mirror of https://github.com/macssh/macssh.git
79 lines
2.7 KiB
C
Executable File
79 lines
2.7 KiB
C
Executable File
/* mpfr_mul -- multiply two floating-point numbers
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Copyright (C) 1999 PolKA project, Inria Lorraine and Loria
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This file is part of the MPFR Library.
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The MPFR Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Library General Public License as published by
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the Free Software Foundation; either version 2 of the License, or (at your
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option) any later version.
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The MPFR 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 Library General Public
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License for more details.
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You should have received a copy of the GNU Library General Public License
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along with the MPFR Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
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MA 02111-1307, USA. */
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#include <stdio.h>
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#include "gmp.h"
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#include "gmp-impl.h"
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#include "mpfr.h"
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/* Remains to do:
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- do not use all bits of b and c when PREC(b)>PREC(a) or PREC(c)>PREC(a)
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[current complexity is O(PREC(b)*PREC(c))]
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*/
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void
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#if __STDC__
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mpfr_mul(mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, unsigned char rnd_mode)
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#else
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mpfr_mul(a, b, c, rnd_mode)
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mpfr_ptr a;
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mpfr_srcptr b;
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mpfr_srcptr c;
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unsigned char rnd_mode;
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#endif
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{
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unsigned int bn, cn, an, tn, k; int cc;
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mp_limb_t *ap=MANT(a), *bp=MANT(b), *cp=MANT(c), *tmp, b1;
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long int sign_product;
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TMP_DECL(marker);
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/* deal with NaN and zero */
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if (FLAG_NAN(b) || FLAG_NAN(c)) { SET_NAN(a); return; }
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if (!NOTZERO(b) || !NOTZERO(c)) { SET_ZERO(a); return; }
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sign_product = SIGN(b) * SIGN(c);
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bn = (PREC(b)-1)/mp_bits_per_limb+1; /* number of significant limbs of b */
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cn = (PREC(c)-1)/mp_bits_per_limb+1; /* number of significant limbs of c */
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tn = (PREC(c)+PREC(b)-1)/mp_bits_per_limb+1;
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k = bn+cn; /* effective nb of limbs used by b*c */
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TMP_MARK(marker);
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tmp = (mp_limb_t*) TMP_ALLOC(k*BYTES_PER_MP_LIMB);
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/* multiplies two mantissa in temporary allocated space */
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b1 = (bn>=cn) ? mpn_mul(tmp, bp, bn, cp, cn) : mpn_mul(tmp, cp, cn, bp, bn);
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/* now tmp[0]..tmp[k-1] contains the product of both mantissa,
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with tmp[k-1]>=2^(mp_bits_per_limb-2) */
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an = (PREC(a)-1)/mp_bits_per_limb+1; /* number of significant limbs of a */
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b1 >>= mp_bits_per_limb-1; /* msb from the product */
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if (b1==0) mpn_lshift(tmp, tmp, k, 1);
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cc = mpfr_round_raw(ap, tmp+bn+cn-tn,
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PREC(b)+PREC(c), (sign_product<0), PREC(a), rnd_mode);
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if (cc) { /* cc = 1 ==> result is a power of two */
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ap[an-1] = (mp_limb_t) 1 << (BITS_PER_MP_LIMB-1);
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}
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EXP(a) = EXP(b) + EXP(c) + b1 - 1 + cc;
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if (sign_product * SIGN(a)<0) CHANGE_SIGN(a);
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TMP_FREE(marker);
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return;
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}
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