sim.c

zigzag纠错码是一种非常简单但却具有非常优秀性能的码。非常适合用于中码率或者高码率编码的系统。此为一位教授提供的源码。

#include <stdio.h> 
#include <stdlib.h> 
#include <math.h>
#include "input.h"

extern int  DataLength;

int RawData[DATALENGTH];
int Guess[DATALENGTH];
float CodedSgnl[DATALENGTH+IVALUE*KVALUE];
float CodingRate;

int Counte( );
int random01( );
void Presim( );
void CoDec( double snr );
void CoDec( double snr );
void DataGen( int *r );
double Sim( double EbOverNo, int num );

extern int InterleaverReset;
extern void Channel( float *sb, double sigma );
extern void Prepare( );


void Presim( )
{
	srand48(0);
	Prepare();
}

double Sim( double EbOverNo, int num )
{
	int i = 0;
	double en = 0.0, EsOverSigma2 = pow( 10, EbOverNo / 10 ) * CodingRate;
	
	while( en<num )
	{
		i++;
		if(  ( InterleaverReset > 0 ) && ( i%InterleaverReset == 0 ) )
		{
			fprintf( stderr, "\n\nInterleaver Reset\n\n" );
			SetShafflerule( );
		}
		DataGen( RawData );
		CoDec( EsOverSigma2 );
		en += Counte( );
		fprintf( stderr, "total error number = %.0f \n", en ); 
		fprintf( stderr, "for snr=%lfdB BER=%e\n",  EbOverNo, en / (double)( i * DataLength ) );
	} 
	fprintf( stderr, "for snr = %le \n", EbOverNo ); 
	fprintf( stderr, "%.0f", en ); 
	fprintf( stderr, "erorrs found in %d data\n", i * DataLength ); 
	return en / (double)( i * DataLength );
}

 
void CoDec( double snr )
{	
	double sigma = sqrt( 0.5 / snr );
	
	Coder( &RawData[0], &CodedSgnl );
	Channel( &CodedSgnl[0], sigma );
	Decoder( &Guess[0], &CodedSgnl[0], sigma );
}

void DataGen( int *r )
{
	int i;
	for( i=0; i<DataLength; i++ ) r[i] = random01( );
}

int Counte( )
{
	int  i, e=0; 
	for( i=0; i<DataLength; i++ )
		if( RawData[i] != Guess[i] ) e++;
	return e;
}

int random01( )
{
	return ( lrand48( ) >> 16 ) % 2;
}