package decode.p25;

import java.util.BitSet;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import bits.BitSetBuffer;

/**
 * Utility class to process interleave of P25 196-bit packet blocks.
 */
public class P25Interleave
{
	private final static Logger mLog = 
			LoggerFactory.getLogger( P25Interleave.class );

    private static int[] INTERLEAVE = new int[] { 0,1,2,3,52,53,54,55,100,101,
        102,103,148,149,150,151,4,5,6,7,56,57,58,59,104,105,106,107,152,153,154,
        155,8,9,10,11,60,61,62,63,108,109,110,111,156,157,158,159,12,13,14,15,
        64,65,66,67,112,113,114,115,160,161,162,163,16,17,18,19,68,69,70,71,116,
        117,118,119,164,165,166,167,20,21,22,23,72,73,74,75,120,121,122,123,168,
        169,170,171,24,25,26,27,76,77,78,79,124,125,126,127,172,173,174,175,28,
        29,30,31,80,81,82,83,128,129,130,131,176,177,178,179,32,33,34,35,84,85,
        86,87,132,133,134,135,180,181,182,183,36,37,38,39,88,89,90,91,136,137,
        138,139,184,185,186,187,40,41,42,43,92,93,94,95,140,141,142,143,188,189,
        190,191,44,45,46,47,96,97,98,99,144,145,146,147,192,193,194,195,48,49,
        50,51 };

	private static int[] DEINTERLEAVE = new int[] { 0,1,2,3,16,17,18,19,32,33,
	    34,35,48,49,50,51,64,65,66,67,80,81,82,83,96,97,98,99,112,113,114,115,
		128,129,130,131,144,145,146,147,160,161,162,163,176,177,178,179,192,193,
		194,195,4,5,6,7,20,21,22,23,36,37,38,39,52,53,54,55,68,69,70,71,84,85,
		86,87,100,101,102,103,116,117,118,119,132,133,134,135,148,149,150,151,
		164,165,166,167,180,181,182,183,8,9,10,11,24,25,26,27,40,41,42,43,56,57,
		58,59,72,73,74,75,88,89,90,91,104,105,106,107,120,121,122,123,136,137,
		138,139,152,153,154,155,168,169,170,171,184,185,186,187,12,13,14,15,28,
		29,30,31,44,45,46,47,60,61,62,63,76,77,78,79,92,93,94,95,108,109,110,
		111,124,125,126,127,140,141,142,143,156,157,158,159,172,173,174,175,188,
		189,190,191 };

	/**
	 * Deinterleaves the 196-bit block in message, identified by start and end
	 * bit positions.  Note: end index (exclusive) should be one more than the 
	 * last bit in the block.
	 * 
	 * @param message - source message to deinterleave
	 * @param start - starting bit index for the block
	 * @param end - ending bit index for the block, plus 1
	 */
	public static BitSetBuffer deinterleave( BitSetBuffer message, int start, int end )
	{
		BitSet original = message.get( start, end );

		/* Clear block bits in source message */
		message.clear( start, end );

		/* Iterate only the set bits in the original message and apply 
		 * the deinterleave -- we don't have to evaluate the 0 bits */
		for (int i = original.nextSetBit( 0 ); 
				 i >= 0 && i < DEINTERLEAVE.length; 
				 i = original.nextSetBit( i + 1 ) ) 
		{
			message.set( start + DEINTERLEAVE[ i ] );
		}
		
		return message;
	}

    /**
     * Interleaves the 196-bit block in message, identified by start and end
     * bit positions.  Note: end index (exclusive) should be one more than the 
     * last bit in the block.
     * 
     * @param message - source message to interleave
     * @param start - starting bit index for the block
     * @param end - ending bit index for the block, plus 1
     */
    public static BitSetBuffer interleave( BitSetBuffer message, int start, int end )
    {
        BitSet original = message.get( start, end );
        
       /* Clear block bits in source message */
        message.clear( start, end );

        /* Iterate only the set bits in the original message and apply 
         * the deinterleave -- we don't have to evaluate the 0 bits */
        for (int i = original.nextSetBit( 0 ); 
                 i >= 0 && i < INTERLEAVE.length; 
                 i = original.nextSetBit( i + 1 ) ) 
        {
            message.set( start + INTERLEAVE[ i ] );
        }
        
        return message;
    }
    
    public static void main( String[] args )
    {
    	int start = 0;
    	int end = 196;
    	
    	BitSetBuffer b = new BitSetBuffer( end );
    	
    	for( int x = 0; x < end; x += 3 )
    	{
    		if( x > 20 )
    		{
        		b.set( x );
    		}
    	}

    	mLog.debug( "Origi:" + b.toString() );

    	P25Interleave.interleave( b, start, end );
    	
    	mLog.debug( "Inter:" + b.toString() );
    	
    	P25Interleave.deinterleave( b, start, end );
    		
    	mLog.debug( "Donee:" + b.toString() );
    }
}