ogold.c

在linux系统下开发研究移动通信的工具型代码

/*
 * $Log: ogold.c,v $
 * Revision 1.1  2000/05/03 14:30:04  bjc97r
 * Initial revision
 *
 */
char *_ogold_id = "$Id: ogold.c,v 1.1 2000/05/03 14:30:04 bjc97r Exp $";

#include <stdio.h>
#include <stdlib.h>

#include "ogold.h"

/*
 * It create an OGold code generator with the two preferred m-sequences
 * with the given index. The OGold code generator is returned.
 * The possible range of index is 0 to (2^deg - 1).
 */
OGold *ogold_create( unsigned deg, unsigned long p0, unsigned long p1,
		     unsigned long index )
{
  OGold *ogold;

  if ( deg > 31 ) {
    fprintf(stderr, "ogold_create: ..cannot handle deg > 31\n");
    return NULL;
  }

  ogold = (OGold*) malloc( sizeof(OGold) );
  ogold->gold    = gold_create( deg, p0, p1, index, 1 );
  ogold->period  = 1 << deg; /* 2^deg */
  ogold->counter = 1;

  return ogold;
}

/* ogold_free() deallocates the memory space for the OGold code generator. */
void ogold_free( OGold *ogold )
{
  gold_free( ogold->gold );
  free( ogold );
}

/* ogold() gives the next OGold sequence in unipolar value, ie 1 or 0. */
char ogold( OGold *id )
{
  if ( id->counter == id->period ) {
    id->counter = 1;
    return 0;
  }

  id->counter++;

  return gold(id->gold);
}