I need help with implementing the missing function outputing the rightmost bit of the state variable. The code is in C language.

Question

#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>

/*The following struct will represent an LFSR with a 64 bit state.
The taps are represented by a 64 bit number, where the ith bit (from the right)
corresponds to p_i.
The uint64_t is a 64 bit unsigned integer.

typedef struct {
uint64_t state;
uint64_t taps;
} LFSR;

int parity(uint64_t N)
{
/* Return the parity of N*/
int p = __builtin_parity(N); // parity of first 32 bits
N = __builtin_bswap64(N); //move back 32 to the front
return (p+__builtin_parity(N))%2; //overall parity
}

int read_lfsr(LFSR* L)
{
/*Return the current output bit (the rightmost bit of the state variable) */

/* You implement this*/

return 0;

}

Answer 1

You can read the rightmost bit of a number x with `x & 1`.