "(%5i,%5i)\n", out[i].real, out[i].imag );
  }

  swr_sdb_get_stats_struct( context->id, (void**)&stats );
  swr_sdb_free_stats_struct( context->id, (void**)&stats );
  return(0);
}

/*
 * This is the `destructor'.
 */
int send_finalize( swr_sdb_t *context ) {
  if ( sizeof( private_t ) > 0 )
    swr_free( private );
  MOD_DEC_USE_COUNT;
  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 send_id;
int send_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( 1, 1, 2, 0 );

  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( "amplitude" );
  UM_CONFIG_INT( "type" );

  /**
   * The in- and outputs have also to be defined in the right order. First
   * port first. The additional flag is not used yet, but it will...
   *
   * UM_INPUT( SIG_{U8,SYMBOL_{S16,COMPLEX,MMX},SAMPLE_S12,S32}, 0 );
   * UM_OUTPUT( SIG_{U8,SYMBOL_{S16,COMPLEX,MMX},SAMPLE_S12,S32}, 0 );
   */
  UM_INPUT( SIG_U8, 0 );
  UM_OUTPUT( SIG_SYMBOL_COMPLEX, 0 );

  // Initialise the callback-functions. Delete the ones you don't use
  desc->fn_init              = send_init;
  desc->fn_reconfigure       = send_reconfig;
  desc->fn_process_data      = send_pdata;
  desc->fn_configure_inputs  = send_configure_inputs;
  //  desc->fn_configure_outputs = send_configure_outputs;
  desc->fn_finalize          = send_finalize;

  // And register the module in the SPM. Change the name!
  send_id = swr_cdb_register_spc( &desc, "snr_send" );
  if ( send_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 send_module_exit( void ) {
  PR_DBG( 4, "Freeing id: %i\n", send_id );
  if ( swr_cdb_unregister_spc( send_id ) < 0 ) {
    PR_DBG( 0, "Still in use somewhere\n" );
  }
}