cmp_si.c
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上传日期:2022-08-06
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- /* mpf_cmp_si -- Compare a float with a signed integer.
- Copyright 1993, 1994, 1995, 1999, 2000, 2001, 2002, 2004 Free Software
- Foundation, Inc.
- This file is part of the GNU MP Library.
- The GNU MP Library is free software; you can redistribute it and/or modify
- it under the terms of the GNU Lesser General Public License as published by
- the Free Software Foundation; either version 3 of the License, or (at your
- option) any later version.
- The GNU MP Library is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
- License for more details.
- You should have received a copy of the GNU Lesser General Public License
- along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
- #include "gmp.h"
- #include "gmp-impl.h"
- int
- mpf_cmp_si (mpf_srcptr u, long int vval)
- {
- mp_srcptr up;
- mp_size_t usize;
- mp_exp_t uexp;
- mp_limb_t ulimb;
- int usign;
- uexp = u->_mp_exp;
- usize = u->_mp_size;
- /* 1. Are the signs different? */
- if ((usize < 0) == (vval < 0)) /* don't use xor, type size may differ */
- {
- /* U and V are both non-negative or both negative. */
- if (usize == 0)
- /* vval >= 0 */
- return -(vval != 0);
- if (vval == 0)
- /* usize >= 0 */
- return usize != 0;
- /* Fall out. */
- }
- else
- {
- /* Either U or V is negative, but not both. */
- return usize >= 0 ? 1 : -1;
- }
- /* U and V have the same sign and are both non-zero. */
- usign = usize >= 0 ? 1 : -1;
- usize = ABS (usize);
- vval = ABS (vval);
- /* 2. Are the exponents different (V's exponent == 1)? */
- #if GMP_NAIL_BITS != 0
- if (uexp > 1 + ((unsigned long) vval > GMP_NUMB_MAX))
- return usign;
- if (uexp < 1 + ((unsigned long) vval > GMP_NUMB_MAX))
- return -usign;
- #else
- if (uexp > 1)
- return usign;
- if (uexp < 1)
- return -usign;
- #endif
- up = u->_mp_d;
- ulimb = up[usize - 1];
- #if GMP_NAIL_BITS != 0
- if (usize >= 2 && uexp == 2)
- {
- if ((ulimb >> GMP_NAIL_BITS) != 0)
- return usign;
- ulimb = (ulimb << GMP_NUMB_BITS) | up[usize - 2];
- usize--;
- }
- #endif
- usize--;
- /* 3. Compare the most significant mantissa limb with V. */
- if (ulimb > (unsigned long) vval)
- return usign;
- else if (ulimb < (unsigned long) vval)
- return -usign;
- /* Ignore zeroes at the low end of U. */
- while (*up == 0)
- {
- up++;
- usize--;
- }
- /* 4. Now, if the number of limbs are different, we have a difference
- since we have made sure the trailing limbs are not zero. */
- if (usize > 0)
- return usign;
- /* Wow, we got zero even if we tried hard to avoid it. */
- return 0;
- }