---

compare.c

解説を見る。

#include "multiprec.h"

inline int
ymp_compare_abs(mp_cref_t lhs, mp_cref_t rhs)
{
  if (lhs->used > rhs->used)
    {
      return 1;
    }
  else if (lhs->used < rhs->used)
    {
      return -1;
    }
  else
    {
      size_t i;
      for (i=lhs->used; i-- > 0; )
        {
          if (lhs->digits[i] > rhs->digits[i]) return 1;
          else if (lhs->digits[i] < rhs->digits[i]) return -1;
        }
    }
  return 0;
}


int
ymp_compare(mp_cref_t lhs, mp_cref_t rhs)
{
  if (lhs->sign != rhs->sign)
    return rhs->sign - lhs->sign;
  else if (lhs->sign)
    return ymp_compare_abs(rhs, lhs);
  else
    return ymp_compare_abs(lhs, rhs);
}

int
ymp_compare_digit(mp_cref_t lhs, digit_t rhs)
{
  if (lhs->sign) return -1;

  if (lhs->used > 1) return 1;
  else if (lhs->used == 1)
    {
      if (lhs->digits[0] > rhs) return 1;
      else if (lhs->digits[0] < rhs) return -1;
      else return 0;
    }
  else return -(rhs!=0);
}


int
ymp_is_zero(mp_cref_t self)
{
  return !self || !self->used || (self->used==1 && !self->digits[0]);
}

int
ymp_is_even(mp_cref_t self)
{
  return !self || !self->used || !(self->digits[0] & 0x01);
}

---