int fano(unsigned long *metric, unsigned long *cycles,	unsigned char *data,unsigned char *symbols,	unsigned int nbits,int mettab[2][256],int delta,	unsigned long maxcycles);int encode(unsigned char *symbols,unsigned char *data,unsigned int nbytes);double gen_met(int mettab[2][256],int amp,double noise,double bias,int scale);extern unsigned char Partab[];