Development version of DS18B20 ROM search algorithm

romsearch.c

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define ROMCNT 20

unsigned char roms[ROMCNT] = {0};
unsigned char active[ROMCNT] = {1, 1, 1, 1};
int bitcnt = 0;

char getbit( )
{
	int i = 0;
	int bit = 1;
	int mybit;
	
	for ( i = 0; i < ROMCNT; i++ )
	{
		mybit =  ( roms[i] >> bitcnt ) & 1;
		if ( !active[i] ) continue;
		if ( !mybit ) bit = 0; 
	}

	return bit;
} 

char get2bit( )
{
	int i = 0;
	int bit = 1;
	int mybit;
	
	for ( i = 0; i < ROMCNT; i++ )
	{
		mybit =  ( roms[i] >> bitcnt ) & 1;
		if ( !active[i] ) continue;
		if ( mybit ) bit = 0; 
	}
	
	bitcnt++;
	return bit;
}

void reset( )
{
	bitcnt = 0;
	int i = 0;
	for ( i = 0; i < ROMCNT; i++ )
	{
		active[i] = 1;
	}
}

void sendbit( int bcnt, char bit )
{
	int i = 0;
	for ( i = 0; i < ROMCNT; i++ )
	{
		if ( ( ( roms[i] >> bcnt ) & 1 ) != bit ) 
			active[i] = 0;
	}
}

int main( )
{
	int i;
	reset( );
	int a, b;
	int currom = 0;
	//unsigned char zero = 0;
	unsigned char recvd[ROMCNT] = {0};
	//unsigned char *temp = &zero;
	unsigned char junction = 0;
	
	int resp;
	int j;
	long seed = time(NULL);
	
	srand( seed );
	printf( "%ld\n", seed );
	
	for ( i = 0; i < ROMCNT; i++ ) roms[i] = rand( );
	
	do
	{
		//currom = j;
		for ( i = 0; i < 8; i++ )
		{
			a = getbit( );
			b = get2bit( );
			int k;
			for ( k = 0; k < ROMCNT; k++ )
				printf( "\x1b[%dm%d\x1b[0m ", active[k] ? 32 : 31, active[k] );
			printf( "- [%d %d]", a, b );
		
		
			if ( a == 0 && b == 0 )
			{
				if ( ( junction >> ( i + 1 ) ) )
				{
					resp = ( ( ~junction >> i ) & 1 );
				}
				else
				{
					resp = ( ( junction >> i ) & 1 );
					junction ^= ( 1 << i );
				}

				if ( resp )
				{
					recvd[currom] |= ( 1 << i );
				}
				else
				{
					recvd[currom] &= ~( 1 << i );
				}
				sendbit( i, resp );
				printf( " - send %d <%02x>", resp, junction );
			}
		
			if ( a == 0 && b == 1 )
			{
				recvd[currom] &= ~( 1 << i );
				printf( " - it's 0" );
				sendbit( i, 0 );
			}
		
			if ( a == 1 && b == 0 )
			{
				recvd[currom] |= ( 1 << i );
				printf( " - it's 1" );
				sendbit( i, 1 );
			}
		
			//printf( "(%d)", !!( recvd[currom] & ( 1 << i ) ) );
			printf( "\n" );
			//temp = recvd +currom;
				
		
		} 
		//printf( "<junction: %2x>\n", junction );
	
		printf( "----------------\n" );
		reset( );
		currom++;
	} while ( junction );
	
	for ( i =0; i < ROMCNT; i++ ) printf( "%02x, ", recvd[i] );
	printf( "\n" );
	for ( i =0; i < ROMCNT; i++ ) printf( "%02x, ", roms[i] );
	printf( "\n" );
	for ( i =0; i < ROMCNT; i++ )
	{ 
		for ( j = 0; j < ROMCNT; j++ )
			if ( roms[i] == recvd[j] )
			{
				printf( "XX, " );
				break;
			}
		if ( j == ROMCNT ) printf( "  , " );
	}
	printf( "\n" );
	
	return 0;
}