void sc25519_window5()

in sc25519.c [258:293]

• 34 lines of code
• 3 McCabe index (conditional complexity)

void sc25519_window5(signed char r[51], const sc25519 *s)
{
  char carry;
  int i;
  for(i=0;i<6;i++)
  {
    r[8*i+0]  =  s->v[5*i+0]       & 31;
    r[8*i+1]  = (s->v[5*i+0] >> 5) & 31;
    r[8*i+1] ^= (s->v[5*i+1] << 3) & 31;
    r[8*i+2]  = (s->v[5*i+1] >> 2) & 31;
    r[8*i+3]  = (s->v[5*i+1] >> 7) & 31;
    r[8*i+3] ^= (s->v[5*i+2] << 1) & 31;
    r[8*i+4]  = (s->v[5*i+2] >> 4) & 31;
    r[8*i+4] ^= (s->v[5*i+3] << 4) & 31;
    r[8*i+5]  = (s->v[5*i+3] >> 1) & 31;
    r[8*i+6]  = (s->v[5*i+3] >> 6) & 31;
    r[8*i+6] ^= (s->v[5*i+4] << 2) & 31;
    r[8*i+7]  = (s->v[5*i+4] >> 3) & 31;
  }
  r[8*i+0]  =  s->v[5*i+0]       & 31;
  r[8*i+1]  = (s->v[5*i+0] >> 5) & 31;
  r[8*i+1] ^= (s->v[5*i+1] << 3) & 31;
  r[8*i+2]  = (s->v[5*i+1] >> 2) & 31;

  /* Making it signed */
  carry = 0;
  for(i=0;i<50;i++)
  {
    r[i] += carry;
    r[i+1] += r[i] >> 5;
    r[i] &= 31;
    carry = r[i] >> 4;
    r[i] -= carry<<5;
  }
  r[50] += carry;
}