text: #include "verify.h"
  #include <stdint.h>
  #include <string.h>
  
  /*************************************************
  * Name:        verify
  *
  * Description: Compare two arrays for equality in constant time.
  *
  * Arguments:   const unsigned char *a: pointer to first byte array
  *              const unsigned char *b: pointer to second byte array
  *              size_t len:             length of the byte arrays
  *
  * Returns 0 if the byte arrays are equal, 1 otherwise
  **************************************************/
  int PQCLEAN_NEWHOPE512CPA_CLEAN_verify(const unsigned char *a, const unsigned char *b, size_t len) {
      uint64_t r;
      size_t i;
      r = 0;
  
      for (i = 0; i < len; i++) {
          r |= a[i] ^ b[i];
      }
  
      r = (-(int64_t)r) >> 63;
      return (int)r;
  }
  
  /*************************************************
  * Name:        cmov
  *
  * Description: Copy len bytes from x to r if b is 1;
  *              don't modify x if b is 0. Requires b to be in {0,1};
  *              assumes two's complement representation of negative integers.
  *              Runs in constant time.
  *
  * Arguments:   unsigned char *r:       pointer to output byte array
  *              const unsigned char *x: pointer to input byte array
  *              size_t len:             Amount of bytes to be copied
  *              unsigned char b:        Condition bit; has to be in {0,1}
  **************************************************/
  void PQCLEAN_NEWHOPE512CPA_CLEAN_cmov(unsigned char *r, const unsigned char *x, size_t len, unsigned char b) {
      size_t i;
  
      b = -b;
      for (i = 0; i < len; i++) {
          r[i] ^= b & (x[i] ^ r[i]);
      }
  }
  