110 lines
2.7 KiB
C
110 lines
2.7 KiB
C
/* mpf_cmp_si -- Compare a float with a signed integer.
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Copyright 1993, 1994, 1995, 1999, 2000, 2001, 2002, 2004 Free Software
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Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#include "mpir.h"
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#include "gmp-impl.h"
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int
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mpf_cmp_si (mpf_srcptr u, mpir_si vval)
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{
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mp_srcptr up;
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mp_size_t usize;
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mp_exp_t uexp;
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mp_limb_t ulimb;
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int usign;
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uexp = u->_mp_exp;
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usize = u->_mp_size;
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/* 1. Are the signs different? */
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if ((usize < 0) == (vval < 0)) /* don't use xor, type size may differ */
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{
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/* U and V are both non-negative or both negative. */
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if (usize == 0)
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/* vval >= 0 */
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return -(vval != 0);
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if (vval == 0)
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/* usize >= 0 */
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return usize != 0;
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/* Fall out. */
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}
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else
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{
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/* Either U or V is negative, but not both. */
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return usize >= 0 ? 1 : -1;
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}
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/* U and V have the same sign and are both non-zero. */
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usign = usize >= 0 ? 1 : -1;
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usize = ABS (usize);
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vval = ABS (vval);
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/* 2. Are the exponents different (V's exponent == 1)? */
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#if GMP_NAIL_BITS != 0
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if (uexp > 1 + ((mpir_ui) vval > GMP_NUMB_MAX))
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return usign;
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if (uexp < 1 + ((mpir_ui) vval > GMP_NUMB_MAX))
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return -usign;
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#else
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if (uexp > 1)
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return usign;
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if (uexp < 1)
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return -usign;
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#endif
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up = u->_mp_d;
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ulimb = up[usize - 1];
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#if GMP_NAIL_BITS != 0
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if (usize >= 2 && uexp == 2)
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{
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if ((ulimb >> GMP_NAIL_BITS) != 0)
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return usign;
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ulimb = (ulimb << GMP_NUMB_BITS) | up[usize - 2];
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usize--;
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}
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#endif
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usize--;
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/* 3. Compare the most significant mantissa limb with V. */
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if (ulimb > (mpir_ui) vval)
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return usign;
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else if (ulimb < (mpir_ui) vval)
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return -usign;
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/* Ignore zeroes at the low end of U. */
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while (*up == 0)
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{
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up++;
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usize--;
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}
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/* 4. Now, if the number of limbs are different, we have a difference
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since we have made sure the trailing limbs are not zero. */
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if (usize > 0)
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return usign;
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/* Wow, we got zero even if we tried hard to avoid it. */
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return 0;
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}
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