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/* mpf_get_si -- mpf to long conversion
Copyright 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 https://www.gnu.org/licenses/. */
#include "gmp.h"
#include "gmp-impl.h"
/* Any fraction bits are truncated, meaning simply discarded.
For values bigger than a long, the low bits are returned, like
mpz_get_si, but this isn't documented.
Notice this is equivalent to mpz_set_f + mpz_get_si.
Implementation:
fl is established in basically the same way as for mpf_get_ui, see that
code for explanations of the conditions.
However unlike mpf_get_ui we need an explicit return 0 for exp<=0. When
f is a negative fraction (ie. size<0 and exp<=0) we can't let fl==0 go
through to the zany final "~ ((fl - 1) & LONG_MAX)", that would give
-0x80000000 instead of the desired 0. */
long
mpf_get_si (mpf_srcptr f) __GMP_NOTHROW
{
mp_exp_t exp;
mp_size_t size, abs_size;
mp_srcptr fp;
mp_limb_t fl;
exp = EXP (f);
size = SIZ (f);
fp = PTR (f);
/* fraction alone truncates to zero
this also covers zero, since we have exp==0 for zero */
if (exp <= 0)
return 0L;
/* there are some limbs above the radix point */
fl = 0;
abs_size = ABS (size);
if (abs_size >= exp)
fl = fp[abs_size-exp];
#if BITS_PER_ULONG > GMP_NUMB_BITS
if (exp > 1 && abs_size+1 >= exp)
fl |= fp[abs_size - exp + 1] << GMP_NUMB_BITS;
#endif
if (size > 0)
return fl & LONG_MAX;
else
/* this form necessary to correctly handle -0x80..00 */
return -1 - (long) ((fl - 1) & LONG_MAX);
}
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