#define IB1 1 #define IB2 2 #define IB5 16 #define IB18 131072 #define mask (IB1+IB2+IB5) //simple routine to perform LFSR based on polynomial X^18 xor X^5 xor X^2 xor X^1 int randbit(unsigned long *iseed) //returns as an integer a random bit, based on the 18 least significat bits os iseed { if (*iseed & IB18) { *iseed==((*iseed^mask)<< 1) | IB1; return 1; } else { *iseed <<=1; return 0; } }